Fuel system on 1993 3.8L LX thunderbird

Mattmobile1993

Mattmobile1993

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United States
Vehicle Details
1993, LX, 3.8L thunderbird
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Hey everyone. I'm having problems with my fuel pressure maintaining pressure to start up instantly. I replaced the fuel pump, filter, and pressure regulator. The car starts up, but only after 7-10 minutes of priming. After the car starts, it is fine and can be driven as if nothing was wrong. I have no idea what the problem could be since I've replaced dang near everything in the fuel system. My only guess is that it's a signal thing in the system's electronics telling the computer that it isn't at proper pressure. I don't know. I don't have a pressure tester to test that theory, so I am here. Thanks in advance.
 
The pump only runs for a few seconds after you turn the key to the "on" position; you need to leave the ignition on for 7-10 minutes before it will start?
 
theterminator93 said:
The pump only runs for a few seconds after you turn the key to the "on" position; you need to leave the ignition on for 7-10 minutes before it will start?
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The pump is running for about 7-10 minutes. Once it stops running I can then start the car and it runs fine after that.
 
The pump should not run continually with the key on unless the engine is running. If it is, there's some electrical issue with the CCRM or PCM.

If I am interpreting what you say correctly, it sounds similar to what happens on my 97, but nowhere near as extreme. I have to turn the key on and wait 5-10 seconds until I hear the CCRM relays click and see the SES light flash otherwise it cranks indefinitely. It's not a fuel issue but a PCM issue. I just haven't bothered to swap it out because it's just a minor quirk. If you're really having to wait 7-10 minutes for it to do its thing I'd try to source a known good PCM and/or CCRM to swap in, then observe the result. It doesn't sound like a fuel (pump) problem.
 
theterminator93 said:
The pump should not run continually with the key on unless the engine is running. If it is, there's some electrical issue with the CCRM or PCM.

If I am interpreting what you say correctly, it sounds similar to what happens on my 97, but nowhere near as extreme. I have to turn the key on and wait 5-10 seconds until I hear the CCRM relays click and see the SES light flash otherwise it cranks indefinitely. It's not a fuel issue but a PCM issue. I just haven't bothered to swap it out because it's just a minor quirk. If you're really having to wait 7-10 minutes for it to do its thing I'd try to source a known good PCM and/or CCRM to swap in, then observe the result. It doesn't sound like a fuel (pump) problem.
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So the exact sounds I'm hearing are the low hums from the fuel pump sending fuel to my engine, then it will stop once it has been pressurized. Once it stops, I can then start the car just fine, if I try to start it before it pressurizes, then I'll just be cranking the starter with no combustion
 
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The pump running prior to startup is just a time delay programmed into the PCM, there is no pressure feedback to the electronics to keep the pump running until "it has been pressurized". If it runs constantly with the key on but engine off, the only explanation I have is that it is a PCM (or less likely CCRM) issue. Even if the pump was dead, the PCM should only provide voltage to run the pump for about 2 seconds each time to click the key to ON after OFF.

I have a hunch that if you were to rent a fuel pressure tester and hook it up to the rail, you would see the spec ~39 PSI in it during the entire period where the pump runs before startup.
 
theterminator93 said:
The pump running prior to startup is just a time delay programmed into the PCM, there is no pressure feedback to the electronics to keep the pump running until "it has been pressurized". If it runs constantly with the key on but engine off, the only explanation I have is that it is a PCM (or less likely CCRM) issue. Even if the pump was dead, the PCM should only provide voltage to run the pump for about 2 seconds each time to click the key to ON after OFF.

I have a hunch that if you were to rent a fuel pressure tester and hook it up to the rail, you would see the spec ~39 PSI in it during the entire period where the pump runs before startup.
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Okay interesting. I'll have to look into the electronics of the car then. I should get a pressure tester anyways. After it has done it's "pressurizing" it does a click sound
 
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Yeah it sounds exactly what mine does except exponentially longer.

You'll hear that "click" sound when the PCM finishes its startup/self-test/prime and is ready to start the car.

I assume you are not in CA? If that's the case, I'm not certain, but I think any non-CA 89-93 T-bird/Cougar N/A 3.8 PCM will swap in. CA cars had EDIS, which wasn't standard for the N/A 3.8 until 96, then in 94 the PCM started running the trans too.
 
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theterminator93 said:
Yeah it sounds exactly what mine does except exponentially longer.

You'll hear that "click" sound when the PCM finishes its startup/self-test/prime and is ready to start the car.

I'm not certain but I think any 89-95 T-bird/Cougar N/A 3.8 PCM will swap in.
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So do you think it's the pcm specifically? Not wiring but the actual device? And if so, a swap of that part would be all I do? As in i don't need to do any sort or "programming" since it's already programmed to do "X" task
 
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