924Board.org

formula05 · Joined: 19 Oct 2004 Posts: 32 Location: miami,fl

i recently bought an 87 924. The engine worked fine when i bought it but now it just turns but doesn't crank up. I had the dme relay and fuel pump checked and both are working fine. please help if you can.

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

You need air, fuel, and spark. Are you sure power is making it to the spark plugs? Any blocked fuel lines or filters?

Sleykin · Posted: Tue Oct 19, 2004 1:57 pm Post subject:

And the valve timing must be correct. Check spark, fuel pressure, and compression. How did the engine fail? Were you driving it and it quit or just wouldn't start one day?
_________________
Glenn Neff
Medford, OR
87' 924S

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Does it seems like the engine is spinning very fast (faster than normal)on the starter?

Try taking off the distributor cap. and make sure that the distributr rotor is turning when you run the starter.

If the distributor rotor is not turning, then the timing belt has broken, and you are looking at about $3000-$3500 for repairs.

If the distributor rotor is turning normally when you spin the starter, then you need to check the sensors on the flywheel.

formula05 · Joined: 19 Oct 2004 Posts: 32 Location: miami,fl

I replaced the fuel filter and it does spin i checked that. The engine spins normally it just doesn't crank up. The way it failed was when i got home and turned it off it wouldnt start up again.

Sleykin · Posted: Sat Oct 23, 2004 5:26 am Post subject:

Does the tach bounce when you crank it? If not the position sensors Gohim was refering to are suspect.
_________________
Glenn Neff
Medford, OR
87' 924S

formula05 · Joined: 19 Oct 2004 Posts: 32 Location: miami,fl

Yes the rpm tach.

Sleykin · Posted: Sat Oct 23, 2004 8:55 am Post subject:

That would make the refrence sensors an unlikely suspect. Do the other checks and let us know how they come out.
_________________
Glenn Neff
Medford, OR
87' 924S

formula05 · Joined: 19 Oct 2004 Posts: 32 Location: miami,fl

I was wrong i double checked the fuel and spark. It has fuel pressure but no spark. Maybe i should check all the grounds. Can someone email the locations of the grounds thanks and when i bought the porsche the guy told me he had replaced the refference sensor.

Paul · Posted: Wed Oct 27, 2004 10:00 am Post subject:

Time to try a new DME relay, check the glove box there may be a spare in there...

NJ924 · Joined: 13 Jun 2004 Posts: 20 Location: New Jersey

I bought a non-running 924s this summer. The PO said it died and would not start. I took it to a mechanic who had to replace the fuse block to get it running.

I don't know how common it is for the fuse block to go bad, but it is something else to check.

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

I'd go ahead and try a new DME - at the least you know you won't get stuck anywhere from that thing going out on you if that's not what's wrong. I'm not sure where the ignition system grounds - there's a main on the rear/top of the engine (real pain to clean, I know this one will affect the starter), a small one with a single wire screwed into a cross-member with a phillips screw, and the two near each headlight.

Edit: do you have power going into the coil?