Problem Starting
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Junior User
Joined: Sep 2003
Posts: 72
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From: O'Fallon, Il
Problem Starting
Hey guys i am having trouble when i first start my 1990 bronco...it starts then sputters out...if i get on the gas i can get it to run after a few more sputters...then when i drive it, it does not die on me but runs normally...i am thinking that mabey its the fuel pump or possibly the fuel filter...i was just wondering what anyone else thinks it could be...also i just replaced the cap and rotor and plugs and wires and checked and cleaned all grounds so its not an electrial problem that i know of...ok please give me some input...
~Jared
~Jared
New User
Joined: Feb 2005
Posts: 6
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From: Wexford, PA
Dude
I had the same problem on mine. It is a '90 302. I dont remember what codes it showed but the problem was the idle air bypass valve. Fairly cheap, it bolts on the side of the throttle body and has a pigtail connected to it. It will get progressivley worse if that is what it is. When it is cold and you rev the engine does it seem to want to bog out??? that is what mine would do besides the hard starts. What was happening I was getting a lot of blow by and the plunger in the valve was all gunked up so it was not able to move as efficiently.
Hope this helps.
I had the same problem on mine. It is a '90 302. I dont remember what codes it showed but the problem was the idle air bypass valve. Fairly cheap, it bolts on the side of the throttle body and has a pigtail connected to it. It will get progressivley worse if that is what it is. When it is cold and you rev the engine does it seem to want to bog out??? that is what mine would do besides the hard starts. What was happening I was getting a lot of blow by and the plunger in the valve was all gunked up so it was not able to move as efficiently.
Hope this helps.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
Airby is on the right track. Pull the codes first. This will help avoid chasing possible causes that AREN'T the real cause for the problem. It does sound like a malfunctioning IAC (Idle Air Control solenoid) as Airby mentioned but to be certain, pull the codes. For code-pulling info try www.fordfuelinjection.com
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Junior User
Joined: Sep 2003
Posts: 72
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From: O'Fallon, Il
still having the same problem
ok i pulled the codes and it all checked out as ok...the fuel pressure is all fine and of course when i went to get it looked at it didnt do any of what i said it was doing for the shop...anyway...it started right back up when i left...i droped in some fuel injector cleaner and no change...i was then driving it later that night and it started to chug and die as i was driving it not only now when i started it up...it also took me close to 40 min to start the truck and when i started it i had to race the engine to even get it to want to start...please let me know what you all think about this...
Senior User
Joined: Sep 2003
Posts: 254
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From: Colorado
When you say fuel pressure is fine, when did you check it? Was it at idle, high rpm? Two other things to check: How long do the fuel rails hold pressure after turning off the vehicle, and what does the pressure in the rails jump to when you turn the switch to "on" after the pressure in the rails has gone away? Also check to see what the fuel pressure does when you jump from idle into high RPM's. If I remember correctly, you shouldn't loose more than 5 psi when you jump out of idle into high RPM, and I think idle psi on these engines is 38-40 psi? Someone correct me if I'm wrong.
New User
Joined: Feb 2005
Posts: 6
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From: Wexford, PA
Dude
Just pop the idle air bypass valve off. I still think that is what it sounds like. If that is messed up or stuck the computer will try to compensate big time. It was weird when i changed mine cause i could hear and feel it when i first drove it.
Take the valve off the side of your throttle body, and look where the mating face is. You should see the plunger in there. See if it gunked up.
It is worth try; a cheap non knuckle busting diagnostic procedure.
Hope it helps
Just pop the idle air bypass valve off. I still think that is what it sounds like. If that is messed up or stuck the computer will try to compensate big time. It was weird when i changed mine cause i could hear and feel it when i first drove it.
Take the valve off the side of your throttle body, and look where the mating face is. You should see the plunger in there. See if it gunked up.
It is worth try; a cheap non knuckle busting diagnostic procedure.
Hope it helps
Freshman User
Joined: Aug 2004
Posts: 30
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Mine is doing the same thing and has gotten progressively worse. I took it in to have the codes pulled and like you said it didn't act up for the dealer for 2 days. Anyway, it got worse and worse to where I can't even drive it. I got it to the dealer to pull the codes again and it showed the EGR valve, EVP sensor, and MAP sensor were giving hard faults. I originally thought of the IAC because I had previously had a '98 F-150 truck and it did the same thing once and it was the IAC. I'd say it could be either the EGR or the IAC. greystreak gave me some really good pointers a couple of weeks ago about the EGR but I haven't had the time to do anything with it yet. So for now my Bronco sits and waits. Looks like it's going to be another couple of weeks before I get to do anything with mine. Good luck.
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