Baldeagle

Guys, I'm at the end of my wits on this problem. My son and I am trying to convert his 91 305TBI to a 91TPI. We've got everything hooked and it will start, but only idle well with 15 degrees advance. Then when you give it the gas, it sputters and dies. It seems that it's lacking fuel or timing. We did put in a new TPI fuel pump. But my question is...is there a way to check and make sure we have the right injector plugs on the right injectors? The wiring harness and the TPI unit we unbolted when we got it. I'm wondering if we have an injector plug or two on the wrong injector. Is there a way to use a continuity light to verify???? Hope some one can help!!!!

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innocence faded

the TPI cars are batch fire, meaning that the left side fires together, and the right side fires together. the left and right sides should be color coded differntly from each other. I would make sure that each injector has the same color wires as the others on the same side. it shouldn't matter which injector gets connected to which harness connector on one side. the way the harness lays out, it pretty much goes by the wire length and where it comes closest to the injector.
are you sure that you got a TPI fuel pump? I had a simila problem when I swapped a MPI motor in where a TBI had been without changing pumps. I was told it would work. I was told wrong obviously. If possible check the fuel pressure. You should be up around 43-45 psi at least. Did you put new fuel lines on and a TPI fuel filter?

Is the harness you are using a factory harness? If it is according to the wiring manual I have for TPI engines, the pink/black wire and light blue wire harness should be on the 1, 3, 5, 7 side. The pink/black wire and light green wire harness should be on the 2, 4, 6, 8 side. Also they have seperate fuses in the fuse block for either side. This is according to the 1987 factory manual, I would imagine the 91 wire set-up is the same.

Hope this helps.

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Jay
My Car web site
1987 IROC - 5.7 16.43 @ 82 mph ( yeah that bites )
1986 S10 pickup w/1993 Vortec 4.3

D_Amlee

B.Eagle, first of all I agree with everything that innocence said. Definitely check your fuel pressure. If that doesn't help, I think you may need to verify that your MAP sensor and TPS sensor are giving proper signals to the ECM. The computers on our cars are pretty stupid, and they only know what the sensors tell them. On a speed density setup, the inputs from the MAP and the TPS sensors are two of the most important ways that the computer knows what the engine is doing. It uses the inputs from those two sensors, plus the tachometer signal, to determine injector pulse width and spark timing. If either one or both of those sensor signals was not reaching the ECM, it wouldn't know when to increase the fuel flow or advance the timing. You would depress the throttle to increase the air flow, but the computer would not increase fuel or spark timing, resulting in a massive bog which would rapidly kill your engine.

A scanner would definitely be the hot ticket right now. You could plug directly into the ALDL port and see what the sensors were telling the computer.