All of a sudden, fuel pump keeps running

[Joe Bob]

With the ignition off. Kind of annoying plus not a good thing.

83 SC, 3.6 with a updated fuse box. 3.0 FI original fuel pump. Been normal for 15 years. Now it's a Karen. Runs fine, volt meter shows a drain. Less than 12 volts at 3K rpms.

Pulled the fuse, it stopped buzzing. So something be wrong.

[Joe Bob]

10 amp fuse, trickle charger is working.

[mikesarge]

What happens when you pull the relay?

[Joe Bob]

Still runs, fuse kills it.

[Joe Bob]

Red relay on the fuse box box, correct? Towards the driver not the front of the trunk....

Is this one of those pull the relay and spread the pins fix?

[Joe Bob]

Spread the pins, plugged it in, put the 10 amp fuse back in and no fuel pump noise.

Fired up the engine and turned off the engine....fuel pump noise again. Assuming it is running....ignition switch issue?

[Joe Bob]

Kill me now....runs WITH the fuse and RELAY OUT. Had to disconnect the battery.

[Cdnone1]

You have an electrical problem

[Joe Bob]

Ah.....thank you for the insight....

[Joe Bob]

Pelican search engine now like Manny Moe and Jackoff.

Put in 1983 SC ignition switch in the search engine, nada.

Ya gotta go thru the drop down menus.....model make year crap. OEM, $110, Porsche $140. WTF is the difference?

[Joe Bob]

Talked to another Pelican.....thinking the DME. Gotta spare, gonna try that.

[uwanna]

A 964 3.6 gets 12v to the fuel pump thru the DME relay. DME relay has two relays
in the "can", first relay "picks" to supply 12v to DME computer when you turn the
key on. Second relay (fuel pump relay) "picks" from a signal from the DME computer while cranking the motor and turns on the fuel pump.
Pull your DME relay to see if it stops the pump.
I am assuming you have correct 3.6 conversion wiring. The fuel pump wire from the DME has to go to your fuel pump fuse in your SC fuse block. At least that's how I
wired my conversion. You really don't need the SC red fuel pump relay.

[Joe Bob]

Yup....Swapped in another DME....fixed...thanks...

[Joe Bob]

Ben Parrish suggested it just before you....tie. It seems it was some kind of short that allowed it to start but screwed with the fuel pump circuit.

[mikesarge]

Originally Posted by Joe Bob

Ah.....thank you for the insight....

LOL

Glad you got it sorted anyway

[Joe Bob]

CDnone1 is now on my blocked list for his insightful advice. If I needed any crap I'd squeeze my ex wife's head.

Ordered a Focus 9 Solid State DME for a spare. The old one doesn't have any obvious flaws when I opened it up. Fortunately the spare corrected the problem.

Surprised that Pelican doesn't carry them.

Oh well back on the road again. My third DME replacement in 15 years. Had another on my 3.2 914 conversion.

[Joe Bob]

Ah, had to replace the fan belt. Deferred maintenance, gotta love it. Oil change this weekend.

[GothingNC]

Faulty Relay?

I had a red relay that suddenly allowed the fuel pump to run with the ignition key on without the motor running on my SC.

New relay solved the problem.

I kept the old relay so I can run the pump without the motor running to test the fuel pressures if needed.

[Joe Bob]

Not the red one in the Frunk. The 3.6 engine DME relay under the seat was the culprit.

[GothingNC]

Originally Posted by Joe Bob

Not the red one in the Frunk. The 3.6 engine DME relay under the seat was the culprit.

Got it, Thanks !