What were the symtopms, I think mine may be bad because everything else has checked out.

Also, how much do they usually run? (Hopefully not as much as a cooling fan relay !)

Christian

 

I saw it for $19.90 at paragon

 

Car would turn over but not start. There are two parts to the relay, the fuel pump and the DME (this may just be on the early cars) When you put the key in have someone hold their hand on the fuel pump and see if it is working. You can also feel the relay click when you turn the ignition on.

 

so the car will not run with a bad dme relay?

Christian

 

OMG look at them look at them!!!!!!!!!!!!!!!!! their kissingggggggggg!!!!!!!!!!!!!! <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" />

no, it won't start.

 

If your car will turn over but won't start. Here is a quote from SoCal Driver:

"With your existing DME relay in turn on the key and check for battery voltage at one of the two pins on any fuel injector. Check for battery voltage at one of the two wire connections at the coil.
If the coil has voltage then the ignition key switch is working.

If the injectors have voltage then the DME relay has pulled in it's first of two contacts. This means the brain is getting voltage too.

Crank the car with someone back under the rear passenger side to listen for the fuel pump. If the fuel pump is running during cranking then the second set of contacts in the DME relay have pulled in AND the fuse for the fuel pump are good.

All this means the DME relay is good and there is voltage to the coil.

The DME grounds out the coil and the injectors to "operate" them. The coil and injector timing is calculated from the input of the reference and speed sensors that look at the flywheel.

If you have fuel pressure and spark then the speed reference sender is suspect.

If you have power to the coil and no spark then the HV wires and the reference sensor are suspect.

I've seen the HV wire from the coil to the dist corrode inside the weather boots and break apart. Any bad HV wires should be replaced as the arcing to ground or possibly the injectors can fry the brain."

 

Now Im stumped, my car runs but cuts out randomly.

Christian

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by led:
<strong>OMG look at them look at them!!!!!!!!!!!!!!!!! their kissingggggggggg!!!!!!!!!!!!!! <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" />

no, it won't start.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Yeah I think I will be sticking with this avatar for a while. hehehe

 

And to think that I was breaking my head looking for a nice 944 pic to use <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

 

Der Schlep.

MEaning you'll be driving, or idling and it will just die. crank crank crank, nothing. Wait a few minutes and crank crank vroom.

That was one of my early symptoms, as well as poor running only noticeable at the end. Even through Porsche the Relay is 24.95. so if your symptoms are like mine give it a shot.

 

Christian, Your symptoms sound like mine a few years ago, turned out to be the DME itself. The cold soldered boards are known to go bad. Being that it's the correct time of year, keep a long handled snow brush/scraper in the passenger seat, when the car cuts out use this brush to give the pass. side floorboard (the angled part nearest the firewall) a good smack. If the engine comes back to life with a smack or two, it's the box. I got a rebuilt box back then because I didn't know any better, they aren't thet difficult to re-solder at home. Good luck.

BTW; the symptoms could still point to the relay, this is just something else to check.

 

Christain,
Your problem sounds like the one I had on my '89 944 a few years ago. The car had about 80K miles at the time. After starting up it would run for a few miles / 10 minutes or so and then it would cut out and I would have to drift over to the side of the road in an embarrasing fashion. The car would not start up immediately - but if I waited about 5 minutes for things to cool down it would then start. It turned out to be the fuel pump relay (I think this is also the DME relay). I was told by the repair shop that the relay has a pcb in it. If the pcb deteriorates electrical opens / shorts etc can occur due to temperature swings. They replaced the relay and I never had another problem for the next 90K miles when I sold the car. The relay was only about $40 or less.

brianh

 

FWIW, last summer, I had an intermittent no-start problem, but only on hot re-starts. Given time, it would always eventually start. Only happened occasionally. No problem when running, or on cold starts. When it happened, it would crank normally, sputter for a few seconds like it was going to start, then die, and further cranking got nothing. Maybe one hot-start in ten or fifteen, random, no pattern, but gradually becoming more frequent.

It happened one day when I started to leave the shop where a buddy works. He checked for spark, it was fine. But when he cracked the nut on the fuel rail, it just dribbled, with no pressure. He put his fuel pressure gage set on the fuel rail, zip-tied it in place, and let me keep it for a week while he was on vacation. I just happened to have the hood up at home one day with the engine hot, and cranked it. Could see the FP gage from the driver's seat... it showed good residual pressure, but as soon as I cranked, it dropped to zero as the engine sputtered and died. Clearly, the 'sputter' was due to residual pressure letting a little fuel pass thru the injectors, but this exhausted the residual pressure. Diagnosis pretty obvious: Fuel pump not coming on. Possible causes? Several. I replaced the DME relay first, based on stuff I've read here, and the fact that the fuel pump & filter were less than 2 years old.... no further problems. Cured. Relay was about $20 or $25, IIRC. Paragon or Zim's, which ever you prefer. I keep the old one as a spare, since it _usually_ works... 8)

Jim, famous last words.....

 

It's really interesting that the DME (fuel pump) relay can cause all of these different symptoms.

I don't like to see owners use the shotgun approach to fixing by replacing everything first. Been there done that.

A little digging with a volt/ohm meter works wonders.

Once the DME relay is eliminated as a non-start cause then it can be the DME brain with broken solder joints or the speed sensor or even the high voltage (spark) wires arcing to the engine. The AFS is another non-start item too.

Just a clarification: The fuel pump will not run unless the engine is being cranked or actually starts. A recent thread I read implied that 200 rpm is the magic number that the fuel pump cuts off at.

 

After reading these posts about the DME relay malfunction and the problem's it has caused for many P-car owners, I have decided to order a new relay and replace my existing one, just to prevent these situations that I have read happen to my P-car. I will call it preventive maintenance!

Lead Foot 944