Troubleshooting dead car.

rmcdonnell · 05-05-2009, 04:36 PM

Car has been reliable for the last couple of years. A few days ago, I sorted some dead bulbs at the back of the car, car engine was warm. After, car wouldn't start. Starter turning normally. Left it for 10 mins, wiggled the relays including dme relay, kicked the floor over the dme. Locked and unlocked car. Turned off the immobiliser, tried to start car. No start. Car smelt of fuel. Left it five more minutes, and then it started with the accelerator pedal well down. Put it down to an immobiliser anomaly. Q. Does the fuel pump harness run with the loom to the rear lights?

Car fine next couple of days. Today, returning from work, a 20 minute run, it died a mile from home. I coasted to a halt. Wiggled the DME relay. Restarted the car, drove towards home. Died 100 yards from home, coasted to 20 yards away. Left the car, went and had a cup of tea, and found my DME relay jumper. Returned, started it normally, drove it onto the drive.

A couple of hours later, started the car, and drove it around the block. Noticed it drop out, and come back to life. Got it back home, and left it idleing. Got out and went to listen to fuel pump. Fuel pump is changing speed, not running constantly. A minute later, the fuel pump slows, and the car dies. Thinking it may be DME relay, wiggled it. Tried to restart but it wouldn't.

Put in the DME jumper. I expected the fuel pump to run quickly, but it didn't. Sounded a bit feeble, as if full battery voltage not available. Tried to start, car wouldn't fire. Stinks of fuel, I assume it's flooded, and plugs now wet. Try to start two hours later, no go, battery sounding a bit tired.

So what next?
First guess is: Remove and dry plugs and replace, charge battery. Use DME jumper and see if car starts. If it does, listen to the fuel pump at idle, see if it changes speed when jumpered.
Check for correct voltages at the fuel pump. Check voltages at DME relay. If DME jumper sorts all, then new DME relay needed.

If it doesn't start when cold with clean plugs, charged battery and the DME relay jumper...
Any thoughts? How come they bust at the most inconvenient times?

cheers
Rissole.

thekidd · 05-06-2009, 11:46 AM

If the fuel pump didnt sound right, I would certainly do the tests from Clarks and see what you get. You did say that you smelt of fuel- possibly a Fwul Pressure Regulater. I am going through the same thing as you. Replaced DME, battery, and checked the ignition system and still no start. Put in speed/ reference sensors, and she ran for about 4 days, but never ran for more than 10 minuets. Clarks Garage said some symtoms of a bad FPR, and I think I had 4/7 symptoms. Check for fuel pressure also, if your getting good gas pressure, then the fuel system is working, if not, there is you problem somewhere in the fuel system.

rmcdonnell · 05:32 PM

Battery on charge, will clean the plugs and try jumpering out the dme relay tommorrow morning.
I think my fuel pump slowing down as it conked out is just as likely to be the supply to it failing, so I'm keping an open mind on that.

I'm not hopeful that the DME jumpering will work: with the DVM tonight I couldn't even find +12V on DME relay supply pin 30. So I think I have either poor +ve supply, or poor earth, or poor understanding!!

On my circuit diagrams main supply 30 (+12V always on) is supposed to come straight from the battery +ve via two 6mm red wires, I think. Does this supply for circuit 30 actually come via the alarm and immobiliser? Or is that just the DME relay pin 30?

If the DME relay circuit 30 really should come straight from the battery, then that's my problem.

If I unscrew the holding down knobs on the fuse panel, and lift it up, do I find these two main 6mm red battery supplies for circuit 30 to the fuse box underneath? Or are they tucked away somewhere I haven't spotted yet...

cheers
Rissole