# F250 Drivability / Hesitation Problem ? HELP



## SCAPEASAURUSREX (Aug 21, 2001)

OK, The problem I have is that under hard accelleration or under load ( same thing ) The truck starts to bog a bit and hesitate badly the harder you go on the throttle. If I accelerate slowly , it's fine , and unloaded its' not too bad , but climbing a hill or with a trialer, its' horrible........ I brought it in to a shop and they hooked up to a computer and said there were no codes or any problems with it ?? they clamed it was because i put the gibson exhaust and a K & N filter ?? WHAT ?? From what I have read and know it seems to be some sort of fuel delivery problem... I think ?? But where do I start to diagnose the probem ?? could it be a weak fuel pump , faulty regulator, clogged injector, bad throttle body / Or what ??? any idea s or similar experiences ?? I changed the fuel filter already , and that did nothing to ease the suffering of my 351W... Any help would be appreciated.... Thanks guys...


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## Pelican (Nov 16, 2001)

Do you still have the cat on? The symptoms you describe sound like a clogged converter.

Another thought, is timing correct, are advance systems working?


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## Rooster (Dec 13, 1999)

Another thought:

Is the filter clean?

Had a friend one time that was getting 3 mpg on his Bronco 8 cyl.

I helped him do a tune-up, when I took out the air cleaner it was like emptying a vacuum cleaner bag.

I have a K&N system myself, mine has never gotten that dirty, but you might consider cleaning the filter, and retreating then see what happens.

Rick


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## SCAPEASAURUSREX (Aug 21, 2001)

Rooster...

Yeah , thought it was the cat too.. blew $5 beans to swap in a new cat and that not the prob... wish it was .. now I have a new cat and $500. less in my pocket and stil have probs.... ughhhh.. I have a K& N too and recently cleaned and reoiled it.. I will chekc the plugs.. the engine light comes on from time to time, and someone was telling me that that only goes on for ignition problems ? dont know if that s tru or not, but who knows.. I'll change the plugs for some Bosch platinums, so I dont have to worry about them for a while , and see what that turns up . I am also going to test the Oxygen sensor, and the coil , and see what those are doing too ?? I miss good ol carburated V-8's ... 
Thanks for the replys...


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## sno-mover (Jan 12, 2002)

Your check engine is most likely from o2 sensors, mine does the same thing. I have a 93 f-250 and there was a recall on the fuel preasure regulator, and untill I took it in to get fixed it would hesitate and run like crap. Runs good now


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## GreginAlaska (Sep 14, 2002)

Don't forget to check the Positive Crankcase Ventilation valve...I guess gas engines still have them?

You know, that plastic thing with a hose attached to it on the valve covers. Pull it off and shake it, if it rattles it is probably OK.


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## John DiMartino (Jan 22, 2000)

Have a fuel pressure test performed,under a load,I tape the guage to the base of the winshield,and head for the hill that bogs it down,a fuel pressure test sitting there at idle is useless,since it hardly needs any fuel it will show good pressure sometimes,with a bad pump,if you haven changed the fuel filter in 10K miles or more change it first.If your fuel pressure falls within factory specs,id be suprised.I doubt your injectors are bad,since the truck runs fine on the flats,it seems to be running out of fuel,on hills it will burn fuel faster that a weak pump or plugged fuel filter can provide it.


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## Pelican (Nov 16, 2001)

Another thought...

There's a sock on the end of the fuel pickup tube in the tank, I've seen where these have become clogged enough to cause your symptoms.

You have to drop the tank to access it, the pickup tube and gauge come out through the top of the tank. All you need is a flat punch to knock the lock ring counter clockwise to release it.


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## John DiMartino (Jan 22, 2000)

Pelican is right about the sock,but it will show up as low fuel pressure ,and either way the tank has to come out,and while the tank is out both the pickup,and fuel pump should be replaced,especially if the sock was blocked,this means it was starving the pump for fuel,fuel flow is what cools the fuel pump,so its been run hot,and wont last very long,so replace it along with the sock,try to use a Motorcraft pump if you can afford it,ive had bad luck lately with aftermarket everything,especially fuel/water pumps it seems,dropping the tank is no fun,so do it once,do it right,if thats what it needs.


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## Brickman (Jun 17, 2002)

Some times it is easier to lift the bed up.


Lazy as I am I would cut a hole in the bed right above the tank access area, do my work and then weld a cover over the hole.  In the words of a local mechanic, that would look very "farmered".


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## plowjockey (Dec 3, 2000)

Yeah let us know when you are going to weld right over a fuel tank so we can stay far enough away. LOL

Bruce


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## SCAPEASAURUSREX (Aug 21, 2001)

Think I may have found my problem ??? I have an MSD box and I disconnected it to see if that could be doing it , and well under hard accelleration I am not haveing the hesitation anymore, Havent pulled the traler up hill since I disconnected , but I am assuming that it will be fine now too.. ?? I hope, Need to send that thing in and have it fixed ? or into the oval file cabinet... LOL.. Thanks for all the feedback and help guys...


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## SCAPEASAURUSREX (Aug 21, 2001)

and I forgot to mention... The oxygen senson was bad... very bad.. LOL.. so I replaced that and everything seems to be back to normal for now , anyway...... Exhaust smels cleaner too not thick... Was dumping too much fuel out of it ... Thanks again ..


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## SIPLOWGUY (Mar 21, 2002)

There is a factory bulletin about this. The shielding on the junction block harness cuts into the wire making a problem like this occur. I found it on Mitchell on demand at work. I printed it. I have somewhere I'll have to find it. We discussed this at work today. Go figure!


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