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Mike, Technician
Category: Porsche
Satisfied Customers: 39198
Experience:  Motor Technician of 34 years+ in vehicle repair and diagnostics.
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1989 Porsche 944 NA 2.7L 8 valve engine. Car died. No fuel.

Customer Question

1989 Porsche 944 NA 2.7L 8 valve engine.
Car died. No fuel. Sent DME (ECU) and AFM off for repair/refurbish. Security alarm fuse was blown so did security alarm system delete. Jumpered two connections. DME and AFM came back. Put them in. Car ran 40 miles. Then the engine died four times in four minutes. The first three times it restarted. The fourth time it didn't. Sent DME (ECU) off to same shop. It tests out fine and is coming back tomorrow.
When I jumper pins 30 and 87b in the DME/Fuel Pump relay socket, the fuel pump runs.
What now? I suspect a wire somewhere may be fried. Where should I look? I see nothing amiss with the DME connector, but one of the wires in the security alarm module connector has some insulation melted off but does not appear to be burnt through.
Submitted: 1 year ago.
Category: Porsche
Expert:  Mike replied 1 year ago.

Hello and Welcome -

My name is ***** ***** Im happy to help / advise. Im sorry to see you have had a wait.

The usual cause of this - melted wires, is crossed polarity somewhere- did you get any sparks when re cnnecting the battery etc - modules... If so that can cause this... so long as you rule out the cause of the melted wires.

Further to this... check the earths / grounds - especially the main battery ground circuit - anything bad there can cause what you have.

It could be too as you are summising that the insides of the fuse / relay board has suffered damage - that will cause loss of circuit to your relay there - you will need to strip that open to check and then go from there---with what you find there -

The fuel pump relay is activated from the Ecu - though the fuse / relay board.

Working through as above, you should get through this / sorted,

Let me know how you go..and / or let me know if you need anything further on this..

~~~>>>>>>~ Meanwhile - Please do click on the "Exc / Ok rating" for me at this time.. Thank you in advance for that . ..

Note that you can get back to me anytime at all after doing the rating - it doesn't close you out -

- Best Rgds, MIKE.