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914World.com _ 914World Garage _ No power to fuel pump
Posted by: warrenoliver May 24 2013, 10:04 PM
Car stalled on me this morning. When I tried to restart, the fuel pump would not turn on so no luck with the start. Towed it home and checked it out. It is a 73 2.0 with FI.
The pump runs when I jumper directly to the battery. I have continuity from pump connector to the #13 pin on the relay board. If I jumper from the fuse to the #13 pin, the pump comes on. The fuse is good.
I have replaced the main power relay and the fuel pump relay with known good ones. With the ignition on, when I remove and reseat the main power relay, I can feel the relay click but I do not hear the injectors click nor do I hear the fuel pump start (I got this test from Dr. 914's Tech Tips).
On the fuel pump relay socket, I have power at the 30 pin and also the 85 pin. When I jumper to the 87, it does not turn on the fuel pump.
I don't know if it is related, but I have the same problem with the heater blower relay also. I jumpered 30 to 87 and I do not have power. I am not sure but I think the car died when I had the heater blower running.
I'm stumped. What do I check next?
Posted by: Tom May 25 2013, 03:46 AM
Jumpering pin 87 of the fuel pump relay is the same as jumpering pin 13 of the 14 pin connector to power. You say pin 13 to power makes the fuel pump work. Try jumpering the fuse to pin 87 of FP relay. Pump should come on. If not, you have a problem with the fuel pump relay socket to relay board traces. Try cleaning the fuel pump socket with a small wire brush or rolled up fine sandpaper.
Here is a different pic of the relay board.
Tom
Attached thumbnail(s)
Posted by: Jon H. May 25 2013, 04:20 AM
Do you still hear the clicking coming from the TPS when you have the ignition in the run position and you move the TPS by hand? If not then your ECU might not be getting power which controls the ground on the fuel pump relay. Or the grounds for the ECU might need to be cleaned. I just had this happen on my 73' 2.0l. It ended up being a poor connection at the molex connecter on the power board.
Jon
Posted by: warrenoliver May 25 2013, 07:17 AM
Tom,
When I jumper from the fuse to 87 of the fuel pump relay, the pump comes on. That really makes no sense to me since the 30 pin for that relay also has 12V but when i jumper from 30 to 87 - no joy. What gives?
Jumpering pin 87 of the fuel pump relay is the same as jumpering pin 13 of the 14 pin connector to power. You say pin 13 to power makes the fuel pump work. Try jumpering the fuse to pin 87 of FP relay. Pump should come on. If not, you have a problem with the fuel pump relay socket to relay board traces. Try cleaning the fuel pump socket with a small wire brush or rolled up fine sandpaper.
Here is a different pic of the relay board.
Tom
Posted by: Cap'n Krusty May 25 2013, 07:36 AM
Install the 2 headlight motor relays in the FI control and fuel pump relay positions and see what happens.
The Cap'n
Posted by: warrenoliver May 25 2013, 08:00 AM
I tested the heater fan circuit also. The fan runs when I jumper from the fuse to the 87 pin. It does not run when I jumper from the heater fan 30 pin to 87. Both the heater fan blower and the fuel pump relays get their power from the power supply relay (I think), but it still doesn't make sense why I can't get either one to turn on from the 30 pin of their respective relay.
Posted by: 76-914 May 25 2013, 08:09 AM
. Here ya go http://members.rennlist.com/pbanders/FPChecklist_frame.htm
Posted by: warrenoliver May 25 2013, 08:37 AM
I spread the pins on the relays and cleaned the contacts. When I jumper from the 30 pin of the power relay to the 87 pin of the fuel pump relay, the pump runs. Seems to be something between those two relays.
I don't really know where the white wires in the molex connector go but I assume they go to the ECU. I looked at the ECU and it looks like the wiring harness is hardwired into the ECU so I don't know if those wires go into it.
When I ground pin III on the relay board, the pump does not turn on.
I am stumped. I have an AX tomorrow that I would like to go to so I hope someone can help.
Posted by: Dave_Darling May 25 2013, 08:45 AM
Your thought about the fan and pump relays being powered from the "power supply" relay matches the diagram above, so it should be correct.
It makes sense to me. A relay is just a switch that is flipped electrically. What these do is connect pin #30 to pin #87a by default. When current passes through the coil (i.e., when you have +12V at either #85 or #86 and you have ground at the other) it flips to connect #30 to #87. That's how it supplies power; it takes whatever it is getting at 30 and connects it to 87.
So, jumper from the fuse to #87 of the power relay socket. You should now have +12V at #30 of the blower and pump relays. If those operate normally at that point, you have a good idea that the power supply relay is at fault.
....Of course, you could follow the Cap'n's advice and swap those relays for the headlight relays. That puts different relays in, and turning on the headlights will also check the relays you just swapped into them...
--DD
Posted by: warrenoliver May 25 2013, 09:23 AM
I tried that previously but I just tried it again and no joy.
Install the 2 headlight motor relays in the FI control and fuel pump relay positions and see what happens.
The Cap'n
Posted by: warrenoliver May 25 2013, 09:37 AM
Thanks Dave,
The relays are good. When i have the power supply relay in, and the key on, I have power to fuel pump relay 30. When I jumper from that fuel pump relay 30 to the fuel pump relay 87 i do not get the pump to turn on. If I jump from the fuse to the 87 of the fuel pump relay, the pump turns on. The problem is that i don't know what that means.
Your thought about the fan and pump relays being powered from the "power supply" relay matches the diagram above, so it should be correct.
It makes sense to me. A relay is just a switch that is flipped electrically. What these do is connect pin #30 to pin #87a by default. When current passes through the coil (i.e., when you have +12V at either #85 or #86 and you have ground at the other) it flips to connect #30 to #87. That's how it supplies power; it takes whatever it is getting at 30 and connects it to 87.
So, jumper from the fuse to #87 of the power relay socket. You should now have +12V at #30 of the blower and pump relays. If those operate normally at that point, you have a good idea that the power supply relay is at fault.
....Of course, you could follow the Cap'n's advice and swap those relays for the headlight relays. That puts different relays in, and turning on the headlights will also check the relays you just swapped into them...
--DD
Posted by: warrenoliver May 25 2013, 09:43 AM
Thanks for the Anders troubleshooting tips. When i follow his guide, it instructs me to "remove the ECU from bracket and remove wiring harness plug" - I don't see a plug, the wiring harness goes directly into the ECU. Do I have to open the case of the ECU?
. Here ya go http://members.rennlist.com/pbanders/FPChecklist_frame.htm
Posted by: Bob L. May 25 2013, 10:26 AM
Thanks for the Anders troubleshooting tips. When i follow his guide, it instructs me to "remove the ECU from bracket and remove wiring harness plug" - I don't see a plug, the wiring harness goes directly into the ECU. Do I have to open the case of the ECU?
. Here ya go http://members.rennlist.com/pbanders/FPChecklist_frame.htm
There's a clamp that holds the harness at the corner of the ECU where the wires go in.
Loosen it and slide the plastic cover off.
You will then be able to grab the plastic handle and unplug the harness from the ECU. Carefully pull it straight out.
Posted by: warrenoliver May 25 2013, 12:17 PM
OMG, thanks Dave for the pictures. Without those, if i had opened the ECU and seen that mess, i would have closed it up! I will have to get after it this afternoon.
Thanks again.
Posted by: Bob L. May 25 2013, 12:50 PM
OMG, thanks Dave for the pictures. Without those, if i had opened the ECU and seen that mess, i would have closed it up! I will have to get after it this afternoon.
Thanks again.
You're welcome.
BTW, I'm Bob.
Posted by: warrenoliver May 25 2013, 02:52 PM
Oops, sorry! Thanks Bob.
You're welcome.
BTW, I'm Bob.
Posted by: Tom May 25 2013, 03:39 PM
Warren,
Sorry to not answer back sooner. I have been dealing with the loss of my 16 year old puppy. It is hard when a pet you have had for so long passes.
For some reason you are not getting current flow thru the pin 30 connection on the fuel pump relay socket. It could be corrosion in the socket or corrosion where the #30 pin connects to the traces on the relay board.
Most folks assume that if there is 12 volts there when they test, then the equipment should work. Voltage is potential, current is power. Dirty or corroded connections may give a voltage reading, however when current is needed to run the equipment, the connection will not supply the necessary current. You can think of it like this: a 1/4 inch hose will give a reading of 50 PSI, so will a 5 inch hose. The 5 inch hose will flow a heck of a lot more water than a 1/4 inch. Think of the 5 inch hose as a good clean connection and the 1/4 inch as a dirty/corroded one. They both may give you a voltmeter reading of 12 volts, only one will give the current necessary to power the equipment.
Here is what I would check given your tests and results; check the sockets and relay prongs of the power relay and the fuel pump relay to make sure they are clean and make tight connections. You can spread the relay prongs slightly with a small knife to try to ensure they make good tight connections with the relay sockets. The sockets can be cleaned with a small bit of sandpaper rolled up to fit in the socket, or a small wire brush will clean the sockets also. It sounds if your relays are working, so concentrate on the prongs and sockets to see if you can get good connections.
Hope this helps,
Tom
Posted by: warrenoliver May 25 2013, 04:42 PM
Tom,
I think you may be right but I just don't know. I am hesitant to tear into the ECU and make more problems. I have already spread the prongs slightly and have tried to clean the sockets but I will try to do some more to see if I can make some sense of it.
Thanks.
Posted by: Tom May 25 2013, 04:59 PM
Warren,
From what you have said, it doesn't sound like an ECU problem.
Also powered at the same time as the fuel pump is the AAR, which has a noted problem of shorting and draining power. Try disconnecting it and see if things work better. You can by-pass the ECU function by providing a ground to the fuel pump relay by jumpering a ground to pin #3 of the 4 pin connector that goes to the ECU. This will energize the fuel pump relay anytime the key switch is on.
If all else fails, you can run your auto-x tomorrow by jumpering the fuel pump relay, jumper fuse 13, the rear most fuse, to the pin #13 of the 14 pin connector. Just remember that the fuel pump will continue to run anytime the key switch is on, even if the engine has stopped.
Tom
Posted by: Jon H. May 25 2013, 05:22 PM
Don't forget, he is also not hearing the injectors click. If both the fuel pump and the injectors are affected then there is an issue with either the ECU or the power supply to the ECU. Do you hear the clicking from the TPS when you move the throttle by hand when the key is in the run position?
Jon
Posted by: warrenoliver May 25 2013, 06:42 PM
I can hear clicking when I reseat the relays but I am hard of hearing and wear hearing aids so I am not always able to hear things. The clicking I hear sounds like it is onl coming from the power supply relay.
When I move the throttle by hand, I can hear it clicking when the key is on.
Posted by: warrenoliver May 25 2013, 07:00 PM
Tom,
I unplugged the AAR and it didn't help.
I have found a discrepancy in the relay board diagrams and now I am unsure exactly which pin/socket i am supposed to have power to at the fuel pump relay with the key on. All of the descriptions say 86 should should have 12V on the fuel pump relay - mine doesn't. Brad Ander's diagram shows 85 and 86 pins swapped on the relays. I made a new post asking about that.
Posted by: Jon H. May 25 2013, 07:02 PM
I can hear clicking when I reseat the relays but I am hard of hearing and wear hearing aids so I am not always able to hear things. The clicking I hear sounds like it is onl coming from the power supply relay.
When I move the throttle by hand, I can hear it clicking when the key is on.
That's good then, what about the injectors, are they clicking? If they are and if you jump the power to the fuel pump and you are still getting spark then you should be able to start the car.
Jon
Posted by: warrenoliver May 25 2013, 07:21 PM
Yes, when I jumper from the fuse to the 86 socket on the fuel pump relay, it starts and runs just fine. When i remove the jumper and replace the relay, no fuel pump - although one of the times I removed the jumper and replaced the relay, the pump came on and the car started. Several subsequent tries and no luck. I am leaning toward a relay board problem like an intermittent short or break in the 86 trace.
Posted by: Tom May 25 2013, 07:47 PM
Warren,
That could very well be the problem. The sockets are kind of riveted to the traces and that is a good place for corrosion to cause exactly the problem you are experiencing. One of my spare relay boards has the coating removed and those rivets soldered and now works OK.
Tom
Posted by: Jon H. May 25 2013, 07:52 PM
Yes, when I jumper from the fuse to the 86 socket on the fuel pump relay, it starts and runs just fine. When i remove the jumper and replace the relay, no fuel pump - although one of the times I removed the jumper and replaced the relay, the pump came on and the car started. Several subsequent tries and no luck. I am leaning toward a relay board problem like an intermittent short or break in the 86 trace.
Then it could be a hairline break in one of the traces on the board.
Jon
Posted by: warrenoliver May 25 2013, 07:55 PM
Thanks for all your help guys. Anyone know where I can get a good relay board?
I will try the classifieds
Posted by: Jon H. May 26 2013, 05:55 AM
Thanks for all your help guys. Anyone know where I can get a good relay board?
I will try the classifieds
You can pull the board off and test for continuity first. If there is broken trace you can heat up the black stuff and scrap it off and solder the broken trace.
Posted by: Dave_Darling May 26 2013, 11:26 AM
When i have the power supply relay in, and the key on, I have power to fuel pump relay 30. When I jumper from that fuel pump relay 30 to the fuel pump relay 87 i do not get the pump to turn on. If I jump from the fuse to the 87 of the fuel pump relay, the pump turns on. The problem is that i don't know what that means.
That is weird. There is power at 30, and when you go from 30 to 87 the pump doesn't work. But when you go from a hot fuse to 87 the pump does work.
Do you get voltage at the pump when you jumper the fuel pump relay? If so, then the problem is that not enough current is getting through to run the pump. Could be a problem with the traces on the board, could be the power supply relay has a problem... Maybe there's a problem with the jumper or the socket?
It sounds like you're narrowing the problem down!
--DD
Posted by: Tom May 26 2013, 12:24 PM
Warren,
I agree, you are getting very close to the problem here. Actually read the whole post first and try cleaning up the fuseholder to trace rivet area. Sometimes just cleaning and moving this area can regain good contact.
Here is the next test I would do to confirm that pin #30 of the fuel pump relay socket has a connectivity issue. Remove the relay itself and wrap a small wire around the #30 pin, reinsert the relay back into the socket with the small wire sticking out, ( a small paper clip could be used also or some small solid conductor wire), now try the key on - pump should run for 1.5 sec. It didn't before and expect it still won't. Now hook up a jumper from the rear fuse to the wire around the #30 pin, pump should cone on for the 1.5 second. If it does, then you have a connectivity issue with pin #30 to the trace that comes from the fuse. I seem to remember that you have/had an issue with the heater fan/blower also? It could be as simple as the fuse holder to trace is not getting good contact. When I had mine out years ago, I carefully wire brushed each fuse holder and lightly soldered them to the rivet head. I had no more issues after that.
Tom
Posted by: warrenoliver May 26 2013, 03:31 PM
Some great ideas there Tom. I really appreciate everyone's help. I took a break and went to the local PCS AX. The car ran great - I have jumpered from the coil to the 86 socket. I decided to jumper from the coil so the pump would turn off when the key was off.
Thanks for the idea of the small wire on the 30 pin that will help to narrow it down. I like the idea of concentrating on the fuse holder to make sure it is clean and solidly connected although I am getting good power to the 30 pin on power relay.
Warren,
I agree, you are getting very close to the problem here. Actually read the whole post first and try cleaning up the fuseholder to trace rivet area. Sometimes just cleaning and moving this area can regain good contact.
Here is the next test I would do to confirm that pin #30 of the fuel pump relay socket has a connectivity issue. Remove the relay itself and wrap a small wire around the #30 pin, reinsert the relay back into the socket with the small wire sticking out, ( a small paper clip could be used also or some small solid conductor wire), now try the key on - pump should run for 1.5 sec. It didn't before and expect it still won't. Now hook up a jumper from the rear fuse to the wire around the #30 pin, pump should cone on for the 1.5 second. If it does, then you have a connectivity issue with pin #30 to the trace that comes from the fuse. I seem to remember that you have/had an issue with the heater fan/blower also? It could be as simple as the fuse holder to trace is not getting good contact. When I had mine out years ago, I carefully wire brushed each fuse holder and lightly soldered them to the rivet head. I had no more issues after that.
Tom
Posted by: Tom May 26 2013, 05:03 PM
Warren,
The #30 pin for the two relays are from different pins on the 14 pin connector.
The power relay, when it energizes, gives power to the + side of the fuel pump relay and the switched power thru the fuel pump relay comes thru the fuse and pin#30 of the fuel pump relay. So two different sources of battery power.
Tom
Posted by: warrenoliver May 27 2013, 09:05 AM
I must be missing something then. When i look at the relay board schematics, it looks to me like the 30 pin on the power relay and 30 on the fuel pump are on the same trace.
Posted by: Tom May 27 2013, 09:45 AM
Warren,
Take another look. Follow the lines from the power relay from the relay off of the board over to the socket connection. You are probably thinking the dotted lines go to the power relay. Follow the trace from pin #12 (14 pin connector), it goes up and over the trace for pin #14, then down to pin #30 of the power relay. Now look at pin #14 and trace it back to the fuse connection on the right side. From the left side of the fuse (This could be where there is a bad connection) the trace goes to pin #30 for the rear window heater relay and then down to the pin #30 for the fuel pump relay, and finally down to the heater blower. The fuse is the common point for power transfer for all of these relays except the power relay. I would not be surprised if your fuse holder has a bad connection to the traces on the relay board, probably on the top side where it gets exposure to humidity. That is where I had to repair mine.
Tom
Posted by: warrenoliver May 27 2013, 12:22 PM
Tom,
Aha! I think you may be on to it. Even though i have 12V to the 30 socket of the fuel pump relay, perhaps the fuse holder is not connected well enough on the left side or the trace is broken from that point giving me 12V but not enought power to run the pump. I think I will check resistance from the left fuse holder to the 30 socket for fuel pump relay. If it is loose, the resistance should change when I wiggle it and that will tell me if the rivet is loose. If not, it may be that trace. I can check that by running a jumper wire from the fuse to a small wire that i can put around the 30 pin of the fuel pump relay and then plug it in. If it works from that jumper, I think that will tell me if I have a bad relay board.
I am busy for the afternoon and will try to test it this evening. I will let you know.
Posted by: warrenoliver May 27 2013, 03:36 PM
DAMN!!!!!! This thing is frustrating me.
When I check the sockets for the pump relay, I have 12V at 30 and 85 (3 0-clock postion). I have ground at the 86. When I jumper from 30 to 87, the pump does not turn on. When I jumper 85 to 87, the pump turns on. When I attach a jumper from the fuse to the 30 leg of the relay, the pump does not turn on. I have tried this with 4 separate relays that work in the headlights so I know they are good.
What gives? I know I am missing something obvious. 
Posted by: warrenoliver May 27 2013, 07:28 PM
I think I have finally tracked it down. With the key on or off, I have 12V to the 30 pin which should be normal. With the key on, I have 12V to the 85 pin which is coming from the power supply relay. These are measured on my digital multimeter. If I jump from the 85 socket, the pump runs. If I jump from the 30 socket, the pump doesn't run. So I tested with a headlight bulb to see if i could draw power from the sockets. The 85 socket tests great, the 30 socket does not light the bulb. Since the 30 socket gets its power from the fuse, I checked with the fuse holder and it lights the bulb. So this leads me to believe that there is a break somewhere between the fuse holder and the 30 socket of the relay board. Until I get a good used relay board, am using a jumper under the fuel pump relay between the 85 and 87 pin - pump runs good.
I want to thank everyone for helping - especially Tom, Dave Darling, and John H 
Warren
Posted by: Jon H. May 28 2013, 04:17 AM
I find these electrical Gremlins to be the most frustrating part of owning old cars. I'm glad you found your problem, now the fix is easy.
Jon
Posted by: Tom May 28 2013, 10:56 AM
Warren,
Very happy I could help. Glad things worked out and you did find the problem. 
As I mentioned in an earlier post, my relay board had a connectivity issue with that same fuse holder. I wire brushed it and soldered the rivet head to the fuse holder. No more problem and that was 6 years ago.
EDIT: Who is to say another relay board will not have the same problem at some time!? Unless you could find a new one at ??? cost, I would fix the one I had and be assured it wouldn't rear it ugly head again anytime soon, but that is just me. I do have a spare that has been checked out and repaired on the bottom for the voltage regulator contacts and it works just fine if that is the direction you want to go. It does need to be resealed in the area of repairs however. If you decide to repair yours, I am sure there are folks here that can give you advice on how to repair and then reseal the bottom of the board.
Tom
Posted by: revhi109 Mar 30 2015, 10:12 AM
I am also having issues with my fuel pump not coming on. I can apply power to the 87 pin of the fuel pump relay and it turns on. I've concluded that the ECU is not triggering the fuel pump relay. I think its a bad wiring harness to ECU connection. Is there a solvent I could dip the connector in to clean off some possible corrosion? Coca-Cola?
Posted by: warrenoliver Apr 1 2015, 07:20 PM
I am also having issues with my fuel pump not coming on. I can apply power to the 87 pin of the fuel pump relay and it turns on. I've concluded that the ECU is not triggering the fuel pump relay. I think its a bad wiring harness to ECU connection. Is there a solvent I could dip the connector in to clean off some possible corrosion? Coca-Cola?
Revhi,
Read post #37 of this thread. You will see that I got mine to work temporarily by using a thin jumper wire on the relay. The ultimate fix was a new relay board. I found a loose connection on my old relay board.
Posted by: jk76.914 May 17 2015, 05:23 PM
Warren,
I agree, you are getting very close to the problem here. Actually read the whole post first and try cleaning up the fuseholder to trace rivet area. Sometimes just cleaning and moving this area can regain good contact.
Here is the next test I would do to confirm that pin #30 of the fuel pump relay socket has a connectivity issue. Remove the relay itself and wrap a small wire around the #30 pin, reinsert the relay back into the socket with the small wire sticking out, ( a small paper clip could be used also or some small solid conductor wire), now try the key on - pump should run for 1.5 sec. It didn't before and expect it still won't. Now hook up a jumper from the rear fuse to the wire around the #30 pin, pump should cone on for the 1.5 second. If it does, then you have a connectivity issue with pin #30 to the trace that comes from the fuse. I seem to remember that you have/had an issue with the heater fan/blower also? It could be as simple as the fuse holder to trace is not getting good contact. When I had mine out years ago, I carefully wire brushed each fuse holder and lightly soldered them to the rivet head. I had no more issues after that.
Tom
Hey guys, This post save me a bunch of time. I had the same problem- car restarted then died on Friday morning at the Staples store parking lot. I got it flatbedded back to the house, then came in to research the symptoms, and found this thread. I got to this part, and tried the small wire test- the pump ran for 1.5 seconds, then the car started, and ran with no problem!!! I ended up soldering a wire to one end of the fuse, and the other end to the pin on the relay. Installed them both and the car's running fine. Since this wire just parallels the trace under the relay board, I don't see any reason I can't leave it in place for the season, and then remove/rebuild the relay board as my next winter's project.
Thanks for the writeup!
Jim
Posted by: flylarry May 17 2015, 08:15 PM
If the relay works and a jumper between the fuse and pin #13 makes the pump work, you have corrosion in the runs under the tar under the relay board. You can put an ohm meter on #87 fuel pump socket and pin #13 on the 14 pin plug to verify.
Check this, pretty sure this was a repair for the fuel pump problem...
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