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New fuel pump has power but wont pump

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Old 07-03-2014, 09:03 PM
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New fuel pump has power but wont pump

Hey guys i have just about finished my restoration on my 1985 iroc and today was suppose to be the day to start her for the first time.

The fuel pump in the tank right now is brand new never used. So is the sending unit, strainer and filter. I cleaned the lines out so i already no there is no blockage in the lines.
I also tested the pump before installing it and it worked fine.

So at this moment the engine is complete besides an alternator but i wanted to crank this motor over today.

I tested the power at the pump under the car and it is getting power. But it is not pumping fuel at all.

I disconnected the oil/fuel pressure sensor and that did nothing.

Any help would be awesome thank guys.
Old 07-03-2014, 09:09 PM
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Re: New fuel pump has power but wont pump

Ill drop the tank and recheck everything is no one can think of anything else.
Old 07-03-2014, 09:31 PM
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Re: New fuel pump has power but wont pump

Do you hear the fuel pump prime at all? Check the fuse in the fender well and the fuel pump relay?
Old 07-03-2014, 09:46 PM
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Re: New fuel pump has power but wont pump

Originally Posted by antares57
Do you hear the fuel pump prime at all? Check the fuse in the fender well and the fuel pump relay?
there is not any priming noise and im not getting any power at the relay. Which is weird bc i thought there had to be power at the relay to have power at the pump. I do not think there is an inline fuse on an 85 harness. Just the one under the dash which is ok.
Old 07-03-2014, 10:39 PM
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Re: New fuel pump has power but wont pump

No use dropping the tank if you're not getting power at the relay. The problem should be power line before the relay. Apply 12v to the harness at the relay to the pump and see if it primes.
Old 07-04-2014, 03:10 PM
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Re: New fuel pump has power but wont pump

Originally Posted by antares57
No use dropping the tank if you're not getting power at the relay. The problem should be power line before the relay. Apply 12v to the harness at the relay to the pump and see if it primes.
ok im gonna try that im also thinking the problem might be a bad ground under the dash to the junction box. ill be looking hard
Old 07-04-2014, 03:18 PM
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Re: New fuel pump has power but wont pump

Even with the power off, make sure your frame has ground from the battery to it with an ohm meter, don't use a light since if it has a poor connection the light may still be on.
Should read zero ohms, and check one side of that relay, it should also read zero ohms, what does it read with the key off
Old 07-04-2014, 03:37 PM
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Re: New fuel pump has power but wont pump

Originally Posted by garydiamond
Even with the power off, make sure your frame has ground from the battery to it with an ohm meter, don't use a light since if it has a poor connection the light may still be on.
Should read zero ohms, and check one side of that relay, it should also read zero ohms, what does it read with the key off
ill need to get an ohm reader but at this moment i only have one ground coming off the battery and it is to the serp bracket.
Old 07-04-2014, 05:54 PM
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Re: New fuel pump has power but wont pump

Originally Posted by TBRays98
ill need to get an ohm reader but at this moment i only have one ground coming off the battery and it is to the serp bracket.
Buy one from here, and quickly fix it, I'm in electronics not a mech., your issue is electrical not something else, rust and water are your issue in the end. So buy one, and I will walk you through, if you need more help

http://www.harborfreight.com/7-funct...ter-98025.html
Old 07-04-2014, 08:00 PM
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Re: New fuel pump has power but wont pump

Originally Posted by garydiamond
Buy one from here, and quickly fix it, I'm in electronics not a mech., your issue is electrical not something else, rust and water are your issue in the end. So buy one, and I will walk you through, if you need more help

http://www.harborfreight.com/7-funct...ter-98025.html
thanks man ill buy one tomorrow and let you know whats going on.
Old 07-04-2014, 10:20 PM
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Re: New fuel pump has power but wont pump

Originally Posted by TBRays98
thanks man ill buy one tomorrow and let you know whats going on.
Doing the electric part is the easy part, worse issue, we find a wiring diagram of your car, and we fix it!!! Don't sweat the very small stuff I just joined here only to try to find out what my buddy's car is worth, but I saw your post and I love fixing things so if anyone else here needs my help with a weird electrical issue try me, I like a good challenge
Gary
Old 07-05-2014, 07:51 PM
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Re: New fuel pump has power but wont pump

ok i hooked up a power line directly to my fan relay power line and that gave the fuel pump relay power and now my fuel pump works.

Unfortunately im not getting spark.

As of now i have a power wire hooked up directly to my starter, alt., and fan relay power wire. Where do i need to place power to get power to the distributor is the new question. I dont have a factory positive cable and i think that why im having problems.
Old 07-05-2014, 08:13 PM
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Re: New fuel pump has power but wont pump

Originally Posted by TBRays98
ok i hooked up a power line directly to my fan relay power line and that gave the fuel pump relay power and now my fuel pump works.

Unfortunately im not getting spark.

As of now i have a power wire hooked up directly to my starter, alt., and fan relay power wire. Where do i need to place power to get power to the distributor is the new question. I dont have a factory positive cable and i think that why im having problems.
It's possible the same loss of power for the gas pump relay is also causing your spark issue, you may just have a bad fuse, not a blown fuse buy the meter, to test them let me look up the wiring diagram for your car
Old 07-05-2014, 08:19 PM
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Re: New fuel pump has power but wont pump

Pick yours out from this link, and post the url link here, I will hold your hand so you get a spark ASAP BUT BUY THE METER it makes thing so much easier, plus it's so easy to use, your dog can even test with it, what no dog sorry LOL

https://www.google.com/search?q=1985...=isch&imgdii=_
Old 07-05-2014, 08:56 PM
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Re: New fuel pump has power but wont pump

Unless you have a12 volt light bulb with two wires on it, we can't do too much, but I'm sure, you must have an old light bulb and socket kicking around with the wires still on the socket

Does this car use a control module? If so you got to check if it's getting power, because that would explain the fuel pump issue or it's been disabled, it maybe looking for another signal from a sensor, telling it to shut down, or even it could be bad!!!!
Old 07-05-2014, 09:06 PM
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Re: New fuel pump has power but wont pump

I figured out part of my spark problem there was a bent tooth from the the harness to the coil. Fixed that now i have power up to my two wire plug into the control module but i have no power coming out the control module.
Old 07-05-2014, 09:24 PM
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Re: New fuel pump has power but wont pump

Originally Posted by TBRays98
I figured out part of my spark problem there was a bent tooth from the the harness to the coil. Fixed that now i have power up to my two wire plug into the control module but i have no power coming out the control module.
Is yours a carb or fuel injection model? Do you have the light bulb? How did you measure YOU have power going into the control module?
Old 07-05-2014, 09:33 PM
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Re: New fuel pump has power but wont pump

She's FI and im using the test light still.
Old 07-05-2014, 10:33 PM
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Re: New fuel pump has power but wont pump

Originally Posted by TBRays98
She's FI and im using the test light still.
The control module has more than one hot input, which diagram is yours the one i'm looking at is this one, but I'm not sure it's even close to your car

It will not give power out, unless all the hot inputs are there


Last edited by garydiamond; 07-05-2014 at 10:42 PM.
Old 07-05-2014, 10:44 PM
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Re: New fuel pump has power but wont pump

One side of the coil is hot, is it? The other side will be Ac controlled by the module
Old 07-05-2014, 10:49 PM
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Re: New fuel pump has power but wont pump

Ok thanks for your help man i figured out the problem. I had a bad connection with my coil to module harness. It is brand new but i guess any pos can be sold through ebay. Thanks again hopefully this car will start real soon.
Old 07-05-2014, 10:54 PM
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Re: New fuel pump has power but wont pump

Originally Posted by TBRays98
Ok thanks for your help man i figured out the problem. I had a bad connection with my coil to module harness. It is brand new but i guess any pos can be sold through ebay. Thanks again hopefully this car will start real soon.
OK, great, still buy the meter
Old 07-14-2014, 09:51 PM
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Re: New fuel pump has power but wont pump

Hi guys! I got a similiar issue.... I got spark, and power EVERYWHERE, EXCEPT to the FUEL PUMP... IF I CUT the GREY WIRE and connect a FUSED DC power cable to the GREY WIRE and a GROUND WIRE, DIRECT to the BLACK wire... I GOT to have power to the pump, CORRECT? I THINK I have a failed ECM... I have power under the hood, at ALL POINTS of the fuel system, but from the FIREWALL to REAR BULKHEAD, I got NO POWER TO THE PUMP... Car is original, 90 K on it.. Been sitting but run every few weeks, and moved around the yard... Gave it to my daughter as a Graduation gift, and now want to let her run it, and THIS happens.. AAARRGFGHH! Owned it for 12 years and only put 3000 miles on her, with NEVER an issue and it died in the front yard as I was going to take it to put tires on it... Can not win...
Old 07-15-2014, 07:37 PM
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Re: New fuel pump has power but wont pump

Can you find a wiring diagram online, so we can check to see if the ECM is happy one of the end puts could be wrong, because of a sensor, or signal missing, giving the wrong info, that would cause the voltage to the pump to be missing
Old 07-19-2014, 11:24 AM
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Re: New fuel pump has power but wont pump

Originally Posted by rknm88
Hi guys! I got a similiar issue.... I got spark, and power EVERYWHERE, EXCEPT to the FUEL PUMP... IF I CUT the GREY WIRE and connect a FUSED DC power cable to the GREY WIRE and a GROUND WIRE, DIRECT to the BLACK wire... I GOT to have power to the pump, CORRECT? I THINK I have a failed ECM... I have power under the hood, at ALL POINTS of the fuel system, but from the FIREWALL to REAR BULKHEAD, I got NO POWER TO THE PUMP... Car is original, 90 K on it.. Been sitting but run every few weeks, and moved around the yard... Gave it to my daughter as a Graduation gift, and now want to let her run it, and THIS happens.. AAARRGFGHH! Owned it for 12 years and only put 3000 miles on her, with NEVER an issue and it died in the front yard as I was going to take it to put tires on it... Can not win...
I know this sounds obvious but did you check the fuses under the dash first?
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