'69 F-100 Sputtering
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'69 F-100 Sputtering
Ok guys I own a 1969 Ford F-100 and it has some fuel issues. It has a 360 V8 4 bbl engine in it. You can turn the key and it fires right up and idles but once you step on the gas some it just sputters and has no power what so ever. Even in Park it sputters when you put your foot on the gas. I took the top of the carb off and gas sprays out of the nossles and into the 2 front barrels when you tap on the gas. I think it may be dirty main or secondary jets but I have no idea where these jets are located. Can anyone help??
Thanks.
Thanks.
Lead Driver
Joined: Jan 2003
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From: Ohio
Ok, what kind of carb? Holley, Autolite or Edelbrock? Depending on the kind of carb is were the jets are. There are only MAIN metering jets(no other jets).
The fuel shot you are seeing is very critical as if it's too little or too late it will cause issue. Will the engine slowly rev up at all? Just lightly move the throttle and see what the motor does.
The fuel shot you are seeing is very critical as if it's too little or too late it will cause issue. Will the engine slowly rev up at all? Just lightly move the throttle and see what the motor does.
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not sure what kind of carb it is? It has an acc. pump on the front of the carb and one on the back of the carb. The fuel hose comes in right at the front left of the carb. when you slowly step on the gas the rpm goes up and it sputters the whole way through. when you take the the top off the carb there is a float in the front and in the back. Hope this helps to determine what brand it is.
Thanks.
Thanks.
Senior User
Joined: Jun 2004
Posts: 249
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From: Sacramento, CA.
Did it run well prior to this or did you get the truck running this way? Has any thing been changed since it ran well?
You might check your timing(gear starting to let go) and do a compression test to make sure you haven't burnt any valves.
You might check your timing(gear starting to let go) and do a compression test to make sure you haven't burnt any valves.
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The only thing that happened was that I added a boat gas tank (3 gallons). it has a bulb primer so that is nice. It had 2 stoke gas mixed in the can (100:1) It ran fine before adding this new gas tank. (my other tanks have failed). (I added regular gas to the can, there was only about 1 gallon of mix in there) Runs fine if I dump gas in the top of the carb, when that runs out then it is back to it's old ways. BTW it is just a farm truck. I leave the choke pulled all the time, ran good with it full choke before the new tank. Maybe the 100:1 clogged it up??? has about 300,000+ miles.
Lead Driver
Joined: Jan 2003
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From: Ohio
Ok, by your description it's an original Ford Autolite 4bbl.
If it takes FULL choke to keep it running then it sounds like it's got a severe LACK of fuel issue.
Look in the front fuel bowl area and you'll see TWO jets in the floor area. Make sure they aren't clogged up, as if you don't have a filter on it then likely you've gotten some junk in it. If you have a large flat screwdriver, they will unscrew.
The oil mix won't really hurt things, especially at 100:1(pretty light mix), but won't run very good on it. The gas you added likely mixed it down to a point of not a problem.
If it takes FULL choke to keep it running then it sounds like it's got a severe LACK of fuel issue.
Look in the front fuel bowl area and you'll see TWO jets in the floor area. Make sure they aren't clogged up, as if you don't have a filter on it then likely you've gotten some junk in it. If you have a large flat screwdriver, they will unscrew.
The oil mix won't really hurt things, especially at 100:1(pretty light mix), but won't run very good on it. The gas you added likely mixed it down to a point of not a problem.
Senior User
Joined: Jun 2004
Posts: 249
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From: Sacramento, CA.
It could be your boat tank won't let your fuel pump pull the volume it needs.
Is the bulb acting as a restricter?
Is the bulb acting as a restricter?
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well the last tank that was on it was a snowmobile tank that had a bulb on it and it worked fine...but who knows, could be different stylle bulb too. I will also check those two jets....are those the only 2 orfices in the carb that could get dirty and can be cleaned? Thanks again guys all good ideas....
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Sounds to me like the usual problem: Bad accelerator pump diaphrams.
No 360 engine ever came with a 4V carb, so the manifold and carb are off something else.
Is the carb marked Auto-Lite or Motorcraft?
If Auto-Lite, the accelerator pump diaphragm(s) are the same as the 2V Auto-Lite or Motorcraft carbs (1962/74) used.
C4AZ9B559A (Motorcraft CM425)
The Motorcraft 4V (4300) carb uses different pumps: D5AZ9B559A. I don't recall the Motorcraft part number. I'm in Utah, the parts catalogs are in CA.
Regardless, when these diaphrams fail, the truck sputters, hesitates, bogs down upon acceleration, or when the engine is revved in Park or Neutral.
It's very common for this to occur.
No 360 engine ever came with a 4V carb, so the manifold and carb are off something else.
Is the carb marked Auto-Lite or Motorcraft?
If Auto-Lite, the accelerator pump diaphragm(s) are the same as the 2V Auto-Lite or Motorcraft carbs (1962/74) used.
C4AZ9B559A (Motorcraft CM425)
The Motorcraft 4V (4300) carb uses different pumps: D5AZ9B559A. I don't recall the Motorcraft part number. I'm in Utah, the parts catalogs are in CA.
Regardless, when these diaphrams fail, the truck sputters, hesitates, bogs down upon acceleration, or when the engine is revved in Park or Neutral.
It's very common for this to occur.
Lead Driver
Joined: Jan 2003
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From: Ohio
He mentions that it sprays fuel, but I know how those accel pumps work on those carbs....terrible. They are spring loaded and they get stiff and don't follow the linkage and fail to shoot fuel soon enough, thus giving it a stumble. The reason I HATE those carbs.
He also mentions it stumbles and won't rev up at all. If it takes choke to get it to run at all, then it's lacking fuel big time. I'm thinking a jet is plugged(or both) and restricting fuel. Just my thoughts.
He also mentions it stumbles and won't rev up at all. If it takes choke to get it to run at all, then it's lacking fuel big time. I'm thinking a jet is plugged(or both) and restricting fuel. Just my thoughts.
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Well the diaphram as been replaced 2 times in a few short years, but when if fails the fuel comes out externally from the acc pump on the front of the carb.
The truck says Custom on the side of it so mabey thats the reason that there is a 4 bbl carb on it. I do not see any markings on the carb specifying a brand but it is covered in soil and stain.
I still can not find any real jets to try to clean either. I also by passed bulb primer and didnt see any real improvement. Well thanks so far for the input guys!
The truck says Custom on the side of it so mabey thats the reason that there is a 4 bbl carb on it. I do not see any markings on the carb specifying a brand but it is covered in soil and stain.
I still can not find any real jets to try to clean either. I also by passed bulb primer and didnt see any real improvement. Well thanks so far for the input guys!
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
There were no 4V carb options on any F100/350 till 1973.
All previous F100/350's with V8's were 2V's regardless of the engine size.
1973/79 F100/350's with 460's all came with 4V's.
1974/76 F100/350's with 390's offered a 4V carb as an option. Engine VIN code is an M.
Post Fiend
Joined: Apr 2008
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From: Grants Pass, Oregon
Get some carb cleaner,give it a thorough cleaning so you can ID the carb, then you will probably find someone here who can give you a more informed answer. If youve replaced diaphrams already,i would think that you would have needed to know what carb you had to get the right part?
Lead Driver
Joined: Aug 2003
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From: **** hole San Jose ca.
That sounds the idel circuit is plugged and time to rebuid carb. if you've had to run with the choke out. Maybe the carb needs the 2 idle screws turned open more most set at 1-1/2, 2 turns Have you checked these?? my 2cents
orich
orich