Faulty DME relay? Car won’t start

[WilliamDunkel]

Drove my 944 -87 yesterday and suddenly the engine acted like it had a temporary loss of fuel. It happened 4-5 times within 5 minutes (seconds of lost momentum), then it was hard to start. Disconnected the battery and hooked it up again, started with a bit of a rough idle/some delat in the gas response. In addition, the low oil lamp suddenly turned on, filled it up to max. Let it sit until today. Doesn’t start. It cranks well, 12.4 at the battery (Will charge it full until tomorrow). Tried the DME-relay with a multimeter which showed the 0.5 between 30 and 87b, OL between 30 and 87. Should read OL at both, right? Could of course be a faulty fuel pump or a lot of other things as well I guess?

Best regards!
William

[originalowner]

That is bad, replace it. It may or may not be the reason your engine is cutting out.

[944 Ecology]

Build yourself a two wire, three spade connector jumper. *Think of a V with a connector at each of the vertices.) Costs about 10 cents to make, removes all of the doubt about the relay.

Remove the relay and insert each of the spade connectors into the three wide slots in the relay location.

It provides uninterrupted power to the ECU and the fuel pump. You will need to pull the jumper when stopping the car so the fuel pump does not draw down the battery.

[Jfrahm]

Testing with the jumper is the right thing to do, but you have to pull the jumper when not running or it'll run the fuel pump all the time and run the battery down.

[944 Ecology]

Originally Posted by Jfrahm

Testing with the jumper is the right thing to do, but you have to pull the jumper when not running or it'll run the fuel pump all the time and run the battery down.

Good point... I had misunderstood that it powered the fuel pump only when the ignition was on.... prior post corrected...

[GregAmy]

Where are you located? I have a spare I removed to install this one:

https://www.ftech9.com/new-products/993-ssr-pp

[walfreyydo]

Everything you need to test the DME relay and create a jumper is here (among much much more related to your car):
https://www.clarks-garage.com/shop-manual/fuel-05.htm

[WilliamDunkel]

Tried replacing the DME relay without any luck. Also bypassed the relay according to Clarks Garage tutorial, the car started once and run a bit uneven, then again no luck. Also tried checking the alarm system, which could be faulty with similar symtoms, however it was already bypassed with an aftermarket alarm (Cobra) fitted. Recorded a video of the fuel pump, it sounds really loud? Unsure of what it is Suppose to sound like, but could be a faulty pump?

Video on youtube here:

https://youtube.com/shorts/2cX0fFqYXtI?si=HUdFjm0-p7jK9U7r

Best regards!

[WilliamDunkel]

Originally Posted by GregAmy

Where are you located? I have a spare I removed to install this one:

https://www.ftech9.com/new-products/993-ssr-pp

In Sweden unfortunately, do you have the LED relay? If you could Considering shipping send me a PM! Best regards

[GregAmy]

Originally Posted by WilliamDunkel

In Sweden unfortunately, do you have the LED relay? If you could Considering shipping send me a PM! Best regards

My spare is a stock relay. And you could probably find it locally at a lower cost (and less shipping hassles).

[Jfrahm]

The fuel pump is loud but perhaps it is aftermarket and higher flow.
Or there is an issue with the tank screen/sock and it's cavitating.
Fuel pumps rarely go bad and when they do it's usually stuck or sticky and not loud.


A fuel flow test would be interesting, as would a pressure test. But a flow test is easy, just put scrap hose on the fuel rail (do not lose the sealing ball!) and run it to a container, see if you get a half litre in a few seconds or what.

It's best to use the jumper for this so there are no ignition sparks.

Cheers, -Joel.

[944 Ecology]

Sounds like the pump is cavitating...