Pre-1997 Models

4.9l 1995 F150 Hesitation under Acceleration

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Old Jan 28, 2010 | 12:22 PM
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4.9l 1995 F150 Hesitation under Acceleration

Howdy everyone, i've come to these forums yet again looking for help from all of you wise people!



Recently I had a problem with my truck where it would crank and crank and crank, but would never turn over. I had pulled the plugs and wires and replaced the plugs that looked like they were totally shot. Upon putting the wires back on, I foolishly did not label them and relied upon the factory wiring diagram to position them. After a couple months of head scratching and confusion about why in the world the truck still wouldnt start.. (along with replacing almost everything along the way).. I broke down and towed it to the shop. They found out that the distributor was 180 degrees off from the factory position. They rerouted the plug wires and "retimed" it for me as they put it. Charged me $60 for the ordeal and I had a running truck! YAY!



Replaced by me under this ordeal:

Fuel Filter

Plugs

Coil

Starter Solenoid

ECT sensor

Cap/Rotor

Battery



"Running" would be an optimistic term. "Starting" truck would be more appropriate.



First off in my long list of WTF happened...

-Rear fuel tank is no longer working. The rear fuel tank sender is the only one working, so I usually kept about 5 gallons in the main tank as a backup, and ran the truck off the rear tank so I could have a visual on my gas level. After the starting problem, the truck will no longer start on the rear tank. It will start on the main tank, and will stay running when I switch it over to the rear, but will not go anywhere under acceleration. I tested the fuel pressure from the rear tank and im showing around 20psi at KoEoff and a shaky 20psi at KoEon.



-Main fuel tank starts like a champ. Fuel pressure test showed 53psi static pressure/running pressure. According to my Haynes, thats pretty pro, giving it gas while running in neutral showed a steady 53psi also.



-UNDER ACCELERATION! My truck feels possessed and trying to rid me from its cabin.

+1st gear is pretty smooth, note that i drive it like a grandma, so throttle position is very low coming through 1st.

+2nd gear has some jumping in it. Bucking if you may...

+3rd gear will jump and snort and buck until reaching a cruising speed, whereupon it will cruise pretty smoothly. I'll leave it at 3rd sometimes in town around 30-35mph as to not have to deal with 4th.

+4th gear will act like 3rd but will settle out when I reach a desired cruising speed.

+5th gear... Well, lets just not try to mess with 5th gear, as having any sort of inclines in the road will lead to excessive swearing and hard liquor upon arrival to my destination...





These little tidbits, along with an awful grinding noise from underneath the truck upon startup and 1st gear/2nd gear roll offs, (Though the grinding has been going on for quite some time, I had it pegged to the throwout bearing perhaps, but I could very well be wrong), are the bane of my existence right now...





Any insight on what is plaguing my truck? I have tried pulling the EGR vacuum hose and plugging it, but no such luck. Just tested the fuel pressure in hopes of pinning it on my main tank fuel pump (rear one is shot im pretty sure by the looks of the pressure test). But it seems as if the main tank pump is going strong. I know there are some vacuum lines in need of replacement, and that is scheduled for this Saturday along with a new set of plugs and wires and an oil change (god knows when the previous owner last had it done). The bank of vacuum lines coming off the intake manifold on the drivers side in the back has a few lines capped off and a few that look pretty shoddy, im really wondering why anything would be capped. Just wish i could find a picture of someone's who has everything running perfect!





Thanks for any advice that may be inc.





and sorry for the long read!
 
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