I've searched through this forum and the internet and while I've seen several threads on this topic, i've not found one that resolves the problem, they either stop open ended or the problem went away or someone fixed by installing a kill switch, so I'm starting a new thread in case someone might have another suggestion/resolution.

Recently my car was running rough and periodically stalling. Finally it stalled while driving and when we pulled it to the side of the road no matter how much we cranked it would not start, eventually draining the battery. Took it to a garage they boosted the battery, but it would not start. Eventually they kept messing with this and that and it started, but they don't know why, but it also ran rough and after sitting for awhile they noticed the battery was weak again and it wouldn't fire so they gave it another boost and it ran fine a little rough but it ran. I had the battery tested at Sears (it's actually not a die hard and it was in the car with I purchase it over 2 years ago). Sears said it was actually fine, but next morning (35 degrees) it was dead as a door nail. I assumed since it was cold over night that this battery just could not hold the charge in the cold so I swapped it out for a die hard. Still ran rough and stalled, but would restart fine. I switched out the PCV valve on a whim and wala it now runs like a champ, no more rough idle, no more stalling and check engine light disappeared. Ran it over an hour beautifully. Next morning batter dead as a door nail (new battery!) again. I charged her drove her an hour and again ran beautiful, like a champ.

My new problem now. After I shut it off I noticed the fuel pump remained running. A after 15 minutes it is still running. That is what I believe is causing the battery to drain over night. I ran the following tests, disconnected the fuel pump relay while the car was running and she kept running fine (so I guess the oil pressure switch is working?) I turned off the car and disconnected the fuel pump relay, but pump kept running. I then disconnected the oil pressure switch above the oil filter and the pump kept running. I disconnected the oil pressure switch that sends info to the gauge (just for the heck of it) and the pump still keeps running.

Only way I have found to stop it is to either disconnect the battery or the fuse that is on the passenger side of the car and near the front of the engine.

I tried disconnecting the fuse under the dash that says F/P pump, but the pump keeps running. I disconnected the fuse under the car that says ECM and the pump keeps running.

No idea what is telling it to keep going. Any thoughts/recommendations and solutions would be appreciated. Thx all for reading.

 

Need to know what car, year, engine and fuel system (TPI, TBI or carb).

 

What year and what engine?

The inline fuse under the hood provides power to the fuel pump relay that ends up going to the pump, and battery power for the ECM.

The fuse labeled FP/INJ2 is for a bank of 3 injectors. The relay coil gets +12v from the ECM to enable it.

The fuse labeled ECM is ignition switched power to the ECM.

I've seen this, at the fuel pump relay the wires going to it has the insulation falling off. And the right ones are shorted together causing the pump to run.

RBob.

 

Thx, sorry I should have posted that info. It's a 1988 V6 2.8L. Bob, regarding the insulation falling off and shorting together, given I've disconnected the fuel pump relay and the OPSU that shouldn't be a problem I'm guessing. Thx guys any thing you can thing of will be appreciated.

 

I noticed too that since this problem started i'm going through gas quickly. On another forum a bronco owner who had the same problem said the EGR sensor was the cause of his problem. I can't find the EGR sensor on this vehicle, but I do see the EGR valve and I don't see a sensor coming off of it. I do know where there is what I think is the EGR solenoid? It has a vacuum hose connected to it, but I disconnected the power connector to that and pump still was running.

 

Power for the fuel pump ONLY goes through either the fuel pump relay, the oil pressure switch (not pressure sensor to gauge) or the "fuel pump test" terminal at the ALDL connector (test terminal needs to be connected to 12 volts for pump to run). If you disconnect the fuel pump relay and the oil pressure switch, the pump should not have power going to it. If it continues to run, you will have to start tracing the wire back from the pump to see where it is getting power.

 

Yup, sounds like your FP relay or oil psi sending unit is bad.

 

Thanks gentlemen. I've seen other posts that say some sensors can make the fuel pump think the engine is running and thus cause pump to keep running if those sensors are malfunctioning, like the EGR sensor, the Ignition Control Module (ICM) or the computer itself (ECM.) Thoughts?

 

No! the only way the fuel pump gets power is through the fuel pump relay or the oil pressure switch. If these are removed/disabled, the fuel pump can not run unless there is a wiring problem. Go to AustiThirdgen.org and look at the wiring diagrams for your car to see what I mean.

 

He says he has unplugged both and that the pump keeps running . No way an unplugged sending unit or relay could be keeping the pump running , Gotta be either a short in the harness or a botched wiring hack in that circuit ....

Our cars , with their OBD 1 systems , have no such functionality programmed in . The only sensor that could malfunction and keep the pump running would be the oil pressure sensor that switches power to the pump . And since you've unplugged that , we know that's not your problem , same for the relay you say you unplugged . Let me ask , cause my 89 2.8 has 3 relays very near each other (fuel pump , electric radiator fan , and A/C compressor clutch) are you SURE you unplugged the correct relay ?

Well said Big Al ...

 

If they both failed (stupid rare) unplugging one at a time instead of both at the same time may not uncover the problem. (I have seen it happen)
And yes, unplugging the correct rectangle shaped relay is important also.

 

It would be the wires that go to the FP relay. Even without the relay if the correct two wires short together the fuel pump will run. This would be the power feed to the relay and the wire that goes to the pump.

RBob.

 

If I remember correctly, if the fuel pump stays on with the engine off/key off, try disconnecting the computer. If the fuel pump stops running the computer is bad; usually bad fuel pump timer circuit.

 

Hi Orange Bird, definitely unplugged the fuel relay, i've replaced it once before in the spring so I know it was the fuel relay I unplugged and yes both the fuel relay and the OPSU were unplugged at the same time and the pump continues to run. Right now I can't get the car started at all. It just cranks and cranks and after a bit I smell fuel so I know fuel is making it to the engine. I'm going to test for a spark tomorrow and see if I can test the Ignition control module as we'll. However, the pump continues to run no matter what I do. I've looked high and low and don't see any exposed wires anywhere at least not visible. The wires on the fuel relay and the OPSU look perfectly covered. I made sure to move the wires for each of them apart so there is space between each wire connecting to each at least at the connector ends, but didn't help, pump runs. It's possible one of these is grounding somewhere else along the way, but not easy to find I think. When she was running I did have a check engine light which translated to fuel system as noted below. Back in the spring I changed the fuel relay in case this was the cause of the code but it did not go away. On occasion it would disappear but come back shortly after, then for the last two months it stayed constant. Funny thing is that when I changed the PCV valve the check engine light disappeared and never came back until she would no longer start.

Cod 54 Means:
Fuel
pump circuit
(1985 and later vehicles) - Mines an 88
=============================
Voltage
at terminal B2 is less than 2 volts for 1.5 seconds since last
reference pulse was received.
=============================
Faulty
fuel pump relay, circuit and connections.
Faulty
oil pressure switch.

However, I'm not getting this code anymore.

When I look at the fuel relay connector I do notice that amongst the pins inside one appears not to be there and two wires (green wires) are wired to the first. Is this normal? I can post a picture if it helps. However, the car was like that since I got it about 2 years ago and it's run fine till recently and check engine light only showed up this past spring while it was there.

So now I have at two problems (at least.) Fuel pump runs, car cranks but won't start. She's always had a hard start in cooler weather (10 seconds of cranking to start her, but now not even that will get her going.)

 

Again, the computer is bad, it has a bad fuel pump timer circuit. Verify this by disconnecting the computer, if the fuel pump stops running when you disconnect the computer, it's definitely a bad computer.

 

Thx MSgt, I pulled the fuse to the ECM, but the fuel pump kept running, at least it was a fuse under the dash (driver side) that listed as ECM, not sure if that is a sufficient enough test though. RBob above wrote "The fuse labeled ECM is ignition switched power to the ECM", so maybe not sufficient as a test for the pump. I'll try disconnecting and see what happens.

 

Yeah, you have to disconnect the computer harness for this test.

 

OK got up early this morning and disconnected the computer harness from under the passenger side dash and pump still ran so doesn't look to be the computer. I was able to get the car running this a.m. too.

 

Hi ,

The computer (ECM) could not cause this , providing you took out the relay and the pump still ran . The ECM provides a signal to the relay's coil only , and the relay's coil uses this signal to engage the relay's switched contacts to provide power to the pump . No where does the ECM power the pump directly as seen by a quick look at the wiring diagrams hosted at austinthirdgen.org , and so there is no possible failure mode of the ECM that could keep the pump running with the relay removed .

At this point I gotta ask , has anyone done anything with any of the car's wiring ? Such as a radio , foglight , alarm system , or other accessory install ? Because it's sure starting to sound as if someone has miswired something and now has constant power going to the pump . Sure , there could be a short circuit in the harness between the fuel pump wire and a constant 12V wire , but this is far less likely than the mistakes some folks make when installing aftermarket equipment .

Bottom line = Inspect every inch of the under hood and under dashboard harnesses , paying particular attention to any areas that look like someone has messed with them . Good Luck and report back with your findings .......

 

Thx Orange bird, we've had the car two years and have not done any wiring work to it. It has the radio that came with the car and not added any new peripherals. We did swap out speakers last December, but used existing wires to simply plug them in. This constant running of the pump appeared to start after the car died on the road and I had it towed to a local shop. The battery was dead so they boosted it and later noticed it had charged down again and gave it another boost. They never found the cause of any issue as the car started back up. I replaced the battery thinking it had just had it and could not hold a charge and when the new one was dead the next morning that's when i first noticed the pump running constantly. Prior to that I know it wasn't an issue because she always had a hard start problem and I'd actively listen to the pump prime for about 3 seconds and stop. I wonder if the pump itself might be going and have a wiring grounding right at the pump. I'll have to keep searching for wires that look suspect, but so far every wire i've inspect has very good insulation over them and nothing looks to be exposed. I just spent the last hour driving her around and she performed like a champ, but if I don't pull the fuse after I shut her off the pump humms away. I am determined to post whatever I find to be the solution (even if it's five years from now.) so that someone else might benefit from a potential fix. Thanks all so far for the recommendations.

 

Hi igende ,

I promise you , with 101% certainty , that there is no failure of the pump itself , or any of it's in the fuel tank wiring , that could cause the pump to stay constantly running . If you are 101% certain that NO work whatsoever has been done to the car , and your 101% certain you unplugged both the relay and the oil pressure switch at the same time and the pump kept running , then it's just about 100% certain you have a short in the harness somewhere that involves the fuel pump wire and a constant +12V wire having come into contact with each other .

Sorry to have to ask this , but since this is SO unusual and I know I already asked you if your sure you unplugged the correct relay , you are sure you did in fact unplug the oil pressure sending unit that's down near the oil filter and has a 3 wire plug , yes ? If so , the harness is shorted somewhere along where the fuel pump and some other +12V wire run next to each other . This , in all practicality , could be under the hood , under the dash , or even in the harness running to the back of the car , since the trunk pull down has a constant +12V feed in there . As a helpful diagnostic , have you with the pump running pulled each fuse , one at a time from the fusebox , to see if you can find a fuse whose unplugging makes the pump stop ? This would isolate which circuit is mistakenly powering the pump full time , and may lead you to a particular spot in the harness to check ....

 

PS , this pulling of fuses should also include the ECM fuse mounted separately under the hood . In fact I think there may be two fuses mounted this way , and if so both should be unplugged . Yes , pulling the fuel pump fuse makes it stop , but with that fuse in place , does pulling any other fuses make it stop ? If so , that's your guilty circuit ......

 

Now you are saying, "When I look at the fuel relay connector I do notice that amongst the pins inside one appears not to be there and two wires (green wires) are wired to the first. Is this normal? I can post a picture if it helps. However, the car was like that since I got it about 2 years ago and it's run fine till recently and check engine light only showed up this past spring while it was there. " Check this drawing, it does not show any green wires at the fuel pump relay. The wire connection going to the ECM is for fuel pump voltage monitoring, not to power the pump. The ECM can not power the pump directly which has been stated many times in this thread. It does sound like someone bypassed the fuel pump relay by jumping the power directly to the pump (green wires). This would also account for the code 54 you got intermittently. Your fuel pump probably has been running all this time it's just that you just noticed it now. Why the po wired the relay that way, who knows but it isn't right. Check the diagram.

 

I think Big Al is on to something here , my only concern is that there is only supposed to be one green wire going to the fuel pump relay (green with a white tracer) and igende mentions two green wires (with no mention of tracer color) so I am left to wonder where the "extra" green wire is coming from ? (the A/C relay does in fact have a solid dark green , and a green with white tracer , which prompted my earlier question if the correct relay was unplugged)

 

If you can, it would be good if you posted a pic of the fuel pump relay and wiring to it. Try to follow those green wires and see where they are getting power.

 

I stand corrected, there is 1 green wire going to the relay which is the ECM signal to close the fuel pump relay. Thanks OrangeBird for pointing that out.

 

And I'll second your great suggestion of a few pictures of the relay and it's wiring . A picture really is worth 1000 words here , and would really help Big Al and myself to fine tune our suggestions ...

 

Thanks all. OrangeBird yes i disconnected both the OPSU (by the oil filter) and the fuel pump relay (for the heck of it I also disconnected the oil pressure gauge switch just above the OPSU too at the same time as the others even though I know it has nothing to do with this issue.) All three were disconnected at the same time and pump ran. I know the fuel pump relay because when I got the code 54 in the spring I replaced it with a new one from auto zone (it was $15 bucks and worth the shot.) The old one is still actually attached to the new one, but not connected. The relay has a rubber backing that is riveted on to the fuel pump relay and i never drilled it out. I'll try to post a picture tomorrow showing the green wires I mentioned. The connector looks ugly inside from all the dielectric grease the previous owner must have added. Bigal55 I am certain the pump was not always priming. She has sat for over a week at times and the battery surely would have been dead if it was priming that long. Also it's always had a hard start in cooler weather and I often would move the ignition forward for 3 seconds and listen for the pump to come on, doing that 2-3 times before starting just in case it helped (not sure it did really). I could definitely hear that it was not on and hear it come on when I did that. Regarding pulling fuses the only ones i've pulled so far are the ones under the dash labeled ECM, F/P (which I'm told in this thread is the relay), and one other, I think the Crank. I'll try all the rest one by one see if the pump cuts out, that's a good idea thx. Under the hood the only one i've pulled is the one for the fuel pump and that does stop the pump. I've visually checked every wire under the hood and none that are visible seem to show any raw wires, but they all eventually end up going into black plastic sleeves so I can't actually see them in their entirety. I have also tried jiggling all the harnesses and wires to see if the pump suddenly cuts off and on, but no dice. On a separate note I mentioned over the last couple of days I was unable to start the car, seems the wiring clip that holds the connecter attached to the ignition coil was broken and the connector was riding up the plug causing a week/no spark situation. I've pressed her down and she started fine. I'm going to zip tie it down. As soon as I have a chance, i'm going to try to visually inspect wires under the car to see if any might be exposed or touching another wire possibly causing this. Thx again all.

 

Here is a picture of the Fuel Pump relay. The connector is the next picture showing two green wires just under my index finger (might be hard to see but they are green with a white stripe, both of them, and they connect to the same clip internally. Next is a picture of the internal clips of the connector itself. You can see on the left side one clip is not there. The two green wires connect to the internal clip on the far left. It was like this when I got the car two years ago and always worked fine so I assumed it was made this way. Also you can see the OPSU in the last pic. The one with the white clip is the oil pressure gauge sensor. I replaced that one in the summer and spliced a new clip on it since it was broken. You can see the splice/connector in red. Even though that one doesn't matter both were disconnected along with the fuel pump relay for my test. The OPSU in the picture is towards the bottom left. By the way I disconnected every fuse under the dash one by one including two silver fuses that appear to be small relays and the pump continued to prime. I also disconnected one fuse under the hood titled pep? Right next to the fuel pump fuse on the front left passenger side but that one did not stop the pump either, not sure what that one is for, will have to google it. I still need to spend some time looking under the car, will do so as soon as I have a chance to jack her up.

 

By the way here is a picture of my baby :-) She's a 2.8l V6 1988, but I threw a formula hood on her.

 

Ok I found the problem and I'm embarrassed to say it, but it WAS the Fuel Pressure Relay that was bad. After all my insistence that I knew which was the fuel pressure relay because I'd replaced it in the spring, I was wrong. Yup, Here's the deal, there are only two relays on the firewall on the right side of my car, while there is a place for a third there is nothing there. I'd seen this on other cars in pictures on the net and assumed because I had a v6 the missing relay was for an option my car did not have. However, as I was moving wire harnesses around trying to find an exposed wire, I noticed, hanging down behind one of the harnesses another relay. I decided to disconnect it to see if it might stop the pump and to figure out what it was. Wala it stopped the pump! Then I noticed that at the top of that relay it was broken and I suddenly realized this must be the real fuel pump relay and it's not attached to the firewall because the place for the screws to hold it to the bracket is broken off. See pictures below.


Notice the first picture is a picture of my firewall with three spots for relays. the one on the right which I just removed is the same as the picture above with the yellowish relay which I indicated was my fuel pump relay. The spot on the left has always been empty because the relay was broken off it's mount and hanging behind a wire harness. Notice the second picture from the left the yellowish relay is the replacement fuel pump relay I bought last spring from Autozone on the right is what I thought was the old fuel pump relay (I have no idea what it is now.) I plugged the wires for that relay into the new fuel pump relay I bought last spring. No idea what that was doing or not doing. Possibly an AC relay? My AC does not work so maybe why I did not notice anything else fail in the car at the time? Anyway third/middle picture is the actual fuel pump relay I just located dangling behind a harness. As soon as I pulled it off the pump stopped. Notice in the fourth picture from the left that at the top it's broken and why it was not attached to the firewall. Last picture on the right shows what I thought was the bad fuel pump relay with the rubber holder on it (left side of pic) and the real fuel pump relay on the right, they are identical matching/looking relays. Not sure what that relay with the rubber holder is for then. Notice in the first picture from the left there is a round relay too. I'm guessing that is the fan relay? Sorry all to spin folks in circles on this thread, but very glad it's finally figured out. If anyone knows what these other two relays round one and one with the rubber backing might be let me know. Thx! Next thing I need to try again is disconnecting the fuel relay while the car is running just to make sure the OPSU keeps the car running and is working since my previous test was not a true one. Thanks again all!

 

Very Good , I'm really glad it was that simple !

Every single person on this earth has made a similar mistake at one time or other , no one is immune from the "oops" . Thank God there will be no tearing into harnesses looking for a short cause that's what it was starting to look like . For future reference on the underhood relays of our 6 cyl cars , the three relays at the driver's side firewall are A/C compressor clutch , fuel pump , and electric fan . On the passenger's side near the heater box there will be a relay that runs the heat/AC blower on high speed (bypasses the lower speed resistors and puts full 12V to the blower) and up near the radiator on the passenger's side will be the MAF power relay . There is only one relay for MAF on our cars as opposed to 8 cyl cars that have 2 relays for MAF (8 cyl has MAF power and MAF "burnoff" relays) .

PS , Thank You for sharing the pictures , white looks good on our cars ! (OrangeBird was orange when I bought it and is the very LAST color I'd have painted it )

 

Thanks again for your help. I too was dreading searching for a short, so glad no need for that! And yes that orange looks awesome, I'd not change it.

 

I been following and sitting on the bench to see what came of this. Glad you got it figured out. For reference, on 5.7 TPI, the Mass Air Power Relay, The MAF Burnoff Relay, and the Fuel Pump Relay are all mounted on the Drivers Side Firewall.....just where your AC, Fan, and FP Relays are.

Take care

 

Good to hear you got it figured out!

 

I'm back, hoping for some additional help. If folks prefer I can start a new/different thread. The car drove around OK for a couple of days and then threw a code 54. I swapped out the Fuel Relay to another just to check and the code remained. I used the troubleshooting steps posted in this forum and final result identifies either bad fuel relay (I've tested three all with the same results) or possibly dirty connections. I cleaned them with a connection cleaner and an old tooth brush, got them fairly shiny and the code went away. Drove her around for a day and left her idling for about 10-15 minutes and code came back.


Basically I have the reverse problem as before. She will not prime at all now. the tan/white wire shows no power when probed and grounded. Also when switched on for 2-3 seconds still no power at the tan/white wire. The orange outer most is fine 12+ volts, the black/white to orange also 12+ volts etc. I touched the orange to tan/white and got 12 volts, but pump did not run. I then jacked up the car unhooked the rear connector near the fuel tank which bolts to the underside of the rear passenger seats and sprayed connection cleaner on them (they were pretty clean already.) I also tested the OPSU by placing a probe to the G terminal and to ground and got no reading which is suppose to mean she's fine. I have found that if I disconnect the fuel relay the car stays running, but if I reconnect it and disconnect the OPSU the car dies. Seems that I'm running off of the OPSU and the fuel relay is not really doing it's job. Any thoughts on further tests I can perform? Funny thing is when I disconnect the battery to clear the codes I can start her up run her fine, but if I turn her off and start her again then rev the engine immediately after starting her the code comes back. If I start her and let her come up to a constant idle on her own then drive her around the code doesn't come back. Not sure what if anything that means, flaky ECM or still bad grounding somewhere? Regardless of whether code disappears or not she won't prime now.

 

Refering back to the fuel pump circuit diagram, the tan/wht wire feeds a signal to the ECM (fuel pump voltage monitor). This wire must see 12 volts within a few seconds or the ECM will fire a code for low fuel pump voltage (code 54). If your fuel pump relay is not working, when starting, your engine will require a few seconds to build oil pressure and close the oil pressure switch which then powers the fuel pump and allows the car to start and run. Yes, you are back full circle to the fuel pump relay again, all be it the opposite problem. First step is to see if your ECM is telling the fuel pump to run. HTH!

 

OK. The dark green w/white tracer is the signal from the ECM to energize the fuel pump relay. The ECM will provide 12 volts at this wire through the relay's coil and on to ground. This will then close the contacts in the relay which connects the orange wire (12 volts) to the tan/wht wire which in turn powers the fuel pump. Again, the tan/wht wire going back to the ECM is only for monitoring the fuel pump voltage, this is not the power source. With your engine running, you should have 12 volts from the dk grn/wht wire to ground. Check this and see what you have. If you have 12 volts at the relay on the dk green/wht wire, then the "new" relay may be bad.

 

OK i will try that test. I can't believe it is the relay, I've tested 3 relays on this connector so far (One I bought in the spring, a brand new one I just purchased this week, and one I borrowed from another connector on the firewall and all had same results. I also performed the test below with the noted results below which led me to clean the contacts, but no change. I'll test it with the car running and let you know what I find. Thx.

4. Connect test light between pump connector terminal "C" (dk green/white wire, CKT 465)
____and ground. Ignition to "off" for 10 seconds. Note test light within 2 seconds after
____ignition "on".

__YES__Light on? See "4A"

___4A: Faulty Relay! Hey that's cool, a $10-$15 part from the GM dealer! But, if you
________replaced that already, something's funny. You might want to do the chart again.
________Check for intermittant connections, possibly caused by dirty connector contacts.
________Note: The manual continues to test the "oil pressure safety switch", I'll put
________that test at the end of this message.

 

You need to follow a systematic approach to troubleshooting this problem as with any electrical problem. First you need to see if the ECM is powering the relay as described in my above post, engine running, dk green wire tested for voltage. If 12 volts at dk green wire, check voltage at orange wire (you said you tested it and had 12 volts). Test voltage at tan/wht wire for voltage, should be 12 volts. IF, power at dk green and orange wires but not at tan/wht then can only be 2 possibilities: 1) bad relay or 2) bad ground at blk/wht wire on relay.

 

Thx, I will test this morning. I did test each of these wires previously, but not with the car running. All appeared to show power except the tan wire. I test these all with car running and let you know. Thx.

 

OK ran some tests.

Car on and running relay in place and back probing the wires/connetor:
Green/white wire to ground shows nothing
Orange to ground shows 14 volts
inner Orange shows 14 volts (this wire is right next to the outer orange wire.)
Black/White shows nothing (since this is the ground that is expected I think)
Tan/White shows 14 volts

Car on but engine not running with relay in place and back probing the wires:
Green/White shows nothing
Orange shows 12 volts
Inner Orange shows nothing
White/Tan shows nothing

Car on engine not running and relay removed touching the front of the connector pins
Green/White shows 11 volts, shows 12 and drops to 11 pretty quickly
Orange shows 12 volts
Inner Orange shows nothing
Black/White nothing
Tan/White nothing

 

The problem is you have no power on the green/white wire when running. The ECM will power this wire for approximately 2 seconds when the key is turned to run or start (this is why the troubleshooting chart you posted says turn key off for 10 seconds then watch voltage at green/wht wire when key turned to "on"). Did you try this and did you get 12 volts at the green wire?
Once the engine starts, the ECM will supply 12 volts at the green/wht wire constantly to run the pump. The orange wire is what actually supplies power to run the pump when the contacts (switch) inside the relay close thereby connecting orange to tan/wht. The ECM is not providing power to the relay coil via the green/wht wire. You will need to trace the wire back to the ECM and/or check right at the ECM for power on the green/wht wire.

 

I wonder if the output driver for the fuel pump relay went bad. Check for voltage at the ECM when the key is turned to "on" within the first 2 seconds and then again with the engine running. Let us know what you find.

 

What I found previously was that if I touched the green/white wire with no relay in place with car on but not running it would show 12 volts for 2 seconds and go to zero, but when I tried this test today it showed a constant 11 volts and never dropped to zero. I'll run that test and that same test with the relay in place and let you know what i find. Thx!

 

OK retested the green wire with power on car not running. With the relay in place and back probing it I get .01 volts and it does not drop after 2 seconds, doesn't drop at all. With relay removed probing the green/white from the front of the pin I get 11.73 volts and does not drop at all again car on but engine not running, of course as soon as I turn car off the volts disappear on this wire. When I go to probe the ECM directly i'm assuming I'll see a green/white wire connected to it? Is that what you want me to probe?

 

To eliminate all wiring from the fuel pump relay, and the relay itself, to the fuel pump and prove that all wiring is good, you can jumper the orange wire to green/wht wire at the fuel pump relay. By jumping the orange to green/wht, you will power the relay coil and it's contacts should close. If all this is true, then the fuel pump will run. Now if the relay is bad, the contacts won't close and the fuel pump will not run. This can be done with the key "off" as the orange wire has power at all times. If you do this and your fuel pump runs, you have either a bad connection from the ECM to the fuel pump relay or your ECM is bad and not providing power for the fuel pump relay.

 

Yes. The drawing shows connector C! at position A6 should be the green/wht wire for the fuel pump relay.

 

igende, for future reference, ChevyThunder.com and AustinThirdgen.org are very good sites for reference materials such as electrical drawings and troubleshooting charts. These 2 sites are invaluable for working on these cars in particular and any car in general.

 

OK with car completely off I jumped using my red probe to the orange wire and black probe to the green/white wire, relay connected (back probed it) I got 12.47 volts and pump did not run. I tried this with a second relay I have and same results. This would mean both relays are bad then?

If I pull the relay off and jump the orange connector pin to the green/white connector pin should the pump run? Is that even safe to do (possibly damage the ECM) with out a relay in place.

It's possible both relays are bad, maybe something is shorting them out, loose wiring in at the connector inside or something?