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By RayCarter18 - 10 Years Ago
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I started a topic a while back about my f100 with a 292 being hard to start and having major compression when the choke is pulled out but once you push the choke in it goes back to normal. I know a lot of you all mentioned the dizzy and adjusting the timing. I plan on it just haven't gotten the chance yet. However I pulled the dipstick today and there was a bit of fuel in the oil. I have replaced the entire bottom end. Bearings pistons and rings. So what could be causing fuel to get past the rings into the cylinder? I have already changed the oil once cause there was fuel in it. I thought it was just cause it was getting flooded. But would that cause it to get into the cylinder? Any advice would be apprieciated. Thanks
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By stuey - 10 Years Ago
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fuel pump diaphragm?
stuey
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By RayCarter18 - 10 Years Ago
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Is there a rebuild kit for them or do you need a while new pump
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By DryLakesRacer - 10 Years Ago
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Sounds like your carb may be draining. Fuel can seep by rings into the pan when cold. Your comment on major compression kinda indicates this. An electric fuel pump and a bad seating float needle and seat may be your problem. If you don't have an electric pump your stock mechanical can be on the pressure stroke when you shut off and the fuel can enter the fuel bowl because of the bad needle and seat.
This is a little work but you can check this cold; before trying to start take out all the spark plugs and see if fuel runs out any chamber. Disconnect the coil and protect any thing from sparking and then turn over the engine with the key. If fuel flys out any of the spark plug holes you've got a draining carb. Good Luck
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By RayCarter18 - 10 Years Ago
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I rebuilt the carb and it has a new needle and seat. Like I said it only seems to have major compression when the choke is closed. Does it do something inside the carb to send more fuel into the cylinder when the choke is closed?
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By DryLakesRacer - 10 Years Ago
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Sorry not positive on what happens other than restricting the air for enrichment. Fuel can only get to your oil thru the carb. You say major compression when choke is pulled. I don't understand what you mean? It's hard to crank over with the choke pulled? Have you tried to start it by giving more fuel by pumping the carb a few times. For me that does the same as a choke with out using it.....good luck
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By Daniel Jessup - 10 Years Ago
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I would imagine it is hard to start because of an ignition issue. If that is the case, once you are choking, cranking, pumping, etc, and you are not getting enough spark, weak spark, or a spark at the wrong time, then that fuel is seeping right past the rings - once the piston gets to the top of the compression stroke especially because the compression will push it past the rings (gasoline is obviously thinner in viscosity than oil).
Dry Lakes Racer is right about the drainage. These carbs tend to drain out when SITTING for any period of time. My take is today's fuel that has a chemical content/makeup that lets it seep past the old power valves pretty easily. I know I have had that problem in the past.
"I know a lot of you all mentioned the dizzy and adjusting the timing. I plan on it just haven't gotten the chance yet." - you really need to do this here.
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By Rusty_S85 - 10 Years Ago
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A bad mechanical fuel pump can leak fuel into the engine putting raw fuel into the oil. If it is a fuel pump depending on what kind of pump you have, there are rebuild kits out there. I rebuild a cheap used dual action fuel pump for a Y8 and installed it, it pumps up 5 PSI cranking (spec is 5 PSI @ 500 rpm idle) and it holds pressure. Ive cracked open the hard line after sitting a few days and it still had pressure on the hard line. The kit wasn't cheap how ever but I would not rebuild a fuel pump if it is not what is putting the fuel into the crankcase.
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By HT32BSX115 - 10 Years Ago
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Rusty_S85 (3/4/2015)
A bad mechanical fuel pump will leak fuel into the engine putting raw fuel into the oil. Yeah. I would vote for the bad fuel pump. If the fuel was getting into the engine through the carb, it would cause so much black smoke, you'd see it right away.
If it was a little bit of fuel getting into the intake after shut-down, it wouldn't last long because the oil would still be hot. The fuel would evaporate quickly.
The most common source of fuel in the oil in marine gasoline (V-8/6/4 cyl) engines with engine mounted mechanical fuel pumps is via a leaking fuel pump diaphragm. Since marine engines also have a transparent hose from the fuel pump case to the carb (air intake) , you see it right away when when you notice the engine running rich (like the choke is "stuck")
Automotive fuel pumps don't usually have the case mounted hose connection.
Cheers,
Rick
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By Ted - 10 Years Ago
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If the oil level is noticeably higher on the dipstick, then the fuel pump is a real consideration. It’s not unusual for the fuel pump diaphragm to be leaking fuel to the crankcase while still supplying pressure to the carburetor so be sure to check that out. The oil will need to be changed again if it has a significant amount of gasoline in it.
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By DryLakesRacer - 10 Years Ago
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I should have thought about the fuel pump. It has happened to me a long time ago with a scrub 6.
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By RayCarter18 - 10 Years Ago
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Is there a way if completely
Tilling out the fuel pump. Is there a test to know if the diaphragm
Is leaking or not? This is not the original
Pump but it has been on the truck for a long time before I rebuilt it. Is it a fair
Assumption that it had dried out and I just need to replace the pump. Thoughts?
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By speedpro56 - 10 Years Ago
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Change the pump, it's cheap insurance.
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By Rusty_S85 - 10 Years Ago
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Yep, if you can change it out I would do it just to be safe. Unless you are very picky like me and want the sediment bowl on a dual action pump. But single action pumps can be picked up easily from any of the vendors or even your local auto parts.
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By RayCarter18 - 10 Years Ago
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Ok I changed out the fuel pump. I am pretty sure it was leaking cause there was fuel inside the timing cover housing. After that I messed with the dizzy a bit moving it around a bit trying to get it to start but no luck I completely drained my battery from
Cranking. I took the battery off my new truck with 850 cold cranking amps it cranked it a while but even it was having trouble trying to crank it over. It got to were it would not hardly turn it over. I finally put it back in my truck and my newer truck started right up like the battery was not even drained. So now I am really confused. Before I changed out the pump it took a
While
To get it started but it would eventually start. Now I can't even get it to start. I shoulda like it want to but I think it can't get enough power to the plug wires. It is getting plenty of fuel to the fuel filter right before the carb so I know it's getting fuel. Thoughts.
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By miker - 10 Years Ago
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Ray, I think it's time you checked all the electrical connections. Both hot and ground. Since cranking is a problem, I'd start with the big leads, bat to solenoid, solenoid to starter. Then the ground side. Any amount of rust or corrosion will generate heat, and the hotter it gets, the more resistance there is. The fact the big battery laid down, but worked fine in your truck, makes me wonder if the connections are the problem. Everything needs to be cleaned, and on the ground side, don't believe a clean connection solves it. If the battery ground goes to one spot, and a jumper goes from another to the engine, your relying on a 50 year old body to provide the ground path. Paint, rust and grease are your enemy.
I like to have a clean path (read single cable) from the battery to the bellhousing bolts, or a starter bolt. All clean, with a conductive paste on the bolts, etc.
Nest step, is the starter Itself, starting with the brushes.
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By RayCarter18 - 10 Years Ago
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Ok I will do that. Does it matter which side the positive goes to on the silinod from the battery right now on my truck it goes from the battery to the driver side of the silinod than from the other side it goes to the starter. The neg is hooked to the starter bolt. I did notice after cranking a while the positive cables got really hot like starting to melt
The insulation cause it
Was loose at the silinod I tightened it but it still didn't
Crank any better.
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By Rusty_S85 - 10 Years Ago
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If your cables are good have your starter tested. Mine just wasn't spinning the motor over fast enough and I went down the line replacing the cables and the grounds with no luck. I ended up getting a 6V starter and installing it on mine. It was actually recommended to do that by the rebuilder I took it to, he said he has some that he orders with 6V windings and it spins the engines over way faster on 12V systems. I have to agree on that. If your engine still refuses to run but spins over better check you ignition and make sure you check your plug. I couldn't get mine to run till I replaced the plugs and found out the old ones were gapped at almost 0.060".
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