Car dying (going lean) when giving hard acceleration

[filburn]

I have recently performed an engine rebuild on my car. Every scence the rebuild when I give the car some fast rpm's the car dies (goes lean) and wont start again. If I give it rpms slowly it has no problems. The car under zero load (just sitting in my driveway). The engine is a 302 stroked to a 347 with a bunch of other mods. The reason for the engine rebuild is I needed to change a piston ring, so i changed them all. All the mods worked together before the rebuild with no issues.

has anyone ever seen this, or has a good starting point on diagnosing it? Think its electrical or fuel related?

Please let me know, any input is appriciated.

filburn

 

[mtlman22]

sounds like a fuel issue. check you fuel pressure idling and give it some Rpm's and see what the gauge does

 

[dastang2]

well you didn't say if it is a carbed engine. i am guessing it is. do you have a deadhead style regulator on it. i had a truck with a 300 I6 and a 4bbl. i had a reg. on it and when i got on it, the fuel bowls would go dry and the same thing happened. i took the reg. off and adjusted the floats to keep it from leak fuel out and it fixed my problem.

 

[gt1986]

its most likely a fuel issue however if that doesnt do the trick check the spark my buddies mustang did the same thing we replaced every fuel component but it was a new distributor that did the trick
just a thought
good luck

 

[vristang]

I have recently performed an engine rebuild on my car. Every scence the rebuild when I give the car some fast rpm's the car dies (goes lean) and wont start again. If I give it rpms slowly it has no problems. The car under zero load (just sitting in my driveway). The engine is a 302 stroked to a 347 with a bunch of other mods. The reason for the engine rebuild is I needed to change a piston ring, so i changed them all. All the mods worked together before the rebuild with no issues.

has anyone ever seen this, or has a good starting point on diagnosing it? Think its electrical or fuel related?

Please let me know, any input is appriciated.

filburn

We need much more info.
As mentioned above, we don't even know if the car is efi or carb.

Setup a signature with all the specifics on your car. List out the major mods, year, anythinng else that you want to share.

IF you are working with efi, then start by pulling the codes.

Good Luck
jason

 

[filburn]

Thanks for the info guys, im convinced its the fuel. My fuel pressure guage will jump up to 60 psi then drop to zero and back up to 60 then drop to zero when I am trying to start the car. is that normal? Im prety sure it is not.

When the car is idling the pressure is at about 42psi

could it be the fuel pump is shutting off? I have an external fuel pump. anyone know the voltage that I should be reading off hand? I also have a BBK fuel pressure regulator. When adjusting it what pressure should the car be at?


thanks for all the help guys.


filburn

 

[mtlman22]

40 psi sounds about right. there might be a problem with the pump or some sort of restriction somwhere

 

[dastang2]

ok so it is efi.