'96 Cherokee Cold Temp Start Issue

[tgeej]

This winter, my 1996 Cherokee Sport developed a cold temperature start problem. If overnight temps are below 50 degrees or so, the engine cranks just fine but without firing. If I pump the accelerator, while doing short cranking bursts, it eventually roars to life. Of course being fuel injected, I have no idea if the pedal pumping is really affecting the start. Sometimes after this type of start, the engine will not idle until it warms up. When temps are warmer, the cold engine always starts right up like normal. No vacuum leaks are apparent, and the Manifold Air Temp Sensor seem to check out as OK. Sound familiar to anyone?

[JPNinPA]

Check fuel pressure key on and off and while it is running. Should be constant.

Check spark to the plugs.


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[tgeej]

After a year with the problem getting worse, and replacing plugs, wires, cap, and rotor, and noting fuel pressure irregularities, I replaced the ECU. Fixed!

[JPNinPA]

Glad to hear you repaired it.


Never look down on anyone unless you are helping them up - Jesse Jackson

[tgeej]

Thanks for checking back on this . . . however . . I think the timing chain just broke. I'm almost to the chain, and should get the cover off tomorrow. Do you, by chance, know if this 4.0 inline 6 is an "interference" engine? At 265,000 miles, I'm not likely to tear the motor down to check for damage. Thanks, again. TJ

[JPNinPA]

I do not believe it is an interference engine.
Also these chains stretch but do not normally break. The engines have been known to go 500k mi with no chain issues. Pics if it did.


Never look down on anyone unless you are helping them up - Jesse Jackson

[tgeej]

Thanks. I'll post a picture if it's broken.