2000 Jimmy Yet Another Fuel !ssue....

My wife's 2000 Jimmy 4 door 4.3 died on her on the highway. I have nothing on the fuel gauge and low fuel light is on. There is definetly fuel in the tank. I also have no sound at all from the fuel pump at all. Truck cranks fine. I had this exact same problem one time before about 8 months ago and it turned out to be a fuse. Checked the relays in the fuse box under the hood and everything is good. Any ideas???

Mike

Does the fuel pump relay click when the key is turned to the RUN position? It should click again after approximately 2 to 3 seconds.

don't remember hearing it click.

There should be a label on the underside of the underhood fuse panel lid that shows where the relay is located. There are four terminals in the underhood fuse panel that the fuel pump relay plugs in to. Remove the relay and check the circuits. One terminal comes from the ECM B 20 amp fuse. It should have battery voltage at all times. One terminal comes from the ECM and should have battery voltage for 2 to 3 seconds after the key is turned to the RUN position, and then drop to zero volts. It should also have battery voltage any time the ignition switch is in the START position. One terminal goes to ground and must be less than 5 ohms resistance to ground. The fourth terminal goes to directly to the fuel pump. If the circuits check out OK, there are several identical relays in the fuse panel, try swapping with one of them. If the pump works, you need a new relay. If not, continue on…

Next to the fuel pump relay there is a single unused, recessed terminal. This terminal goes directly to the fuel pump. Connecting a 20 amp fused jumper wire from battery positive to this terminal should result in the fuel pump running continuously, regardless of ignition switch position. If the pump does not run, voltage and ground need to be checked at the fuel pump, (tank must be dropped to access the connector). Hope this helps.

I swapped around the relays this morning and got nothing. I'm gonna go out now and check the circuits now. i'm running out of daylight and working on the street so I don't know how much more i'm going to be able to do today.
Thanks for the help.

OK when I rin the jumper wire to the single terminal that goes to the pump the pump runs. Ground at the fuse panel is around 3 ohms. One terminal has power with ignition off and with the key to run. The other 2 only have power when the key is in the start position.

Are you checking with the relay removed? If so, one of the terminals, the one that goes to the pump, should not have voltage at all during the test.

Your ground at the relay is good. The pump running when jumped means the pump is getting voltage and ground. Your feed from ECM B to the relay is good. There should only be one terminal that the voltage ever changes on, and that's the triger from the ECM. It should be hot in RUN for 2 to 3 seconds, then drop to zero. It should be hot in START continously. Check it again to be sure.

You can check if the relay is switching by checking for voltage in the unused terminal. With the relay plugged in, it should show battery voltage for 2 to 3 seconds after the ignition is turned to the RUN position, then drop to zero. It should also show battery voltage continously when the ignition switch is in the START position.

Yeah I was checking with the relay removed. let me go check it again with it in quick before I run out of light.

just checked again and everything tests the same with the relay in.

If the results in the third paragraph of post 7 are ok, it's time to check the fuel pressure.

The truck doesn't seem to be getting spark either. I just sprayed a bunch of starting fluid down the throttle body and it didn't even sound like it wanted to start. I can't verify for sure on the spark until tomarrow after I do the brakes on my Mazda. Am I still looking at a fuel issue or can this be a PCM/ECM issue??

Try not to guess, it gets real expensive real quick ;) See if you have a blue, not orange, spark at more than one spark plug.

Yeah i hear you on the guessing. LOL This whole truck gets real expensive real fast:lol: . I've got the battery out and charging. As soon as I get my brakes taken care of I'll check the spark and let you know how I make out.

O.K. I definetly have NO spark. Absolutely nothing at all.

no spark at plugs. do you have a spark at the coil wire ?

No spark at the plugs or the coil.

Anyone have any ideas??? Right now i'm thinking a 5 gallon can of gas, a match , and some marshmallows:banghead:

can you borrow a code scanner? you should have some codes, see what codes you have..

I have no access to a scanner. Can you still jump the diagnostic terminal and get the CEL to flash the codes?? If so what terminals do I need to jump? I can check this out as soon as I get out of work.

lokk do you have an autozone where you live? they will loan you the scanner you will have to leave a deposit until you take it back .

yeah I have one about 10 minutes from me. I'll swing by there tomarrow after I get out of work and pick one up.

The Autozone's in my state do not loan out the scanners. Neither do the Advance Auto Parts stores. they all said they'll scan it if I bring it down , but that's pretty impossible ATM.

With out a scanner or code reader it is hard to know what is going on.
Might borrow one from a buddy on consider getting a cheaper unit.
Or have a molbie mechanic test it for you.
In the mean time you might pull dist cap and check for rotor turning good or for cracks or moisture in there.
And remove dist coil and dist moduel and see if parts place can test them for you.
Also check rotor position as in picture link below.
http://files.automotiveforums.com/gallery/showphoto.php?photo=51302

OK I finally found someone with a scanner that I can borrow. I won't be able to get it untill tomarrow. I'll post in the afternoon sometime with the results.

ok got the scanner. I keep getting an error message that the scanner cannot communicate with my vehicle.:banghead:

Read instruction manual and make sure you punch the right vin stuff.
All fuses are good?
Here is a link to diagnostic plug pin out.
http://www.troublecodes.net/OBD2/
Check for grounds and for 12 volt battery power on pin 16.
Dome light and cig lighter may be on same fuse as diag plug power.

The Actron Cp9175 I'm using does not require VIN input. All the pins on the diagnostic connector check out fine and every fuse in the truck is good (checked em twice)

Anyone else have any ideas?? I have my gas can and my matches but I'm having trouble trying to find marshmallow this time of year.:iceslolan

Still no spark from the coil when cranking? Is there battery voltage to the pink wire at the coil when the ignition is in the RUN position?

Still no Spark when cranking. I'm getting power to the pink wire at the coil and power to the pink wire at the ignition module.

At the coil, does the white with black stripe wire pulse when cranking? Easier to check with a test light, rather than a voltmeter.

all I have is a voltmeter. I should be able to craft a test light though.

OK I am getting a pulse on the white with black stripe wire when cranking.

You have battery voltage and pulse at the coil, and no output, bad coil.

ok bad coil. this shouldn't have anything to do with my fuel issue correct?

Correct, totally different circuits.

any ideas on why the scanner won't talk to the computer?? scanner works on all of my other vehicles. We've had the truck scanned before and it worked about 3 months ago.

Here is a link that shows each terminal in the data link connector.

http://www.circuitcellar.com/pastissues/articles/Tom119/2006003FIG1.gif

this should help you test the circuits.

i read somewhere a some models the icm [ignition control module] has something to do with the fuel control i can't remember where i read it to re-read it to see what motor it was on. i'll bet thats where your problem is..

The Crankshaft Position Sensor sends a signal to the ECM. The ECM has total control of fuel control, (and ignition module).

but if the ecm uses the icm to get the injector pulse rate then if the icm is bad it will screw with the firing and fuel correct?

The crankshaft position sensor tells the ECM where #1 piston is in it's rotational cycle. The ECM gathers data from other sensors and calculates when the plug needs to be fired. Then it sends a signal to the ignition control module, which in turn sends a signal to the ignition coil. The ECM sends a pulsed ground signal to the injectors. The length of the pulse determines fuel mixture. The crank sensor is an ECM input, the ignition module and injectors are outputs.

So in theory I could have a bad ECM? I'm really thinking that these 2 problems need to be related as they both happened at exactly the same time.

In theory yes, it could be a faulty ECM, but don't holler Eureka quite yet. The ECM is a VERY substantial part in these vehicles, and the odds are it's not the ECM causing the problem(s).

Have you replaced the ignition coil yet? If so, do you have spark output from the coil?

I have not replaced the coil as of yet. It's hard to tell if it's pulsing because the battery voltage was a little low. i'll have to see if the parts guy will let me "borrow" a few parts to check out. Cash will be extrememly tight for me for about another week especially with me driving the wife back and forth and not being able to do any OT because of it.

Ok so, the truck is in the shop. So far we've replaced the coil, ICM, and the ECM and STILL NO SPARK, NO FUEL PUMP, AND NO FUEL GAUGE. any other ideas before I cut it up, put it in the scrap bin, and report it stolen??????????

Does the scan tool communicate with the ECM yet? Did you check for voltage, ground, etc etc in the data link connector so the scan tool will work?

OK after 6 weeks the problem has finally been fixed. We found a bad wire from the ECM to the underhood fuse block. We also found that the fuel pump was not putting out enough pressure. When we were changing out the pump we noticed that the pump had been replaced before we got it with the wrong pump. Now it's time to start the other Jimmy repairs. Tune up, rear hatch fix, and heater blend motor repairs are coming up in the next 2 weeks or so, and tomarrow I'm doing the headlights and the multifunction switch. Thanks for all the help, it was much appreciated.

Mike