Non-start - fueling prob?

[Guest]

Don't believe this ... went to pick the new car up this morning. My mate crawled all over and under it for an hour or more, he identified a few jobs that needed doing, nothing majorly serious though, track rod arm bushes, a couple of oil pipes that need replacing, that sort of thing, general wear and tear items. We ran the engine for 15 mins or so, checked the exhaust and various other bits and bobs, turned the engine off and chatted for another 10 mins or so.

Then came the test drive. Turned the key, starter motor spins away merrily, not even a sniff of a catch. The guy had let the fuel run right down to empty. Off he goes and fills it up with a 5 litre can. Still nothing. Not a whiff of petrol hitting the engine.

Owners first thought - the DME unit under the passenger seat (it has gone before and been replaced).

Me/Stuart's thought - knackered/tired fuel pump.

Anyway - off back to Goole with no car! Not a happy bunny.

Called owner a couple of hours later and he had spoken to his friend who is restoring a 930. He was pretty certain that it is the fuel pressure regulator.

The engine had started first time on the button 45 mins after we had left and it had cooled down. (It started first time from stone cold this morning).

Stuart doesn't think the fuel pressure regulator is likely to fail as it doesn't really have to do that much hence doesn't often break. He reckons it is still the fuel pump.

However, the owner says the pump looks pretty new (although at least 18 months old).

Any ideas/past experiences guys?

A very frustrated Burriana[]


p.s. On the plus side, Strasse remember the car and confirm it as a good un!

 

[Guest]

I had problems similar to yours and it was a simple fix - clean the fuel pump fuse contacts. Corrosion had built up whilst it had been sitting a few months.
So have you checked for spark? DME relays go up the swanny at regular intervals. They crack in the solder. Tapping it lightly with a screwdriver handle is worth a try.

 

[Guest]

better explain - if the fuse contacts are corroded it will start ok from cold but once its been running for a while the fuse will warm up and this increases the resistance to the point that the fuel pump cant deliver enough oomph to get it running. Once it's cooled down its ok again. At least that was what was happening in my case.

 

[Guest]

Thanks Adrian - is the fuel pump fuse near the pump or in a main fuse box (why don't they use a bigger rating fuse?).

DME, that's the one. He said that it had failed before (in the last 12 months) so I will be buying one for my "might be useful one day" spares bag!

What i don't want is to constantly live in dread of it not starting again after a fuel stop or something. Is there a way to cure the fault for good?

 

[Guest]

A few people on Pistonheads reckon it could be the DME - but why would the DME be affected by hot or cold?

They also said:

"I second that opinion, but would futher add that there is a problem with the DME circuit which will eventually cause the ECU to fail."

Is this true, and if so, how can i make sure that it doesn't happen?

 

[Guest]

Fuse is in the main fuse box under hood.
The rating of the fuse is not the problem - it doesnt blow. Just clean the contacts and see if it cures it..
The DME - I've never heard of a DME relay causing the ECU to fail.
I remember the day I bought my car - sitting in Henrys yard cranking away nothing happening until we tapped on the DME casing. I bought a new one next day for about 35 quid and its been fine since. Do not let a DME fault put you off an otherwise good car. You should always change it /carry a spare one anyway. Bit like always changing a cambelt on a car you just bought.
best of luck

 

[Guest]

Fuel pump relay is a classic on these, also check that the fuse body is the correct length as if it gets hot it can melt and shorten just enough to isolate the pump.

When you turn on the ignition you should hear the pump buzz for a couple of secs to prime the line, if there's no buzz then there's no volts to the pump, easy sort it after that.

 

[Guest]

Just a thought but mine did exactly the same. It would cold start every time but then would'nt re-start when hot. I changed the DME, had the fuel pressure checked which was fine. Through process of elimination my problem was traced to the crank sensor. Its mounting bracket had corroded slightly crushing the actual sensor. I think the part cost about £70.00 and (touch wood) its not been a problem since. The mechanic who sorted the problem "borrowed" a crank sensor off a 944 and bodged the wiring just to try it first - saved me wasting more money buying parts that weren't faulty.

 

[Guest]

Thanks guys. I think I'll pass this link onto Iain the owner so he can get it all checked out.

al.

 

[Guest]

Guys, I had exactly the same symptons but it wasn't the DME relay although I replaced that, no it turned out to be the flywheel sensors.

Apparently when these become worn, they work when the engine is cold and the car will start as normal but once the engine has reached operating temp and you switch the engine off it will refuse to restart untill it has cooled sufficiently.

Sorry to confuse the issue but it may possibly be the flywheel sensors.