ginch

I'm sorry if this is a ridiculous question however I'm going to ask it anyways.
Does the DME relay either work or not work? I guess what I mean is does it eventually start not working or is it either on or off? The reason I ask is that my car lately takes a bit of cranking to get it started. It used to come to life immediately after turning the ignition. It eventually starts (maybe 5-7 seconds cranking max). This might happen 1 in every 20 starts.

Thanks in advance!
Derek

71-3.0-911

It may be a sign of it failing, but usually it's a good or bad from my experience. When my relay failed, it was scorched and no good. I also had a fuel pump that was getting pretty noisy. It didn't fail and the fuel rail pressure was fine, but from what I could tell, it was original and probably would need replacement soon anyway. A 1 in 20 hard cranking is not my experience of dme failure.

Triple G

Lately as in after the engine rebuild?

ginch

Yes after the rebuild but only within the past 2-3 weeks. Starter is new BTW!

nine9six

Solder cracks can indeed cause intermittent issues as you describe.

You can either replace your dme, or try reflowing the solder joints.

New dme's can also be bad outta the box, or exhibit intermittent failures.

Steve Weiner of Rennsport Systems, claims they reflow solder joints on all the dme relays they sell; or is it install...? At any rate, a known failure mode.

TheOtherEric

...

PRSWILL

When mine failed on my 85 911, it went out slowly- similar to OP's lots of cranking then would fire, and occasionally i'd be cruising along at 3,000 RPMs and then nothing for a second- then back to normal. I always carry a backup now.

abiazis

Mine went out and that was it....

trophy

Hey Derek, do you have a spare one you can test?

ginch

Hey Steven,

This thread was from a few years ago. Seems weird but I ended up replacing the battery in the car and have never had another issue since! Fires up immediately every time regardless of cold or warm!

ronnie993tt

I read somewhere that the Hungarian made DME's were better because they used lead based solder. They certainly are cheaper. Stronger lead based solder is apparently not used in the more environmentally regulated producing countries. Might be BS, and sorry I don't recall the source but, I'm using them with no issues.

bw993

Get a solid state DME relay fro Ftech9. I swapped these into my cars and no longer have to carry spare DME's.

http://www.ftech9.com/new-products/993-ssr

BobbyT

If you want to stop worrying about your DME failing once and for all, you might consider a solid-state one. I like this one, which also has a "pump-prime'" feature that lets you hear the fuel pump power up at each start, so you know for sure that all is well:

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

chsu74

Believe 993s already does that. This is for 964s.

BobbyT

Stock 993 DME relay does not pump-prime. The pump isn't energized until the engine cranks over a specified number of times (30?) at a specified speed, at which time the pump cannot be heard over the cranking noise.