Hesitation/misfire

[turboxr]

Ok. So my MJ has had a hesitation or misfire for a while. It's getting worse. It happens mostly under load in OD. If I leave it in 3rd, it will do it but not as bad. Previous owner replaced the CPS, ECM, coil, wires, rotor. All of those within 2 years. I've replaced the TPS and checked for a bad ballast resistor but my 87 doesn't have one. Fuel filter isn't clogged. I'm leaning towards the pump or pump screen. I've searched a million times and have come up with ECM, CPS, TPS, coil, plugs, wires, ballast resistor, etc but all those things have been changed and are good. Could this be related to the intermittent no crank situation when the truck has been sitting in the hot sun? What am I overlooking?

 

I'm thinking I should pull the pump, inspect the screen, replace if necessary, replace pump, filter, and rubber hoses.

[jimoshel]

Ok. So my MJ has had a hesitation or misfire for a while. It's getting worse. It happens mostly under load in OD. If I leave it in 3rd, it will do it but not as bad. Previous owner replaced the CPS, ECM, coil, wires, rotor. All of those within 2 years. I've replaced the TPS and checked for a bad ballast resistor but my 87 doesn't have one. Fuel filter isn't clogged. I'm leaning towards the pump or pump screen. I've searched a million times and have come up with ECM, CPS, TPS, coil, plugs, wires, ballast resistor, etc but all those things have been changed and are good. Could this be related to the intermittent no crank situation when the truck has been sitting in the hot sun? What am I overlooking?

 

I'm thinking I should pull the pump, inspect the screen, replace if necessary, replace pump, filter, and rubber hoses.

I would. :wrench: