diesel engine suddenly stops. always instantly restarts?

Can anyone help? My diesel car motor stops unexpectedly.
Mechanics don't know why.

My diesel engine powered motor vehicle sat for over a year without being driven and now runs perfectly under all circumstances except two (see below). It always starts almost instantly, idles perfectly at all times, and runs normally in city, suburban, and motorway traffic. However the diesel engine occasionally suddenly dies under two circumstances:

1. Occasionally but not always when I go over a large bump such as a speed bump. Small bumps don't affect the motor.

2. Occasionally but not always after a few minutes when it is under full power going up a slight hill.

Three garages have checked the engine and have found nothing wrong.

In both cases 1 and 2 above the diesel engine suddenly dies and pushing or pumping the accelerator has no effect. In all cases I can always instantly restart the engine by pushing in the clutch, waiting until the motor fully stops (red lights such as oil pressure and generator charge come on), and then either 1) jump-starting by letting out the clutch or 2) restarting the engine by turning the ignition key off and then on to activate the starter. The engine then always restarts instantly and runs normally at all speeds.

Sometimes when the engine suddenly dies it is dead completely and pumping the accelerator pedal has no effect whatsoever. Other times the engine doesn't die completely but continues to run at idle speed with enough power to pull the vehicle along on level pavement but pushing or pumping the accelerator pedal has no effect. The only way to get the engine running at power is to jump start or turn off the ignition key and then restart normally.

The problem seems to be in the diesel fuel pump which is a relatively complex device that puts out fuel at very high pressure to the four diesel fuel injectors. With the vehicle parked and stationary I can open the hood and manually push the accelerator mechanism on the diesel fuel pump and the motor revs up normally and sounds normal but after about 20 to 30 seconds at high revs the engine suddenly decelerates down to idle speed and stays at idle speed or dies despite my holding the fuel accelerator mechanism on the diesel fuel pump fully open or opening and closing it. The engine always instantly restarts when I turn off the ignition key and then turn it on to the starter motor position.

I've checked everything I can think of:

· I hooked up a separate 10 liter diesel fuel can to the input of the diesel fuel pump with the excess fuel feedback from the diesel fuel pump going back into the 10 liter diesel fuel can. This eliminated the possibility that there was a problem with the input fuel line from the main diesel fuel tank in the back of the vehicle or a problem in the excess fuel feedback line that goes back from the diesel fuel pump to the main diesel fuel tank in the back of the vehicle. This also eliminated the possibility that there was something wrong in the fuel filter assembly at the rear of the engine. The same two problems noted above still occurred.

· I hooked a wire direct from the 12V battery to the fuel cutoff solenoid on the diesel fuel pump. This eliminated the possibility that there was a loose electrical connection somewhere in the wires from the ignition key switch to the fuel cutoff solenoid on the diesel fuel pump. The same two problems noted above still occurred. With the engine stopped I can repeatedly connect and disconnect the wire and can hear the fuel cutoff solenoid clicking open and close. With the engine running I can stop the engine by disconnecting this wire to the fuel cutoff solenoid. This is normal, that's how diesel engines are shut down.

I removed the fuel cutoff solenoid to see if it was sticking or the spring broken but the solenoid is fine.

· I checked the air filter to see if there is anything that might be blocking the air inlet and even took off the entire air filter assembly. The same two problems noted above still occurred. I also tried blocking off the air intake and this did not cause the engine to suddenly stop. It started laboring and eventually stopped due to lack of air.

· I removed the four fuel injectors and had them checked by a garage that specializes in fuel injectors. All four fuel injectors work correctly under pressure and each injector produces 3 atomized sprays when under pressure.

· There is a second mechanism on the diesel fuel pump that opens closes according to the engine water temperature. I've wired this mechanism nearly full open and nearly full closed. This does not cause the engine to die.


Details below:

My vehicle is a 1989 Ford Transit powered by a 2.1 liter diesel engine.

The fuel pump is a CAV Lucas rotary fuel pump mfg around 1989. The metal label on it has the following info:

type: (blank) dps: 8520A1231 ser: 12182HFG (G could be a 6) mfg. in UK
stamped on the metal body of the fuel pump: 9 CGC 91.

Can anyone please help? Any suggestions? You can contact me via email:

jjstonne at hotmail.com (note two j's and two n's in jjstonne)

Thanks in advance.