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Master Auto Tech.
Master Auto Tech., master tech.
Category: Ford
Satisfied Customers: 600
Experience:  A.S.E. Master technician. Over 20 years working on import & domestic. Owner/operator of an auto shop
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My 1992 4.0 Explorer has a high-speed engine miss: it starts

Customer Question

My 1992 4.0 Explorer has a high-speed engine miss: it starts and runs fine in the morning but after driving at highway speeds for several hours, it begins to miss. As you continue to drive, the miss increases until it won't run and won't start. The next morning, after "resting" overnight, it starts and runs completely normally and gives no problems while driving around on short trips. It seems like higher speed, higher outdoor heat, and going uphill all make the problem worse, maybe higher altitude worsens the problem too.
For me—no expert—it feels lil a fuel deliverability problem: 1. slowing the car seems to lessen the miss; 2. if you "floor it" while it's in miss mode but not missing too badly, there's an immediate hesitation miss before things smooth again, feels like the accelerator pump isn't doing it's job; 3. when you try to re-start it after it dies on the road, it has that "ran out of gas" feel: while the starter is spinning the engine, there are a few little "ka-pocketa-pocketa" hits like a small amount of gas is getting through and it's trying to fire up but is starved.
Lastly, the car seems to be using more gas than usual while running normally.
Thanks, ***** *****
Submitted: 11 months ago.
Category: Ford
Expert:  Master Auto Tech. replied 11 months ago.
I'm sorry you are having problems with your vehicle. I will try to help.I'm a full time mechanic and have been a mechanic for over 20 yrs and I work part-time here on JustAnswer to help you and others repair their own vehicles, and I get credited by your ratings.. So before leaving the site make sure and leave me a rating. You can still reply to me as many times as neeed, even after the rating.. I will need for you to be my hands and eyes since I'm not there.I think you are on the right track.
It sounds like your fuel pump is going bad. As it works it gets weaker until it doesn't pump enough. Have you done a fuel pressure test?I strive to provide 5 star service. If I have satisfactorily answered your question please rate it as such and hit submit. Doing so is the only way I get compensated for my time. Also it doesn't close the discussion so we will still be able to communicate if there are further questions.