looking for help
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,150
Likes: 5,785
From: S/W Missouri, Polk county
So it starts, idles and shifts fine in 2wd? And when you lock in the front axle hubs, put the transfer case lever in 4H or 4L it (the motor) will not run right? Auto or manual transmission?
Cargo Master
Joined: Jul 2005
Posts: 2,309
Likes: 364
From: Kansas
you might start with some details on what your truck is, year, engine (and trans as Rich mentioned)...since the '73-'79 ford 4x4 system is activated with a manual shift lever, that "should" have no effect on how your engine runs...
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,150
Likes: 5,785
From: S/W Missouri, Polk county
Like just stated the engine (operation as in idling and or running) and 4wd are not connected in no way. Electric or other wise, so one should not affect the other. BUT the auto trans is connected to the engine via a vacuum line. Does the trans shift up and down just fine when the truck is in 2wd?
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5th Wheeling
Joined: Jan 2023
Posts: 27
Likes: 1
From: IDAHO
Like just stated the engine (operation as in idling and or running) and 4wd are not connected in no way. Electric or other wise, so one should not affect the other. BUT the auto trans is connected to the engine via a vacuum line. Does the trans shift up and down just fine when the truck is in 2wd?
Fleet Mechanic
Joined: Feb 2022
Posts: 1,370
Likes: 705
So… get back to us when that work is done and you are trying to drive the truck again. There will be specific questions that you need to provide specific answers to. We can’t really do much more to help at this point. Ambiguity and lack of data, even if it’s just empirical, only serves to muddy the waters.
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Lead Driver
Joined: Jul 2017
Posts: 9,580
Likes: 1,162
From: San Jose, CA
This theoretically wouldn’t act like you were saying, but double check that the front and rear differentials share the same gear ratios.
If for some reason someone put 4.11s in the rear and kept 3.50s in the front, that would cause a binding. But it wouldn’t normally stall the engine or cause it to run rough.
It would certainly make shifting into and out of different transfer case gears harder.
When you get a chance too, make sure there are no wires dangling near the front driveshaft or any shift levers.
Just throwing out wild idears for you to consider while scratching your head or pulling out hair. 😁😉🙄
If for some reason someone put 4.11s in the rear and kept 3.50s in the front, that would cause a binding. But it wouldn’t normally stall the engine or cause it to run rough.
It would certainly make shifting into and out of different transfer case gears harder.
When you get a chance too, make sure there are no wires dangling near the front driveshaft or any shift levers.
Just throwing out wild idears for you to consider while scratching your head or pulling out hair. 😁😉🙄
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5th Wheeling
Joined: Jan 2023
Posts: 27
Likes: 1
From: IDAHO
well i'm back and took it for a drive and it barley runs any thoughts.
i hooked up a vacuum gauge and tried to tune it and it did nothing and it runs better with choke on so i assume its vacuum
mainly because the tree was literally being blocked by a screw so if you guys have a vacuum diagram would really help thanks
by the way incase you guys did forget what my truck is it is a 1978 f150 with the 6.6 lt 400 4wd with a automatic transmission
thanks and have a great one
i hooked up a vacuum gauge and tried to tune it and it did nothing and it runs better with choke on so i assume its vacuum
mainly because the tree was literally being blocked by a screw so if you guys have a vacuum diagram would really help thanks
by the way incase you guys did forget what my truck is it is a 1978 f150 with the 6.6 lt 400 4wd with a automatic transmission
thanks and have a great one
Lead Driver
Joined: Jul 2017
Posts: 9,580
Likes: 1,162
From: San Jose, CA
possibly indicating vacuum leaks. Which leads to the next questions.
The vacuum tree is not supposed to be open. If part of it was blocked with a screw, it was probably to close an unused port, or stop a vacuum leak.
Did you remove the screw? And if so is the port it was blocking now open?
Any chance you can post up some detailed pictures of the area around the engine? Specifically the area around the carburetor and vacuum tree?
thanks.
Hotshot
Joined: Feb 2004
Posts: 10,764
Likes: 2,590
From: The Shenandoah Valley
Poster isn't running it in 4wd when noticing a drag or "unwillingness to git" ... on hard surface roadway is he? Even with factory close match gear sets, the difference in tire pressures / loading / and things like 3.54 frt and 3.50 rear gear will bind the power train. Even 4.10 vs 4.11 while seeming to match, will do it.
Thread Starter
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5th Wheeling
Joined: Jan 2023
Posts: 27
Likes: 1
From: IDAHO
The engine running better when the choke is closed, usually indicates something such as it’s running very lean (because the choke richens up the fuel/air mixture) or the spark from the ignition is very weak.
possibly indicating vacuum leaks. Which leads to the next questions.
The vacuum tree is not supposed to be open. If part of it was blocked with a screw, it was probably to close an unused port, or stop a vacuum leak.
Did you remove the screw? And if so is the port it was blocking now open?
Any chance you can post up some detailed pictures of the area around the engine? Specifically the area around the carburetor and vacuum tree?
thanks.
possibly indicating vacuum leaks. Which leads to the next questions.
The vacuum tree is not supposed to be open. If part of it was blocked with a screw, it was probably to close an unused port, or stop a vacuum leak.
Did you remove the screw? And if so is the port it was blocking now open?
Any chance you can post up some detailed pictures of the area around the engine? Specifically the area around the carburetor and vacuum tree?
thanks.
Thread Starter
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5th Wheeling
Joined: Jan 2023
Posts: 27
Likes: 1
From: IDAHO
this is all i got besides this old ad for a school project when i first bought the truck and had only put in a new fuel pump and fuel sender unit and cleaned out the tank back in 2021 december i think though it runs even rougher now then the video portrayed Download 5A262B02-D85D-4528-BF23-7E0827FE4CD8.MOV
Thread Starter
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5th Wheeling
Joined: Jan 2023
Posts: 27
Likes: 1
From: IDAHO
Poster isn't running it in 4wd when noticing a drag or "unwillingness to git" ... on hard surface roadway is he? Even with factory close match gear sets, the difference in tire pressures / loading / and things like 3.54 frt and 3.50 rear gear will bind the power train. Even 4.10 vs 4.11 while seeming to match, will do it.