So I've searched for an issue like mine but of course every situation is a little different. Just wondering if anyone can shed some light.
1 just turning over
2 replaced fuel pump
2 new pump won't work
3 tested old fuel pump on battery 12v it worked
4 getting 12v at sending unit but only 6v at pump
5 guage doesn't work stuck at 3/4 but tank is full but when unplugged it it goes to full
6 also to note: maybe unrelated but I thought it was weird that the fan turns on instantly with key on and stays on.
So what cause 12v at plugin to fuel pump but only 6v for pump and 12v for sending unit off of same plug? And what cause the guage to fluctuate?
Clip your old timing light to a spark plug wire while cranking, getting any spark? Or get a cheap in-line spark tester.
What about fuel pressure? What about the fuel filter? Have you checked those already or did you jump ahead to changing the fuel pump? Release some propane into the throttle body while cranking, does it start (or try to start)?
Thanks, forgot to add that I also hooked up the pump (while inserted in the full tank) in the car straight to a battery and turned the key. The car fired up. So spark is good and filter is good.
You are correct. The radiator fan should only stay on for a few seconds after you first turn the key on. If it stays on there is either a CCRM or PCM problem.
I'm ill just go for a new/refurbished ccrm I've scoured the wiring for chewed or broken wire and can't find anything. The ground runs all the way back from the pump to the pcm by the passenger kick panel correct? I couldn't find a ground near the pump.
Well I thru a refurbished ccrm at it and nothing. (Did fix the fan issue tho) as far as fuel stuff goes same result. Gas guage read 3/4 and won't start. Guess I'll pull pump again..... I noticed this today tho, when I unplug the pump the guage goes to full then slowly drops.
Given the replacement CCRM didn't affect the no-start/fueling issue, I would probe the trigger wire from the PCM for the pump relay at the CCRM to be sure the PCM is commanding the pump to come on. The relay should energize for about 3 seconds after an off-on key action, and continuously while cranking (or running). If there's nothing, check it again at the PCM itself. If nothing again, I would try a known good PCM. If so, there is probably a short betwen the PCM and CCRM to hunt down.
If both check OK, next I would probe the pump leads at the CCRM and the same at the inertia switch, then again at the tank to be sure there's no major voltage loss. Try to do this with the pump connected and engaged; if there's a short in the wires, it will certainly show a major voltage drop with a load - it may show [close to] normal voltage if you measure it while disconnected.
Can I just swap another pcm? I thought I read somewhere that pcm is connected to the specific ignition key. There is a 97 thunderbird at my local picknpull so it is doable. I'll do all the testing first tho thank you so much. Just gotta get a new battery for my multimeter. Mine just died.
MN12s don't have PATS, so you can swap PCMs to your heart's content (given the same engine/model cycle donor - e.g. a 96/97 4.6 PCM will work on any other 96 or 97 with a 4.6; a 96/97 3.8 PCM will work on any other 96/97 3.8 etc)
So I got bored waiting for my multimeter (I'm on quarantine for a couple weeks and stuck at home) I wired up the fuel pump to the battery again with a manual switch and a fuse, engine will crank but still won't start. You would think it would start right?
I'm trying to figure out how far to dive into this as I've also got a 93 mark 8 parts car that I was planning on stripping and installing all the aluminum stuff and the 4v.
No ses light but has the service engine soon, i do still have spark. Tried plugging into the obd 2 and it says unable to connect. Thanks so much this going I kicking my butt.
Like I said in post #15, it is a common problem with 97's. The fans and fuel pump run with the key on, and it's a bad PCM. This comes up about once a month on here, and it happened to me. My Ford mechanic diagnosed it over the phone it 2 seconds because he knows these cars.
You can pick up a used PCM (which is good to have on the shelf anyway), or keep testing things and throwing parts at it.
So the local picknpull had a 97 bird in its yard . I couldn't make it down for a couple weeks and then when I could I had to quarantine for a couple weeks. I got to the picknpull the day after my quarantine and found out they crushed it that morning. I ordered a refurbished pcm on rockauto and it arrived yesterday, plugged it in and vroom. First start in 6 years. Thanks everyone.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
TCCoA Forums
1.5M posts
26.9K members
Since 2002
A forum community dedicated to Ford Thunderbird, Mercury Cougar and Lincoln Mark owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, maintenance, and more!