Fuel Pump Not Powering Up, Code 95

[Irish Pride]

I'll start by saying this is on my 91+. The car is fully 60k'd. It received its front 60k in June of this year right before the convention. Drove it up to Chicago and back without issue other than a rusted brake line(s) issue. The weekend after the convention I stopped to fill up the tank and it would not restart. It was evident right from the start that the fuel pump was not powering up. I had to have it towed home. After it was towed I tried it again and it did start and run, I moved it into position in my driveway and when I shut it off it would not restart. If I let it sit for a couple hours it would restart but once I turned it off it was completely dead again. Once it was dead it would not power up again unless i let it sit. I switched out the CCRM with a known good one with no change. I switched out the PCM with a known good one with no change. I switched out the inertia switch with a known good one with no change. The pump has always been weak. Ive always had to cycle the ignition switch twice to get the car to start. At that point I came to the conclusion that the pump was finally dead and needed to be swapped. I had new pump sitting on the shelf in my shed but decided if I was going to swap out the pump then I wanted to go ahead and upgrade the tank to the larger 18.6 gallon one so I ordered parts and let the car sit for a few weeks.

Fast forward 6 weeks. The car now has a new Walbro 155lph pump, brand new sending unit, brand new fuel tank, brand new fuel filter, and I even replaced the pigtail going to the pump. Everything is new and the car is still dead. It doesn't even fire once now. I can turn the key over and over and the pump will not power up. Ive swapped in several CCRMs with no change and several PCMs with no change. All of them work fine in my other SHOs so I know they are good. If I ground out the fuel pump pin in the EEC tester the CCRM will power up but the pump does not.

The only thing I can think of is when I did the 60k back in June I took some time to clean up the engine compartment too. I repainted the inner fenders and the radiator support. Maybe it has a bad ground now but ive gone through all the grounds that I know of and they all look good. Ive removed them all several times and reinstalled them with no change. Im finally at a loss here. this is the first time this car has ever given me serious trouble.

I'm in need of advise. Where do I go from here? What am I missing? Is there something else that could be preventing the pump from firing other than what ive checked?

Any input will be appreciated.

 

[sperold]

Do your have the door under the back seat that allows access to the pump?
I would start at that plug on the gas tank by giving it a good look and test it out. I would run its own power right from the battery and get the pump to run that way. If it runs, you can trouble shoot the wiring to see where the break is.
You seem to have looked at everything else.

 

[luigisho]

Seems like you are on the right track. The obvious stuff has been covered. If you can jumper power to the pump and it runs strong then wire/ground somewhere. Yuk.

I thinking that might be the deal. If you are checking out power to the pump it might not read with a probe and ignition on. I'm thinking it gets that momentary priming charge and that might be it until the car is running-- so you might need an extra set of hands.

Is there a Fuse in the engine compartment that controls power to the fuel pump, ccrm and pcm?

http://www.google.com/url?sa=t&rct=...mXjN8sGNY7AVjifwz7XPdQ&bvm=bv.105841590,d.cGc

Since you got power to the ccrm from the EEC tester you'll have to back probe the fuel pump wire. I would shoot nick chrimes an email and see if he has come across something similar. He does as much or more work on these cars as anyone and he is pretty methodical with his work.
I don't have the facebook but I can usually find him on the yahoo v6sho mailing list

 

[itwonder]

Some pointers picked up over the years from earlier posts:

Make sure the IRCM in the car is the proper one for the model year. Early IRCM's had a dropping resistor to operate the fuel pump in IDLE mode; later years eliminated that resistor and the fuel pump runs at just one speed.

Initial checks:

1. Check all of the under hood fuses. (especially 30A fuses and 10A accessory fuse)
2. Make sure the small wire that goes from the negative battery terminal to body ground is secure.
3. All voltage readings are referenced to a good chassis ground, unless otherwise specified.

Fuel Pump Diagnostic

"1. Ground the FP test point on the EEC-IV connector. This activates the FP Relay.

Note: Under the control of the PCM, this line is grounded whenever the FP relay is supposed to energized. Do not apply voltage to it. To energize the relay, ground this pin. If grounding the pin does not cause the relay in the IRCM to energize, look for an open circuit between the self test connector and IRCM pin 18

2. Turn ignition switch to RUN. IRCM pins 1, 2, 10, & 12 should have 12V supplied to them (if all the fuses are good) The Fuel pump SHOULD be running . If not, go to Step 3.

3. Measure at pin 5 of the ICM (PK/BK)to ground. You should measure partial battery voltage. If so, go to step 6.

If reading is full battery voltage, there is an open circuit in the load side - Inertia switch, or FP. Go to step 4.

If reading is 0 volts, GO TO STEP 5.

4. Check inertia switch, reset as needed. Measure voltage on both leads. A good switch will have the same voltage on both leads as measured in step 3 above. If not, jumper across the switch and see if the FP runs. If so, replace the switch. Measure the voltage at the FP terminals. If you measure the same voltage at the input and the ground is good (verify it), replace the FP. If the voltage is lost at some point, you have an open circuit between that point and the previous point that did have voltage.

5. Early cars with dropping resistor:

6. The FP should be running . Listen carefully or have an assistant help.

 

[Irish Pride]

Are there any fuses under the hood on a Gen1? I don't know of any.

 

[rubydist]

I would check to see if the ccrm is putting out power to the fuel pump.
If no power there, then ccrm is bad. If power there, check to see if the power is making its way back to the fp. If no power there, wiring issue in the harness. If power there, then check grounds from fp back to the chassis.

 

[Irish Pride]

I can swap the CCRM into my other SHOs and it works perfect so I don't think that is the problem. I'll start by checking voltage at the inertia switch and go from there.

I checked the ground inside the trunk on the passenger side and it looked good. Can anybody tell me what other grounds could be tied to the FP?

I wanted to swap the tank as well as the pump so I didn't cut the access under the rear seat. It will be a pain to drop the tank again so I'd like to check everything I can before that become necessary.

 

[Irish Pride]

Also, what I've noticed is when I turn on the ignition switch the fuel gauge goes all the way up. Past where it would be with a full tank. There is only about 4 gallons in the tank so that points to a voltage problem correct?

 

[SHOdded]

Or a bad sender. Did you use Airtex parts by any chance? Have not heard good things of them in our applications.

 

[Irish Pride]

Spectra sending unit for the larger tank.

 

[rubydist]

all the way up on the fuel gauge means too much resistance (i.e. bad connection, bad ground, bad wire), which piggy backs onto your "fuel pump doesn't run" issue. I think you have a connection problem somewhere (hopefully not inside the tank).

 

[Irish Pride]

all the way up on the fuel gauge means too much resistance (i.e. bad connection, bad ground, bad wire), which piggy backs onto your "fuel pump doesn't run" issue. I think you have a connection problem somewhere (hopefully not inside the tank).

Problem is fixed!! Pump has power and car is running again.

This morning my girlfriend challenged me to get it running. She said as **** as I am with this car and as thorough as I am with my upgrades it had to be something simple. In the end she was correct.

I started by doing what I should have done in the first place, verify that the old pump was indeed bad. I ran 12 volts to the old pump and it was completely dead. Once I verified that the old pump was bad I didn't feel so bad about spending the money on the upgrades but I still didn't have a running car. Since I knew that the old pump was bad I came to the conclusion that either A - the new pump was bad too or B - I had a wiring issue at the pump. I ended up doing what I tried to avoid and cut an access hole under the rear seat. Once I could get to the top of the pump I ran 12 volts to it and still nothing, completely dead.

Ok, I got a bad pump right out of the box. I had the pump that came with the sending unit so I decided to put that one in just so I could get the car running. When I pulled the sending unit out I immediately saw the problem. For whatever reason, the sending unit I got for the larger 18.6 gallon tank is wired backwards. When I replaced the pigtail I wired the wires exactly as they were on the old pump. This sending unit needed them wired in reverse. I redid the pigtail, kept the Walbro pump installed and ran 12 volts to it and it powered right up. Im a little upset that I ended up having to cut the access hole but it is what it is. Just finished taking it for a drive and I now have a smile on my face again.

Thanks for the input guys. I really appreciate it.

 

[SHOdded]

Great to hear, Chad! Enjoy the ride

 

[rubydist]

bad news that the wiring problem was inside the tank, but good news that you got it sorted out!

 

[Imnotsureyet]

I'll start by saying this is on my 91+. The car is fully 60k'd. It received its front 60k in June of this year right before the convention. Drove it up to Chicago and back without issue other than a rusted brake line(s) issue. The weekend after the convention I stopped to fill up the tank and it would not restart. It was evident right from the start that the fuel pump was not powering up. I had to have it towed home. After it was towed I tried it again and it did start and run, I moved it into position in my driveway and when I shut it off it would not restart. If I let it sit for a couple hours it would restart but once I turned it off it was completely dead again. Once it was dead it would not power up again unless i let it sit. I switched out the CCRM with a known good one with no change. I switched out the PCM with a known good one with no change. I switched out the inertia switch with a known good one with no change. The pump has always been weak. Ive always had to cycle the ignition switch twice to get the car to start. At that point I came to the conclusion that the pump was finally dead and needed to be swapped. I had new pump sitting on the shelf in my shed but decided if I was going to swap out the pump then I wanted to go ahead and upgrade the tank to the larger 18.6 gallon one so I ordered parts and let the car sit for a few weeks.

Fast forward 6 weeks. The car now has a new Walbro 155lph pump, brand new sending unit, brand new fuel tank, brand new fuel filter, and I even replaced the pigtail going to the pump. Everything is new and the car is still dead. It doesn't even fire once now. I can turn the key over and over and the pump will not power up. Ive swapped in several CCRMs with no change and several PCMs with no change. All of them work fine in my other SHOs so I know they are good. If I ground out the fuel pump pin in the EEC tester the CCRM will power up but the pump does not.

The only thing I can think of is when I did the 60k back in June I took some time to clean up the engine compartment too. I repainted the inner fenders and the radiator support. Maybe it has a bad ground now but ive gone through all the grounds that I know of and they all look good. Ive removed them all several times and reinstalled them with no change. Im finally at a loss here. this is the first time this car has ever given me serious trouble.

I'm in need of advise. Where do I go from here? What am I missing? Is there something else that could be preventing the pump from firing other than what ive checked?

Any input will be appreciated.

I'm having the same trouble but have not done all that you have how ever I found a 10 Amp fuse in the power distribution box under the hood and every time I replace it it blows and the car will not run I can crank it all day due it will not start and I have not been able to find where it's shorting out as I can not crank the car after putting in a new fuse because it will blow as soon as I try. So how do I find the short?
This is the front 10 Amp fuse I'll send a picture and I hope it helps

 

[rubydist]

The only way to find a short is to trace the wiring until you find the short. There is no "easy" button for this one.

And next time, please do not revive a 7 year old thread - start a new one.