fuel pump issues ( please help )

[just4bob50]

All right, about 6 weeks ago I started to have an intermitent fuel pump problem. Sometimes it would continue to run after I shut the car off, a couple of times the pump was off when I shut the car down & when I came back a short time later the pump was running. This happened more than once. Most of the time it worked like it should. I ended up changing the FP relay and until the other day it has been fine. I had to drive the car in the rain and about 2 miles from my home the car started cutting out and drive poorly anything past a light pedal. So I pull into the garage and I get out of the car and I hear the pump running again. It was getting late so I just pulled the the negative terminal for the time being. Well I go out this morning to track the problem down, put the cable back on the battery and I dont hear the pump running. So I start it up and go for a drive. The car ran great, drove smooth at part throttle and I had 3rd gear to 6000 rpms heavy throttle and it ran fricking great. So now Im like what do I do now. I stopped at Wal-mart on the way home. The FP was not running when I shut the car off. When I came back out the pump was running again. When I put the key in the ignition and turned it to full forward I heard the normal noises that happen when the pump primes, after that the pump stopped running and the car started right up and ran fine. I got home with no problems and pulled into the garage, when I turned the car off the FP was still running and then it stopped for a few seconds. When it stopped I heard a slight chattering coming from the FP relay, Wen I grabbed the relay it was very hot, and the FP started running again, but the chattering in the relay was gone. I turned the car on and off a few more times and both symptoms happened again but never at the same time. I dont see any wiring issues that are plainly visible, but I was hoping someone might be able to give me a step by step methodology to tracking this down. Worst case senario I drop the tank and check the wires from front to back, but I was really hoping for a simpler solution. Thanks in advance
This sucks because I was ready for a tune until this happened!

 

[HISSIN50]

You should find that it's a control issue on the relay or a latched relay.

I would get it to act up and probe the FP relay with the key off (but the pump apparently running). The coil should be dead on both sides, the common terminal will obviously be hot but the N.O. side should be cold.

If the coil is cold but the Common and N.O. are both hot, the relay latched.
If the coil is hot on both ends, the EEC relay can be the issue.

 

[just4bob50]

You should find that it's a control issue on the relay or a latched relay.

I would get it to act up and probe the FP relay with the key off (but the pump apparently running). The coil should be dead on both sides, the common terminal will obviously be hot but the N.O. side should be cold.

If the coil is cold but the Common and N.O. are both hot, the relay latched.
If the coil is hot on both ends, the EEC relay can be the issue.

What is the latched relay, and where are the EEC, and latched relays located. It is a 92 LX

Thanks for the info.

 

[HISSIN50]

A latched relay is a phenomenon where the normally-open and common terminals remain connected in the absence of the coil being energized. You've probably heard of a guy complain that his starter cranks whenever the battery is connected, even though the key is in his pocket. This is often an example of a latched relay.

Your FP relay is probably beside the passenger strut tower, next to the WOT relay. If you see two relays there, one is the FP relay. If there's only one relay there, your FP relay is still under the driver's seat.

The EEC is in the passenger kick panel. The EEC relay is above the EEC. Small hands are nice if you need to access the EEC relay.
The EEC relay will be the last one you check - you might find your issue lies elsewhere. If the EEC relay is remaining 'on', your injectors and a host of other systems can have power going to them as well (it makes it real easy to know if the FP relay has an issue vs the EEC relay).

 

[just4bob50]

I already replaced the FP relay, it is now in my pass side fender. Its funny that you mentioned the starter example because I had a coil go bad about 2 weeks after I got the car and the starter would run with the key in my pocket. I also change the ignition switch because when I was looking for a switched 12 volt soure to hook my guages to I saw that the housing was seperating every time I turned the key. I currently have the EEC sitting on the floor because I thought I would be getting a tune done soon. So the EEC relay would be above where the EEC was originally located. I swapped my A9L with my SCT chip into this car from my vert.