So, today while trying to figure out my fuel problem I noticed that my fuel pump was running off of the coil, and batt ground. I've been told that the coil should not have to push any other devices, so I decieded to wire it back to the stock wireing. Well that went smoothly and now my pump primes for 2 second's and shut's off , YA!, but the car won't fire. I know it's the new wireing because it did fire when running off of the coil. It seams to me that if I'm hearing it prime that would mean that it is getting 12 volt's. So does this mean I have a bad relay?
Eric

So there was a hardwire to the + side of the coil... and..

Look, this is not only frustrating, and maybe I am paranoid, but man.. these cars burn really hot. Wiring issues point to other wiring issues, in my brief history here, on Planet Porsche.

It just needs constant power, if you just want to tie it to that one wire on the ignition.. take a fire suppressor..



M

Check the fuse on the relay board for the fuel pump (rotate it in the holder several times and/or clean it and put it back in). Also reset the fuel pump relay several times.

If you have an extra black relay laying around.. pop the top off of it and use it as a test relay. Once you pop the top off of it.. you can manually actuate the relay by pushing down. This is how I test ALL electrical issues that involve the relay.

You can also locate the pin on the 14 pin front connector that runs over to the fuel pump. Locate it and use a small jumper wire to some 12volt source and see if the pump runs when you put 12volts to the pin for the fuel pump.

I'll get a pic for you.


B

Eric,

Another thing to check is on the relay board. Someone may have re-wired it to solve a problem on the relay board. But you can test it to verify its working properly.

FOR FUEL INJECTION
At the white connector in the lower-left corner of the relay board there are five leads coming out of four pins in the connector. Most of these leads go to the ECU.
(This is looking forward at the relay board - from back to front.)

Looking down on the four pins of that connector - the upper-left & lower-right pins need to be tested.

The upper-left pin is the fuel-pump power. If you turn on your key (without starting) you will get 12V at this pin.
Once you start cranking the car, the 12V for the fuel-pump drops from this pin and it is now powered off the starter lead - the pin in the lower-right. You should get 12V at the fuel-pump when the car is cranking.

Once the car is running (you've stopped cranking), 12v returns to the upper-left pin.

This is assuming you've checked the relay as previously suggested.

FOR CARBS
If you're running carbs, then someone has tried to bypass the fuel-pump voltage swap designed onto the relay board - so that the pump is powered at all times. And you cannot simply jumper the upper-left pin and the lower-right pin - cause then you're starter will have power constantly.

You can power the fuel-pump off the main switched 12v power lead which is the upper-right pin of this connector. Keep in mind the fuel pump will be running at all times when the key is in the ON position.

Let me know the results,

Regards,

imho you want the pump to run when you turn the key to the on position with carbs.

kevin

Alright, so tried the test relay idea, and it worked like a charm. I'm getting power to the pump and to the heater fan, which also never worked. But still when I go to hit the key it won't fire, but the pump does prime like it is suppost to. I've tired all of the relays off of the wreck and still no go. Any ideas?
Eric

Ok. This tell me three things:

1. the ground is good to the pump
2. the pump can be powered.
3. the fuse is good to the pump.

Now we need to figure out why the relay is not being triggered.

Keep that relay you popped the top off of. It will be a valuable tool in the future.


b

Hummm. I just put in the old coil wireing and it still won't fire. hummmm theres about 1/8 of a tank full, and I get pressure in the lines about 32 lbs. Could the relay board itself be bad?
Eric

This is a dumb question, but have you double checked your spark? If you fiddled with the distributor maybe it's not popping like it should. Just a thought.

-Pete

Good point. You may have removed the coil pos. when you removed the fuel pump lead.

B

Found it! Everything was fine with the relay's and wireing except the wireing to the MPS. Onf of the wires had popped ot of the connector for the mps. I shove it back in and made the connection. It fired up off of the stock wireing. Thanks everyone!
Eric

Everyone needs a Bowlsby harness they just dont know it...LOL


B

lol, this is a bowlsby harness It's a great harness, just a bad angle for the MPS , to much bend in the cable, I need to move it.
Eric