Mysterious Sputtering


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By Rods - 16 Years Ago
I'm back. Been a while so the old bird decided it was time to act up. Been trouble shooting but have not come to any conclusions.



Get the car started and head out for a drive runs fine

Exit off the highway and it begins to sputter a bit

Come to a stop and smells of gas and is idling rough

Press on gas and seems to smooth out

Back onto highway and still has some hesitation as I can see the tach bounce a bit

Get it home and shut it off for a while

Start back up, will run fine

Been doing this same pattern for 2-3 weeks now

____________

Weber carb has been rebuilt (yea we talked about this..it is a Weber)

Fuel tank was boiled and lines flushed in May

Points/distributor rebuilt

New plugs

1957 T-bird with 312

____________

Thought it might be bad fuel but if that was the case, how come it only does it after you have been driving a while and let off the gas?



Any thoughts?



Also, this is different from the last post I had about it missing which was a was the distributor wire touching the side of the distributor.



Appreciate your help
By Ted - 16 Years Ago

Alcohol laden fuel?  This will play havoc with air/fuel ratios.

 

Too high a fuel pressure at the exit side of the fuel pump?  Edelbrock (Weber) carbs are sensitive to fuel pressure.  Float levels must be adjusted to compensate on these particular carbs.

 

A needle/seat assembly that’s not sealing good?  Fuel pressure again or just a defective needle/seat assy.

 

Distributor not returning to the same stop or resting place each time it comes off of a advanced position?

 

Spark plug gap too wide?  Variances in voltage can be a player here but simply reducing the gap and seeing if that helps is the easy out on this one.

 

Distributor rotor not tight on the shaft?  If the rotor is not tight at the slot, then it can move fore and aft and causing a slight timing change.

 

Too small a screw in the vacuum advance chamber that locates the distributor cap?  This can cause the cap to also move around a bit.

 

These are just some random ideas to look at.

By Rods - 16 Years Ago
Ted,



Just put a new timing chain & gears on about 100 miles ago. Do think it could need some fine tuning? If it was this, wouldn't it affect the motor all the time?



Thanks



Rod
By crenwelge - 16 Years Ago
If your needle and seat is leaking a little, you really won't notice it under power and it may not be leaking as much at idle. When you let off the gas, it can load up. Also as mentioned before, are you using an alcohol blend? Alcohol is a solvent and has an affinity for water. It will absorb water out of fuel storage tanks as well as your tank. At varying temperatures, you can experience phase separation. I am still able to get gasoline without ethanol, but not for long. Marketers are experiencing real nightmares with E10. This article explains phase separation. http://www.epa.gov/oms/regs/fuels/rfg/waterphs.pdf
By Tom Compton - 16 Years Ago
Hey, Kenny, what stations in Central TX are not supplying "may contain up to 10% alcohol"?

By the way, was at Bastrop Sat.  two 56 Crowns, one 56 Sunliner, 2 retractables, two 55 Crowns, 64 PU, 57 Fairlaine, three little 'Birds,  a 59 Galaxie and my 56 Victoria -  all with Ys.  Show was scattered over several blocks and side streets so could have missed one or two.

TC

By crenwelge - 16 Years Ago
I still have gasoline without E10 at both my Fina stations in Fredericksburg. I'm not looking forward to having all the headaches when I am forced to put it in.
By Ted - 16 Years Ago
Rods (11/15/2009)
Ted,   Just put a new timing chain & gears on about 100 miles ago. Do think it could need some fine tuning? If it was this, wouldn't it affect the motor all the time?
Not necessarily.  You could be borderline on a setting and any number of variables can be throwing your tune over the edge.  Try readjusting the idle mixture again and see if that makes a difference.  Assuming the carb is in good condition, I’ll suspect that the mixture is on the lean side and fattening it up a ½ turn per screw will make a difference.
By PWH42 - 16 Years Ago
Don't worry too much about using E10 in any of your vehicles.I've used it almost exclusively in every gas powered car and truck I've owned for the last 30 or so years.That includes about a million miles on about 25 different vehicles,ranging from a Model A to 50s Ford cars to late model Ford cars and pickups and a couple of grain trucks.E10 has been required by state law here in Missouri for the last few years.I've never experienced any kind of problem associated with E10.In fact,I think there are some real advantages to using it.The old cars can be tuned up to run a little stronger because of the higher octane and the alcohol insures that there is never any water in the system.

My 2 cents worth.

By crenwelge - 16 Years Ago
My big concern is not about the performance of E10, but in the handling of it. I am in a non vapor recovery region and my storage tanks vent. For every gallon of fuel I sell, a gallon of moisture laden air is sucked into the tank. The alcohol absorbs the moisture and if it phase separates in the vehicle, there are problems.
By PWH42 - 16 Years Ago
Our storage tanks here are vented also,as far as I know.At least mine are.As I said,we have never had a problem with our E10 picking up inordinate amounts of water,but I guess in a part of the country like S.E. Texas where humidity levels are generally high it could be a problem.

One of the apparent benefits of E10 is that since it's inception here frozen gas lines in winter are a thing of the past.I no longer have to buy everal cases of HEET every year as I did in past years.

By Rods - 16 Years Ago
[quote]Ted (11/15/2009)

 

Too high a fuel pressure at the exit side of the fuel pump?  Edelbrock (Weber) carbs are sensitive to fuel pressure.  Float levels must be adjusted to compensate on these particular carbs.quote]

 

Is it a difficult adjustment to make?  A bit of novice when it comes to the carb adjustments other than the basic type...