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sgm11155
sgm11155, ASE Master tech
Category: Ford
Satisfied Customers: 589
Experience:  I have worked in the automotive feld for over 20 years
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Ford F150 Pickup 4x4: I have a 1984 Ford F150 pickup truck

Customer Question

I have a 1984 Ford F150 pickup truck with the 4.9 litre 6 cylinder gas engine and a 4 speed transmission. we bought it brand new and it has been a dandy. sometimes, after the engine warms up, i put it into gear, press the accelerator and the truck will go to a certain speed and then start bucking and trying to throttle down, if i continue to "put my foot" into the accelerator, it will increase speed and then do the same thing. I shift gears and it will do the same thing, reach a certain speed and then start this jerky motion. Most of the time, after it has been driven for a little while, and is running at operating temperature, it will quit and the truck runs smooth like silk.
it hasn't been tuned up in years, i am going to do plugs, wires, dist cap, rotor, ignition module this weekend and set timing.
the truck has 158,000 miles on it but still passes emissions. I have been thinking that the catylitic converter and muffler could be plugged up, they are original equipment. what do you think??
Submitted: 2 years ago.
Category: Ford
Expert:  sgm11155 replied 2 years ago.

sgm11155 :

hi i am shannon i will help on this issue

sgm11155 :

the tune up sound like a good idea

sgm11155 :

i would add a new ignition coil to that too

sgm11155 :

as far as the cat converter being blocked you can test for that with a engine vacuum gauge

sgm11155 :

i will post a video and a vacuum chart.

sgm11155 :

hear is an inexpensive gauge

sgm11155 :

i hope this answer,s all your questions. if not please post back any question on this issue you need

Expert:  sgm11155 replied 2 years ago.
Our chat has ended, but you can still continue to ask me questions here until you are satisfied with your answer. Come back to this page to view our conversation and any other new information.

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If you haven’t already done so, please rate your answer above. Or, you can reply to me using the box below.
Customer: replied 2 years ago.

I appreciate your informative and timely reponse. your suggestion about testing engine vacuum to determine the condition of the exhaust system may save me $750 bucks. i even think i have a vacuum testing gauge. What do i need to do to insure that you are paid the $59 bucks.


i am thinking that if i have additional questions regarding this same issue, i can continue to post those questions using this procedure. thank you again.

Expert:  sgm11155 replied 2 years ago.
when doing the vacuum test be sure to hold the engine speed at 2000 rpm in park . the vacuum should not drop below 15.hg. if it goes below 10. hg. and stays there at 2000 rpm . you got a exhaust blockage.
yes you can always post to this thread just go to (MY QUESTIONS ) at the top then click on this question .then post a question on this issue any time you want .
i will get a Email and answer as soon as i see it. for me to get credit click on 3 to 5 happy faces i will be paid .thanks Shannon
sgm11155, ASE Master tech
Category: Ford
Satisfied Customers: 589
Experience: I have worked in the automotive feld for over 20 years
sgm11155 and 6 other Ford Specialists are ready to help you
Customer: replied 2 years ago.

I am going to continue to pester you for information, if i can get it for the fee i have already paid ;-)


 


i did a compression test on the engine and came up with 110 PSI for all the cylinders, i was tickled. i have done some research and cannot find an actual specification for that. I think the fact that all the readings were exactly the same says a lot. anywho, if you can give me the actual specifications for a nominal compression test for the 4.9 liter ford 6 cylinder, i would be thrilled


i am thanking you ahead of time

Expert:  sgm11155 replied 2 years ago.
be sure to let me know what you find. thanks shannon
Expert:  sgm11155 replied 2 years ago.
i do not have a spec. for compression. but you are right all reading the same is good. how did the vacuum test come out?
Customer: replied 2 years ago.

there has been nothing new to report
i have followed your directions and suggestions and the truck project is kind of at a standstill right now.
i can only spend so much time and money trying to restore my old pick'em up trucky
thank you again

Expert:  sgm11155 replied 2 years ago.
no problem just post a question or results of testing when you are ready

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