Roque Kerstin Gomez

So I searched the forums and didn't find this one. First off, my engine is a rebuilt 350 Rocket. After it warms up going down the road then come to a stop at a light for example...sometimes when taking off, the engine sputters and actually dies. Trying to restart it, I have to pump the gas about 4-5 times and then it will start again and run "fine" to a degree. The hotter the ambient temperature outside the worse this affect is. The cooler the ambient temperature, like early morning, not too much of an issue. One question I do have though is do I have to run leaded fuel even though it has been rebuilt and could this maybe be the cause...or two, could it be air fuel mixture and possible timing. Thoughts, ideas, general knowledge of same issue? Thanks in advance.

Fun71

What carburetor do you have, and is the choke adjusted properly?

One = no and two = yes.

redoldsman

Where are you located that you can get leaded fuel?

cherokeepeople

exactly.leaded gas went out years ago.maybe he meant ethanol?if you have to pump 4 or 5 times i would look at the accelerator pump.this will fall on it's face from a stop.with engine off pull air cleaner off and grab throttle shaft an turn while looking down the throat.see if you get 2 good streams of gas.

OldsAl

Sampson

Since it sounds like it is worse after the car warms up, and when the ambient temp is higher I suspect that it is vapor locking. Check the fuel line to make sure it is isolated from manifolds or heat. Make sure the fuel filter is not touching the intake. You did not mention if the carb or intake is stock, but some carburators need an insulator between the base and the intake manifold.

olds 307 and 403

It could be rotted or cracked hoses on fuel lines. Of course it could be a plugged filter, dying fuel pump or a worn out or misadjusted carb as well.

Roque Kerstin Gomez

Sorry I didn't get back with you all right away. So you can buy lead additive for those wondering. But as far as the culprit goes... It was the cheap POS electric fuel pump that someone put. It is a Mr Gasket #12S. Heard of it? Well apparently it is rated as one of the worst. So looking at suggestions for a new one. The GPH needs to be 33/34 and run 4-7 PSI.

oldcutlass

Why not just put a stock mechanical back on it? They are virtually trouble free.

jaunty75

You can buy lead substitutes, not actual tetraethyllead that was what was originally the "lead" in leaded fuels.

oldcutlass

This product has actual lead in it.
http://www.wildbillscorvette.com/OctaneSupreme01a.htm

olds 307 and 403

What pistons were used in the rebuild? What carb? As said, a stock mechanical replacement fuel pump is the way to go.

Rustbucket2

VP racing fuel station can get leaded gas, at least the one in my town can.

jaunty75

The EPA banned the sale of leaded fuel for on-road vehicles effective January 1, 1996. Permitted uses are in aviation, racing, marine, and farm vehicles and machinery. Otherwise, it is illegal to put it in your car. Doesn't mean people won't do it, but it is illegal.

jcdynamic88

you didn't say where the electric pump is mounted but i believe they are better at pushing than pulling so it should be near the tank as opposed to being under the hood.they seem to last longer and perform better.