I presently have a customer with a newly purchased 740GLE. The vehicle has 105000 km(app 63000miles). It is a 1988 model, in very good and pampered condition, purchased from the original owner. The car is very hard to start when cold or after sitting for a few hours even when hot. Over the three weeks she has had the car, it has failed to start numerous times.
I have traced the problem to flooding when cold. If I remove the fuel pump fuse, the vehicle will start right away, but of course stall within seconds because of lack of fuel. I have found it starts good if the accelerator is depressed fully on cold starts.
I have determined the problem to be excessive fuel pressure, my gauge shows it to be 75 to 85 psi (I believe over double what it should be). I have checked the return line from regulator to tank, it is obstruction free. If I dead end the return line to tank momentarily, the pressure spikes to over 150 psi.I have replaced the fuel regulator, the pressure remains high, at up to 85 psi.
Checking into the history of this vehicle, an original Volvo dealer work order dating to November 1988 notes this starting problem as a customer complaint in the w.o. text. It does not say what steps the dealer took to alleviate the problem.
I am still contemplating where to turn to next...
Car runs beautifully as soon as it goes into closed loop mode, as the ECU cuts back on the injector pulses as per exhaust sensor readings, consequently fuel mixture is leaned out to proper values.
Help!!