First Conversion Help Needed!

[mtbraun]

I finally got around to installing the harness in my first conversion attempt. I believe I have installed everything correctly based on Eagle Marks writeup and available wiring diagrams.

I used a 12v terminal block from my battery with fused lines from the terminal block to both the power and fuel pump relays. When I connect the terminal block to the battery, I can hear both relays momentarily "click".

Now, when I turn the key to "on" my fuel pump will not cycle. I've checked for power at the fuel pump/sending unit connection harness (new 87 GM model tank and sending unit/pump) and there is none. I then checked for power at the supply line coming out of the fuel pump relay and there is none. It's my understanding there should be power to this wire for a couple seconds while the system cycles the fuel pump. So I think its an issue related to my fuel pump relay.

Here's how I wired the factory fuel pump relay (from 91 Chevy donor truck):

Orange - 12v fused input from battery, also connected to ECM B1/C16
Black/White - system ground
Red - to fuel pump
Green/white - to ECM A1
Grey - to ECM B2

Wiring diagrams I have referred to says ECM B2 should be tan/white, but my ECM B2 was solid grey.

What I'm still confused on is the wiring diagram shows ECM B2 connected to the fuel pump relay and then on to the pump. If that is the case then what do I wire the fuel pump relay red wire to? I cannot find a wiring diagram for the 1991 fuel pump relay. The build threads I have read only reference four wires for the fuel pump relay. I didn't take good enough notes when disassembling the stock harness on this particular item.

And lastly, when I turn the key to "on" my SEL flashes 7 times and then turns off. It does not stay on when the key is on. I verified that it is wired to a circuit that has power with key "on" but not crank.

[mtbraun]

I think I may have figured this out. I found another build thread and problem feedback that showed a fuel pump relay diagram. I think the red wire from the fuel pump relay should be left unconnected as it is the test wire. The grey from my fuel pump relay should be tied to B2 and the brown wire from the oil pressure switch. I did not have the oil pressure switch installed because it wasn't referenced in the build thread or wiring diagram I was referencing.

so the only remaining question I have is where do I connect the grey wire from the oil pressure switch. It is fused so I presume this needs to connect to power somewhere, just don't know where.

[mtbraun]

Update - I corrected my wiring error and installed the oil pressure switch with its wiring. The tan wire from the oil pressure switch is currently unhooked as this is for the dash display.

Anyway, when I turn the key on the fuel pump will not cycle. I can cycle the pump from the test port on the fuel pump relay. I went through the troubleshooting diagram for code 54 Fuel Pump Circuit and when I try to test the circuit between 465 (green/white wire from ECM) and ground, after turning on the key the circuit does not show power within two seconds. The troubleshooting guide suggests a open circuit 465, short to ground, or faulty ECM. I have traced the wire from the ECM to the fuel pump and all looks fine.

Now here is where it gets weird. Every time we turn off the key, the fuel pump will cycle for approximately 2 seconds. The fuel pump will not cycle when the key is turned on, only immediately after it is turned off.

In addition to this, when I turn on the key, I still get 7 flashes on my SEL. Does this suggest a faulty ECM?

We tried jumping pins A/B on the ALDL and then the SEL flashes 2 times. Also, for whatever reason as long as the ALDL pins are jumpered the IAC valve extends into the throttle body. The only reason I noted this is I heard a faint sound from the engine when we jumped the pins. I'm not sure if that means anything or not.

Really need some help here.

[Six_Shooter]

Yeah, there's something up with the ECM or the way it's powered.

When you turn the key on, there should be a single flash, and then stay on until the engine is running.

[mtbraun]

I'm going to grab a different ECM. Question - when grabbing another 1227747, do I need to switch the small chip from the old ECM if the new ECM is not from the same size engine? I have a burned PROM chip already.

[jim_in_dorris]

I would try a stock chip first, you may just have a bad chipburn. If you do switch the ecm, for test purposes, leave the old chip in until you verify the cel blinks properly