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
 
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 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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Do you happen to have a rough idea of where the pcm would be? Internet said behind the passenger kick panel, but i haven't found it. I removed the glove box, and pulled the carpet and seat out of the passenger side, and haven't found the pcm.
 
Mattmobile1993 said:
Do you happen to have a rough idea of where the pcm would be? Internet said behind the passenger kick panel, but i haven't found it. I removed the glove box, and pulled the carpet and seat out of the passenger side, and haven't found the pcm.
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It’s behind and above the passenger kick panel. I only the connector is really visible, the pcm itself is obscured by insulation beside the dash
 
XR7-4.6 said:
It’s behind and above the passenger kick panel. I only the connector is really visible, the pcm itself is obscured by insulation beside the dash
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Yeah i just found it. I'm trying to pull the panel and insulation out of the way without having to mess with removing AC stuff, but it's a tad bit of a challenge lol
 
No. The way it comes out is down, into the kick panel area. The insulation and whatnot stays in place. There’s a white bracket that holds the pcm in place that you can unscrew from the glove box to make accessing a little easier (you’re supposed to be able to push the pcm toward the firewall away from the bracket and you can pull it down, but often the harnesses are in the way behind it)
 
XR7-4.6 said:
No. The way it comes out is down, into the kick panel area. The insulation and whatnot stays in place. There’s a white bracket that holds the pcm in place that you can unscrew from the glove box to make accessing a little easier (you’re supposed to be able to push the pcm toward the firewall away from the bracket and you can pull it down, but often the harnesses are in the way behind it)
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Will I be able to mess with just that bracket and remove the pcm, or will it involve removing the AC system? Well do you know if it's possible
 
Mattmobile1993 said:
Okay cool. Do you know if I would have to get the replacement reprogrammed to my car or could any 3.8 v6 specific one work for my car?
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The ECM in these cars has no security programming or vin number assigned. As long as it's for the correct year and engine it should work fine
 
Mattmobile1993 said:
I'm surprised. I would think that it would need programming
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These cars never got the Passive Anti-Theft System keys so there isn't really anything to program. There are a couple different options for emissions. The consensus here from previous discussions is that the emissions are either the same, or won't make any noticeable difference to the way the car runs
 
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