I've had a vacuum problem for the past fewmonths that I cant figure out. Today I was going to make another stab at it, buts its raining....horribly.

Anyway I was looking in my haynes manual and it says the 4 TBI mounting bolts can sometimes work loose and cause vacuum problems....That would make sense because theres a pretty good hiss right around the TBI unit... ANyone ever heard of this?

I'm going to make a real soapy water bottle solution and try to hunt down the leak...

It HAS to be a vacuum leak... makes my car run erradically, lopy idle, pings sometimes, lacks power sometimes, hard starting, lazy throttle responce, sometimes studders aand stalls...

I've replaced the AIC, TPS, O2, Temp sensor... And Im about to replace the old spark wires as well... Hopefully I'll fix it.. Anyone have any ideas?

 

To start there are 3 mounting bolts and not 4 that hold the TBI down on the intake manifold. If it is hissing and has a bad leak its probably the TBI base gasket, most common thing to go and very cheap to replace. Just pull the 3 bolts out and change the gasket. To diagnose use come kind of aerosol and spray around the base, if there is a change in engine rpm its the gasket.

 

Another thing... I just read a post where a guy unplugged his egr and stopped up the vacuum line with a golf tee... I just tried this and MY CAR NO LONGER BOGS DOWN!!!! I just took it around the blocks a few times, and it no longer bogs down untill a certain RPM, then all the sudden runs normal!!!! This is
UNREAL!!! My car has NEVER ran like this before!!!

I'm still going to hunt around for any other vacuum leaks, and I'll change out the TBI gasket just to be sure... I really think new spark wires are going to help alot too... I've replaced two of them so far and the old ones were burned pretty good.

THIRDGEN.ORG WORKED FOR ME!!!

 

thatw as first thing i tried was the egr valve and no dice, got an 88 4.3L TBI that bogs and stumbles and chokes and bucks and i assume fuel pump is crapped out.

good luck'

 

Do you happen to know the size and thread pitch of the 3 bolts?

 

Measure the holes they thread into for size and thread pitch. Measure the TBI unit, add some extra for thread engagement to get bolt length.

https://www.thirdgen.org/forums/tbi/...ing-bolts.html