Isuzu Trooper Fuel System

friedemannfriedemann Member Posts: 2
edited September 2014 in Isuzu
Problem is fuel delivery. Pump was just changed 2 years ago for $5oo. Don't want to go there again if I can avoid it(especially if that is not where I should be looking) spark and everything else seems good. However car will occasionaly drop its idle very low (for an automatic) and then stall out. Or on the highway it will starve and die if the engine revs to high (like the speed limit of 60mph) Or it will not start if I stop at a Starbucks for a coffee for 10 minutes after driving it 5 miles to get there. A friend took off the air cleaner and put some fuel down the "throttle body" and I cranked it and it fired up and I was able to keep it going for a while while the revs remained in the middle zone(like driving 30MPH while in drive)

- Now is it the fuel pump again
- Or possiblely a tube that connects to the top of the fuel
tank to relieve negative pressure so that the tank does not
collaspe inward (I have worked on foreign cars other than
this one with this vacuum break line)
- Or possibly something in the TBI I can check? to make
sure all is good there?
The fuel filter to the engine compartment is clean and has been changed.

Any experts on this machine?


  • darrelkdarrelk Member Posts: 3
    As unlikely as this may sound...check out the alternator and make sure when running it is sending "juice" to the fuel pump relay. there is a switch inside the alternator that controls the fuel pump relay. this seems to be a very common problem with these. if this is the problem, be sure to get a good quality rebuilt alternator and make sure they have replaced the switch. really hope this helps. good luck
  • mtdelphiamtdelphia Member Posts: 12
    I have an 88 Trooper II with the 4ZE1 4cyl engine, which had issues. I rebuilt the engine and installed a new head. The valves are all at .008". I set the crank timing mark on "0°" (zero), set the camshaft gear notch to the arrow on the plate, and I get spark at "0°" with the distributor set at midrange. But I'm not getting fuel injector action.
    When I crank it over it sputters but won't start. The fuel pump is new and it works if I apply power to it.
    If I set the cam sprocket two teeth advanced, the engine will start and run but the distributor is at the extreme retarded position of it's adjustment range, it runs rough and lacks power.
    Can anyone tell me why the FI works then but not when things are set according to the book?
    I also noted that fuse # 8, #10, #11 & #12 get power from the main engine relay but have no power with the key turned on, and the relay is good. Fuse #10 powers the fuel pump relay. Does that energize after the engine starts?
    Does anyone know where I can find a "Theory of operation" manual on the fuel system?
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