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86 XT Gl-10 with no power @ fuel pump?


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34 replies to this topic

#1 Rossi86

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Posted 23 April 2011 - 04:43 PM

Where is the relay, It's not ware the books told me to look?

#2 john in KY

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Posted 23 April 2011 - 04:58 PM

It is either under the radio or behind the trim panel, back seat, passenger side. I recall there is a relay there and fairly sure it is for the fuel pump.

If the car has been sitting for years, which I think it has, good chance the fuel pump is now toast.

Could just run 12 volts to it and ground the other side to check if it still works.

#3 Rossi86

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Posted 23 April 2011 - 07:38 PM

I tested the fuel pump using a 12 battery and it and the engine run fine, I have traced the wire to the passeger side dash panel then to the center of the dash thanks for letting me know I'm looking in the right place :) . I'll pull the radio when it stops raining in PA.

#4 john in KY

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Posted 24 April 2011 - 05:46 AM

I think those 4 relays in a rack under the radio can be gotten to by pulling the center console. Just been too many years to be sure.

#5 Cougar

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Posted 24 April 2011 - 10:41 AM

If you haven't checked the fusible links already that may be a good thing to do also.

#6 ruparts

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Posted 24 April 2011 - 11:45 AM

hi,
are you sure its the 12v side? i had several that the ground side was the problem,, the ground is inside the ECM ,and it went out, i made a new ground near the pump to the body and worked fine. be aware that 12v does not go to the pump with the switch on, only for a couple of seconds. if you plug together the read memory connectors , with ign switch on it cycles the voltage to it every few seconds so you can do tests.

#7 Rossi86

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Posted 24 April 2011 - 10:11 PM

I used a computer safe test light with a good ground off of the blue wire to the clean built on the body and no juice. No voltage at all when my friend turned the key to on or start. How do I get the radio out with out taking the hole dash out there are four screws I can't get to?

#8 Rossi86

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Posted 24 April 2011 - 10:14 PM

If you haven't checked the fusible links already that may be a good thing to do also.


Yes all fuses are good I put in all new fusible links. Thank you for the reminder though.

#9 john in KY

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Posted 25 April 2011 - 05:24 AM

Fairly sure the center console will need to be pulled. Shifter handle has one or two small screws. The console has 4 screws, two on a side, down by the carpet. They are hidden behind small plugs about one inch square. Have to find them and remove to get to the screws. Those plugs aren't easy to find but they are there.

#10 Rossi86

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Posted 25 April 2011 - 06:56 PM

Fairly sure the center console will need to be pulled. Shifter handle has one or two small screws. The console has 4 screws, two on a side, down by the carpet. They are hidden behind small plugs about one inch square. Have to find them and remove to get to the screws. Those plugs aren't easy to find but they are there.


I have the center console lose, I would take it out but the cable for the fan control is still attached, the fan control won't come out and I can't find a good diagram of it. Blue wire to the fuel pump is led me to the center of the dash...

#11 john in KY

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Posted 25 April 2011 - 09:28 PM

I emailed some photos today. Follow that cable and it connects very near the gas pedal. Just unclips. If you can see the 4 relays, the fuel pump relay is on the right and in the back.

#12 ruparts

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Posted 26 April 2011 - 12:39 PM

I used a computer safe test light with a good ground off of the blue wire to the clean built on the body and no juice. No voltage at all when my friend turned the key to on or start. How do I get the radio out with out taking the hole dash out there are four screws I can't get to?


hi, not sure on how you made the test, you should put the test meter neg- lead to a good body ground , ( not either wire) , then check for +12v on the blue wire when the ign is switched on (about 1 second ) it should stay on if the ign switch goes to start mode ,, also if you plug the green test connectors together it will cycle the blue wire + every few seconds with the ign switch in the on position. the idea is , we're checking the ground side of the circuit , try it this way. i have had problems on several cars that the pump would not run and none were the +voltage side of the circuit, but a bad ground inside the ECM .

Edited by ruparts, 26 April 2011 - 12:51 PM.


#13 Rossi86

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Posted 01 May 2011 - 01:33 PM

I got the fuel relay, the relay is working. The computer test good but still no fuel, and no power coming to the fuel pump. I can't seem to find how the computer is aware of the need for fuel? I'm thinking it's a sensor, air, crank, or throtle.

#14 naru

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Posted 01 May 2011 - 02:47 PM

ECU needs to see ignition pulses from the coil in order to run the pump more than 1 second or so.

Does the tach move when cranking?

Does the blue output wire see any voltage at the relay?
Does the white(?) input wire remain powered all the time?

Relay might operate,but, if white is unpowered,blue output will be too.
If blue powers up at the relay but not the pump,then it is broken.

#15 Cougar

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Posted 01 May 2011 - 04:03 PM

Looking at some info I have it shows that power to the FP relay comes from the green fusible link on a red wire to the relay. Have you checked the connection to power there and made sure that is ok? If that is good then you could try running a hot wire to the blue fuel pump wire or jumper the relay, and run a ground wire to the blk wire on the ECU. My data doesn't show the ECU pin numbers but the blk wire is in between blk/yel and blu/blk wires near the end of the plug. It also ties to pin 9 of the diag connector so it may be more convenient to make the ground there. If the pump works doing that then the pump circuit wiring from the relay to the ECU is ok. The ground through the ECU may be the trouble. If I understand correctly though you aren't getting power from the fusible link.

Edited by Cougar, 01 May 2011 - 04:08 PM.


#16 Rossi86

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Posted 03 May 2011 - 07:37 PM

How can I get to the ECM, too test the wires for any brakes or a pinchs? How can I test the ECM? I know the fuel pump works, the fead wire is solid, the relay is working, but no power, or a signal from the ECM. the Igniton is working. the is no ground signal as well.

#17 Cougar

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Posted 04 May 2011 - 02:20 AM

The power to the pump comes from the green fusible link, which passes through the relay on to the pump. If there is power on both sides of the green link then there is a break in the red wire that ties to the relay.

#18 Rossi86

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Posted 05 May 2011 - 10:08 AM

Update. There is power at the yellow wire, from the coil. What calls for more fuel? the pump has no voltage thanks to the ECM. It is not sensing the need for fuel. How on a Subaru dos the EMS do this? On a camaro its the MAP sensor.

#19 ruparts

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Posted 05 May 2011 - 02:46 PM

How can I get to the ECM, too test the wires for any brakes or a pinchs? How can I test the ECM? I know the fuel pump works, the fead wire is solid, the relay is working, but no power, or a signal from the ECM. the Igniton is working. the is no ground signal as well.


hi, i have followed this thread and am still not sure you have eleminated the ground side of the fuel pump problem. have you tested the blue positive wire for voltage while providing a completely separate independent ground for the white wire ??
the white ground wire goes from the pump and into the ecm to ground, i have had several that did not make a ground and i had to cut the white wire near the pump and run it to a good body ground near the pump,, . when originally tested these did not show voltage because there was no ground.. connect the white wire to a good ground, then see if the blue will show volts. use a temporary jumper to ground to do the test if you don't want to cut first.

Edited by ruparts, 05 May 2011 - 02:52 PM.


#20 Cougar

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Posted 05 May 2011 - 03:14 PM

Update. There is power at the yellow wire, from the coil. What calls for more fuel? the pump has no voltage thanks to the ECM. It is not sensing the need for fuel. How on a Subaru dos the EMS do this? On a camaro its the MAP sensor.


Power does not come from the ECM for the fuel pump. It comes from the the fusible link, through the relay and to the pump. The return side of the pump grounds through the ECU. You need to verify power is getting to the relay.

#21 Rossi86

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Posted 06 May 2011 - 10:06 AM

Power does not come from the ECM for the fuel pump. It comes from the the fusible link, through the relay and to the pump. The return side of the pump grounds through the ECU. You need to verify power is getting to the relay.


Their is power to the relay (hot red wire), the relay is not being activated nether is the ground from the fuel pump to the ECM (black wire in a gray casing). Is there a signal from the Airflow-meter in these cars to call the ECM to switch on the fuel pump? And how can I test it?

#22 Cougar

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Posted 06 May 2011 - 10:39 AM

Since the fuel pump relay isn't turning on I think you now need to make sure the ignition relay is working ok and the ECU is getting proper power to it for the next step in this process.

Here is a link that may help you with the ECU pins that require power. It is for an 87 model but may be the same for yours. One of the posts mentions what pins to check on the ECU for power.

http://www.ultimates...ad.php?t=122621

See if there is a wht/red wire on pins 27 and 35 of the ECU connnector. If there is and there is no power on them then the ignition relay needs to be checked.

Edited by Cougar, 06 May 2011 - 10:44 AM.


#23 naru

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Posted 06 May 2011 - 01:17 PM

Their is power to the relay (hot red wire), the relay is not being activated nether is the ground from the fuel pump to the ECM (black wire in a gray casing). Is there a signal from the Airflow-meter in these cars to call the ECM to switch on the fuel pump? And how can I test it?


No airlow meter fuel pump switch on subes.

BTW,An 86 w/a flapper style MAF will have different ECU pin-outs than an 87 w/a hotwire MAF.

Edited by naru, 06 May 2011 - 01:22 PM.


#24 Cougar

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Posted 07 May 2011 - 04:15 PM

BTW,An 86 w/a flapper style MAF will have different ECU pin-outs than an 87 w/a hotwire MAF.


I was hoping that they would be the same for both years but I'm not surprised that they are different. Thanks again for that info Naru. The OP would be wise in investing in a service manual to help with this issue and others that may occur in the future.

#25 Rossi86

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Posted 07 May 2011 - 06:49 PM

The ignition Relay is working find I tested it with both a Volts ohms meeter and buy running the car on a bye pass to the fuel pump. I will check the ECM pins for the ground and the ignition imputt.




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