Please help with strange electrical problem.

gt93mustang · 05-19-2001, 08:22 PM

I posted a few days ago about some suspected fuel pump problems I was having. This is the link to the thread:
http://www.mustangworks.com/msgboard...ML/018670.html

But here is a quick summary of what happened for those who don't want to read the other thread. I pulled out of my driveway for work about a week ago and the car shut off 15 feet down the road. I tried to crank it back up but it would only turn over, not start. I turned off the key, and turned it back on, and noticed the fuel pump would not prime and none of the relays seemed to 'click' on. Well, here it is a week later and I still can't figure out what is wrong. I am usually pretty good about diagnosing and fixing my car problems, but this one has me stumped. After further investigation, I have found that I am only getting 2.9volts back to the fuel pump and the ground wire from the negative battery cable was not secured on fender wall. I tried running a code check, but it the scanner doesn't seem to be reading the computer at all. It doesn't click like it used to when I turned it on for a KOEO test. Does anyone have any ideas? Think I fried my computer? I changed the fuel pump relay and the PCM relay, and neither helped at all. Thanks in advance for any help. This is my daily driver so I really need to get it back on the road.

Joe

------------------
MAC equal length headers, MAC Off-Road H-Pipe, Flowmaster mufflers, 373's, underdrive pulleys, 76mm MAF, 65mm TB, TFS Track Heat Intake(ported & gasket matched), Edelbrock 6037 heads (ported, polished, 3 angle valve-job 255CFM @.500), 1.6 FMS RR's, Wolverine 1087 Cam, 30lb injectors, MSD 6AL, Subframe connectors, Griggs Adustable Lower Control Arms, Lakewood 50/50 shocks, SSM Upper Control Arms... and 8lbs of Procharged boost

Stampede · 05-19-2001, 09:21 PM

Do have power through out the car?
Does the windows, radio, lights work?
Have you checked to see if you have spark?
And does any of your friends have a 5.0L, to check the computer?
Stampede.

gt93mustang · 05-19-2001, 10:24 PM

I do get power through the car.
Lights, radio, windows, and locks work.
There doesn't seem to be any spark. And yes, I can borrow a computer from a friend. That is going to be my next step.

90dpscoupe · 05-19-2001, 11:33 PM

I had a similiar problem, do you have voltage going to the harness above the tank? i just replaced the fuel pump and it cranked.

Might be time to drop the tank.

------------------
90 lx coupe: Mac cold air fenderwell, accel supercoil,ADS chip (not yet track tested),3-core radiatr, FMS alum D/S, Black magic fan, 3.27grs, 3chbr flows.
Best time: 13.9116(on 225/60/15 firehawks)
Best mph: 98.17
Best 60': 1.9607

next mods: subframes, mac h-pipe

BlackFly · 05-20-2001, 12:46 AM

this sounds unbeleivably like a problem i ran into with assembling a convertible of my cousins, right down to the 2.9volts.his harness had some splicing in it and the computer was of questionable condition. we replaced the harness(we were there anyways) and the computer with a known to be good one and it fired right up. i beleive it was the computer. the computer doesnt control accessory power like wipers windows and such.good luck.

gt93mustang · 05-20-2001, 08:07 AM

Sounds like I will be replacing the computer next. I'll swap out with a friends before I buy a new one, just to make sure that is the problem. Are any aftermarket (or OEM) computers that are better than my 1993 computer? I know to stay away from the cobra computers though. Thanks again everyone.

gt93mustang · 05-30-2001, 09:47 PM

Well, I have an update and still no progress. This is getting really frustrating and I am about to have to put the car in the shop to let some experts figure out the problem.

Anyways, heres what's new. I swapped my computer into a friends car and it started right up. I guess this means the computer is ok and I am going to have to start looking for another problem.

Here again are some symptoms:

No spark
No relays 'clicking'
no fuel pump priming
Motor cranks but will not start
2.9v at the fuel pump
12.5v at battery
Code scanner doesn't 'engage'

Please help! My car has been down for over two weeks and I really need to get it back on the road, but I don't want to pay a mechanic retarded amounts of money to tell me the alternator is bad. Thanks again for any help.

90dpscoupe · 05-30-2001, 10:56 PM

Dude its gotta be the pump, i tell ya what, drop the tank, its not hard once youve done it about 3 times, someone here told me to hook up a battery charger to the pump, BUT he said, BE CAREFUL NOT TO BLOW YOURSELF UP PLEASE, but i bet its the pump, my car just shut off like you explained.

------------------
90 lx coupe: 175k miles, steeda water pump pully, hurst shifter, Mac cold air fenderwell, accel supercoil, ADS chip, aluminum D/S, Black magic fan, 3.27grs.
Best time: 13.9116(on 225/60/15 firehawks)
Best mph: 98.17
Best 60': 1.9607

next mods: subframes, mac h-pipe

crewzin · 05-30-2001, 11:07 PM

HOW BOUT CHECKING THE IGNITION SWITCH ON THE COLUMN. I HAD A SIMILAR PROBLEM ONCE ON MY F350, CHANGED THE SWITCH AND BINGO! ALSO HOW ABOUT CHECKING THE SAFETY SHUTOFF SWITCH TO THE FUEL PUMP.

gt93mustang · 05-31-2001, 08:00 AM

Thanks for the replies guys! I already dropped the tank and put in a Walbro 255HP fuel pump because I thought my 190 gave up from overworking it with the blower. That didn't help at all. While I had the tank down, I checked the volts to the fuel pump connection from the wiring harness and it was only seeing 2.9v. Also, would the ignition switch on the column cause the car not to get spark to the spark plugs AND keep the fuel pump from turning on? Thanks again everyone.

05-19-2001, 08:22 PM	#1
gt93mustang Registered Member Join Date: Feb 1999 Location: Kennesaw, Georgia, USA Posts: 252	Please help with strange electrical problem. I posted a few days ago about some suspected fuel pump problems I was having. This is the link to the thread: http://www.mustangworks.com/msgboard...ML/018670.html But here is a quick summary of what happened for those who don't want to read the other thread. I pulled out of my driveway for work about a week ago and the car shut off 15 feet down the road. I tried to crank it back up but it would only turn over, not start. I turned off the key, and turned it back on, and noticed the fuel pump would not prime and none of the relays seemed to 'click' on. Well, here it is a week later and I still can't figure out what is wrong. I am usually pretty good about diagnosing and fixing my car problems, but this one has me stumped. After further investigation, I have found that I am only getting 2.9volts back to the fuel pump and the ground wire from the negative battery cable was not secured on fender wall. I tried running a code check, but it the scanner doesn't seem to be reading the computer at all. It doesn't click like it used to when I turned it on for a KOEO test. Does anyone have any ideas? Think I fried my computer? I changed the fuel pump relay and the PCM relay, and neither helped at all. Thanks in advance for any help. This is my daily driver so I really need to get it back on the road. Joe ------------------ MAC equal length headers, MAC Off-Road H-Pipe, Flowmaster mufflers, 373's, underdrive pulleys, 76mm MAF, 65mm TB, TFS Track Heat Intake(ported & gasket matched), Edelbrock 6037 heads (ported, polished, 3 angle valve-job 255CFM @.500), 1.6 FMS RR's, Wolverine 1087 Cam, 30lb injectors, MSD 6AL, Subframe connectors, Griggs Adustable Lower Control Arms, Lakewood 50/50 shocks, SSM Upper Control Arms... and 8lbs of Procharged boost

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05-19-2001, 09:21 PM	#2
Stampede Registered Member Join Date: Jun 2000 Location: oh Posts: 93	Do have power through out the car? Does the windows, radio, lights work? Have you checked to see if you have spark? And does any of your friends have a 5.0L, to check the computer? Stampede.

05-19-2001, 10:24 PM	#3
gt93mustang Registered Member Join Date: Feb 1999 Location: Kennesaw, Georgia, USA Posts: 252	I do get power through the car. Lights, radio, windows, and locks work. There doesn't seem to be any spark. And yes, I can borrow a computer from a friend. That is going to be my next step.

05-19-2001, 11:33 PM	#4
90dpscoupe Registered Member Join Date: Jun 2000 Location: sanantonio, Tx, usa Posts: 1,407	I had a similiar problem, do you have voltage going to the harness above the tank? i just replaced the fuel pump and it cranked. Might be time to drop the tank. ------------------ 90 lx coupe: Mac cold air fenderwell, accel supercoil,ADS chip (not yet track tested),3-core radiatr, FMS alum D/S, Black magic fan, 3.27grs, 3chbr flows. Best time: 13.9116(on 225/60/15 firehawks) Best mph: 98.17 Best 60': 1.9607 next mods: subframes, mac h-pipe

05-20-2001, 12:46 AM	#5
BlackFly Registered Member Join Date: Feb 2001 Location: winnipeg , manitoba , canada Posts: 83	this sounds unbeleivably like a problem i ran into with assembling a convertible of my cousins, right down to the 2.9volts.his harness had some splicing in it and the computer was of questionable condition. we replaced the harness(we were there anyways) and the computer with a known to be good one and it fired right up. i beleive it was the computer. the computer doesnt control accessory power like wipers windows and such.good luck.

05-20-2001, 08:07 AM	#6
gt93mustang Registered Member Join Date: Feb 1999 Location: Kennesaw, Georgia, USA Posts: 252	Sounds like I will be replacing the computer next. I'll swap out with a friends before I buy a new one, just to make sure that is the problem. Are any aftermarket (or OEM) computers that are better than my 1993 computer? I know to stay away from the cobra computers though. Thanks again everyone.

05-30-2001, 09:47 PM	#7
gt93mustang Registered Member Join Date: Feb 1999 Location: Kennesaw, Georgia, USA Posts: 252	Well, I have an update and still no progress. This is getting really frustrating and I am about to have to put the car in the shop to let some experts figure out the problem. Anyways, heres what's new. I swapped my computer into a friends car and it started right up. I guess this means the computer is ok and I am going to have to start looking for another problem. Here again are some symptoms: No spark No relays 'clicking' no fuel pump priming Motor cranks but will not start 2.9v at the fuel pump 12.5v at battery Code scanner doesn't 'engage' Please help! My car has been down for over two weeks and I really need to get it back on the road, but I don't want to pay a mechanic retarded amounts of money to tell me the alternator is bad. Thanks again for any help.

05-30-2001, 10:56 PM	#8
90dpscoupe Registered Member Join Date: Jun 2000 Location: sanantonio, Tx, usa Posts: 1,407	Dude its gotta be the pump, i tell ya what, drop the tank, its not hard once youve done it about 3 times, someone here told me to hook up a battery charger to the pump, BUT he said, BE CAREFUL NOT TO BLOW YOURSELF UP PLEASE, but i bet its the pump, my car just shut off like you explained. ------------------ 90 lx coupe: 175k miles, steeda water pump pully, hurst shifter, Mac cold air fenderwell, accel supercoil, ADS chip, aluminum D/S, Black magic fan, 3.27grs. Best time: 13.9116(on 225/60/15 firehawks) Best mph: 98.17 Best 60': 1.9607 next mods: subframes, mac h-pipe

05-30-2001, 11:07 PM	#9
crewzin Registered Member Join Date: May 2001 Location: Sour Lake, TX Posts: 211	HOW BOUT CHECKING THE IGNITION SWITCH ON THE COLUMN. I HAD A SIMILAR PROBLEM ONCE ON MY F350, CHANGED THE SWITCH AND BINGO! ALSO HOW ABOUT CHECKING THE SAFETY SHUTOFF SWITCH TO THE FUEL PUMP.

05-31-2001, 08:00 AM	#10
gt93mustang Registered Member Join Date: Feb 1999 Location: Kennesaw, Georgia, USA Posts: 252	Thanks for the replies guys! I already dropped the tank and put in a Walbro 255HP fuel pump because I thought my 190 gave up from overworking it with the blower. That didn't help at all. While I had the tank down, I checked the volts to the fuel pump connection from the wiring harness and it was only seeing 2.9v. Also, would the ignition switch on the column cause the car not to get spark to the spark plugs AND keep the fuel pump from turning on? Thanks again everyone.