Crackership

Hi all,

I'm having an issue with my DME. It started acting up a while ago: Car wouldn't start but tapping on the DME would get it to start. I pulled the DME today and re-flowed the ignition drivers thinking this would solve the problem, but all it did was make the problem different. Now the car starts every time, but it dies shortly after. I have a fuel pressure gauge on the end of the rail and it shows that fuel pressure happens while cranking, but as soon as it catches, it starts to drop until the car dies. I tried jumping the DME relay and the car runs just fine with the relay jumped. I pulled re-flowed all the joints in the relay and tested it on the bench, it's good, but the car still won't stay running. So, if the relay is good, this means that the DME isn't running the fuel pump after the car starts. I must have screwed something up while I was in the DME. Maybe I bridged something, I don't know.

I'm going to pull it apart again tomorrow and really inspect it, but it would really help to know exactly which circuit controls the fuel pump. Can anyone point me in the right direction? Another thing that would be very helpful is good pictures of the DME circuit boards, so I could compare and see if I did something dumb. Anyone happen to have that around?

And, of course, if anyone has any other ideas, I'd love to hear them.

TIA

V2Rocket

I wonder if maybe some solder on the circuit/pin that the DME uses to ground the fuel pump side of the DME relay coil is busted/faulty.

Fuel pump only runs when DME tells it to...

Stephencs601

Boards are populated by an SMT machine then put through an oven. If they did the paste by hand, then when it goes thru the oven, sometimes the contacts are not secure and failure can happen. You need an xray machine to look at it in 3D. Also, conformal coat it but not the whole unit.

Crackership

Something like this must be the issue... or I fried a component or something.

I pulled the DME apart again and re-flowed every solder joint in the whole thing. No change in behavior though. Then, I followed all the troubleshooting steps for no fuel pressure on clarks-garage and every test passes... The only thing I can think is I must have screwed something up in the DME and created a strange failure state. I've got a DME on its way from Lart now. Should be here by the weekend. Guess we'll see if that solves the problem.