2000 Ford F-150 Starts to run horrible after long drives.

Tiny
SHARK8
  • MEMBER
  • 2000 FORD F-150
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 112,000 MILES
Frst happened acouple weeks ago, I was driving alot and all of a sudden when I would stop and a stop sign or light my truck would start to idle really low like it was going to die. Then when I would push the gas peddle to accelerate it would almost kill the egine and I would be barely movie untill it finely would accelerate. So we changed the fuel filter. Then I drove noramal untill I had to make a long trip out of town, then it started doing it again. The check light came on and it had a code for running to lean. But I don't understand what it could be sense it runs fine with short trips and stuff but not long ones. What could the problem be?
Monday, July 27th, 2009 AT 1:02 PM

10 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
Was filter installed properly? Have you ever had a headgasket or intake gasket leak? Cracked head or intake? You may have an exhaust leak. Listen for ticking.

If that isnt it there is a issue with the o2 sensor or fuel/spark system. Get back to me.
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Monday, July 27th, 2009 AT 5:56 PM
Tiny
SHARK8
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The filter was installed correctly. How would you check if it is an exhaust leak? Also could it be the fuel pump? I'm just not sure what could cause it to run so bad then the very next day it runs great after it cools down and sets. It can make short trips no problem but 30 min drive it'll start not accelerating off of stops and wanting to died idling and when gas is pushed.
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Tuesday, July 28th, 2009 AT 5:04 AM
Tiny
BLACKOP555
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Exhaust leaks arnt very easy to tell.

Best bet is to look for black soot on the piping usually around the crack or with truck cold start it and feel around the pipes for hot air coming out indicating a crack.

You will hear a ticking noise if you have an exhaust leak.

Also I would suggest checking for a vaccum leak.

You can perform this by spraying carb cleaner slowly on all gasket surfaces and vaccum liens with vehicle running. When idle changes you have found the leak.
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Wednesday, July 29th, 2009 AT 10:21 AM
Tiny
SHARK8
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How would you check for a cracked or leaking head gasket. Also what senors could it be? Also if it was a cracked head wouldn't it run bad from start up why would it have to warm up first?
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Thursday, August 27th, 2009 AT 5:00 PM
Tiny
BLACKOP555
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Oh ok. Missread that. Have you checked the spark on it.

Check engine light on? Ever been on?

Have you ever checked the TPS? Check the voltage on it while doing a slow sweap through the range of the throttle.

Has fuel pressure been checked?
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Thursday, August 27th, 2009 AT 5:48 PM
Tiny
SHARK8
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The check engine light is on. The code is that it is running to lean.

Have checked the spark and its good, haven't checked the TPS, how do you do that?

It idles really high then after driving it was start to idle up and down at stops. Then after long periods of driving when I push the gas after stops it will idle up and down and run slugish and barely moves at firstthen picks up. Then a little after that it will start to die at stops and then when driving normal it starts to run rough when pushing the gas. But when it dies and I start it up it will take off fine. Then do it agian at the next stop.

Also after it sets for 30 min or so it will run ok. It seams longer it cools off the longer it takes for it to start messing up.
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Thursday, August 27th, 2009 AT 6:58 PM
Tiny
MJR346
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Have mechanic test drive with fuel pump pressure gauge on the fuel rail. Have him drive for about 30 minutes and do hard accelerations with it after about the 20-30 minute mark. Ford has had some issues with fuel pumps that after they get hot, they loose volume loosing pressure and will make vehicle basically idle fine but won't accelerate
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Thursday, August 27th, 2009 AT 7:22 PM
Tiny
BLACKOP555
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Im gonna have to get back to you in the morning its late. Remind me
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Thursday, August 27th, 2009 AT 8:39 PM
Tiny
SHARK8
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You told me to remind you to look at this form today, so I am. Also I didn't say before but the codes said it was running to lean in banks 1 and 2. If that'll help. Please help me with this, I really need to figure out what wrong and fix it and try not to spend to much. Anything you can let me know would be great.
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Friday, August 28th, 2009 AT 4:10 PM
Tiny
BLACKOP555
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Ok checked the tsbs nothing for that on your problem. Ok next step.

Vaccum leaks. Have you checked for those cute little monsters? Also MAF sensor could use a good cleaning. Spray it with qd contact cleaner. Dont touch the wires. Make sure its facing right way. Making sure we get those two out of way before going further.

You said fuel pressure checks good when vehicles running like a pig?

To check for vaccum leaks spray every hose air goes through with brake cleaner when idle changes youve found the leak. Try disconnecting o2 sensors does it run bad now? Trying to get it running in open loop that way to elim a few sensors to see what it is.

Get back to me asap
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Friday, August 28th, 2009 AT 7:06 PM

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