1994 Ford Thunderbird Thunderbird won't start after one wee

Tiny
RYANBLIZZ
  • MEMBER
  • 1994 FORD THUNDERBIRD
  • V8
  • 2WD
  • AUTOMATIC
  • 56,000 MILES
Hello,
I am fairly competent at electrical diagnosis but this one has me somewhat stomped. Any suggestions would be much appreciated.

I have a 1994 Ford Thunderbird that has recently become my third car. I did not drive it for roughly one week and then decided to drive it to the car wash and it would not start.

Starter was running strong, so I pulled apart the fuel line at the fuel rail and had no gas being primed or pumped during cranking. I checked the fuel pump fuse, and then verified it had 12 volts at the inertia switch, then bypassed the inertia switch all together. Everything pointed to an inoperative fuel pump.

About a week later after collecting fuel lines, fuel pump and filter to replace, I thought I would give it one more try, it cranked over and started very rough (stalling if I released the gas). I held the gas to let it run until warm, then it would idle somewhat sporatic (800rpm, then drop to 500rpm and back up).

I decided to change everything anyway, verified the new pump had power and was running correctly before putting the tank back in, started it and it ran the same way - really rough.

I parked it again and have not been able to start it since. I changed the fuel pump relay (CCRM Module) with no change. Anything obvious I might be overlooking? I believe it is the temperature that makes the difference when it starts or not (seems like the warmer days 70+, where the only days it would start).

Oh, I did put in an "remote-start" module about a year ago, but that has worked flawlessly up until now, so I do not think this has anything to do with it.

Thanks in advance,
Ryan
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Monday, October 26th, 2009 AT 6:07 PM

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Tiny
RYANBLIZZ
  • MEMBER
Just double checked and it is for sure getting power to the inertia switch. I bypassed again and still nothing, I also double checked the ground for the fuel pump and as far as I can tell everything is good.

Is it possible I put in another faulty pump? If so, why did it work and pressure okay when I had the tank out? If it is a faulty pump, could water or bad gas make it stop working? I already put fuel stabilizer and cleaner in the tank, then when it was still running roughly I topped it off with premium.

The only thing I haven't actually looked for is a break in the power or ground wire for the fuel pump from the inertia switch. I wouldn't think that would be the problem, but it makes more sense than a new Ford fuel pump just going out.

That would actually make more sense with the weather as well. I associated the car starting to warmer weather, maybe it isn't the warmer weather but not raining that allowed it to start (break in the power wire, which when wet would result in a short to ground)? Seems like this would pop the fuse though. Although when the initial problem occurred it rained for a week straight.

I will update this post when I find the problem for anyone else that may have similar problems.

Thank you,
Ryan
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Monday, October 26th, 2009 AT 7:22 PM
Tiny
RYANBLIZZ
  • MEMBER
Alrighty, problem solved.

It was the connection from the fuel pump to the body harness. There was some corrosion so it might have been getting wet. Not sure, but wiggled it and the fuel pump started working immediately. Took it apart, cleaned it and then sealed the entire connection with electrical tape. I will see if that works.

As for the rough running - during diagnosing I disconnected the battery for about 10 minutes. I am almost positive it reset the "low idle/high idle" settings on the ECU. It is running pretty smooth now so I don't think that had anything to do with the fuel pump.

Hope this helps someone.

Ryan
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Tuesday, October 27th, 2009 AT 7:49 PM
Tiny
RYANBLIZZ
  • MEMBER
One last update on this.

The rough running was not just an idle re-learn. The solenoid that opens/closes the fuel vapor canister had malfunctioned, and was open all the time.

I tapped on it and it began to idled perfect, so one more item to replace.

Ryan
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Sunday, November 1st, 2009 AT 5:17 PM

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