F-150 Problems

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Battenkiller

Minister of Fire
Nov 26, 2009
3,741
Just Outside the Blue Line
I have to get my truck inspected tomorrow. I hadn't started it in a while, and when I went out today the battery was dead. I jumped it and let it run for about 15 minutes, but when I went to move it it started running like a banshee. It hit about 6K on the tach and the peddle seemed stuck, so I shut it off. It ran on for about 30 seconds, dieseling away like crazy before it finally quit.

What gives? I could smell gas when I got out of the truck, but it was too dark to look under the hood. Anybody know any common problems with F-150s that might cause this to happen? It'd be good to have an idea what to look for in the AM.

BTW it's 1999 with a 6-cylinder engine.
 
Old gas in the lines? Choke stuck? (some of the old auto chokes can stick & the heat sensor not kick the choke out after it gets warm)
Dirty air cleaner may cause it to run rich & build carbon deposits on the pistons, which can cause dieseling. Usually when the engine is hot though.
Plugs carbon coated?
Basic tune up stuff, plugs, rotor & cap, air & fuel filter.
Might just need to run a bit to blow the cob webs out & get new fuel to the carb.
 
With EFI the problems after sitting are usually stuck/leaking fuel injectors and vacuum leaks. I'm not real current on Ford's EFI systems tho so hopefully someone here is. Definitely check out that sticking pedal. Pull the intake ducting off the throttle body if need be to make sure the throttle blades open & close correctly.
 
My sister-in-law had trouble with her Focus doing something similar. Dealer said it needed a throttle body and wanted charge her $700. WTH? I took the throttle body off, took the plate out, scraped the gunk off that was making it stick and cleaned everything else up. Still works perfectly and I only charged her half. Not really, all my in-laws are great.
 
Thanks, guys. I thought it seemed like a linkage problem. I've had that happen to my Camry, but the revs would drop in a few seconds, not stay stuck up near the redline. I'll get out there in a few and pull it apart and see what I find. I was mostly concerned that it was a common Ford problem that might be a big ticket fix. Didn't want to find that out once it got towed in. I only paid $2200 for the truck, I ain't paying anything near that to get it fixed.
 
If the miles are getting up there I would suspect the throttle body being dirty. I don't know how Ford controls idle air. It could be a pintle valve or just the throttle butterfly itself. But thinking logically you can't raise the rpms without adding air and fuel both. Many times a dirty throttle body will cause hard starting. But maybe this one just stuck open a little and with no load wouldn't take much to scream the rpms.
 
Clean the throttle body and intake, check the throttle linkage and make sure its properly lubricated and not bindind anywhere and get the old gas out and put some fresh stuff in there with a bottle of seafoam to help clean your injectors out.

Also check carefully for rodents eating wires and making nests.
 
bogydave said:
Old gas in the lines? Choke stuck? (some of the old auto chokes can stick & the heat sensor not kick the choke out after it gets warm)
Dirty air cleaner may cause it to run rich & build carbon deposits on the pistons, which can cause dieseling. Usually when the engine is hot though.
Plugs carbon coated?
Basic tune up stuff, plugs, rotor & cap, air & fuel filter.
Might just need to run a bit to blow the cob webs out & get new fuel to the carb.
This is one of funniest posts I've read in a while. Not only did you miss the EFI thing,(BTW, incase you didn't know, carbs have been off vehicles for ooooh 30yrs hehehhe), every possibility you mentioned could not possibly lead to fast idle rpms except stuck choke and then it would not be 6,000rpm, maybe 1,200. Don't take it personal at all but you don't sound like a powerplant tech to me.
 
It uses an IAC valve (pintle valve). And yes, good idea to pull the throttle body off and give it a good cleaning if the truck has a fair amount of miles.

wkpoor said:
I don't know how Ford controls idle air. It could be a pintle valve or just the throttle butterfly itself. .
 
That kind of RPM's he's describing means the throttle is open. Prolly 25% or more. Don't know what it takes to get that 4.2L to redline but the IAC could be completely missing and I'm betting it wouldn't make 6K on the tach.

And Batten, if you find creature "comforts" binding up your throttle linkage, check your air filter, it's a favorite place for them to munch.
 
wkpoor said:
bogydave said:
Old gas in the lines? Choke stuck? (some of the old auto chokes can stick & the heat sensor not kick the choke out after it gets warm)
Dirty air cleaner may cause it to run rich & build carbon deposits on the pistons, which can cause dieseling. Usually when the engine is hot though.
Plugs carbon coated?
Basic tune up stuff, plugs, rotor & cap, air & fuel filter.
Might just need to run a bit to blow the cob webs out & get new fuel to the carb.
This is one of funniest posts I've read in a while. Not only did you miss the EFI thing,(BTW, incase you didn't know, carbs have been off vehicles for ooooh 30yrs hehehhe), every possibility you mentioned could not possibly lead to fast idle rpms except stuck choke and then it would not be 6,000rpm, maybe 1,200. Don't take it personal at all but you don't sound like a powerplant tech to me.

Pen had a animated gif of a guy beating his head against the wall. Could be handy......
 
I had no idea what a "pintle" valve was, so I Googled it. Found this explanation on a website describing rocket engines:

Finally, while explaining the Pintle Injector to a friend, I realized that almost everybody who has a garden or tends a lawn has personal experience with pintles. You all use a nozzle on the end of your watering hose. Crank it down and you get a steady, narrow stream of water shooting out in a long arc. Crank it back the other way when you want to shut it off, and you get a wide, cone shaped fan spray. Now, turn off the water and look at the business end of the garden hose nozzle (please shut the water off first). There in the middle is a round pintle that moves back and forth as you crank the outer casing one way or the other. And the fan shaped spray of water with which you are familiar is what the fuel and oxidizer spray looks like inside the rocket engine. So take another look at the two images above and imagine the fan shaped spray. The only difference is that your spray of water doesn’t explosively combust and throw a rocket into space.
 
I also have a '99 4.2L it a nice little truck that I didnt intend to keep for long but now just cant part with it and its still going strong. The only real common problems I have heard is the timing cover gasket and intake gasket, which seem to affect only the earlier ones as bad (97 & 98 I think it was) lots of them hydro locked. After I got my F350 a couple years ago the 150 would sit sometimes for a season. Only issue I ever had with it sitting is that the throttle linkage would get 'sticky'. It wasnt nearly as bad as you say though, and the couple times it did it I just pumped the pedal a few times with the motor off would free it up and then it would work normally. Good luck hope you get it figured out.
 
I had a 97 F150 4.2 that I just traded in. 15 year old truck with only 95k miles and still looked almost perfect. Hasn't been in the shop in about seven years and nothing major EVER. Never leaked or burned a drop of oil.

My new ride is a 2009 F150. Love it. I've been driving F150s for almost 30 years.

There is a great website where you can get all sorts of info on F150s from whatever era. WWW.f150forum.com

Check it out.
 
well, I know a vacuum leak can cause a high idle, but i don't think it would send you to redline like that.

I'm more inclined to believe that it's a linkage problem.

What about an engine speed sensor or crankshaft sensor or something like that? Maybe a bad TPS? I'm not a mechanic, and I didn't even stay at a Holiday Inn Express, but I live near one, so maybe that helps?
 
From the sounds of the symptoms: diesels after shutoff and high idle speed I'd guess a gummed up throttle body/plate. Was the truck that warm too induce the dieseling?
Pull the intake tube to the throttle body, open it manualy and look in with flashlight. I'd guess its all snotted up and hanging open. I'm not sure if this is TBI or DPI Fi setup probably the later but I haven't worked on 300/6cyl any older than early 90's model. You're EGR tube is probably gummed up as well. Is it throwing any codes?
 
NATE379 said:
It uses an IAC valve (pintle valve). And yes, good idea to pull the throttle body off and give it a good cleaning if the truck has a fair amount of miles.

wkpoor said:
I don't know how Ford controls idle air. It could be a pintle valve or just the throttle butterfly itself. .
Makes sense as thats how Chevy did it in the 90s to. I'm pretty sure that valve couldn't let enough air through to get 6K. Got to be linkage or something held the throttle open.
 
Doesn't hurt to play around w/ the throttle cable, but a fuel injected motor shouldn't diesel like that. A carb'd motor will diesel because the key simply shuts off the ignition but still can suck fuel in from the carb. W/ an EFI motor, the injector(s) shut off as soon as the key is turned off. I'm thinking there is a leaking injector that is either cracked or stuck in the open position and keeps spraying / leaking fuel.

If this is motor has throttle body fuel injection (which I don't think it does) it's easy to check as you can look at the injectors in the throttle body as see if they start spraying as soon as the fuel pump kicks on (key in the ON position). If it has an injector per cylinder, it's not as easy to visually check.

pen
 
pen said:
Doesn't hurt to play around w/ the throttle cable, but a fuel injected motor shouldn't diesel like that. A carb'd motor will diesel because the key simply shuts off the ignition but still can suck fuel in from the carb. W/ an EFI motor, the injector shut off as soon as the key is turned off. I'm thinking there is a leaking injector that is either cracked or stuck in the open position and keeps spraying / leaking fuel.

pen
good point with dieseling and injector...but then you already knew that.
 
OK... I had almost no time to look at it today. Sucks big time because I need it to move, and that won't be until after the inspection runs out.

It seems like it has to be the throttle linkage because the accelerator pedal is still stuck in the down position. I feel kinda dumb, but for the life of me, I can't see where it comes into the engine compartment. And, yes, the "check engine" light is on, but I don't have a code reader, so it could just be something simple like an O2 sensor and I wouldn't know it.

Very frustrating, and it will be getting dark soon and I have to hang inside here because I need to take care of a bunch of business/moving issues. Never fails. I could waste two or three days here on the forum arguing about creosote and draft and wood drying, but the minute I absolutely have to get something done outside, the phone won't stop ringing off the hook.

Anyway, thanks for all the ideas. I'm sure I'll figure it out with a half hour of poking around under there. I hope I will anyway.
 
wkpoor said:
bogydave said:
Old gas in the lines? Choke stuck? (some of the old auto chokes can stick & the heat sensor not kick the choke out after it gets warm)
Dirty air cleaner may cause it to run rich & build carbon deposits on the pistons, which can cause dieseling. Usually when the engine is hot though.
Plugs carbon coated?
Basic tune up stuff, plugs, rotor & cap, air & fuel filter.
Might just need to run a bit to blow the cob webs out & get new fuel to the carb.
This is one of funniest posts I've read in a while. Not only did you miss the EFI thing,(BTW, incase you didn't know, carbs have been off vehicles for ooooh 30yrs hehehhe), every possibility you mentioned could not possibly lead to fast idle rpms except stuck choke and then it would not be 6,000rpm, maybe 1,200. Don't take it personal at all but you don't sound like a powerplant tech to me.

No carburetors :bug:
When did that happen.
My 1973 ford had an oil bath air cleaner on top of a carb, 8 spark plugs, points & condenser, rotor & rotor cap & room under the hood for quite a few splits.
I'm gonna have to lift the hood on my 06 truck to be sure, but i think there is a carburetor under there. Just can't find it with all the un-needed stuff in the way. :)
 
I was going to bring up that the main problem is that you got a Ford, but I won't. ;-) lol

Do the Ford's have a throttle position sensor, I think that is going bad on my Durango and it wants to surge at idle from time to time.(not wide open like yours does though)
 
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