Fuel Pump Mystery....
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Audiworld Junior Member
Joined: Jan 2009
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Fuel Pump Mystery....
HI All,
I have a 2001 AR Tip and recently the fuel pump started acting up.
At first the car would just stop running for no apparent reason. My indy mechanic thought he had it fixed with a new MAF, but when he took it for a test drive it died again. He tried smacking the rear passenger seat and tank with a mallet and sure enough it started - it happened once more and he got it started the same way, so his conclusion was the fuel pump - at $1100.
So, I'm taking it on as it's pretty straight forward and I've followed the guide from this site successfully - everything fit perfectly and all connections are solid.
However, now it won't start and I don't sense any power to the pump.
Is there something obvious that I need to reset? Bleed? I've checked the #28 fuse. I've replicated the position of the jumpers on the backside of the pump top plate, but should I try reversing them? I'm hesitant to think that it's a relay problem, since hitting the tank seemed to get the pump going previously... any thoughts, suggestions?
Thanks in advance!
I have a 2001 AR Tip and recently the fuel pump started acting up.
At first the car would just stop running for no apparent reason. My indy mechanic thought he had it fixed with a new MAF, but when he took it for a test drive it died again. He tried smacking the rear passenger seat and tank with a mallet and sure enough it started - it happened once more and he got it started the same way, so his conclusion was the fuel pump - at $1100.
So, I'm taking it on as it's pretty straight forward and I've followed the guide from this site successfully - everything fit perfectly and all connections are solid.
However, now it won't start and I don't sense any power to the pump.
Is there something obvious that I need to reset? Bleed? I've checked the #28 fuse. I've replicated the position of the jumpers on the backside of the pump top plate, but should I try reversing them? I'm hesitant to think that it's a relay problem, since hitting the tank seemed to get the pump going previously... any thoughts, suggestions?
Thanks in advance!
Thread Starter
Audiworld Junior Member
Joined: Jan 2009
Posts: 25
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I first tested power to the new pump, just to be sure, with a 12v battery charger and confirmed it works.
Then I put a meter on the pump plug and am only getting @9v +/-. So, I'm charging my battery (since I've been draining
it with long cranking) and I'm going to pop a new relay in. The wiring around the fuse plate looked solid.
I'm nearing 200,000 now and I suppose almost everything in this beast can and will go out at any moment.
Then I put a meter on the pump plug and am only getting @9v +/-. So, I'm charging my battery (since I've been draining
it with long cranking) and I'm going to pop a new relay in. The wiring around the fuse plate looked solid.
I'm nearing 200,000 now and I suppose almost everything in this beast can and will go out at any moment.
Thread Starter
Audiworld Junior Member
Joined: Jan 2009
Posts: 25
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UGH!! Why is this being a PITA?!
So, I cleaned the battery terminals and leads.
Put new relay in and now pushing @11.6v at the pump connection- which is great....but it still wont turn the pump on!
Put the 12v charger on and let it run for @20 seconds to confirm that fuel gets to engine - which it does.
What am I missing here?!!
I did notice that the connection has 4 slots - the 2 outer ones are where I checked for the 12v, but I see that the 2 inner carry @1.5v when the key gets inserted.
Is this a problem? I assume this is sending energy to the aux pump side...?
Even though I put the leads on the bottom side of the pump as they were mounted on the old pump- should I try reversing them?
Put new relay in and now pushing @11.6v at the pump connection- which is great....but it still wont turn the pump on!
Put the 12v charger on and let it run for @20 seconds to confirm that fuel gets to engine - which it does.
What am I missing here?!!
I did notice that the connection has 4 slots - the 2 outer ones are where I checked for the 12v, but I see that the 2 inner carry @1.5v when the key gets inserted.
Is this a problem? I assume this is sending energy to the aux pump side...?
Even though I put the leads on the bottom side of the pump as they were mounted on the old pump- should I try reversing them?
I first tested power to the new pump, just to be sure, with a 12v battery charger and confirmed it works.
Then I put a meter on the pump plug and am only getting @9v +/-. So, I'm charging my battery (since I've been draining
it with long cranking) and I'm going to pop a new relay in. The wiring around the fuse plate looked solid.
I'm nearing 200,000 now and I suppose almost everything in this beast can and will go out at any moment.
Then I put a meter on the pump plug and am only getting @9v +/-. So, I'm charging my battery (since I've been draining
it with long cranking) and I'm going to pop a new relay in. The wiring around the fuse plate looked solid.
I'm nearing 200,000 now and I suppose almost everything in this beast can and will go out at any moment.
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From: In the Cloud
So, I cleaned the battery terminals and leads.
Put new relay in and now pushing @11.6v at the pump connection- which is great....but it still wont turn the pump on!
Put the 12v charger on and let it run for @20 seconds to confirm that fuel gets to engine - which it does.
What am I missing here?!!
I did notice that the connection has 4 slots - the 2 outer ones are where I checked for the 12v, but I see that the 2 inner carry @1.5v when the key gets inserted.
Is this a problem? I assume this is sending energy to the aux pump side...?
Even though I put the leads on the bottom side of the pump as they were mounted on the old pump- should I try reversing them?
Put new relay in and now pushing @11.6v at the pump connection- which is great....but it still wont turn the pump on!
Put the 12v charger on and let it run for @20 seconds to confirm that fuel gets to engine - which it does.
What am I missing here?!!
I did notice that the connection has 4 slots - the 2 outer ones are where I checked for the 12v, but I see that the 2 inner carry @1.5v when the key gets inserted.
Is this a problem? I assume this is sending energy to the aux pump side...?
Even though I put the leads on the bottom side of the pump as they were mounted on the old pump- should I try reversing them?
Thread Starter
Audiworld Junior Member
Joined: Jan 2009
Posts: 25
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Thanks for the reply georgeb!
If the pump is delivering fuel to the engine with the 12v charger, then it should be delivering fuel to the engine with 11.6 volts. Only the two outer wires (one green with a yellow stripe (12vdc) and one brown (ground) operate the fuel pump. The other two are for the fuel gauge connection.
AudiWorld Senior Member
Joined: Jan 2015
Posts: 1,186
Likes: 43
From: Sierra Vista, AZ
Make sure the pins inside the connector aren't being pushed back or deflected when you hook up the connector. On these type of problems I like to use a Power Probe tester. It works similar to a test light but will read voltage as well as apply current so you can energize a circuit. The Power Probe isn't cheap (about $150-$170 US) but it earns its keep on electrical work and saves a lot of time. Consider taking the connector apart and repairing it. Are you getting 12v out of the connector? If not and you hooked the charger direct to the pump then it's a wiring/ connector problem.
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Thread Starter
Audiworld Junior Member
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Thanks for the reply Harleyguy!
Make sure the pins inside the connector aren't being pushed back or deflected when you hook up the connector. On these type of problems I like to use a Power Probe tester. It works similar to a test light but will read voltage as well as apply current so you can energize a circuit. The Power Probe isn't cheap (about $150-$170 US) but it earns its keep on electrical work and saves a lot of time. Consider taking the connector apart and repairing it. Are you getting 12v out of the connector? If not and you hooked the charger direct to the pump then it's a wiring/ connector problem.
I sure wish I had the extra $ to throw on the Probe, but alas I can't. The pins getting pushed back or something with the connector seems like a good bet, so I'll try to dismantle it and see if that helps.
Any other suggestions by anyone will be happily tried and I'll post back if I don't just sell this money/time pit.
Thanks!
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From: Ocean Isle Beach NC
I will first say I am not competent at reading wiring diagrams. I seem to remember something on this forum about the power to the fuel pump being dependent on other issues being correct before the power is sent to the fuel pump. I assume it is a safety issue. No fuel pumped unless everything else is good. So, maybe you are getting power to the pump with ignition on but it does not continue to provide power after cranking starts because some other condition is not being met. Have you checked the power to the pump only with the ignition in the on position or with it actually cranking the starter and after?
Thread Starter
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What's driving me crazy about this...
I will first say I am not competent at reading wiring diagrams. I seem to remember something on this forum about the power to the fuel pump being dependent on other issues being correct before the power is sent to the fuel pump. I assume it is a safety issue. No fuel pumped unless everything else is good. So, maybe you are getting power to the pump with ignition on but it does not continue to provide power after cranking starts because some other condition is not being met. Have you checked the power to the pump only with the ignition in the on position or with it actually cranking the starter and after?
1) the harness to the pump acts and sends voltage as it should. It's at like .01v with key in and then jumps to @11.65v when cranking.
2) I've moved the harness while cranking and the voltage flow remains constant. (The wiring is stiff though.)
3) verified new pump works with 12v charger. (Fuel sent all the way to engine and it started briefly)
4) replaced relay. (because the old one was only pushing @ 9.5v)
5) replaced fuse. (just in case)
6) cleaned battery post and leads.
7) tried conduct grease on the harness to pump connection
I'm thinking that its got to be something with the harness connection? But even if the pins are being pushed back - there would still be contact...?
Ugh!! Please- someone make me feel stupid with an obvious fix I'm not seeing!!
Last edited by alonkut; Feb 27, 2018 at 07:36 AM.
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