Fuel Pump Fuse

[pshoremo]

Hi everyone, new to this forum. I'm having a problem with the fuel pump fuse and was wondering if someone can help me. Fuse no. 7 which controls the fuel pump keeps blowing. I'm thinking it must be a bad connection somewhere. Here is what I've done so far to try to figure out the problem. I removed the 3 wiring harness connections one at a time around the fuel pump and put a new 20 amp fuse in each time to see if it doesn't blow. In my thinking, if it didn't blow one of the time I would then know that the problem had to be somewhere in the line of that connection. I did that each time and blew a fuse each time. I also pulled relay #30 and put a new fuse in thinking it may have something to do with that. When the relay was out, it again blew the fuse. The key is in the on position each time I do this.

Also, to help figure this out I can see that the fuel pump was replaced at some point. It now has the pump in it that has the small box for the wiring and the hole on the right has been replaced with the plug meaning that the newer all in one fuel pump is in place. I'm not sure if this has anything to do with my problem or not.

I obviously have something that keeps blowing the fuse but just looking for suggestions on what to check and where the locations are on the car.

Thanks in advance!

[DMCMW Dave]

I obviously have something that keeps blowing the fuse but just looking for suggestions on what to check and where the locations are on the car.

Thanks in advance!

First obvious test is to unplug the two-wire connector that goes to the pump wiring harness, see if the fuse still blows. Then plug that back in and unplug the connector on top of the pump. This can isolate the problem between the car, the harness, or the pump motor.

[pshoremo]

First obvious test is to unplug the two-wire connector that goes to the pump wiring harness, see if the fuse still blows. Then plug that back in and unplug the connector on top of the pump. This can isolate the problem between the car, the harness, or the pump motor.

I already unplugged all of the connectors around the pump in the cargo area but it sounds like you are also talking about a connection further back on the car? Where is this located?

Thanks,

[DMCMW Dave]

I already unplugged all of the connectors around the pump in the cargo area but it sounds like you are also talking about a connection further back on the car? Where is this located?

Thanks,

There is a connector on top of the pump (4 wires). About 10 inches away, there is a two-wire connector that is the connection to the car's harness. It may be slightly hidden under the leading edge of the opening in the trunk floor.

The next connection is somewhat difficult to get to as it is inside the left front cavity of the fiberglass, adjacent to the washer reservoir bottle. Sometimes you can pull it out of the grommet just forward of the left front tire, sometimes not. I believe that's the last "connection" all the way back to the RPM relay.

The common place to find a short in the wiring is neaer the shifter. There are usually two screws that hold the shifter plate to the console. If someone got sloppy and move the wiring, and/or used screws that are too long, all kinds of seemingly unrelated things can happen. Try taking out those two screws and see if that solves the problem (assuming you don't find it in the pump area)

[pshoremo]

There is a connector on top of the pump (4 wires). About 10 inches away, there is a two-wire connector that is the connection to the car's harness. It may be slightly hidden under the leading edge of the opening in the trunk floor.

The next connection is somewhat difficult to get to as it is inside the left front cavity of the fiberglass, adjacent to the washer reservoir bottle. Sometimes you can pull it out of the grommet just forward of the left front tire, sometimes not. I believe that's the last "connection" all the way back to the RPM relay.

The common place to find a short in the wiring is neaer the shifter. There are usually two screws that hold the shifter plate to the console. If someone got sloppy and move the wiring, and/or used screws that are too long, all kinds of seemingly unrelated things can happen. Try taking out those two screws and see if that solves the problem (assuming you don't find it in the pump) area)

That sounds like something definitely to check. I think remember the shifter plate looking as if it was loose or something. I'll check it out tomorrow. Thanks

[Bitsyncmaster]

Try unplugging the two pin connector on top of the warmup regulator (WUR). It has been known for the WUR to internally short circuit but normally that won't blow that 20 amp fuse even sorted.

[pshoremo]

Try unplugging the two pin connector on top of the warmup regulator (WUR). It has been known for the WUR to internally short circuit but normally that won't blow that 20 amp fuse even sorted.


Thanks for the replies everyone. I feel very stupid on what I realized this morning while looking at it. I used the shop manual to identify the fuses and realized this morning that something wasn't right. I was looking at the picture in the manual incorrectly. The fuse that kept blowing was actually the fuse that is connected to the cargo area hood light. To add to it, the person that had the car before me put the wrong fuses in that row making it look exactly like the row that actually had the fuse for the fuel pump. The only reason I figured this out was because I have a manual transmission and the car obviously does not have the automatic transmission fuse leaving it blank. I fixed the fuse that kept blowing but now back to my original problem which is related to the fuel pump.

Forget about the fuel pump fuse because that is perfectly fine. I am simply not getting power to the fuel pump. I checked the fuse obviously, checked the fuel pump relay and that is ok. I had an extra inertia switch and tried that but still nothing. I pulled the connectors at the pump and checked for voltage but nothing. I was able to find the connection up by the front left wheel and can pull it out a good bit but not to the point where I can disconnect it. I can see the connection but if I disconnect it I don't think I can get it back. It looks ok from what I can see.

Any other ideas of what to check for why I'm not getting power to the pump?

Any other ideas of where to check for reasons why I'm not getting current to the pump?

[Dangermouse]

Are you getting power to the relay?

It is not unheard of for the connectors at the fuses to back off effectively resulting in a break in the circuit.

[David T]

To check for power at the fuel pump you must jumper the RPM relay. Unless the motor is running or being started the RPM relay shuts off power to the fuel pump when the key is on.

[pshoremo]

Are you getting power to the relay?

It is not unheard of for the connectors at the fuses to back off effectively resulting in a break in the circuit.

I'll check both of those this evening when I get home. It would be great if it was just the connections at the fuse.

Thanks!

[pshoremo]

I'll check both of those this evening when I get home. It would be great if it was just the connections at the fuse.

Thanks!

ok here is where I'm at. I checked the fuse terminal and I do have power on both sides of the fuse. I pulled the RPM relay and jumped terminals 30 and 87 on the harness to bypass the relay and the pump did not come on. So the problem I'm thinking must be somewhere before the relay. Any suggestions on where to look?

[David T]

ok here is where I'm at. I checked the fuse terminal and I do have power on both sides of the fuse. I pulled the RPM relay and jumped terminals 30 and 87 on the harness to bypass the relay and the pump did not come on. So the problem I'm thinking must be somewhere before the relay. Any suggestions on where to look?

Refer to the Workshop Manual D:04:06 If you have power at the RPM relay on term 87 the next place to check is at the plug right at the fuel pump. Do not trust the ground there, provide your own to verify power. If you have power and ground at the plug for the fuel pump and it still won't run the pump may be stuck or otherwise defective.

[pshoremo]

Refer to the Workshop Manual D:04:06 If you have power at the RPM relay on term 87 the next place to check is at the plug right at the fuel pump. Do not trust the ground there, provide your own to verify power. If you have power and ground at the plug for the fuel pump and it still won't run the pump may be stuck or otherwise defective.

I just checked all the terminals and the only one that I have power on is 87b I do not have power on terminal 87

[David T]

If you have power on 87b you have to have power on 30, that's where it comes from. Recheck you are jumpering 30 (brown) to 87 (WP) and then check for power on the W/P wire at the fuel pump to a good ground.

[pshoremo]

If you have power on 87b you have to have power on 30, that's where it comes from. Recheck you are jumpering 30 (brown) to 87 (WP) and then check for power on the W/P wire at the fuel pump to a good ground.

WooHoo I'm getting closer! Ok so I jumped it again and I am now getting the pump to cut on with the jump. I must not have pushed in far enough or something. I looked at all the wires at the pump and I do not see a WP wire. The pump was replaced in the past with a new modern one piece pump that has the black box mounted on the side. I'm guessing the WP wire may have been part of what was replaced? I checked for power on both the two wire harness and three wire harness that sticks out from under the cargo floor. I have no power on any of them and I know the ground is good. I looked at the color of the wires as closely as I could with a light and mirror but do not see one of them being a WP wire. They are under the lip of the cargo floor and I can't seem to pull them out good enough to see the wires perfectly but I'm pretty sure there is no WP. The main four wire terminal that is attached to the pump and comes from the black box mounted does not have a WP wire, it does have a solid P wire however. I checked for power on all of the wires of that terminal before I disconnected the two and three wire harness and didn't have anything on the four terminal harness either.

If I figure out which one the WP is supposed to be, am I looking to see if power is on it while it is being jumped, the key is on or anything like that?

[pshoremo]

WooHoo I'm getting closer! Ok so I jumped it again and I am now getting the pump to cut on with the jump. I must not have pushed in far enough or something. I looked at all the wires at the pump and I do not see a WP wire. The pump was replaced in the past with a new modern one piece pump that has the black box mounted on the side. I'm guessing the WP wire may have been part of what was replaced? I checked for power on both the two wire harness and three wire harness that sticks out from under the cargo floor. I have no power on any of them and I know the ground is good. I looked at the color of the wires as closely as I could with a light and mirror but do not see one of them being a WP wire. They are under the lip of the cargo floor and I can't seem to pull them out good enough to see the wires perfectly but I'm pretty sure there is no WP. The main four wire terminal that is attached to the pump and comes from the black box mounted does not have a WP wire, it does have a solid P wire however. I checked for power on all of the wires of that terminal before I disconnected the two and three wire harness and didn't have anything on the four terminal harness either.

If I figure out which one the WP is supposed to be, am I looking to see if power is on it while it is being jumped, the key is on or anything like that?

Problem Solved! I found another RPM Relay laying in a box. I popped that in and it started up. Thanks for all the help! I learned a lot diagnosing this.