Fuel pump relay question

[sspeedstreet]

My 1992 3.4DOHC is in a Fiero. When I did the swap I eliminated the Lumina right side electrical center and stayed with the Fiero relays. The Fiero fuel pump relay is a four wire and the Lumina is five connections. This may be the cause of my Code 54.

The wiring schematic in my manual shows this additional wire as a .8 RED connection called the "Fuel Pump Prime Connector", but I can't trace where it goes to.

Can anyone tell me what this connects to?

Thanks.

[pocket-rocket]

It flops in the wind. You only use it to test the fuel pump by hooking it to a battery +.

[sspeedstreet]

It flops in the wind. You only use it to test the fuel pump by hooking it to a battery +.

That explains it going nowhere on the schematic, but not the answer I was hoping for.

Maybe you can help me diagnose this problem with the Code 54. I never get the code on a cold startup. Last weekend I drove it 110 miles straight through and no code. If the motor is shut off for even a second after warmup and restarted, I get the code. Occasionally it will go off on its own, so I guess that qualifies as intermittent.

Any ideas?

[pocket-rocket]

ill have to look my book over to see what code 54 is, but the nice thing is with the Helms manuals, they give you a nice block diagram/flow chart to use for troubleshooting and schematics for related stuff for each code.

[sspeedstreet]

Yeah, so does the factory manual, but I haven't managed to get a definitive answer. Starting to look like a bad ECM.

[walterdude]

CODE 54
Trouble Code 54 indicates a low voltage at the fuel pump. If the voltage at terminal "A20" is less than 4 volts for .4 seconds since the last reference pulse was received, the code will be set.
Possible causes include:
1. Faulty fuel pump relay.
2. Faulty connection at ECM.
3. Faulty oil pressure switch.
4. Faulty ECM.

Hope this helps,,,
Tom....

[sspeedstreet]

CODE 54
Trouble Code 54 indicates a low voltage at the fuel pump. If the voltage at terminal "A20" is less than 4 volts for .4 seconds since the last reference pulse was received, the code will be set.
Possible causes include:
1. Faulty fuel pump relay.
2. Faulty connection at ECM.
3. Faulty oil pressure switch.
4. Faulty ECM.

Hope this helps,,,
Tom....

Yeah, I've pretty much got that memorized . . .

[2.8-350TBI]

May be unrelated, but I had a code 54 last week and it was my fp relay going bad. Swapped a new one on and all is good.

Before that, my pump wouldnt prime with ign on, and it would take roughly 10-15 seconds of cranking before it started. After the first day it finally threw the code.

[sspeedstreet]

I do get the 2 second prime in the "on" position and I have replaced the FP relay. It's beginning to look like the ECM is faulty.

[86FieroSEv6]

If 54 is a two trip code, that would explain why you don't get it on the first startup. A couple of my buddies have installed a small LED in the dash/instrument panel tied to the fuel pump secondary circuit as a monitor. They are old dudes and don't trust computers. I'm from the same crowd. When we want power, we use a bigger engine and more carburetors .

[sspeedstreet]

If 54 is a two trip code, that would explain why you don't get it on the first startup.

"Two trip code" is a new term to me. Can you explain?

[86FieroSEv6]

As the systems became more sensitive and consequently accurate, the engineers ran into problems with the MIL popping on when there wasn't necessarily a fault present. Merely a momentary period outside of normal test parameters that did not affect overall driveability, or emissions. To resolve the issue, they determined that certain items would require two "trips" (key on engine running) with a fault detected before illuminating the MIL and storing a code. In some systems, that first trip will set a "pending code" without lighting the MIL. This "two trip detection logic" has made many a tech' a little bit balder if they did not realize it during troubleshooting. In the manual for that code, it should say whether or not it is "two trip" in the section for "code setting conditions".

[sspeedstreet]

Thanks. Learn something every day!