Need Help ASAP!!

[stuckMounty]

This might sound redundant to this forum but I am stranded!


I have a 97 Merc. Mountaineer. Guess what happened?... It stalled and I have a no start condition.

1) No fuel pump sound at key on
2) No CEL at key on
3) No fuel pressure at all
4) FP relay works
5) PCM relay works
6) Inertia switch is not tripped... I tripped it and reset it
7) AAAAAAAAAAAAAAAHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!

I've searched this forum for the past 5 hours and I get real close to an answer but every time the poster either says they have a CEL or they say they have fuel pressure. But I don't have either so what do you think I should do?

Please be plain in your answer. Step by step with locations. I have heard of the PCM ground but have not yet seen where the location is. Where is it??

Thanks for all of your help.

 

[jlsparky7]

Sounds like you need a new fuel pump. Change the fuel filter at the same time.

 

[gijoecam]

I wouldn't jump to the fuel pump right off the bat... I would first check for power at the fuel pump as well as continuity through the fuel pump before going through all teh trouble of dropping it. The question is whether or not the system is calling for the fuel pump to be on and if so, why it's not.

 

[rego]

Another good reason for an access door. Then jump the pump.

 

[marragtop]

Are you sure the PCM and FP relays are good? They both have to work for the FP to prime. If you are just switching them, one could be bad and give you the same result.

 

[stuckMounty]

Thanks for the replies.

My next step will be checking for power at the fuel pump. Is the connector on the frame rail next to the tank? Or do I need to drop the tank to get to the connector?

I believe that I was able to read continuity through the pump by running a resitance/continuity test through the ground terminal on the fuel pump relay receptacle. I just pulled the relay and tested the ground side and got about 2000-3000 ohms. I assumed that meant that I was reading through the motor windings of the fuel pump. Of course, that does not actually mean that there isn't an open on the positive side of things.

I also switched the WOT A/C relay with either of the fuel pump or pcm relays and still no start. If I pull the pcm relay and turn the key on the fuel pump relay (fpr) does not click. When I put the pcm relay (pcmr) back in the fr clicks. Both the fpr and the pcmr click when I turn the key on.

I wish there was already an access door. I am stranded in the parking structure at work! -- at least I made it to work but had to do the motel thing which was a dirty, smelly, stains on the floor that I don't want to mention what I thought it was, sounds coming from the room next door that more than likely confirmed what the stains on the floor was , roach factory! I had to get my money back and walk until I found a much nicer place to lay my head.

Thinking I might take it to the mechanic. I want to sleep in my own bed tonight!

 

[marragtop]

I suggest checking for power at the inertia switch first. It's easier to get to than the fuel pump connection. Pull the plug off the inertia switch to see if you have power to it. If not, then the problem is between the ignition and inertia switches. If you have power to the inertia switch, then bypass/jumper the switch to run power directly to the FP to see if it primes.

 

[budwich]

Forget screwing around with the fuel stuff, IF you don't get your check engine light to come on when you just turn your key to "on".... leave it there "forever", your light should come on and stay on "forever". You said "4) FP relay works 5) PCM relay works", how did you test this.... especially "5"????? Check your fuses. Get a meter and read the output of the PCM relay along with relay coil voltages. One other possibility is your CEL light is burnt out (unlikely)... did you see it on in the past during normal start sequences???

 

[stuckMounty]

Forget screwing around with the fuel stuff, IF you don't get your check engine light to come on when you just turn your key to "on".... leave it there "forever", your light should come on and stay on "forever". You said "4) FP relay works 5) PCM relay works", how did you test this.... especially "5"????? Check your fuses. Get a meter and read the output of the PCM relay along with relay coil voltages. One other possibility is your CEL light is burnt out (unlikely)... did you see it on in the past during normal start sequences???

Checked the fuses -- good
I am just going by knowing the pcm relay turns on the fuel pump relay or at least I know that if the pcm relay is not in the fuel pump relay does not click when I put the ignition in the "on" position. I also switched the wot ac relay in both slots and got the same results. I don't have all the equipment to bench test the relays to see if I get coninutity through them when I add power to the pulling contacts. Where do you test for the relay coil voltages and the output of the pcm? I do remember seeing the cel at key on in the past. I think that it is funny that it does not come on now that I have this problem. By the way, I do have spark if that helps.

 

[budwich]

Thanks for the clarifications. Still not sure I am understanding.... you hear / feel the fuel pump relay operate but don't hear your fuel pump run... right. Remember that it only runs for a couple of seconds during key "on". Of course, you have a SOHC engine... right?
You need to recheck your fuses under the hood... get you hands on a voltage test light some how if a meter isn't available. It's still pretty suspicious that the CEL light doesn't come on at "on".... hence my "check your fuses" statement.

In addition, your statement about "spark" is "interesting"... how are you determining this?

 

[stuckMounty]

Thanks for the clarifications. Still not sure I am understanding.... you hear / feel the fuel pump relay operate but don't hear your fuel pump run... right.

That's right.

You need to recheck your fuses under the hood... get you hands on a voltage test light some how if a meter isn't available.

Got a meter. Checked em about 7 times.

It's still pretty suspicious that the CEL light doesn't come on at "on".... hence my "check your fuses" statement.

I'm stumped too...

In addition, your statement about "spark" is "interesting"... how are you determining this?

I removed a sparkplug wire and grounded it... well I gave it about an 1/8th inch gap and watched the fireworks.

By the way, I know that it is a 5.0LV8. I have to double check to see if it is a single overhead cam engine.

 

[Dan Whitaker]

By the way, I know that it is a 5.0LV8. I have to double check to see if it is a single overhead cam engine.

5.0 is neither. 5.0 engines are OHV (over head valve) The cam is in the block.

 

[budwich]

OK... thanks again for the additional info. Glad you got a meter. Another point, just because the PCM relay operates doesn't mean that the PCM is healthy as the relay pulls up based on your key and nothing to do with the PCM itself. However, the fuel pump relay IS pulled up the PCM so that would seem to indicate a "functional PCM" or at least partially working one. Further, your "spark test" appears good which usually means that the PCM is doing "something". My "guess" of the "SOHC" was just thrown in to get you to tell us what motor you had..... V8 ... much better than a 6 SOHC. Have you tried any kind of starter spray to see if it will run for a "bit"... to better indicate a fuel issue? You could also try running a long jumper wire from the battery or there abouts to just past the cutoff switch which will cause the fuel pump to run irregardless of the key on. This should help eliminate fuel issues or point to the appropriate circuit if the "jumpering" works.

 

[stuckMounty]

Let me tink.....

Well...

I disconnected the inertia switch. I jumped the pnk/blk to the gry/org which gave me 11.5 volts @ the pnk/blk at the fuel pump connector. No pump operation. I also did a continuity check on the ground wire at the connector to the battery ground = ok. So it appears that when there is 11.5 volts to the pump it does not run. -- bad fuel pump??

 

[budwich]

yu dare, man.... basically with that test, it would certainly appear to be a dead pump. On the other side of things, when you get your vehicle some where to work on it with tools and such.... you need to also check you bulb on your CEL.

BUT... I am not certain of a few things you said... sorry I am slow. When you said "I jumped the pnk/blk to the gry/org which gave me 11.5 volts @ the pnk/blk at the fuel pump connector"... I assume this is with "key on"... right.... seems low but the right idea. I would check voltage coming into the fuel pump relay (LB/O) and leaving (grey/orange or what ever... my 96 drawings are different) to confirm the reading.

In addition, do a continuity (resistance measurement) thru the fuel pump motor (ie. pnk /blk to ground)... the readings should be "something" if the pump is "resistively OK", but open is there is a broken wire or bad motor "stuff". This will further confirm your "diagnosis".

 

[marragtop]

Try banging on the gas tank with a rubber mallet. Sometimes that will nudge the pump enough to get it to run. This would only be a temporary fix, but will help you isolate the problem.

 

[stuckMounty]

yu dare, man.... basically with that test, it would certainly appear to be a dead pump. On the other side of things, when you get your vehicle some where to work on it with tools and such.... you need to also check you bulb on your CEL.

Hopefully so... I had it towed home seeing I got quotes ranging from $1000 to $450 to replace the pump and that didnt include the $100 tow fee because I was stuck in an underground parking structure.

BUT... I am not certain of a few things you said... sorry I am slow. When you said "I jumped the pnk/blk to the gry/org which gave me 11.5 volts @ the pnk/blk at the fuel pump connector"... I assume this is with "key on"... right.... seems low but the right idea. I would check voltage coming into the fuel pump relay (LB/O) and leaving (grey/orange or what ever... my 96 drawings are different) to confirm the reading.

Yes with the key on. I have three wires going into the inertia switch. One is green with white (off the top of my head.) one is the pink with black and the other is the orange w/ grey. So I found the pink w/ black at the fuel pump connector and tested it there (jumped the connector at the inertia switch first then tested for voltage at the connector)

By the way, I was able to print out the wiring diagrams at the local library!

In addition, do a continuity (resistance measurement) thru the fuel pump motor (ie. pnk /blk to ground)... the readings should be "something" if the pump is "resistively OK", but open is there is a broken wire or bad motor "stuff". This will further confirm your "diagnosis".

It is real tight right there. I will try this or I may try the "access panel" method and cut a hole in my floor board to get to the pump.

 

[budwich]

perhaps we don't quite "talk the same" or I don't realize how tight it is under there (I haven't crawled under the tank area).... but my suggestion about measuring the resistance was at the plug where you checked to see if the battery voltage had reached that far (ie. from the jumpered inertia switch), if you can, just unplug that plug and instead of checking towards the inertia switch... do a resistance measurement in the other direction. I assume you understand this as you have done good testing to date.... but just in case. good luck.

 

[stuckMounty]

perhaps we don't quite "talk the same" or I don't realize how tight it is under there (I haven't crawled under the tank area).... but my suggestion about measuring the resistance was at the plug where you checked to see if the battery voltage had reached that far (ie. from the jumpered inertia switch), if you can, just unplug that plug and instead of checking towards the inertia switch... do a resistance measurement in the other direction. I assume you understand this as you have done good testing to date.... but just in case. good luck.

Gotcha'!

I'll go for the resistance check through the pump to see if I have any type of continuity.

 

[stuckMounty]

Ok... she's back on the road.

It was the fuel pump. I did the floor board access panel and changed out the pump. By the way, the floor board cuts like butter with a nice pair of metal snips!