The infamous Code 54
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Joined: Dec 2007
Posts: 2
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From: DC
Car: Trucks, of course...
Engine: 7.4L w/ Whipple (Burb)
Transmission: 4L80E (Burb)
Axle/Gears: 14 BFF w/ 4.10's (Burb)
The infamous Code 54
Yep, I've got it...and it's (very) intermittent.
'94 Suburban, TBI 454 w/ 4L80E
About 8 times in the past year, I've backfired and stalled out when accelerating from a cruise. It starts again after about 5-6 seconds of cranking, then runs like crap for 4-5 seconds, then I'm good to go. This weekend it happened again for the first time since I've bought an ALDL cable and Datamaster. I did a search here and there are about a million posts for Code 54 issues.
My fundamental question is this: is anyone sure if the fuel pump relay routinely stays energized once the engine is running, or does the oil pressure switch take over while the relay de-energizes? I ask this because if the relay stays energized, I'd really doubt that both it and the oil pressure switch would both cut out at the same time (thus causing loss of power to the fuel pump).
In the interest of simplifying the problem, I am tempted to build a simple $20 aftermarket circuit as shown, using a power lead straight from the battery and an aftermarket (generic use) relay. The output juice from the aftermarket relay would go into the factory relay connector via a spade terminal. If the problem then happened again, it would be narrowed to 1) the pump, 2) the hot lead going to the tank, or 3) the pump ground. If I drove it for 4 months and nothing happened, it would be either the ECM, pressure switch, OEM relay, or the harness wiring.
'94 Suburban, TBI 454 w/ 4L80E
About 8 times in the past year, I've backfired and stalled out when accelerating from a cruise. It starts again after about 5-6 seconds of cranking, then runs like crap for 4-5 seconds, then I'm good to go. This weekend it happened again for the first time since I've bought an ALDL cable and Datamaster. I did a search here and there are about a million posts for Code 54 issues.
My fundamental question is this: is anyone sure if the fuel pump relay routinely stays energized once the engine is running, or does the oil pressure switch take over while the relay de-energizes? I ask this because if the relay stays energized, I'd really doubt that both it and the oil pressure switch would both cut out at the same time (thus causing loss of power to the fuel pump).
In the interest of simplifying the problem, I am tempted to build a simple $20 aftermarket circuit as shown, using a power lead straight from the battery and an aftermarket (generic use) relay. The output juice from the aftermarket relay would go into the factory relay connector via a spade terminal. If the problem then happened again, it would be narrowed to 1) the pump, 2) the hot lead going to the tank, or 3) the pump ground. If I drove it for 4 months and nothing happened, it would be either the ECM, pressure switch, OEM relay, or the harness wiring.
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