WHY DOES MY TBI ENGINE RUN RICH ND NOW DIES AFTER I START IT AND LET OFF GAS

20

Asked by Mar 29, 2016 at 10:39 PM about the 1989 Chevrolet C/K 1500 Silverado LB RWD

Question type: Maintenance & Repair

Here is my dilemma, I built a 350/4 bolt main with all eagle bottom end
components, vortec heads w/2.02/1.60 valves, 58cc, 1.6 roller rockers,
summit cam 288/298 duration, 446/466 lift, edelbrock performer tbi intake
w/  stock reman TBI, new distibutor w/msd coil, ss headers, lunati timing
components. The problem is, running rich, now it does as soon as i take
foot on gas. Here the following I have done: new fuel pump and filter, new
o2 sensor, new temp sensor, tbi came with new map/tps, new ecm,
checked all grounds, no vac leaks, new plugs and wires now, only thing i
don't have connected is the factory oil pressure gauge, i installed a
mechanical one. no one seems to have an answer, i have  a brand new
motor, is it to much for the ecm. I just bought a new vortec carb intake to
go that route, but don't want to if i can solve this problem.this truck was
built for my 16 year old son who is now bummed out and losing hope in it
running. please help.

1 Answer

107,375

Yes it is too much, the valve overlap alone would send it to wacko land trying to set everything to work. To make this stock setup work you will need to reprogram the computer to match all of the changes you have made to the engine. I don't know of any place that is doing that sort of thing to stock systems. I have seen a TBI Holley setup that ran really sweet, he did say he had a bit of a problem finding the sweet spot but the interface was really accurate, he had changed out the distributor for a full centrifugal advance unit, hotter coil and wires, and of course done away with all of the stock computer controls. With what you have now it might be eaiser to setup the carb system and change out the distributor to either vacuum advance or centrifugal. And don't forget to damper down the fuel pressure, even TBI pressures will lift the needle right off the seat in the carb. HTH

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