Fuel pump electrical issue
#12
RE: Fuel pump electrical issue
I had the same problem on my 93. It was a corroded wiring splice by the battery.
Theres a butt splice that connects the power feed wires together for the asd relay, fuel pump relay and pcm module. Its buryed in the wiring harness that runs alongside the battery and under the relay center.
In mine the pcm wire corroded off and would make contact most of the time but occasionally fail causing a no start. I could jumper the relay and make the fuel pump run and pump fuel but it wouldn't run when I'd crank.
All the spliced wires were corroded but the pcm was the first to go. You have to cut the tape off the harness to see the splice. I'd recomend taking the relay center loose to make acess a little easier.
Theres a butt splice that connects the power feed wires together for the asd relay, fuel pump relay and pcm module. Its buryed in the wiring harness that runs alongside the battery and under the relay center.
In mine the pcm wire corroded off and would make contact most of the time but occasionally fail causing a no start. I could jumper the relay and make the fuel pump run and pump fuel but it wouldn't run when I'd crank.
All the spliced wires were corroded but the pcm was the first to go. You have to cut the tape off the harness to see the splice. I'd recomend taking the relay center loose to make acess a little easier.
#13
RE: Fuel pump electrical issue
Sorry for the long delay in the update. I was busy with other things and also the truck started working again, without me doing anything. Until this weekend... So I just checked the wiring splices under the relay box and all checked out fine. I don't know what to do now.
Is there any security feature that might prevent me from starting? Like some antitheft swich in the ignition or a fuel shutoff relay or anything else people can think off. I also founs another link that descibes the EXACT problem on a Jeep. His solution is crazy, which makes me think that I have some short circuit somewhere. Here is the link:
http://72.14.253.104/search?q=cache:...a&ct=clnk&cd=1
BTW, I started getting some codes: 12, 24, 55. Note that the Check Engine light was not on during driving last time (although code 24 should trigger that). I also checked the TPS and it seems to be OK. At any rate, I don't think that a faulty TPS or even TPS circuit can stop the fuel pump from priming.
I know this, when the pump is priming the truck starts, when it doesn't the truck only cranks!!!
One more question (may be related): I noticed that at the very front of the truck under the hood (near the battery and also on the passenger side) there are these 2 wires (?!). The plastic is marked H and V. One of these is broken off. What the heck are these?
Thanks so much for all the opinions.
Is there any security feature that might prevent me from starting? Like some antitheft swich in the ignition or a fuel shutoff relay or anything else people can think off. I also founs another link that descibes the EXACT problem on a Jeep. His solution is crazy, which makes me think that I have some short circuit somewhere. Here is the link:
http://72.14.253.104/search?q=cache:...a&ct=clnk&cd=1
BTW, I started getting some codes: 12, 24, 55. Note that the Check Engine light was not on during driving last time (although code 24 should trigger that). I also checked the TPS and it seems to be OK. At any rate, I don't think that a faulty TPS or even TPS circuit can stop the fuel pump from priming.
I know this, when the pump is priming the truck starts, when it doesn't the truck only cranks!!!
One more question (may be related): I noticed that at the very front of the truck under the hood (near the battery and also on the passenger side) there are these 2 wires (?!). The plastic is marked H and V. One of these is broken off. What the heck are these?
Thanks so much for all the opinions.
#14
RE: Fuel pump electrical issue
code 24 is the TPS sensor. I would try replacing that and see of that helps. but I dont know if that would cause your truck not to get fuel though. its worth a shot
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Last edited by jonnymagnum; 05-08-2011 at 04:28 AM.
#15
#16
RE: Fuel pump electrical issue
Hey guys its been my experience that when you start hearing relays they aren't working properly,I ask tou this did you hear any relay prior to the fuel pump problem?My guess is no not that you would be listening for it...if you really want to lnow if your relay is working just get a stethascope place it anywhere on the body of the truck and turn the key you'll hear the fuel pump hum for about 2 seconds if you do then rule out the pump check for a possible issue with another fuel component...
#17
RE: Fuel pump electrical issue
Thanks Boomer. Sorry, I must disagree. Any relay that pulls in will make a clicking sound. That's just how they work. I know that the relays are fine. I suspect that I have a short at a place I did not yet find.
Can anyone comment on the possibility of the TPS not working and causing the fuel pump to lose power? Makes no sense to me...
Can anyone comment on the possibility of the TPS not working and causing the fuel pump to lose power? Makes no sense to me...
#18
RE: Fuel pump electrical issue
Just a quick follow up. So after sending my previous message, I go out, put the key in the ignition, I hear the pump prime, so I know I'm in business. The truck started up no problem. The issue is that AGAIN, I didn't do anything to it.
As to the TPS, now that the truck is running, I pulled the TPS off. It still runs (but badly) and still turn on. So there is my answer to my own question. The TPS has nothing to do with this electrical issue. As to the code: I may have accidentally bumped the connector off, so it gave me that error. BTW, when the TPS was off, the check engine light was ON, just as it should have been. Another reason to think that the TPS had nothing to do with this BRUTAL fuel pump issue.
As to the TPS, now that the truck is running, I pulled the TPS off. It still runs (but badly) and still turn on. So there is my answer to my own question. The TPS has nothing to do with this electrical issue. As to the code: I may have accidentally bumped the connector off, so it gave me that error. BTW, when the TPS was off, the check engine light was ON, just as it should have been. Another reason to think that the TPS had nothing to do with this BRUTAL fuel pump issue.