No power to fuel pump, seems to be a common problem around here Options

[warrenoliver]

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.

[warrenoliver]

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.

[Jon H.]

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

[warrenoliver]

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.

[Tom]

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

[Jon H.]

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

[warrenoliver]

Thanks for all your help guys. Anyone know where I can get a good relay board?

I will try the classifieds

[Jon H.]

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.

[Dave_Darling]

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

[Tom]

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

[warrenoliver]

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

[Tom]

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

[warrenoliver]

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.

[Tom]

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

[warrenoliver]

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.

[warrenoliver]

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. (IMG:style_emoticons/default/chair.gif)

[warrenoliver]

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 (IMG:style_emoticons/default/beerchug.gif)


Warren

[Jon H.]

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

[Tom]

Warren,
Very happy I could help. Glad things worked out and you did find the problem. (IMG:style_emoticons/default/piratenanner.gif)
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

[revhi109]

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?