4.3 Gas Intake Problem

jackal25 · February 18, 2004

Ok, I have a 95 S-10 Blazer with a EFI 4.3. Just did an engine rebuild. Timing is good, and will fire. But will not stay running longer than 3 secs. Seems to not be getting gas into to bottom part of intake. Gas is going into top part of intake, fuel pump pressure is good. Plus everytime we take the top part of the intake off there seems to be a gas leak but cannot find it. Also replaced the fuel regulator. Any ideas for the gas leak and the fact that it wont stay running??????

GM GIMP · February 20, 2004

My '94 has plastic fittings on the inside rear of the intake.

This is where the spyder injectors connect. They are quite

delicate and could crack. Also the injectors themselves are

bad about leaking.

jackal25 · February 20, 2004

Ok, I got it to start but still doesnt stay running after we put the 1st piston at top dead center, line up the timing marks on the harmonic balancer, and reset the disturbtor to spec.... The fuel pump still runs for a long time after the engine is off, and still acts like it isnt getting gas, replaced the injector this time too.

blue2kzr2 · February 21, 2004

What's the fuel pressure? Engine needs 59-65 PSI to run right.

jackal25 · February 21, 2004

Fuel pressure is at 60 lbs.

jackal25 · February 22, 2004

UPDATE......We found that the fuel is getting to the injectors, but they just arent firing. This is after i had already replaced the injector spyder assembly. The connection to the injector is getting the voltage it needs. So just really confused right now ? ? ? ?

badhammer · February 23, 2004

sounds like the factory anti theif system is not letting the injectors fire it thinks you are trying to steal the truck. might need to relearn the anti theif system

jackal25 · February 26, 2004

So that theft lock could trip, even if I have an aftermarket radio in the truck before I pulled the engine? Everything was working fine before too.

Cool Zr2 · February 26, 2004

So that theft lock could trip, even if I have an aftermarket radio in the truck before I pulled the engine? Everything was working fine before too.

It isn't the anti theft.

Go get a cheap scan tool and plug it in and it should telll you what is wrong. With todays engines the guess work is almost eliminated because of OBD and OBD II diagnostics.

If the timing is off it will start and run and quit, or a number of other things. Your CSP or CMP could be shot, but get a scan tool and it will find out your problem for sure.