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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22758
Experience:  BEng hons Mech engineering, in auto industry 22 years
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My 2003 3.0litre diesel trooper starts from cold but refuses

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My 2003 3.0litre diesel trooper starts from cold but refuses to start hot. I replaced the oil pressure rail sensor to little avail.l have done the basics...oil and filters, fuel filter, checked for air ingress in fuel system etc. Apparently there is an actuator somewhere that can be a problem. Can you please help?
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Customer: replied 3 years ago.

Dear Chantal. I am still desperate for information about my Isuzu trooper starting problem. Please notify me if your expert needs more info. Thanks in eager anticipation!!! Alan


I'd 1st check the connections to the crankshaft sensor, unplug it and check for corroded contacts and broken wiring, and consider fitting a new sensor - do the same for the cam position sensor

If the EGR valve is stuck open then this too can effect starting so try disconnecting it to see if this helps or changes anything

Could also be an injector leaking fuel back through the overspill pipe, so not getting enough fuel pressure to tell ECU to fire the injectors, this is trickier to find and you’ll need the garage to do a ‘run back’ test to identify which one is the issue

and it may have developed an air leak on the fuel supply pipe from the tank to the engine. The engine has no separate lift pump and relies on the built in one in the injection pump. If a leak has developed on the fuel suction pipe then air entering the system will air lock the pump.
Try pumping up the fuel using the hand pump in the engine bay on the filter housing, then crack off / loosen each injector pipe in turn while cranking the engine and getting an assistant to operate the primer. This will expel air from the injection side and the engine should fire up. The problem will be cured by checking the supply pipe along its length for signs of leakage and repairing any you find.

If you daub each pipe joint with heavy grease and the issue goes away then wipe the grease away one at a time to highlight the problem joint

Customer: replied 3 years ago.

Hi Matt. Thanks for your input. I think the first paragraph is probably the most relevant to me. The other info would be for a more traditional older diesel without the common rail......? I have checked for air leaks. In my experience an engine with failing lift pump or fuel running back to tank is normally difficult to start initially but then easier once the fuel has been got back to the pump purged of air ,becoming difficult again if the vehicle is then left say overnight without the problem being mended. I have the opposite symptoms. Are you specifically referring to the 3.0 litres as fitted to my lsuzu trooper or more generally? Regards, Alan


thanks for the extra information

OK then lets concentrate on the electrical side

This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;

Airflow meter

Crank position sensor

Cam position sensor

O2 sensor

Throttle pedal position sensor

Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22758
Experience: BEng hons Mech engineering, in auto industry 22 years
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