GMC V8 diesel fueling
Question:
I have a 6.2 litre GMC V8 running in my auto Range Rover. I bought the vehicle with the engine already installed. I have always had fuel problems. So far I have had a complete set of injector nozzles and a thorough injector pump overhaul. Now it runs extremely well at speed but refuses to idle without hunting. When cold it will stall every time the gearbox drops out of gear on overrun. Also when it is hot and been left for ten minutes or so it will not start, but is no trouble at all when cold. The only way it will start when hot is to pump what I assume to be the throttle valve at the bottom of the injector pump while someone else turns the key. Not easy when you are on your own!! I have cleared all the air-leaks on both the fuel supply and the return. The mechanical fuel pump is a non serviceable item but seems fine. I have run out of ideas. Can anyone help. Steve
Response:
Sounds like a bad lift pump – the small pump that tranfers fuel from the tank to the fuel injection pump. The need to prime the FI pump is the tip-off, as is the ‘hunting’ when at idle. Since this was a second-hand installation, there is a distinct possibility that it may not even have a lift pump (could have been forgotten). On the original truck, it is typically located on the frame rail just under the driver’s door. Good luck – Jonathan — Acta Non Verba – Deeds Not Words Jonathan Race, Lieutenant/Paramedic II EMS Supervisor, EMS-7 A-Shift – Hide quoted text — Show quoted text – > I have a 6.2 litre GMC V8 running in my auto Range Rover. I bought the > vehicle with the engine already installed. I have always had fuel problems. > So far I have had a complete set of injector nozzles and a thorough injector > pump overhaul. Now it runs extremely well at speed but refuses to idle > without hunting. When cold it will stall every time the gearbox drops out of > gear on overrun. Also when it is hot and been left for ten minutes or so it > will not start, but is no trouble at all when cold. The only way it will > start when hot is to pump what I assume to be the throttle valve at the > bottom of the injector pump while someone else turns the key. Not easy when > you are on your own!! I have cleared all the air-leaks on both the fuel > supply and the return. The mechanical fuel pump is a non serviceable item > but seems fine. I have run out of ideas. Can anyone help. > Steve
Orange County (FL) Fire-Rescue Department
