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By ejstith - 15 Years Ago
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Well I had that vapor lock problem we've talked about on here before. Well I put on an electric fuel pump and just knew that would fix it .. and it was better, maybe, but just like last year during a cruise up and down main street as soon as the heat gauge hit 190 she conked out again. Let her coast to a parking lot and sat there about 10 minutes and she fired right up .. she spit and sputtered a bit and I turned the electric fuel pump on and she ran fine but I headed out of town and the temp came below 190 (usually runs about 160). Now I'm right back where I started. I think my next move is to block off he heat risers under the manifold. I have a 1" plastic spacer under the carburetor. I may replace that with a 1/2" aluminum one... Am grabbin' straws now ... Any ideas?
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By charliemccraney - 15 Years Ago
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Did you check out the ignition? Stalling when hot and starting once allowed to cool can be a sign of a bad coil. I would suspect something electrical.
The 1" plastic spacer will do about the best job at insulating the carb from the heat. If it is a carb related heat problem, a 1/2" aluminum spacer will only make it worse. I don't think 190 degrees is hot enough to cause carb problems. It should be easy enough to check. Get a hold of an infra red thermometer and the moment it happens, open the hood and check the carburetor temperature in various places. You can do a base-line check while it's running fine. That way you can see if it is, in fact, hotter when it stalls.
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By 46yblock - 15 Years Ago
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ejstith (5/7/2010)
Well I had that vapor lock problem we've talked about on here before. Well I put on an electric fuel pump and just knew that would fix it .. and it was better, maybe, but just like last year during a cruise up and down main street as soon as the heat gauge hit 190 she conked out again. Let her coast to a parking lot and sat there about 10 minutes and she fired right up .. she spit and sputtered a bit and I turned the electric fuel pump on and she ran fine but I headed out of town and the temp came below 190 (usually runs about 160). Now I'm right back where I started. I think my next move is to block off he heat risers under the manifold. I have a 1" plastic spacer under the carburetor. I may replace that with a 1/2" aluminum one... Am grabbin' straws now ... Any ideas?I have been through the exact same scenario. Thought it was vapor lock, but it was the coil not firing when hot.
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By ejstith - 15 Years Ago
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Dang I don't know guys, it's got a brand new Mallory hi output coil on it. Last night I started it up one time and it acted like it was about to die again and I turned that electric fuel pump back on and it immediately cleared up. Right after that I was on the road coming home and it was fine from then on like it always is in cruise mode. Thanks y'all.
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By charliemccraney - 15 Years Ago
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Wait, does it have the mechanical pump, too?
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By ejstith - 15 Years Ago
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Yeah Charlie, it's got the old mechanical pump too, the one with the vacuum hoses that run the windshield wipers. I have wondered if it was weak but that electric pump is a 7# pump. I have heard (probably on here) that they get hot as hell. I mean I'm sure this didn't do this back in '56 and I didn't have the 2bbl on it long enough after I got it to know if it did it with it or not... The first time it ever did it was at Turkey Rod Run while cruising Atlantic Blvd. It did it again at the cruise in Cario GA. and that's where it did it the other night. I know 190 degrees is nothing but that's where it conks out at. You don't reckon it could be carb ice do you? I've thought about that too. That Holly 390 has little bitty venturi's... You ever heard of such a thing? I know it could happen in airplanes real easy but normally they ran rough before they died.
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By charliemccraney - 15 Years Ago
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I've experienced icing in the winter with a 1" aluminum spacer. In summer, and in Florida, I would not suspect that as the problem.
Let's start at the basics.
Did it seem to occur after changing anything? What have you changed in an effort to fix it?
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By Y block Billy - 15 Years Ago
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I had an old Mopar that used to vapor lock, the previous owners had tinfoil wrapped under the manifold and around the carb to shield it from this. I bought a kit and rebuilt the carb and it never happened again. So IMHO if a carb is vaporlocking it needs to be gone through, they didn't vapor lock from the factory and I am sure there are many running the same setup as you with the same temps that are not vaporlocking. I don't know exactly which particular item I changed that fixed it, as it was 30 years ago, I just followed the kit instructions and removed all the tinfoil around the carb and it never had a problem for the next ten years I drove the car.
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By ejstith - 15 Years Ago
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Well Charlie & Billy. Here's the deal. When I got the car it had the stock Holley 94 (I think) 2bbl carb on it. I got a B manifold and cleaned it all out and installed it. I ordered a 1/2" spacer from Summit but they sent me a 1" so I installed it. It is plastic. I put a brand new Holley 390 carb on it. I have the vacuum going to the distributor and that is all. It has an electric choke on it. The first time it vapor locked was at Turkey Run in Daytona Beach. I recognized what I thought was a vapor lock. Back in the '70's I had a '67 Ford pickup with an 11' slide in camper on it. When in the mountains of Colorado from time to time, under certain conditions, it would vapor lock. It acted the same as this does. I could wait awhile and things were fine. I had all steel lines, on the '56, and my son said to replace the line from the fuel pump to the carb with a rubber hose. Did that and it made no difference. On the pickup I installed an electric fuel pump and that was the end of it's vapor locking. I installed an electric pump on the '56 not long ago and I just knew that would fix it. It didn't so now I'm at my wits end. I said in my first post what I planned to do next. That's the whole story. I never had it in the configuration with the 2bbl that I had with the 4bbl so I don't know if it would have vapor locked or not ..
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By charliemccraney - 15 Years Ago
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ejstith (5/10/2010)
I never had it in the configuration with the 2bbl that I had with the 4bbl so I don't know if it would have vapor locked or not ..
But did it run with the 2 barrel and if so, did you ever experience it in the stock configuration? Was the installation of the 4 barrel an attempt to fix the problem?
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By Speedbump - 15 Years Ago
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Where did you mount the electric pump? No disrespect intended, but the joy of putting an electric pump on those older pickups with the tank in the cab is no matter where you put the pump, the tank was always higher and it easily gravity fed the pump. Electric pumps push (pressure side) very well but don't pull well at all. (vacuum side) It can be difficult to put a pump close enough to the tank and lower or as low as the bottom of the tank in many cars. If you had to compromise on your pump location, maybe it isn't getting enough fuel to be effective when you really need it. Another thought would be to carry a bottle of water with you and wait for it to happen again. When it does, instead of waiting the ten or so minutes, pour the water over the fuel pump to cool it immediately and start the car. If it starts and runs, at least you know you're dealing with vapor lock. If it doesn't, you need to start looking for another problem. Old trick but I know it works.
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By speedpro56 - 15 Years Ago
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If the mechanical fuel pump on it now has been on it a while I'd put on a new one and see how it does. I had a new one go bad after several months on my 56 tbird and that cost me my runs in columbus Ohio a few years ago. Make sure the gas tank is vented as well, I hardly ever here of 56 fords vapor locking unless the gas line is too close to some sort of heat source. again I would check for vent not working from gas tank or a bad fuel pump and float level being correct in carb and viton needle seat not sticking in carb.
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By ejstith - 15 Years Ago
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No Charlie, it never did it with the 2bbl but I never had the conditions where it vapor locks when it had the 2bbl on it. You know at a cruise how you just poke along for a long time. Ya know like "draggin' Main St." back in the day. I don't know if you know Cario Ga. or not but it's a little town, maybe a dozen blocks where they cruise. Turkey Rod run is a lot longer. I can drive the car all day down the road and through towns with a lot of traffic lights and it never misses a beat. If I park it and just let it sit there and idle for a long time it will do it too. That's about the whole story.
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By ejstith - 15 Years Ago
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Speedpro & Speedbump, it's a '56 car not a pickup. The pump is mounted on the forward wall of the trunk. It comes out of the tank and goes up about 2" and into the pump. It has a new gas tank and all new vent plumbing. Good idea about cooling the pump though. You'd think if it was a weak pump though the place where it would run out of steam would be haulin' buggy and it never misses a beat there. Should be the same with a vent problem. Basically idling shouldn't be a problem as much as hi power as far as venting goes.
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By jepito - 15 Years Ago
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Is anything different that could be raising under hood temps above normal? Like Headers or A/C. How about something that would change air flow through the engine compartment like a belly pan of some type? Do you have a stock fan or electric, does it have a shroud? What temp is you thermostat?
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By Y block Billy - 15 Years Ago
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I had a brand new fuel pump once that the line kept draining back, so it took a long time and a prime to start after sitting. I opened it and found a curled up piece of machining debris in the check valve of the fuel pump. Just because something is new doesn't mean it is working correctly. Are all fuel lines new? It doesn't make sense if you are running 2 fuel pumps, either you have a restriction in a line somewhere and at idle the pumps will just not push the fuel past this restriction. I would remove the mechanical one, both for that matter, check all components out. Blow out lines etc. In my 58 F500 when she starts acting up I have to pull the line off the tank and blow back through it to free the debris plugging up the pick up in the tank and then I am good to go for another few hundred miles. Have you ever had water in your gas/carburator? at open throttle water will suck through a jet but at idle a droplet of water will plug up a jet because the molecules bind together to form a bead of water and it will plug a jet. Its always something simple thats just being overlooked.
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By Speedbump - 15 Years Ago
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If I read you correctly, the pump is mounted two inches above the tank on the forward wall of the trunk? "If" that is correct then that's what I alluded to. Electric pumps need to be mounted at or below the bottom of the fuel tank in order to keep a good prime and push a consistant supply of fuel. It is probably working marginally now only because of the vacuum supplied by the mechanical pump. When the mechanical pump starts to vaporize fuel due to heat, it looses it's vacuum and the electric pump, being mounted above the fuel level , can't supply the fuel to overcome the vapor problem. That's my theoretical WAG at it anyway. 
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By GREENBIRD56 - 15 Years Ago
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What is this engine running for initial advance - and what sort of vacuum advance is on there? Retarded spark builds heat - at idle - if you run ported vacuum to the vacuum advance pot. That is my experience and maybe others have had the same? If I let my outfit sit at idle - and swap the vacuum pot hose between ported ....and straight manifold vacuum....the ported makes the temp climb immediately. This is taking measurements with the infared gun directly on the thermostat housing.
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By ejstith - 15 Years Ago
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Speedbump (5/11/2010)
If I read you correctly, the pump is mounted two inches above the tank on the forward wall of the trunk? "If" that is correct then that's what I alluded to. Electric pumps need to be mounted at or below the bottom of the fuel tank in order to keep a good prime and push a consistant supply of fuel. It is probably working marginally now only because of the vacuum supplied by the mechanical pump. Whenthe mechanical pumpstarts to vaporize fuel due to heat, it looses it's vacuum and the electric pump, being mounted above the fuel level , can't supply the fuel to overcome thevapor problem. That's my theoretical WAG at it anyway.
No bump,it's not 2" above tank, it's about an inch or two above where the line comes out. If the tank was full it would run by gravity to the pump. The line comes out of the tank to the pump and then forward of the back wheel it goes outside the frame to the front of the car. The only think I have done is put dual exhaust on it and now there is an exhaust pipe where there used to not be one. I'll crawl under there and make sure the fuel line is nowhere near that exhaust pipe. I just thought of that when folks were asking if anything had changed. As far as things being stopped up it seems to be that would affect high power more than basically idle power. It will wind up to 5 grand and never miss a beat .. I appreciate all the thought you guys are giving me. Thanks a ton .... Oh by the way, I'm running 12 degrees initial advance with the vacuum hose plugged up.
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By GREENBIRD56 - 15 Years Ago
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When you say "with the vacuum hose plugged up" - is that simply for a test? or are you running a full mechanical advance curve and no vacuum at any time? A tuned full mechanical advance curve can deliver snappy performance as you described when the rev's go up. But when you get off the gas and go to idle - you only get the initial.
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By ejstith - 15 Years Ago
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No Steve, when the initial timing was set .. it's with the vacuum advance(unhooked) blocked off. Total advance is with the vacuum line hooked up.
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By GREENBIRD56 - 15 Years Ago
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Somehow we are mis-connecting here - What is the total centrifugal and mechanical advance when the vacuum is disconnected and plugged - and RPM is raised to the point where no more mechanical advance is being added by the distributor? You have 10° initial - the centrifugal adds to that, and you want it to be all over with at about 36°-38° total. To avoid knocking while running only the initial and centrifugal, this sum should be reached at say 3000 RPM. If it runs way up over 3000 RPM to get to the full mechanical stop - you should consider getting the distirbutor "re-curved". Engines wil run pretty well with mechanical and centrifugal alone and a reasonably "quick" curve. This meaning the sum of inital and centrifugal rises to full at 3000 RPM or so. The vacuum advance is added to provide part throttle fuel economy on the street. When it is added in - total advance with all three features summed - can go up over 45° and more. But when you hit the throttle -and vacuum drops away - you will be running on the mechanical curve (initial plus centrifugal). When the distributor vacuum pot is run on ported vacuum - not venturi vacuum (different subject) - you will not be adding any vacuum advance at idle. The engine will run on the initial alone. Even with the initial set at 10°-12° - my 312 will elevate its water temperature when run at idle on ported vacuum. If you switch to using manifold vacuum advance at idle - the engine speed will elevate, and the temperature will drop. It will cause you to want to "retune" the idle mixture but the temperature reduction will remain.
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By ejstith - 15 Years Ago
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I don't know Steve, I've never checked all of that stuff. When I put the new Holley on it it had a diagram of all the ports & stuff. One of the said "distributor" and that's where I plugged the vacuum line into. I would 't think 190 degrees would be enough to make it vapor lock at, basically, sea level. My next move is going to let it sit & idle until it does it again & I'm going to make sure it's not carburetor ice. Then, like someone on here said, I'm going to do a fast cool down on the fuel pump and see if it will start. Then I'm going to check the line and then maybe cut the line on the outside of the frame and run a rubber line from there to the fuel pump as far away from a heat source as I can get it. That's my plan.
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By jepito - 15 Years Ago
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I had a clogged fuel filter give me trouble before. It would run fine with the rpm up, but was hard to start and would die at stop signs. The pump would aparently push enough at high rpm to force fuel through, but not at low rpm. Maybe this or combined with another problem gives your slow cruise/hot temp symptom. Less pressure means a lower boiling point. Have you tried installing a fuel pressure gauge between the mechanical pump and the carb. Tape the gauge to the windshield and read the psi when it starts to act up. This will at least tell you if it is a fuel delivery problem
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By ejstith - 15 Years Ago
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Jepito, I've got a 7 psi electric fuel pump. I would think that would take care of any fuel delivery problem. Also it starts fine and never quits at a stop sign as long as it's below 190 degrees or so. I don't think it's a delivery problem or an electrical related problem. It is either vapor lock or carb ice .. I saw one of those Nascar cars vapor locked yesterday ..
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By ejstith - 15 Years Ago
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OK, here's the latest. I just went out and cranked her up and let her sit there idling. At about 175 degrees on the temp gauge that gas goes to boiling like crazy. I have a see through filter about 6" before the carburetor. I could hit the electric pump and the bubbles went away. I pulled the hose away from the fuel pump while it was bubbling and it quit bubbling. I let things go back to where they were and turned the electric pump off. When it got to about 185 to 190 degrees she quit. It's strange that when it did quit the filter was full and there was no boiling. I did like somebody said and poured water on the fuel pump. It didn't immediately make any difference. In about 5 minutes she started back up. I put a piece of metal between the pump and the hose and held the hose away from the metal with a stick. I let is sit there and run and again when it got back up to about 185 she quit again. I poured water on the coil just to cool it down. Didn't make any difference. After about 5 minutes she cranked right back up. I don't think it's the line going to the fuel pump because it isn't anywhere near any heat source anywhere until it gets to the pump. I can touch it. I felt the bottom of the carburetor bowls and they weren't hot. I touched the vacuum lines up by the motor and although you could touch them you couldn't hang on to them long. After it quit the first time I took the air cleaner off and looked down in there.
at the venturis there was no ice. Couldn't see down to the butterfly valves. I can't imagine that gas boiling at 175 degrees water temp. but having said that by looking on the net it says it will boil between 100 degrees and 400 degrees. Ummm, interesting. I guess this cheap gas with ethanol has a lower boiling point than normal gas. That is probably why old cars back in in the day didn't vapor lock very much at sea level. I wonder if higher octane would be any better? Aviation gas won't vapor lock that's why it's iffy to put auto gas in airplanes.
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By jepito - 15 Years Ago
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Since you have a carb spacer and two pumps the only thing I can think of to stop vapor lock (if the problem) would be to run a return line to the tank. This keeps the fuel constantly moving in the line and won't allow it to heat up. Also you could just use the electric pump, since the mechanical pump is bolted to the engine it might be heating the fuel as well.
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By Hoosier Hurricane - 15 Years Ago
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Since the 2 barrel didn't do this, my vote is that the viton needles are being softened by the alcohol and sticking in the seats. My .02.
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By ejstith - 15 Years Ago
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Well John, I don't know if the 2bbl would have done it or not. It was never in that configuration with a 2bbl. There are 2 places I go that the whole scenario even makes any difference. Cruising Atlantic BL at Turkey Rod Run in Daytona Beach in November and at the cruise in Cairo GA in May. Those are the only 2 places where it matters. I could crank it up and run the length of Route 66 and it would never miss a beat (unless I got in some really slow traffic that lasted at least a half hour). I may try bypassing the mechanical pump and running it totally electric and see what happens. I mean I'm trying everything now .. that sounds like a logical next move.
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By ejstith - 15 Years Ago
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Well here's the latest. I just went out and put a water hose on the fuel pump and let it sit running with the water at a slow flow right on top of the fuel pump. The gas never boiled and it sat there and idled for a long time. I took the water source away and in a little bit it went to boiling in the filter. It finally died. I let it sit and cool for awhile and cranked it back up and when it went to boiling I put the hose back on top of the pump and the boiling stopped. I noticed even with the water source there and not boiling the throttle response was real sluggish, a big hesitation. Now it's had a hesitation ever since I put that brand new Holley 390 on it but once above an idle it was fine. In this condition it was hesitating any time the throttle was jabbed. It even did this with the electric fuel pump was going. If the throttle was advanced slowly it revved up just fine and to no limit. I was wondering if this cheap 87 octane gas with 10% ethanol has anything to do with it. I'm about at my wits end and I hate to piss off $$$$ looking for the problem. I think maybe my next move my be to run it directly with the electric pump. I don't really want that as my primary fuel pump. I think I would probably need to put a regulator in the line. It's a 7# pump which may be a little much just for regular street use. At least that would take the mechanical pump out of the equation .. What do ya think ?
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By GREENBIRD56 - 15 Years Ago
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Old racer trick was to use multiple gaskets under the fuel pump flange to isolate the housing a bit from the block - doesn't help the operating lever though. An insulating cover on the lines to the filter and carb inlet can be done in a pretty sanitary manner. What does your filter look like?
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By ejstith - 15 Years Ago
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Steve the filter is one of those clear plastic ones that you can take apart and clean. Would that heat come from the block where the pump mounts or from the lever connecting the eccentric?
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By charliemccraney - 15 Years Ago
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The heat comes from all places.
Something else that might help is to use a durable plastic washer under the head of the bolt. This with reduce the amount of heat transferred via metal to metal contact. I'm using a similar setup to insulate my coil from the manifold heat and so far it seems to work. It'll really be tested this summer.
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By YellowWing - 15 Years Ago
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E.J. if I understand correctly you have an electric pump installed before the mechanical pump? If this is the case and the electric pump has check valves in it they could be the cause of your problem. Anything installed before the mechanical pump (such as a check valve) that raises the vacuum required to draw the fuel will also lower the vapor point of the fuel. So for instance if you have enough vacuum (or if you prefer low pressure) the fuel will begin to boil at room temperature. Same thing happens with water, at sea level boils at 212 degrees, at 7000' elevation it boils at somewhere around 195 due to lower pressure. Lower the pressure enough and it will boil at room temp.
Try bypassing the electric pump and see if this helps. Mike
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By ejstith - 15 Years Ago
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Well Mike, the problem was there before I put the electric pump on it .. basically that's why I put the electric pump on it and it still even does it with the electric pump on (takes a little longer).. that's what's really got me baffled. I just knew putting that pump on there would fix it. The bottom line is this: there is just a hell of a lot of heat in that mechanical pump. I used to have a 57 hot rod Ford back in the 60's and it never ever vapor locked. Only difference was it didn't have the vacuum ports out the top of it. I'm just chasin' everything now.. everything that doesn't cost much .. I'm convinced I could bypass the mechanical pump and that would be the end of my problem but I don't really want to do that. I mean, everybody on this forum has what I've got, basically, and theirs isn't doing this.
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By Pete 55Tbird - 15 Years Ago
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E.J. You seem to be FIXATED on VAPOR LOCK ___"I mean, everybody on this forum has what I've got, basically, and theirs isn't doing this__. " YOU ARE SO RIGHT. Nobody else has a car that vapor locks so why don`t you look for another reason your car stalls? Stop using cheap gas with 10% alcohol. Change the float needle tip to a metal one. With the car in your driveway start and idle it with the air cleaner off and when it stalls, look down the carb and open the throttle and see if a stream of gas is shot out of the two squirters. If it has gas then look for something else. Buy or borrow an infa red temp indicator as was suggested and find out what temperatures you are really dealing with. STOP GUESSING. Pete
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By ejstith - 15 Years Ago
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I can get higher octane but I don't think I can get gas around here that doesn't have ethanol in it. Vapor lock or something else it is related to the heat in the fuel pump.
I guess from Pete's yelling and attitude it's apparent I've bothered y'all long enough with this problem. I'm sorry I took up your valuable time with this and I won't bother you any more with it. I'll eventually get it "guessed" out. Accept my apology and to those who helped me thank you very much
THE END
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By ejstith - 15 Years Ago
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Well I chased this problem for the better part of 3 years. I think I finally got it! Some on here said it sounded like a coil to them but I just couldn't imagine a bad brand new Mallory coil but I think that's what it was. I was at Turkey run the other day and was on the road on the back side of the speedway & my car just died. I checked gas & spark & had no spark to the plugs or out of the coil. The coil was hotter'n hell. I went to Autozone & got a new MSD Blaster 2 coil and put it on. Viola! Cranked right up and hasn't died since even while cruising Atlantic BL. So to those who said it was a coil, beggin' your pardon, you seemed to have been right. I shall never doubt you experts again. 100 lashes to me with a limpy, wet noodle! 
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By RB35 - 15 Years Ago
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I was going to suggest checking all of the fuel line connections/clamps to see if the pump was sucking air, but glad you found the root cause. RB
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By 46yblock - 15 Years Ago
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You are welcome  .
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