More idling issues...
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Joined: Apr 2006
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From: Kansas City, KS
More idling issues...
OK, similiar to a thread out there already, I've got an idle issue that is confounding me. In Park or Neutral, truck idles fine. In gear, idle lugs down so low that the engine dies. For the moment, I've got the idle jacked up to keep the thing running. (currently idles up hill at 35 mph!). When sitting in the drive way, I can turn the idle down to a more normal range and the truck is fine until I try to put it in gear.
Just replaced the power booster as I knew I had a leak there. Can't find any other vacuum leaks. I've set the ignition timing by ear several times.
Oops. It's a 79 F150 4x4 with a 351m and an automatic. I'm thrilled with the truck and bought it as a project. I've done the brakes, as they were scary, and then I did the booster in hopes that losing the vacuum leak would help my idle. It did, but not much.
Any ideas?
Just replaced the power booster as I knew I had a leak there. Can't find any other vacuum leaks. I've set the ignition timing by ear several times.
Oops. It's a 79 F150 4x4 with a 351m and an automatic. I'm thrilled with the truck and bought it as a project. I've done the brakes, as they were scary, and then I did the booster in hopes that losing the vacuum leak would help my idle. It did, but not much.
Any ideas?
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Joined: Feb 2006
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Have you tried your fast idle screw, I have the same problem, that seemed to help out.
Although for me I lost my screw so i had to ghetto rig it, So as of right now it's still dies.
I'm gave up and taking it to a carb shop.
Although for me I lost my screw so i had to ghetto rig it, So as of right now it's still dies.
I'm gave up and taking it to a carb shop.
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Joined: Feb 2006
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Fmodster303,
If you're having to put it in nuetral before you come to a stop to keep it from dying, and then rev it up, throw it in gear to take off, here is a problem I once had....
The torque coverter in my '83 F150 went out. I was in traffic when it happened and it was very difficult to drive. Once I got it moving, it was fine. But starting out was a task. If I tried to start out at normal idle speed, I would put in drive and it would lunge forward and die. The only way I could achieve mobility was to rev the rpms and throw it in drive. It sounded and felt like it was starting out in about 3rd gear; hence, the lunge. This may not at all be a problem similar to yours, but I thought I'd share that with you and tcbofade.
If you're having to put it in nuetral before you come to a stop to keep it from dying, and then rev it up, throw it in gear to take off, here is a problem I once had....
The torque coverter in my '83 F150 went out. I was in traffic when it happened and it was very difficult to drive. Once I got it moving, it was fine. But starting out was a task. If I tried to start out at normal idle speed, I would put in drive and it would lunge forward and die. The only way I could achieve mobility was to rev the rpms and throw it in drive. It sounded and felt like it was starting out in about 3rd gear; hence, the lunge. This may not at all be a problem similar to yours, but I thought I'd share that with you and tcbofade.
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From: Kansas City, KS
Um, yep. I've got the lunge. Drive or reverse. If in two wheel drive, it will actually chirp the tires when put into gear. How does one check a torque converter?
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As 75Ford says, check the vacuum modulator line for cracking, and the modulator itself. Remove the line and see if there's ATF inside; if so, the modulator is bad.
Since a new booster helped it, there may be another vacuum leak somewhere. If the vacuum modulator checks out, take a close look at the carb gasket, and the PCV hose going into the base of the carb.
Gotta love these old trucks.....
Since a new booster helped it, there may be another vacuum leak somewhere. If the vacuum modulator checks out, take a close look at the carb gasket, and the PCV hose going into the base of the carb.
Gotta love these old trucks.....
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From: Kansas City, KS
farmnaggie-got your email. Thanks. FTE system won't let me email you back yet as I'm too new of a member. I wouldn't say it feels like the wrong gear, but it certainly is in a big hurry to get somewhere. I've been pretty thorough about checking the other vacuum lines and cannot find any other leaks. Did not check the modulater tho...I'll do that next. Worst case, I'll go to the tranny shop, but I kind of already know what they are gonna tell me... ya know?
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From: okc
well, from what ive read so far, its lungeing because you have the idle turned up...when its idleing does it idle smooth or is it erratic?? take off the air cleaner and let it idle, listen to the sound the carb makes, is it a constant hiss or does it sound like someone is sucking the last of a drink through a straw (best description i can think of) if it sounds like the straw thing then your carb is overloading and needs rebuilt....usually when there is a vacuum leak the idle shoots up but is normaly still smooth, this isnt ALWAYS true but mostly....you need to put a timing light on it to set the timing, just bumping the dizzy a 1/8 inch one way can throw your timing off 2-4 degrees, most Ford engines are impossible to time by ear, you can get it close but still be way off...trust me i know, i timed engines for years by ear until i bought my first Ford, then i ended up throwing away a perfectly good 360 cause i thought it was shot, turned out i didnt time it right....so first off set the timing correctly, and listen to the carb...after that post back with your results....
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You can check your carb for air leaking in from the wrong place by spraying carb cleaner through the wand around every conceivable place it could leak except in the air horn.
Make sure you turn the idle down first so you can notice the difference in the speed of the engine when you do this..
Make sure you turn the idle down first so you can notice the difference in the speed of the engine when you do this..
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From: Kansas City, KS
OK gents. Round 2. I set the ignition timing properly this weekend. I think. Chilton called for 8 degrees btdc. It wasn't until after I'd done that I found a decal under the hood calling for 4 degrees. For the moment, I left it at 8. Had to do major carb adjustments to keep truck running. Vacuum modulator looks ok. No fluid in the vacuum line and the line looks intact. I don't believe I'm having a fuel delivery problem.
Next up, I'm thinking rebuild carb. (Idle is considerably lower, but still way to high.)
In park or neutral, I can drop idle to normal range, but then truck dies when put into gear. Idle seems smooth.
Next up, I'm thinking rebuild carb. (Idle is considerably lower, but still way to high.)
In park or neutral, I can drop idle to normal range, but then truck dies when put into gear. Idle seems smooth.
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when my dad and i put the 351 m in my 79 250 we thought we had all the vaccum lines hooked up but we went over it and we had forgotten to hook the line from the up to the splitter on the intake manifold but it was hooked up on the trans itself it would run fine above 1000 rpm but it would die instantly below that. make sure you turn the two mixture screws on the bottom of the carb just snug not tight then back each out three turns that will get it in the ballparkalso make sure the vaccum splitter on th eback of the manifold is tightened
just some stuff i have done before hope it helps.
just some stuff i have done before hope it helps.