5.7 TBI HELP PLEASE

RAMBOSMURF

MEMBER
CHEVROLET SILVERADO

I have a 1994 Chevy Silverado 4wd Pick up with 350 TBI, Auto, 225000 miles. It was running fine with no problems. All of a sudden it would not start. Upon investigation, I see the upper radiator hose is balloning so I have to fix the thermostate, but I also noted it is running super rich and injectors appear to be dumping fuel in bores. It finally started and blew more black smoke and fumes than a top fuel dragster. It would barley idle untill it got warm, then calmed down and everything appeared to run fine untill I shut it off and it cooled down. Then problem started again. I get code errors 34 (Map signal voltage low) and 54 (fuel pump relay voltage low), but I can't find anything wrong. Please help as I am stuck. Thanks.

2 Replies

PEAR69

MECHANIC
1,482 POSTS

This could be a fuel pressure valve or spring problem. This is located inside the throttle body. I suggest first to check for vaccume leaks and then get an entire TBI rebuild kit. They are not real expensive and pretty easy to install. It's easier if you take the throttle body off but use extreeeeeem caution when disconnecting the fuel lines that go into the TB. It is very easy to twist and kink the steel fuel lines as you loosen the flair fitting. Use two wrenches for this and spray the fitting real good with some penatrating oil and let it soak in. Learned this the hard way. Let me know what you find.

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