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I just finished replacing the fuel injectors in my L98 this past week with the Delphi 22# replacements from SouthBay Injectors.
It ran great for a few days, but now I’ve run into an odd issue.
I started having starting problems. I pulled out my fuel pressure gauge, and discovered that the fuel pump isn’t priming the system when the key is turned on. Extended cranking shows the pressure slowly rising to about 35 pounds, which was enough to limp the car home.
I’m now seeing a consistent Code 54. I haven’t found anything obviously wrong. I replaced the fuel pump relay, in the hopes this was the issue, but it made no difference. It began raining, so I haven’t gotten far with my troubleshooting, but I made a point of having a helper turn the key, while I held the fuel pressure relay next to my ear...there’s no evidence that the relay is actually engaging.
I had a known good ECM, several posts indicate that ‘88 Camaros often had issues with this, but the ECM made no difference.
My suspicion is that the fuel pressure relay isn’t engaging, and the only source of power for the fuel pump is coming from the oil pressure switch, which is likely marginal due to age in being able to supply enough voltage to the fuel pump.
Is this a reasonable hypothesis? I’m wondering if a wire or ground for the fuel pump circuitry was accidently damaged during the fuel injector installation.
So, I’ve spent 6 hours so far, going through Code 54, and fuel pump relay issues on this site.
Almost without exception, the posts are either incomplete, or degrade into an argument of what exactly the role of the oil pressure sensor plays in the operation of the system.
Here’s the basic question, in a nutshell.
The fuel pressure relay NEVER switches on.
I can find NO wiring issue.
Applying 12V to terminal G in the ALDL DOES cause the pump to run normally
I have two known good ECM’s, the same issue occurs with both
I’ve confirmed I have 12V at the fusible link at the battery.
The one question I can’t seem to find an answer to:
On a TPI system, when the key is turned to “ON”, the fuel system is supposed to pressurize for approximately two seconds.
This is NOT occurring.
What would prevent the system from priming?
Obviously, not the oil pressure switch, because at the time the key is turned on, there is no oil pressure. The engine isn’t turning, and there’s no pressure.
The fuel pump relay SHOULD switch on for those two seconds, and allow the pump to pressurize the system. It’s normally loud enough to hear. Nothing is occurring.
Have you checked power at the ecm a1 and the relay green/white while turning the key on for 2 sec prime.
monitor line is b2 of the ecm it gets power from
a splice that feeds ops and pump relay at pin e. Ecm relay and ops should all be about the same voltage.
...The fans were a red herring. Apparently EVERYTHING has chosen this moment to fail...lol.
Hot wired both cooling fans to verify they work. “Stole” the fan relay for the secondary fan, and now the primary fan is working properly...so, bad fan relay.
Swapped the ECM for a spare, and the Code 54 is not present, and the car is starting normally.
I did discover that the likely issue was the replacement fuel pump relay connector. The connectors within the plug are migrating backwards when installing the relay, and I suspect the relay wasn’t making proper connection with the plug contacts. I carefully supported the wiring while plugging in the relay, and the car is starting like I’d expect. The green/white connector shows a little over 13 V now while the car is running.
04-14-2021, 06:38 PM
