[Gooseberry09]

i have an 87 half ton with a 350 CFI i first started having problems with it a couple months ago when i would go to give it gas it would sputter out and almost dies until it died it would run for a bout 15 minutes on a good day, so i figured that the cat was plug, so the next warm day we had i cut the cat out and it still did it for a bit then it started to warm up here and it stopped now its another cool day its it started doing it again i thought and thought and tinkered and i cant figure out what it is i wouldnt think its the fuel pump since it was doing fine again until today, its not the fuel filter i just replaced it, so i am unsure what else it could be ( if anyone has any ideas they would be greatly appreciated thanks in advace guys

 

[stephan]

Even though you think the fuel pump is good, I would still check the fuel pressure. You can borrow a fuel pressure guage at some auto parts stores if you leave a deposit with them. Then I would drive it with the guage installed & see what your FP is doing when it sputters out. If it's dropping then you either have a bad pump, or something is wrong in the electrical power supply or ground to it (bad relay, loose wiring, loose ground etc)
If that checks out then pull the air cleaner lid & watch the injectors while it's running (shine a flashlight on them) & see if you have nice conical patterns from them or if one or both are sputtering. Twist the throttle & bring it up to the RPMs where you were experiencing this problem before & see if you can duplicate the sputtering.

 

[silveradotrailblazer]

Stephan, I may be thinking of another system, but doesn't that year have two fuel filters, a external and a internal filter?

 

[dualdj1]

Stephan, I may be thinking of another system, but doesn't that year have two fuel filters, a external and a internal filter?

regardless if it does or not, checking the pressure and going through diagnosis therein will still tell you if you need to drop the tank and pull the pump, and can check the in tank filter (if it has one) at that point.

 

[silveradotrailblazer]

If its the system I'm thinking it has a frame mounted filter and one in the carb. He said he changed the filter but maybe theres another. I may be wrong thinking it has two filters.

 

[stephan]

If its the system I'm thinking it has a frame mounted filter and one in the carb. He said he changed the filter but maybe theres another. I may be wrong thinking it has two filters.

The CFI Goose is referring to is the Cross Fire Injection... a.k.a. Cease Fire Injection commonly referred to by some disgruntled GM owners when they first came out but it's TBI not carbuerated. There's a sock/screen in the tank but like Jason pointed out if it's getting clogged up by crud in the tank it will show up on his FP test if he runs it long enough to duplicate the problem. On the years that use the plastic fuel line with the woven metal shield, there are two humungeous unions that screw into the TBI body & then the fuel lines screw into them, but they aren't filters. They're big enough that they look like you could stuff one of the bronze carb inlet filters in there, but they don't have them. Is that what you were thinking of??

 

[silveradotrailblazer]

stephan, thats the system I was thinking about. I was thinking it had a frame mounted filter. Oh well. LOL.

 

[Gooseberry09]

guys its stopped again i wanna rebuild it and switch to carburation lol i dont drive it enough to worry about gas mileage but i would still like to know what causes it. how would i hook up the pressure guage?