no power to DME Relay

[Cocacolakidd]

Hello Everyone,

Well this one has me stumped - No power to fuel pump ???

Have taken out the fuel pump and tested for power and if it is still a good pump - No power to brown (- Brown & + Green/black) or green/black. Put known good power to isolated fuel pump - Fuel Pump runs fine.

Have three DME realys and tested with all three - no luck. Used a three wire jumper instead of DME Relay - still no luck. Jumped the wires/slots below DME relay at 85- and 86+checked with volt meter - no power to there - not getting any power to the DME Relay.

Was thinking that I may replace the DME Computer to see if this is the problem ???

Or what next ???

[Rob 924s]

Check the fuse? Even if it still looks good maybe the contacts corroded a little bit. I'd say take it out and try another fuse.

[Cocacolakidd]

Thanks for the reply -

Have already replaced the fuel pump fuse (A couple of different times) to see if that was the problem. - no luck so far.

All other functions seem to work well - Motor turns over, lights come on, plenty of power at the battery.

Still stumped...

[Toran]

Will car start if fuel pump is wired directly to battery?

[marko]

According to the schematic (85.5), 12v goes directly from the battery (Red/Green wire) to the relay base pin #30 (which corresponds to pin #2 of the dme relay) You should have 12v at pin 30 at the DME relay base. Jumper pin 30 to pin 87a (pin #4 of the relay). Fuel pump should run. If not, measure for 12v starting at the pump and step back until you lose it. Fuel pump> connector plug> fuse #34> pin 87a relay base> pin 30 relay base> Red/Green wire to battery.

[Cocacolakidd]

Thanks Marko for the information for the red/green wire from the bat.

What I am finding now is if I jump the 30 pin and the 87b I get power to the fuel pump and it runs.

Even with five DME relays not one will do the connection themselves, the fuel pump will not run with any of the five relays alone.

So is there something going on with pin 87 below the DME Relay???

Curiosor, and curiosor - lol

Again many thanks, Ed.

[v2rocket_aka944]

What ever happened with your car?
Is it still going to be for sale?
I was preparing to book a flight up there but then our conversation died off.

[Cocacolakidd]

The car has an electrical wire problem at 87 under the DME relay which keeps the fuel pump from running.

My problem is that I'm an excellent mechanic for the car, as I have been working on them since the late 70's, but I'm not worth anything when working on the electrical side of the car. I get totally confused when getting into the electrical side..

In the mean time I have sold the car and the new owner is doing the work to get it running with my sitting side chair help. I was in an accident and broke my back, so I do not get around much any more, but still help working on the car with my knowledge of 924's, 931's, 944's , and 951's.

Have jumped the 30 pin and the 87b pin below the fuel pump DME relay to get the fuel pump to run, and it runs that way - and that's where we are now - close but not yet a cigar.

Still need further electrical help on it.

Thanks for all of the reply's, Ed..

[marko]

Ok, so the battery path is good to the fuel pump. The relay is not energizing. Check for a short to ground on pin 85b (comes from the DME) and also a ground on pin 85, and 12v on pin 86 (from the alarm control unit).

[Cocacolakidd]

Hi Marko, hello gang,

I am wondering if it makes a difference since I reached in through the vent (Pulled off finned oval plastic vent cover)that is in the drivers side door jam, reached in through this port then pulled off the wires going to the alarm keyed switch (Thus disabling it). Does this make a difference in the problem we are trouble shooting ? I was hoping that this would eliminate that alarm key switch as a source of a problem.

Thanks for all the help, Ed.

[marko]

Yes, I think that could have something to do with it. Pin 4 from the alarm control unit powers a relay within the DME relay on pin 86, which in turn energizes the fuel pump relay in the DME relay. Check for 12V on pin 86 of the DME relay.