Fuel Pump Draining Battery

Tiny
DANFSMITH
  • MEMBER
  • FORD BRONCO
1990 Bronco, 5.8L, 117K miles - When I shut my truck off, the fuel pump keeps running. I have to disconnect the battery or it'll be dead in the morning. I've replaced the fuel pump relay, but still have the same problem. Someone told me to replace the fuel pressure regulator. What do you think, and thanks for your help. Oh, and sorry about the small donation. I'm kinda broke.
Wednesday, March 14th, 2007 AT 5:52 PM

18 Replies

Tiny
TAURUSWHEEL
  • MECHANIC
  • 718 POSTS
Did you replace the relay or the inertia shutoff switch? Just checking.
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Wednesday, March 14th, 2007 AT 6:45 PM
Tiny
DANFSMITH
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Sorry, I don't know what the inertia switch is. Under the hood on the driver's side (just behind the washer fluid reservoir), there is a plastic housing that holds four plugs/relays. The one I replaced is labled "Fuel Pump." When I reconnect the battery, I could hear it click on, the fuel pump would run, then it would click off. When I removed the relay, I would reconnect the battery and still hear a click. With the relay out, I can actually feel the click on the EFI rails when I reconnect the battery.
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Wednesday, March 14th, 2007 AT 7:02 PM
Tiny
NOS
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It is normal that the relay clicks when you plug it back in. The question is did the relay fix your battery rundown problem when you replaced it. The inertia swith is mounted at the firewall driverside it has a rest button that will kick the fuel pump off incase of an accident the way it works is. You turn the key on power goes through that switch to the fuel pump relay for a second then it shuts off till you start cranking the motor then it stays on till you quit cranking or the engine starts then stays on till you shut the motor off. If the fuel pump stays running after the key is turned off the relay is hanging open and discharging your battery. 8) NOS
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Wednesday, March 14th, 2007 AT 7:48 PM
Tiny
DANFSMITH
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Thanks, NOS. I've changed the relay, so do you think I should leave the battery connected and see if it keeps its charge? Is there anything other than a faulty relay that would cause the relay to hang open?
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Wednesday, March 14th, 2007 AT 8:20 PM
Tiny
NOS
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Yes I would leave the battery hooked up to see if that cured the problem. No I looking at a wiring diagram when I wrote the last post. No when you turn the key on two relays are acctived one is the EEC relay wich is the computer and the other is the fuel pump. I'll keep this post till I get a reply to see what the out come is. 8) NOS
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Wednesday, March 14th, 2007 AT 8:43 PM
Tiny
DANFSMITH
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Thanks again, NOS. I'll have to try it tomorrow night because I need the truck in the morning. Funny thing is, I've given four jumps in the past eight months (including a Porche), here in NYC, and I couldn't get a jump to save my live. Probably because I'm the only hick living in NYC. I think I saw one guy I helped flipping me off on the Hutch Parkway!
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Wednesday, March 14th, 2007 AT 9:01 PM
Tiny
DANFSMITH
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NOS, if the relay was hanging open, wouldn't I hear the fuel pump keep running? Right now, the relay clicks, the pump runs, the relay clicks again, the pump stops. The relay seems to be working, but what will I do if the battery is dead tomorrow?
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Wednesday, March 14th, 2007 AT 9:26 PM
Tiny
DANFSMITH
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By the way, you guys kick the crap out of other online forums. Thanks.
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Wednesday, March 14th, 2007 AT 9:39 PM
Tiny
DANFSMITH
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Battery is dead this morning. Any other ideas?
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Thursday, March 15th, 2007 AT 6:47 AM
Tiny
NOS
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Ok bud a little more in depth.
1. As far as the relay goes it sounds like it is doing what it is supposed to be doing it comes on the pump runs and realy shuts off pump shuts of right?
2. Ok this is going to get a little more involved. Will answer this more this evening. I'am at work now. NOS
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Thursday, March 15th, 2007 AT 11:54 AM
Tiny
NOS
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Man i'am sorry to hear that it is a real shame people got to be that way. But you know the one that flipped you off he'll need help again someday and it will come back on him :=) hang in there. You may have given me an idea have you had your charging system checked. All this jumping chould have recked your voltage regulator and when you shut the truck off the reg is hanging open and draining the battery. Only a thought. 8) NOS
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Thursday, March 15th, 2007 AT 12:02 PM
Tiny
DANFSMITH
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Hey, NOS. To give you a little more history on the truck, it originally belonged to Firefighter Gregory Sikorsky. Greg was one of the firefighters who gave his all at the World Trade Center. Afterward, Greg's truck sat in his driveway for a few years until his wife could finally let it go. His brother-in-law had it for a little while, now I have it. Because the truck sat for so long, I've had a few challenges including changing some electrical components.

Sorry - long story for a short question: Could sitting for so long affect the regulator?
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Thursday, March 15th, 2007 AT 5:48 PM
Tiny
NOS
  • MECHANIC
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1. It is possible, but jumping dead vechiles is harder on them because if they are completely dead your regulator goes wide open to charge there and it is charging your also. And if one of there batterys had a shorted cell in it that just makes yours work all the harder.
And to answer your other question yes it is possible if the battery was down at the time of restart, it again could make the regulator do the same as I dicribed before.
One thing that you can try is charge your battery fully and on the altrernator there is a big plug unplug it and let it hang over night if you battery stay up then wa-la you'll know that it was the alternator if not were back to square one but it is worth a try sorry I know you need the truck but bud i'am not there so I can only tell you what I have experanced before. 8) NOS
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Thursday, March 15th, 2007 AT 6:01 PM
Tiny
DANFSMITH
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I really appreciate your help. When I bought the truck, they had put a new alternator and battery in it, which makes me wonder if the problem was there when I bought the truck.

I'll try the alternator thing tonight. Thanks again, NOS.
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Thursday, March 15th, 2007 AT 6:11 PM
Tiny
NOS
  • MECHANIC
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I know your just tring to help people by giving jumps but sometimes it is harder on a vehicle than people think. But it is nice that you do it. I keep an eye on this one I don't give up easy. 8) NOS
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Thursday, March 15th, 2007 AT 6:15 PM
Tiny
NOS
  • MECHANIC
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Did that fix the truck? 8) NOS
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Monday, March 19th, 2007 AT 9:25 PM
Tiny
DANFSMITH
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Yeah, NOS. It did. Thanks very much for your help! I really appreciate it. Take care.
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Tuesday, March 20th, 2007 AT 3:45 PM
Tiny
NOS
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Sorry didn't know didn't see any vots or feed back so just wondred. I am very glad I could help you :D 8) NOS
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Thursday, March 22nd, 2007 AT 7:07 PM

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