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Hesitation Then After Fire Out Exhaust?


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I got an 86' with 92' 4.0. It left me stranded the other day, after putting a new CPS and fuel pump in I got it home. Just got some new wheels and tires so I threw them on, went for a drive and everything was going good. Then the motor had like a hesitation and when I gave it more gas it had an after fire out of the exhaust, got it back home and it was running at a lower than normal idle and the motor would act almost tryin to catch itself and idle up a bit and then back down again.

 

Anyway, it almost sounds like ignition and timing....but with a new CPS what else is there that does timing?

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how long have you had the motor in your 86? Has it been rebuilt recently? is the new fuel pump for a HO 4.0, or the stock V6 or I4?  When was the distributor replaced last? Have you tried another engine computer?  Have you checked the timing?

 

I can't really help, but more info will likely get better and quicker response.

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This motor has been in this truck for about 4 years. The fuel pump is for a 4cyl because the 4.0 pump doesn't fit inside the unit, I tried last year when I changed it before. Distributor has never been replaced, has performance distributor cap, rotor, wires, and screamn demon coil, all installed like 4 years ago, could probly use a spark plug change. Just did an aw4 to ax swap a couple months back so this is a different comp, haven't tried putting the old aw4 comp back in. I haven't checked timing, I figure it's all electronic controlled, cps, ECM and maybe MAP would influence it the most i think, it was running fine last week.

 

It just started last night, i wish I could just be working on it and look at all your suggestions right now but.....gotta work....

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To my knowledge I aligned it right. The bolts only line up a certain way. BUT the last CPS looked like it got rubbed a bit....but that is honestly my worst fear....gotta pull that whole TNT kit off one weekend to do it! But you may have a point, I'll check the new CPS for wear

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Possibly, but I would think if it was warped it would give trouble immediately on start up. Flywheel is new, fired it up yesterday after work and it idles fine now...so maybe I gotta go drive and put load on the motor to get it to do it again

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