Tried researching prior threads, but couldn't find anything about this. I'm sure it's my searching skills. Out of the blue my 89 low mile 911 won't start. It cranks freely on a strong fairly new battery, but makes no attempt to turn over at all. I saw online to try jumping the fuel pump with a wire going from fuse 6 to 7. Is this correct? How does that actually jump it? I have an older E that on every start up it is easy to hear it run. If I get someone to turn the key, with me under the car, would I be able to hear it run? Is this the best thing to check first, or, remove a spark plug and check for spark? Thoughts?

 

A lot of times it's as simple as the DME relay ...
If you have a spare , swap it in or try a known working one from a friend with a 911 !
I have an 89 911 as well , and although mine never failed i always carry a spare in the glovebox.

Lots of reading on the Pelican 911 forum , do a search on DME relay

Cheers
Phil

 

I believe there is a FP relay ( under the seat?) on an 89.

I would disconnect the fuel line and put it in a catch can to see if you have fuel when you turn the key- if not work your way back

 

You may want to check out going with a solid state DME relay rather than purchasing a replacement that consists of the exact same technology that caused the failure to begin with...

https://www.ftech9.com/new-products/911-ssr-pp



Focus 9 Technology Solid State DME Relay (left) and original DME relay (right). New solid state unit has the Pump Prime feature

 

Ironman has a good point !
The URO brand replacement units have been sketchy to say the least ...

Thanks for the info , going to look into one of those !

Cheers
Phil

 

I also read somewhere there are relays in the engine bay, left hand side, under the plastic cover. Any chance if it is not the dme relay under the seat, it is one in the engine bay. If it turns out to be the dme box itself, assuming it's not the fuel pump.. Are these bought with me sending mine in as a core? Or are they just bought outright? Thanks guys! And thanks for the link, looks like that's the way to go.

 

Sure, all you're saying could be the cause. Troubleshooting by following the circuit diagram would be good.

But the advice you're getting above is simply pointing you to the "usual suspect" being the DME relay (based on the symptoms of strong crank, but no attempt at all to start). It is such a common failure point on these cars. Cheap, easy to replace, almost guaranteed to fail at some point due to internal corrosion. Soon after I bought my '85 26 years ago, I replaced the DME relay pre-emptively, saving the existing one as a spare to carry in the car. (so I've never suffered this problem)

 

Agree - try the DME relay first - most common reason for 3.2 Carrera cranking but not firing.

Had same issue with my 3.2 Carrera Clubsport a few years ago and it turned out to be a duff DME relay. I always carry a spare in glove box now but will probably never need it.....!

 

Replace the DME relay with the pump prime F9 one..if it's not still not cranking, continue diagnosis but that would be the first thing I would do.

https://www.ftech9.com/new-products/911-ssr-pp

 

Read here under No-Start; https://www.systemsc.com/diagnostic.htm

 

On possibility is the crankshaft position sensors.
The connectors are at left side of engine, they can be easily measured.
Here: https://www.ecudoctors.com/pages/por...ce-sensor-test
But easy the check at engine.
Shop around for sensors, many cars use same, only difference is cable length, I bought BMW parts as much cheaper.
These can be changed without dropping engine, don’t mess with the air gap, check it.

 

So I bypassed the number 6 fuse by jumping to fuse 7. I heard pump run for a few seconds with key turned on. Then went to start, and it started and kept running. So next step is dme relay. If that for some reason doesn't work, is the dme box the next thing to try? If so, are these rebuilt, or, buy a new one and throw out the old? Thanks for your help guys. Hopefully just relay.

 

Yes! Check here for a rebuilt unit; www.systemsc.com

 

Well try the DME relay first. That's the cheaper fix. Ftech9 is supposed to be making the whole box soon, which I am excited about.
https://www.ftech9.com/new-products/...-911-sport-dme

here's the difference between a standard dme relay and the solid state one.

 

Well new dme from Ftech9 solved the problem, car runs great again. Thanks all for pointing me in the right direction