Trey

Ok. Here is a question for you Cherokee guru's. I have a 1993 Cherokee 4x4 4.0L. It has a hesitation/jerkiness in overdrive. I put a volt meter on the F.I plugs and noticed that #2 and #6 were not getting as strong of a signal as the rest of the injectors. I removed the fuel rail and cranked the engine. It seemed like the fuel spray from # 2 and #6 was less than the other injectors. I know the Cherokee runs sequential injection as opposed to batch fire. could the problem be the sync generator? Or might the problem be in the wire harness (bad connection) all of the plug housings for the FI's are very clean. Any Help would be greatly appreciated.


Here is a list of parts I have replaced in the last 2 weeks.
6 Injectors
Fuel pump
fuel filter
TPS
Radiator


I also dropped the fuel tank and cleaned it out. when I replaced the injectors I blew out the fuel supply and return line as well as solvent tanked the fuel rail and yes there was some rust sludge in it. : (

Roler

What did you get when measured #2 and #6, compared to the others?

Trey

#2 and #6 are about 2 volts lower than the other 4.

vulcan1701

The wires to those injectors could be marginal due to age.

To test it, you could place a jumper wire inline from as close to the ECU as you can and then to the injector plug with Scoth connectors and see if it clears up the problem.

A permanent fix would be to get new injector connectors and run new wire. You would also need a pin extractor/installer tool and new pins to connect it to the ECU plug.

Trey

Great Idea. Where is the ECU located? You would not by chance have a pin diagram of the ECU. : )

vulcan1701

The diagram is on Autozone's website:
http://www.autozone.com/autozone/rep...00c152800a9de9

It is Fig. 29: 1991-1993 Cherokee (2.4L/4.0L)Engines Schematic

The ECU is located on the driver's side next to the air box on the fender. It is a black box with a single connector bolted to it. If you remove that connector, make sure you clean around it first to keep debris out.

Trey

Outstanding Vulcan 1701 THANKS!!!! I will check into it over the next few days and let you know what I find...