'81 FI fuel pump runs when it should NOT

[dantye]

Mark suggested that I start a topic for this, so Here Goes!

All I want to do here is to stop my fuel pump from running when key is in ACC position, without screwing up something else.

For PHOTOS and DETAILS, RIGHT CLICK and OPEN the following LINK in a NEW window: http://www.cvtn.com/SpiderStuff/relaypanel.htm

(I did not want to clog up the server with uploaded photos .)

Looking for any help with "educated guesses" and starting point(s) for trouble shooting.

Thanks for any pointers!!

[azruss]

yes, that is the imfamous dual relay. Brad Artigue has excellent schematics that show what each connection does.
I suspect, as with my car, that the pump was wired straight to the key and skipped the dual relay. i also remember an in-line fuse in that system that is located behind the instrument panel. trace the 12V+ wire from the fuel pump to the dash and see if you can see where it was spliced. I was able to find mine easily (of course the car was bare with no dash). the problem i had was the dual relay was not wired with the factory color code. (the used the ground wire color for the 12v relay input). may actually be easier to trace the wire back from the dual relay and see where it was cut off. the dual relay can be bench tested to see if it is any good. mine worked fine, so i dont understand why it was by-passed. i hooked it back up and everything works fine. enjoy crawling around under the dash.

[dantye]

yes, that is the imfamous dual relay. Brad Artigue has excellent schematics that show what each connection does.
I suspect, as with my car, that the pump was wired straight to the key and skipped the dual relay. i also remember an in-line fuse in that system that is located behind the instrument panel. trace the 12V+ wire from the fuel pump to the dash and see if you can see where it was spliced. I was able to find mine easily (of course the car was bare with no dash). the problem i had was the dual relay was not wired with the factory color code. (the used the ground wire color for the 12v relay input). may actually be easier to trace the wire back from the dual relay and see where it was cut off. the dual relay can be bench tested to see if it is any good. mine worked fine, so i dont understand why it was by-passed. i hooked it back up and everything works fine. enjoy crawling around under the dash.

I just replaced the fuel hose between the filter and pump yesterday, so I certainly know where to START tracing THAT wire.
Thanks for the tips - very helpful.

[spider2081]

I have an air flow sensor that a previous owner soldered the fuel pump switched closed so the pump runs all the time. It might be worth taking the cover off the AFS and look at the switch contacts. The cover is glued on with a sealant type glue so they are not hard to remove. Once the cover is off the switch contacts are right in the open easy to see.

[dantye]

I have an air flow sensor that a previous owner soldered the fuel pump switched closed so the pump runs all the time. It might be worth taking the cover off the AFS and look at the switch contacts. The cover is glued on with a sealant type glue so they are not hard to remove. Once the cover is off the switch contacts are right in the open easy to see.

Are you talking about the Box with the flap that sits on top of the Air Filter? Same as AFM?

[Fiatmonkey]

Yes that box is the AFM. It can certainly cause a fuel pump to run w/o stop.

[grittracing]

the fuel pumps didnt come from fiat running all the time? i have ask several people and get different answers each time. I would loved to listen to my radio with out flooding my car out with gas.

[Razooli]

All I want to do here is to stop my fuel pump from running when key is in ACC position, without screwing up something else.

Here's your problem ...


Publication1 on Flickr ... Click on the link for a closer look.

... your AFM on the left, mine on the right. Look at the switch by the red arrows - yours is closed while mine is being held open by the arm on the potentiometer. When air starts passing through the AFM, that arm will swing left as the flap opens, allowing the switch to close and send current to the fuel pump. Your switch is always closed because that arm is bent and will never break the circuit to the pump ... runs whenever the ignition is on. Just carefully bend your arm back to the position of mine so the switch is held open and your problem will be solved.

[dantye]

All I want to do here is to stop my fuel pump from running when key is in ACC position, without screwing up something else.

Here's your problem ...


Publication1 on Flickr ... Click on the link for a closer look.

... your AFM on the left, mine on the right. Look at the switch by the red arrows - yours is closed while mine is being held open by the arm on the potentiometer. When air starts passing through the AFM, that arm will swing left as the flap opens, allowing the switch to close and send current to the fuel pump. Your switch is always closed because that arm is bent and will never break the circuit to the pump ... runs whenever the ignition is on. Just carefully bend your arm back to the position of mine so the switch is held open and your problem will be solved.

Oh thanks! I have already re-sealed the cover with silicone sealant, but I will be more than happy to open it up again now that I know what is needed.

Opened it up this morning, set that arm so the contacts have about 1.5mm gap and it works like a charm - much less frustrating than chasing wires!

Thanks again!
This forum really is smarter than any one of us.