944S2NUT

Car won't start, so I toss in a new DME relay, room! she fires up and idles no problem. So I shut it off and go to start it the next day it just keeps cranking over and over. I put in another DME relay room! it fires up again. You get the point. Any ideas what could be wrong?

Yarf

Inspect the relays that you have removed, looking for signs of failure such as burnt or cracked traces.
The relay cover can be removed to to allow for close inspection. Also check the back side of the relay /fuse assembly for loose connectors or wires.
Good luck

Bri Bro

Does the DME relay get hot to the touch while it is running? If it does, you have a part that is drawing too much current and burning up the contacts in the relay. Go to Clarks garage and put in the bypass jumpers. Then, check the current draw through the jumpers as you take out the Fuel pump, DME, idle controller, injectors.

944Ross

Check the back side of the panel for a corroded or poor connection that is high resistance. Could also be a fuel pump that is pushing against a plugged filter and drawing high current, or otherwise in death throes.

Mark944na86

If that's the case, you should also check your fusing is correct, as fuses should blow before a relay burns unless an improperly rated fuse is being used.

Bri Bro

Some of those circuit don't have fuses.

944S2NUT

You guys are awesome! Thanks so much for your input. I am off to test your theories

Mark944na86

Which one are you thinking of? The fuel pump circuit is certainly fused.

Hollywood D

I'm having this same issue. The fuel pump relay gets pretty warm. Let me know what you find. I'll have to work on mine next week.

So, not to hijack your thread but...is there a way to check if the fuel pump is going out with a multimeter? I looked on clarks garage but couldn't find anything other than how to replace the pump itself. Or is it just one of those things that goes out and there's no real way to tell?

Bri Bro

As I remember (on the turbo), the injectors, switched power to the DME and the KLR, idle controller, and cycle valve all are direct power feeds (no fuse) from the first DME relay. As you stated, the second DME relay (two relays are in the DME Relay case) does have a fuse and it goes to the fuel pump and O2 heater and the turbo water pump relay. Some these are not on the S model but you get the general idea.

Maybe that is why the DME relay has such a poor reliability track record, it is the weak link under heavy current loads. Another feed (straight from the ignition switch) that could use a fusible link, is to the ignition coil.