94 idle problems
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94 idle problems
My name is stuart and live in the yukon territory Canada, I own a 94 F150 5.0 4wd that has been giving me a head ache. It idles like (@%#&)! some days it runs nice and others well the problem comes back, when on the highway the check engine light comes on and off, when on it seems sluggish no throttle responce,when it goes off it runs like a dream I have changed every sensor I mean every sensor,execept the mass air flow senser due its price. I keep the truck extreamly clean,you could eat off the engine. so the problem can't be trivial.I think the problem is in the fuel delivery system however im not going to change all 3 pumps if I don't have too.Im not that rich. recently I have removed the engine to redo all the gaskets hoses etc.I have done my leak down and compression tests which all pass, also I have fixed my speed sensor so there is no short. the truck is completly stock. loaded of course, but stock. there are no add ons. I have built my 88 4wd from the ground up.
Was 88 2wd 5.0 auto (stock height)
Is now 88 4wd 4.9 4 spd standard 4'' pro comp lift on 33's
Just so you know im not a green horn.If anyone knows about my idling problem please help thanks.
Was 88 2wd 5.0 auto (stock height)
Is now 88 4wd 4.9 4 spd standard 4'' pro comp lift on 33's
Just so you know im not a green horn.If anyone knows about my idling problem please help thanks.
Post Fiend
Joined: Mar 2002
Posts: 19,402
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From: Bonita Springs FL
Well, you've covered most of the bases - except you didn't pull the codes. When the check engine light flashes, that's a message to you. The PCM is trying to tell you there's a problem. Since the light comes on when you are having problems and goes away when it runs fine, you can be certain the codes stored will point to directly to the problem.
http://fordfuelinjection.com/?p=13
http://fordfuelinjection.com/?p=13
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Thanks Andym. I'm having similar problems, however, mine started out slowly and gradually. First, it was only when the vehicle was cold, but, lately, its gotten to where it misses pretty bad, but only sparatically. I've not had any loss in power, however, and the problem is much worse when the vehicle is cold. This is odd because this vehicle, unlike older Chrysler products, has never been "cold natured".
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Mine is a '93 5.0 and I have posted a similar thread. It is an intermittent problem - some days it starts and runs just fine, others it starts but idles rough and sometimes won't run at low idle at all. I don't know if it is coincidence or not but we have had a cold snap this last week (below 0 to low teens) and it won't come out of it. I have to pull a Sammy Hagar when I need to stop to keep it running. Usually after it warms up, it recovers but this week it hasn't. I have had it to a couple different mechanics and the previous owner has also had it to a number of mechanics but no one is able to come up with a solution. If you find a fix, I would greatly appreciate it if you would post your findings.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
dolanstuart, you only have two Fuel Pumps, one in each tank and no Fuel Selector Valve. If it runs good on one tank and not the other then I suspect a Fuel Pump. The only sensors that may be bad would be the ECT (the one with two wires), and TP sensors. You may also have a bad Idle Air Control Valve.
If these are all good then it may be the PCM. There are Electrolytic Capacitors inside the PCM that may be going bad, an Electrolytic Capacitors can heal themselves and then go bad again. You can try replacing them for under $10.00.
This URL tells you how to do it.
http://www.tmo.com/howto/ecu1g/caps.htm
If these are all good then it may be the PCM. There are Electrolytic Capacitors inside the PCM that may be going bad, an Electrolytic Capacitors can heal themselves and then go bad again. You can try replacing them for under $10.00.
This URL tells you how to do it.
http://www.tmo.com/howto/ecu1g/caps.htm
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Originally Posted by subford
dolanstuart, you only have two Fuel Pumps, one in each tank and no Fuel Selector Valve. If it runs good on one tank and not the other then I suspect a Fuel Pump. The only sensors that may be bad would be the ECT (the one with two wires), and TP sensors. You may also have a bad Idle Air Control Valve.
If these are all good then it may be the PCM. There are Electrolytic Capacitors inside the PCM that may be going bad, an Electrolytic Capacitors can heal themselves and then go bad again. You can try replacing them for under $10.00.
This URL tells you how to do it.
http://www.tmo.com/howto/ecu1g/caps.htm
If these are all good then it may be the PCM. There are Electrolytic Capacitors inside the PCM that may be going bad, an Electrolytic Capacitors can heal themselves and then go bad again. You can try replacing them for under $10.00.
This URL tells you how to do it.
http://www.tmo.com/howto/ecu1g/caps.htm
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im not sure if the outside temp has anything to do with it. it has done the same at -40 to 45c and +20 c its really annoying. however (not sure if i should have) i cleaned my mass air flow sensor with some brakeclean red/white can, it made a considerable difference for a couple of days so when money permits i will get a new one and let you know
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Fleet Owner
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From: Easton,Ks
Originally Posted by dolanstuart
if i only have two please explain why i have a pump in each tank and on on the framerail for pressure. remember its a 94
My help and assistance is only for stock factory installed fuel system. I have no information on non-stock fuel system.
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Joined: Feb 2006
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From: Brook IN
Originally Posted by subford
If you have a 1994 F series truck with a High Pressure Pump on the Frame Rail then somebody put it there, its not stock factory.
My help and assistance is only for stock factory installed fuel system. I have no information on non-stock fuel system.
My help and assistance is only for stock factory installed fuel system. I have no information on non-stock fuel system.
it could be original, i have 2-94 F-250's, my 460 powered super cab doesnt have the inline, but the ol ladies 351 powered std. cab does, we bought both new, so i know noones added anything to ours.
Also, i was always under the understanding that the inline was more of a booster pump, maybe i'm wrong?
Fleet Owner
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From: Easton,Ks
Originally Posted by Ford_for_Brains
it could be original, i have 2-94 F-250's, my 460 powered super cab doesnt have the inline, but the ol ladies 351 powered std. cab does, we bought both new, so i know noones added anything to ours.
Also, i was always under the understanding that the inline was more of a booster pump, maybe i'm wrong?
Also, i was always under the understanding that the inline was more of a booster pump, maybe i'm wrong?
Also no reference to one in the Ford Shop Manual (Service Manual), Ford CD or the FORD Electrical and Vacuum Troubleshooting Manual.
You have a rare machine, there does not seem to be any manuals for her truck.
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