The Car Care Clinic with the Dr John

92 GMC Jimmy - Car has started to die whilst driving

David from Wolverhampton

Question

I have a 1992 GMC Jimmy with a 6 banger and the car has suddenly started to die when driving. It will start and idle with a little two foot action. Seems to be after it is warm. Has just started out of the blue. I have changed the plugs,cap,rotor,pvc,and air cleaner. Any advise? The parts did not solve issue.

Answer

Well you can either have a fuel pump ' flow and pressure ' test performed by the garage, or firstly change the fuel filter. This could be getting plugged and the pump is trying to push the fuel through. It will usually run when cold due to an enriched mixture, and a slight fast idle. However when it is warm the mixture is a lot leaner and this is causing it tobe starved, because the pump can't deliver the fuel fast enough at the higher road speeds. So it stalls.

The other cause could be a problem with the fuel pump itself, being that when you have been running a little while the fuel pump is heating up and this is causing a drop in pressure to the injectors............ If a new fuel filter doesn'tcure it, then you will need to have the pump checked for pressure and flow, when the engine is at normal operating temperature.

Good Luck!
Dr. John