85 Z28 with 350 carb. Just got it back from the shop. Did the old tpi to carb swap. The carb has a very spuratic idel. Then after about 20 mins of driving the damn car just dies. Takes a few min. to get it started. The guy at the shop said it more than likely is vapor lock. I looked at the fuel lines and there is a upward curve off the old fuel line coming from the tank. Could this be some of the problem? Have Edelbrock 750 on my 350. If it seems to be vapor lock, then how can this be corrected and prevented?

 

vented gas cap?

 

I'm not sure in what you mean. Guy at the shop seems to think that old fuel pump is my main problem. Fuel system and electrical were my wost subjects in highschool. I just plan to rerun my entire fuel lines maybe fuel cooler radiator?

 

Are you still running the TPI fuel pump? The thing is, a carb only needs 6-8 psi of fuel pressure, and FI needs 45-55 psi of fuel pressure. So still running the electric pump, without some sort of regulator to turn it way down, is bad. Did your mechanic install a mechanical pump or what? Why does he think the old fuel pump is the problem?

Anyways, a vented gas cap will cure vapor lock, but there should be a vent on the gas tank already. I think more than likely your problem is somewhere else. Tuning of the Carb, who knows. Give us some more details, and ask your mechanic more questions. I have a feeling that this dude is going to give you the run arounds, but I think he needs to fix the problem, and tell you what the problem was. I'm sure you paid good money to have this done, and having it run like crap is not really fair.

Let us know.

 

I'll definately second the fuel pump providing wayyyy to much pressure, because it sure sounds like your mechanic didn't do a complete switch for you- if he didn't replace that pump.

If you paid him to do the switch for you, that's something he should've quoted for, and I would imagine that's why he knows that's what your problem is...

If he did replace it, my (carbed) LG4 vapor-locked on me whenever I put anything but premium gas in it... Maybe you've got watery-gas or something else fuel (not fuel delivery) related... probably not, just an afterthought..

James

 

Our fuel lines run dangerously close to the headers also...some heat resistant wrap may also help you on the fuel lines...after you install a 3 port AFPR