Fuel Pump relay
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Fuel Pump relay
I already PMd Bill Curlee for some suggestions which I haven't had time to try yet as I just got home but figured I would take a shot and ask here if anyone else has experienced this issue. About 6 months ago I went to start the car and it would crank but sounded like it wasn't getting fuel. Naturally it was 10:30 at night in a dark parking lot 
so I had it flatbedded home and figured it out the next morning. So it was all good until this past Friday when I went to start the car for the 5th time that day same issue...damn 
: luckily I had bought a spare so I fixed it quickly and went on my way. Saturday it did it again while I was out of town so I swapped it with the one from the horn because who needs that as long as you have a finger 
So far so good but I cannot figure out why this keeps happening and it was so long between instances and then back to back
Anyone else have this issue? If so what was the cause or what did you do to fix it.
so I had it flatbedded home and figured it out the next morning. So it was all good until this past Friday when I went to start the car for the 5th time that day same issue...damn : luckily I had bought a spare so I fixed it quickly and went on my way. Saturday it did it again while I was out of town so I swapped it with the one from the horn because who needs that as long as you have a finger So far so good but I cannot figure out why this keeps happening and it was so long between instances and then back to back
Anyone else have this issue? If so what was the cause or what did you do to fix it.
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Joined: Jan 2007
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From: Dyer, IN
I already PMd Bill Curlee for some suggestions which I haven't had time to try yet as I just got home but figured I would take a shot and ask here if anyone else has experienced this issue. About 6 months ago I went to start the car and it would crank but sounded like it wasn't getting fuel. Naturally it was 10:30 at night in a dark parking lot so I had it flatbedded home and figured it out the next morning. So it was all good until this past Friday when I went to start the car for the 5th time that day same issue...damn : luckily I had bought a spare so I fixed it quickly and went on my way. Saturday it did it again while I was out of town so I swapped it with the one from the horn because who needs that as long as you have a finger
So far so good but I cannot figure out why this keeps happening and it was so long between instances and then back to back
Anyone else have this issue? If so what was the cause or what did you do to fix it.
so I had it flatbedded home and figured it out the next morning. So it was all good until this past Friday when I went to start the car for the 5th time that day same issue...damn : luckily I had bought a spare so I fixed it quickly and went on my way. Saturday it did it again while I was out of town so I swapped it with the one from the horn because who needs that as long as you have a finger So far so good but I cannot figure out why this keeps happening and it was so long between instances and then back to back
Anyone else have this issue? If so what was the cause or what did you do to fix it.
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known bad from fuel pump slot swapped with good from horn and fuel pump now works and horn doesn't...no...nothing more than that
Tech Contributor
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From: Van Buren Arkansas
Wounded Warrior Escort '11
If you open up the bad relay, check it out for whatever is wrong with it. I'm thinking that a bad crimp on the contacts in the fuse panel might be creating a resistance, therefore turning those contacts into a heater and ruining the relay....just a guess.
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Yeah I wonder if something is causing the relay to stick
Pro
Joined: Aug 2010
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From: Calgary Alberta
Is something wrong with your fuel pump? Generally speaking if a contactor/relay is porperly selected for the application it should virutally last forever. Now with many industries equipment is designed with a life span in mind so costs are considered and short cuts are taken. That said there are millions of cars on the road so I'd suspect the relay is likely right for the application, unless it's an Italian car!
Here's some reading on the subject: http://relays.tycoelectronics.com/ap...fs/13c3236.pdf
Here's some reading on the subject: http://relays.tycoelectronics.com/ap...fs/13c3236.pdf
Racer
Joined: Feb 2004
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From: St. Paul MN
I'd suggest you ensure you have the right relay GM part numbers installed, not aftermarket equivalents. While finding a replacement for my failed relay (the spot-welded contact on the actuated arm broke off), I found several pin-identical relays that have different amperage ratings and duty cycles, and some even listed as "timers". The ones geared to run 100% of the time were more expensive than the ones designed for intermittent use. They can be swapped briefly for testing, but I'd get the right OEM one installed. In my '02 most of the rectangular relays including fuel pump are GM P/N 12088567.
The two relays you chose to swap were used about as oppositely as possible. Unless you use your horn to say "I'm back here" like drivers in India, it should cycle far less frequently than the fuel pump relay.
I agree with the others - a postmortem of the dead relay(s) should tell you why they failed. If they both failed in the same way, you know which direction to look - supply side or load side.
Todd
The two relays you chose to swap were used about as oppositely as possible. Unless you use your horn to say "I'm back here" like drivers in India, it should cycle far less frequently than the fuel pump relay.
I agree with the others - a postmortem of the dead relay(s) should tell you why they failed. If they both failed in the same way, you know which direction to look - supply side or load side.
Todd
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Thread Starter
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Is something wrong with your fuel pump? Generally speaking if a contactor/relay is porperly selected for the application it should virutally last forever. Now with many industries equipment is designed with a life span in mind so costs are considered and short cuts are taken. That said there are millions of cars on the road so I'd suspect the relay is likely right for the application, unless it's an Italian car!
Here's some reading on the subject: http://relays.tycoelectronics.com/ap...fs/13c3236.pdf
Here's some reading on the subject: http://relays.tycoelectronics.com/ap...fs/13c3236.pdf
I do appreciate the info though.
Once I do some digging into this I will post what I find.
I was just curious to see if anyone else has experienced this.
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I'd suggest you ensure you have the right relay GM part numbers installed, not aftermarket equivalents. While finding a replacement for my failed relay (the spot-welded contact on the actuated arm broke off), I found several pin-identical relays that have different amperage ratings and duty cycles, and some even listed as "timers". The ones geared to run 100% of the time were more expensive than the ones designed for intermittent use. They can be swapped briefly for testing, but I'd get the right OEM one installed. In my '02 most of the rectangular relays including fuel pump are GM P/N 12088567.
The two relays you chose to swap were used about as oppositely as possible. Unless you use your horn to say "I'm back here" like drivers in India, it should cycle far less frequently than the fuel pump relay.
I agree with the others - a postmortem of the dead relay(s) should tell you why they failed. If they both failed in the same way, you know which direction to look - supply side or load side.
Todd
The two relays you chose to swap were used about as oppositely as possible. Unless you use your horn to say "I'm back here" like drivers in India, it should cycle far less frequently than the fuel pump relay.
I agree with the others - a postmortem of the dead relay(s) should tell you why they failed. If they both failed in the same way, you know which direction to look - supply side or load side.
Todd
as I said I will post a follow up later once I get into it
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
very easy to test...with a 12 volt source, and a meter. Two things can fry a relay...too much voltage on the coil..or too much current on the contacts. My guess is, you have neither condition.
Le Mans Master
Joined: Apr 2005
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From: Scarborough ONTARIO
Same thing happening to me as well, bought a Racetronix Fuel pump but will check relay and other electrical stuff whn i get a time, car still at job's place but we dont have time to fix our own cars, Super busy these days, being myself a mechanic cant help much myself, too many customer cars.
The only thing i did hooked up FP gauge and it shows 61 psi at the fuel rail, but 2 hrs later car wont start just cranking in this case no Fuel pressure at all O, and again 2 hrs later it will start with no problem, give me a solid problem, no time to emss around with this intermittent problem.
some times car starts but after few tries...what the hell? i was low on gas when it happend but added about 5 gallon of gas still doing same chit.
The only thing i did hooked up FP gauge and it shows 61 psi at the fuel rail, but 2 hrs later car wont start just cranking in this case no Fuel pressure at all O, and again 2 hrs later it will start with no problem, give me a solid problem, no time to emss around with this intermittent problem.
some times car starts but after few tries...what the hell? i was low on gas when it happend but added about 5 gallon of gas still doing same chit.
Tech Contributor
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From: Dyer, IN
Tech Contributor
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From: Van Buren Arkansas
Wounded Warrior Escort '11
I agree. Hard failures are the easiest to troubleshoot whereas the intermittent ones are by far the more difficult and even worse is when two or more issues is causing a single problem.
Le Mans Master
Joined: Apr 2005
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From: Scarborough ONTARIO
Man i have absolutely no time to trouble shoot, and its parked on parking lot at the end and we have rain everyday as well, i myself a mechanic and plenty of electrical testing tools, so will do some test asap, but lemme tell ya intermittent problems like this is hard chief, also we cant wok on our own cars when we have plenty of customers, and we are stupidly busy.
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Ok well the car has been fine since the last incident. I just went to Sams club and filled up, went to leave and it was dead ended up pushing the car into the lot and sat there for 35 minutes trying everything. The relay is certainly getting power you can feel it click but I had 0 pressure going to the motor as indicated by my fuel pressure guage...after several cycles of turning the car on and off the pump eventually gave me pressure and the car drove home fine and restarted fine 3 times afterwards.
Of note, the car maintains fuel pressure the entire time it is driving no erratic readings etc. I am thinking perhaps there is a dead spot in the motor of the pump and it is luck of the draw on where it stops and each time I cycle it on and off it moves just enough until it reaches a good spot so once it is running its fine. The only thing is that doesn't explain why swapping the relay out sometimes makes it work although this time it didn't
ended up pushing the car into the lot and sat there for 35 minutes trying everything. The relay is certainly getting power you can feel it click but I had 0 pressure going to the motor as indicated by my fuel pressure guage...after several cycles of turning the car on and off the pump eventually gave me pressure and the car drove home fine and restarted fine 3 times afterwards.Of note, the car maintains fuel pressure the entire time it is driving no erratic readings etc. I am thinking perhaps there is a dead spot in the motor of the pump and it is luck of the draw on where it stops and each time I cycle it on and off it moves just enough until it reaches a good spot so once it is running its fine. The only thing is that doesn't explain why swapping the relay out sometimes makes it work although this time it didn't
Pro
Joined: Aug 2010
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From: Calgary Alberta
With brushed DC motors it is quite common to have a brush become sticky and not make contact with the commutator. What can also happen is wear on the commutator causes the brushes to not make proper contact. Once running the motor will appear fine as momentum keeps the motor running past the bad spot. Try tapping on the pump if possible next time this happens.
Option B, get a new pump.
Option B, get a new pump.
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Wouldn't he have to reach inside the fuel tank to do that?
FWIW, I'd like to see a dissected relay(s) and take a look at the contacts. If they're toast, the higher-than-normal-current problem mentioned by Lucky is a good place to start.
My first thought on that would be a pump drawing much higher than normal current from:
a.) poor ground, either at the ground stud or somewhere in the ground wiring harness, or
b.) failing pump
I'm surprised that a fuse isn't snapping though since excess current is what they're designed to prevent, unless the excess current is just enough under the threshold of a fuse and yet just enough that over time, the contacts fail prematurely.
Maybe hook an ammeter in series with the B+ going to the pump and see how much current the pump is drawing?
FWIW, I'd like to see a dissected relay(s) and take a look at the contacts. If they're toast, the higher-than-normal-current problem mentioned by Lucky is a good place to start.
My first thought on that would be a pump drawing much higher than normal current from:
a.) poor ground, either at the ground stud or somewhere in the ground wiring harness, or
b.) failing pump
I'm surprised that a fuse isn't snapping though since excess current is what they're designed to prevent, unless the excess current is just enough under the threshold of a fuse and yet just enough that over time, the contacts fail prematurely.
Maybe hook an ammeter in series with the B+ going to the pump and see how much current the pump is drawing?
Last edited by LoneStarFRC; May 19, 2011 at 01:07 PM.
Tech Contributor
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From: Dyer, IN
With brushed DC motors it is quite common to have a brush become sticky and not make contact with the commutator. What can also happen is wear on the commutator causes the brushes to not make proper contact. Once running the motor will appear fine as momentum keeps the motor running past the bad spot. Try tapping on the pump if possible next time this happens.
Option B, get a new pump.
Option B, get a new pump.
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well as soon as I can get under the car I will be doing that before we ever take anything out....heading out to take a look at a few things