DME problem?

[944cabby]

Hi all,
My 944 s2 cab has been laid up over the winter and now the time has come to get her on the road again for summer.
I bought a new battery, connected her up and turned her over but she refuses to fire up!
I've put fresh fuel in, all the electrics etc appear to work and she is sparking on all cylinders, but i'm pretty sure i cant smell any petrol fumes, and i cant hear the fuel pump priming, so i'm thinking fuel starvation.
I was going to start at replacing the DME, but if that was faulty would i get any spark?

[dgcantrell]

First thing to check is the DME Relay. You can jump the DME and fuel pump portions of the relay and see if it runs. If it does, the relay is defective. It is a common problem. Here is some helpful information on that relay. DME Relay Information and Testing

[v2rocket_aka944]

fuel pump does not prime.
fuel pump only activates during engine cranking.

[944cabby]

But if the dme was faulty would i still get a good spark?

[944 Ecology]

Originally Posted by 944cabby

But if the dme was faulty would i still get a good spark?

Possible that the circuit that drives the injectors in the DME is bad, while the circuit that drives the spark is still good.

[944cabby]

Originally Posted by dgcantrell

First thing to check is the DME Relay. You can jump the DME and fuel pump portions of the relay and see if it runs. If it does, the relay is defective. It is a common problem. Here is some helpful information on that relay. DME Relay Information and Testing

Just tried jumping the dme and its made no difference.
Engine turns over, very good spark, but isnt firing up at all.
I guess i need to check fuel is reaching the engine now.
Where should i check first? Fuel pump or fuel lines in the engine bay?

[944 Ecology]

Originally Posted by 944cabby

Where should i check first? Fuel pump or fuel lines in the engine bay?

Check at the test port on the fuel rail (under the large black cover on the top of the engine, there is an acorn nut (17 mm IIRC) and a sealing ball bearing under the nut. When you remove the nut, a spray of fuel under pressure should come out (do it on a cold engine). If there is fuel spraying, you will need to see if the fuel injectors are getting fired by the DME... you will need a noid light for that (available at NAPA).

[dgcantrell]

If you jump the fuel pump section of the relay, you should hear it run. You should also feel fuel running through the fuel rail. If not, check the fuel pump fuse about an inch away. Also the tachometer needle should bounce slightly indicating the flywheel sensors are working. If the fuel pump does not run with the jumper installed, it is probably the problem. Start with the simple stuff first instead of throwing another DME at it. Just about every time I've had a non-start issue, it's been a DME relay, reference sensor, or the fuel pump. Never the DME itself.

[944cabby]

Fuze is ok, and the rev counter was bouncing when trying to turn it over.
I suspect the fuel pump tbh as previously when sat in the car i could hear the pump and now theres nothing.
DME relay is delivered tomorrow so i'll change that first.

[Pauld_94S2]

Did you check the fuse for the fuel pump?

[944cabby]

Originally Posted by Pauld_94S2

Did you check the fuse for the fuel pump?

Yeh, that seems fine.

[dgcantrell]

It's probably the pump itself. I've had the same thing happen. Especially when it's sat for a while. Especially with ethanol/s**t gas..

[Toast54]

Originally Posted by dgcantrell

It's probably the pump itself. I've had the same thing happen. Especially when it's sat for a while. Especially with ethanol/s**t gas..

The fuel pump went out on my 924S, so I purchased one from AA (Auto Atlanta, not ******** AZ..thought I should make that distinction) and it lasted all of 15 minutes before it crapped out. Had to go through the hassle of getting another, paying for it and returning the defective for credit..on the plus side, it's been fine for the last 4 years.