1991 2.9 manual ranger rough idle and dies

[preston c]

1991 ranger starts right up and will idle for a while it but idles rough.when you put it in gear and drive for a minute it starts to sputter and has now power then dies. It had code 21 and 24 which is engine coolant temp sensor and intake air sensor, replaced both sensors and still nothing. under the hood you can hear a hissing sound. we have checked for vacuum leaks and we can’t seem to find one, we have pulled off iac and cleaned it, replaced fuel filter, even brought it to mechanic they said they fixed but but as soon as we got it home it done the same thing.

any suggestions

 

[Josh P]

Does that hissing sound seem loudest near the vacuum booster?

 

[preston c]

idk i’ll have to check i’ll get back to you after i check

 

[rusty ol ranger]

Check the vaccum line running to your MAP sensor too

 

[preston c]

it seems fine

 

[preston c]

it’s really hard to tell but sounds like hissing it’s coming near driver side of engine bay near the break booster

 

[Josh P]

it’s really hard to tell but sounds like hissing it’s coming near driver side of engine bay near the break booster

Pull the rubber hose off the brake booster and bend it to kink the hose. If the hissing sound goes away you need a new booster.

 

[preston c]

i pulled the vacuum line off and kinked it and you can still hear the hissing. After doing that i left it alone for a little bit. I went back to work on it and still started right up and idled high but only idled about 45 seconds then shut off and didn’t want to start back.

anymore suggestions?

 

[alwaysFlOoReD]

What did the mechanic say he fixed? Have you done a fuel pressure test while running?

 

[preston c]

I’ve been wanting to do a fuel pressure test but i don’t have the kit so i just haven’t got around to it. It’s been about 6 months since it’s been in the shop to be completely honest i don’t remember what they said they fixed.

 

[rusty ol ranger]

i pulled the vacuum line off and kinked it and you can still hear the hissing. After doing that i left it alone for a little bit. I went back to work on it and still started right up and idled high but only idled about 45 seconds then shut off and didn’t want to start back.

anymore suggestions?

Check the hose going to the booster itself....maybe unplug the hose at the engine and plug that port and see what it does.

Theres nothing on the drivers side that calls for vacuum except the brake booster.

Do you have cruise control? There is some vacuum stuff associated with that over there.

 

[RobbieD]

Do you have cruise control? There is some vacuum stuff associated with that over there.

Yes, that. If the truck doesn't have cruise, or never had, that can be ruled out.

 

[preston c]

update

I got it to run I started it up and revved it pretty hard so it’s running again but it still idles low and rough.it doesn’t have cruise control. I took the fuel line off and put it in a five star coffee cup and it filled it up pretty quick and shot the fuel out pretty good idk if that tells you anything. i’m gonna try to get a fuel pressure tester soon. I took the hose off of the intake coming from the brake booster and then truck had a very high idle but still spuddered a little when revving up.

 

[rusty ol ranger]

update

I got it to run I started it up and revved it pretty hard so it’s running again but it still idles low and rough.it doesn’t have cruise control. I took the fuel line off and put it in a five star coffee cup and it filled it up pretty quick and shot the fuel out pretty good idk if that tells you anything. i’m gonna try to get a fuel pressure tester soon. I took the hose off of the intake coming from the brake booster and then truck had a very high idle but still spuddered a little when revving up.

Its idleing low?

Check fuel pressure and ignition timing.

 

[preston c]

yes it lopes when idleing

okay i will