jonsampley97XJ

Like the title says, 97 4.0. It usually idles at 600, but last weekend it idled at 900 which is never normal for mine. So I shut it off to see if it fixed it, and when I tried to turn it back on it just cranked hard but didn’t catch at all. Then after 4-5 tries it barely, barely caught and went “rm…rm…rm…” and slowly got faster until it was at normal rpm, like a cold start on a diesel tractor. After it warmed up, it started like normal and didn’t happen again until this weekend. I can’t figure out what would make it do that. It’s almost like the high idle sucks all the gas and the gas rail is empty when I try to start it afterwards? But i’m not good at diagnosing engines i’m just thinking out loud haha. Any help or ideas would be appreciated, I just replaced my tps a month or so ago( not because of problems but I thought it would help some stuff like shifts during hills, it didn’t lol).

cruiser54

any codes?

jonsampley97XJ

Just one code, for an overvolted O2 sensor but that’s been up for almost 2 years, my cat rusted out so there isn’t an O2 at the cat.

cruiser54

test your fuel pressure. In the meantime, try this. Turn the key to On for a few seconds. Then Off and On again. See if that affects the starting.

jonsampley97XJ

I’ll definitely try the key thing, I didn’t even think about the poor man’s prime lol. Fuel pressure is good, at least it was 3 weeks ago when I checked it but I’ll check it again considering the problem didn’t start until last week. thanks!

97grand4.0

If you shut it off with the idle high I’d tend to think it flooded a bit and won’t start easy. The high idle probably either a dirty throttle plate that’s sticking open, or the IAC valve needs a cleaning, and Id go with #1. Mine actually acts up the exact same way and a small bit of carb cleaner and a toothbrush on the plate restores to normal