YZ250

I bought a 86 951 PCA E race car a couple of months ago, and it started the first few times I tried it. Then it would crank well but not fire. Days later, it started fine. Days later, same problem. Days later it started. Days later, same problem.

I read Clark's garage stuff and fully tested the DME Relay using an Ohmmeter and a battery, and it checks out fine. A visual inspection with the cap off shows it to be in excellent condition. In fact, it looks new.

I made the jumper according to Clark's instructions, and the car starts right up and idles fine.

Interestingly, I can hear the fuel pump running with the jumper, but I can't without the jumper.

I've read dozens of threads, but I don't see anything like this.

Is my DME Relay bad anyway despite my thorough testing?

Is it possible for the DME Relay to be good and to still have the jumper allow the car to start?

The second question is what I am thinking: something else is causing the DME to not turn on the fuel pump. If that is right, what is a good suspect? High fuel pressure?

931guru

Bad DME not sending the running engine signal to the DME relay.

TRP951

ok do you have the factory alarm? check the box for it and wires to it, also try the alarm jumper off clarks-garage to see if that helps it if it does there is a short in your alarm. since you have a 86 there are no airbags or abs which would cause this. My car did the same thing the alarm system was the problem.

944CS

check to see if you have battery voltage at the DME with ignition on and DME relay in

YZ250

TRP951: I think I do have the factory alarm because I have a keyed switch near the door on the drivers's side. I will check that out.

944CS: I did the checks on the voltage to the DME according to the tests on Clark's garage, and the voltages checked out.

YZ250

TRP951, that was the problem. Thanks.

I did the Clark's Garage alarm jumper, and the car started right up.

I took the electronics out of the black plastic box and did an inspection. At the top, there was a piece of foam rubber stuck down with tape (the kind they put in to reduce rattles). The tape was ancient and the sticky stuff was all gooy and spread across several conductors. Even if it was not conductive 21 years ago, it might be now. I carefull scraped off all the goo. There was another spot down by the connector that looked suspiciously like a copper bridge, so I scraped that off, too. All the electronics parts (resistors, caps, transistors, relays, etc.) look like they are in good condition.

I reassembled the unit and re-installed it. The car started right up.

So now the car is starting with no jumpers. I'm feeling pretty lucky now. I'll have to wait and see how it holds up.

Thanks for the help.