Inconsistent Fuel Flow from Ford 8N Tank

jwave

New User
Greetings,

I'm asking for help with my diagnosis or alternative explanations for inconsistent fuel flow between the tank and the fuel-shutoff-valve/sediment-bowl assembly.

I SUSPECT I need to either remove the tank, clean it, and possibly coat the inside with a treatment of some sort, or simply replace it.

I have two videos to share. First shows the gas flow at the bottom of the fuel line. Second shows air bubble pattern in the sediment bowl. Sound is included, and relevant to the videos. The second video will be added in a comment to this entry.

SYMPTOMS & ACTIONS TAKEN:
My 88-year-old father's 1949 8N Ford tractor was working fine until two weeks ago. A week after running perfectly, the engine fired up, and shut down after approximately 1 minute as if the carburetor bowl had run out of fuel.

1) Disconnected the fuel line at the L-shaped fitting to the carburetor.
Fuel flow shown in the first video (14-seconds) loaded. Please note air "breathing" sound that suggests an air/vacuum bubble in the line. Sediment bowl bubbles in 2nd video (17-seconds) has the same air gasping sound.

2) Found minimal crud in the glass bowl. Cleaned that out, and got the same result. No further sediment appeared in the bowl after the initial cleaning.

3) Air sounds hinted at clogged vent in the gas cap or vacuum in tank. Removing the cap, leaving tank open to air changed nothing. The same symptom continued.

4) Drained tank, removed shut-off valve, (air compressor) blew out: [a] main fuel inlet, the reserve inlet (by plugging the main inlet with my finger and blowing from the bowl side), and [c] fuel-line port (after removing the cork gasket and brass screen).

No debris, paste, or foreign materials were found. Sprayed valve/bowl assembly with carburetor cleaner.

Stuck little finger into the bottom of the tank, found some fine-grained sand, a couple tiny red paint flecks, and other small debris. Flushed tank by quickly dumping 2-pints of clean gas into the tank at top, and catching the escaping fuel at the bottom 13 times, until no more debris could be decanted out. We quit after 15 flushes.

We refilled the tank, and the engine ran for about 90 seconds. The symptom returned.

5) We re-flushed the tank 20 times, this time, filtering debris through cloth. Same symptoms.

6) On a whim, we bought a new replacement valve assembly to test and verify that it was not something else wrong with our valve. The symptom continued.

7) Because replacement leaked fuel at rubber gasket & poorly fitting plug for Massey-Ferguson interchangeability, exchanged unit at TSC. Same leakage required sealing leaks. Symptoms continued.

The problem seems to be happening between the tank and the bowl; possibly at the tank, or at the valve. Except that the problem persists with an original valve, and two replacement valves.

This is why I suspect problem is in the tank.

Does anybody have any suggestions?

Thank you.

John.

[video play=false:654c4848f0]http://forums.yesterdaystractors.com/videos/mvvideo21040.mp4[/video:654c4848f0]

[video play=false:654c4848f0]http://forums.yesterdaystractors.com/videos/mvvideo21041.mp4[/video:654c4848f0]
 
If it's not already loose or removed, try loosening the fuel tank cap and see if the flow is improved. Perhaps the tanks air vent is plugged.
 
(quoted from post at 13:31:27 08/06/18) Greetings,

I'm asking for help with my diagnosis or alternative explanations for inconsistent fuel flow between the tank and the fuel-shutoff-valve/sediment-bowl assembly.

I SUSPECT I need to either remove the tank, clean it, and possibly coat the inside with a treatment of some sort, or simply replace it.

I have two videos to share. First shows the gas flow at the bottom of the fuel line. Second shows air bubble pattern in the sediment bowl. Sound is included, and relevant to the videos. The second video will be added in a comment to this entry.

SYMPTOMS & ACTIONS TAKEN:
My 88-year-old father's 1949 8N Ford tractor was working fine until two weeks ago. A week after running perfectly, the engine fired up, and shut down after approximately 1 minute as if the carburetor bowl had run out of fuel.

1) Disconnected the fuel line at the L-shaped fitting to the carburetor.
Fuel flow shown in the first video (14-seconds) loaded. Please note air "breathing" sound that suggests an air/vacuum bubble in the line. Sediment bowl bubbles in 2nd video (17-seconds) has the same air gasping sound.

2) Found minimal crud in the glass bowl. Cleaned that out, and got the same result. No further sediment appeared in the bowl after the initial cleaning.

3) Air sounds hinted at clogged vent in the gas cap or vacuum in tank. Removing the cap, leaving tank open to air changed nothing. The same symptom continued.

4) Drained tank, removed shut-off valve, (air compressor) blew out: [a] main fuel inlet, the reserve inlet (by plugging the main inlet with my finger and blowing from the bowl side), and [c] fuel-line port (after removing the cork gasket and brass screen).

No debris, paste, or foreign materials were found. Sprayed valve/bowl assembly with carburetor cleaner.

Stuck little finger into the bottom of the tank, found some fine-grained sand, a couple tiny red paint flecks, and other small debris. Flushed tank by quickly dumping 2-pints of clean gas into the tank at top, and catching the escaping fuel at the bottom 13 times, until no more debris could be decanted out. We quit after 15 flushes.

We refilled the tank, and the engine ran for about 90 seconds. The symptom returned.

5) We re-flushed the tank 20 times, this time, filtering debris through cloth. Same symptoms.

6) On a whim, we bought a new replacement valve assembly to test and verify that it was not something else wrong with our valve. The symptom continued.

7) Because replacement leaked fuel at rubber gasket & poorly fitting plug for Massey-Ferguson interchangeability, exchanged unit at TSC. Same leakage required sealing leaks. Symptoms continued.

The problem seems to be happening between the tank and the bowl; possibly at the tank, or at the valve. Except that the problem persists with an original valve, and two replacement valves.

This is why I suspect problem is in the tank.

Does anybody have any suggestions?

Thank you.

John.

[video play=false:15159b7ce0]http://forums.yesterdaystractors.com/videos/mvvideo21040.mp4[/video:15159b7ce0]

[video play=false:15159b7ce0]http://forums.yesterdaystractors.com/videos/mvvideo21041.mp4[/video:15159b7ce0]


I guess you did not remove the plug from the bottom of the car bowl and check the fuel flow from there. There is also a filter screen on that brass elbow where your gas line hooks up. That may be clogged up restricting gas into the carb..

U9Q5MAQ.jpg
 
How much gas did you have in the tank when you were doing the flow tests? The running problem is not the tank, I would measure fuel flow thru the carb by removing the plug in the bottom of carb as you have been advised to do. It should fill a pint jar in 2 to 3 minutes.
 
At the rate fuel is flowing through that line, there is no way your engine could use gas faster than that. All you've managed to do is prove that gas is going through that line.

Remove the plug on the bottom and check that elbow strainer. You need to see how much gas is going into the carb.
 
First, stop buying tractor parts at TSC. You're paying outrageous prices for off-shore junk.

Get a can & put it under the carb. Remove the bolt in the bottom of the carb; as long as the fuel is turned on, you should see gas flowing out of the carb. It should fill a pint jar in less than 2 minutes.If gas flows well out of the carb & only stops when you turn it off at the sediment bowl, chances are very good it?s not a fuel problem. If it does not have gas coming out of the carb at a steady stream w/ the bolt out for at least 30 seconds, you have a fuel problem. First, remove the gas cap. Your vent could be clogged & it vacuum locked. If that doesn?t work, tap the carb bowl w/ a hammer handle in case the float is sticking closed. (don?t whack it w/ the head of the hammer; you can crack the bowl). If you still don?t see gas flowing, the N has three fuel screens; one in the brass elbow, one in the top of the sediment bowl & one on the stem of the sediment bowl in the gas tank. (see tip # 45) Check the screen in the elbow (see tip # 56) & the screen in the top of the sediment bowl. (don?t worry about the one in the tank) Both probably need to be cleaned. If you have the fuel knob turned on all the way, & 1 gallon or less in the tank, it may be trying to feed off of the reserve inlet which is probably clogged. Only open it 2 full turns. Put at least 2 gallons in the tank. (and do not forget to turn the gas off; see tip # 9)
75 Tips
 
Thank you for the quick responses!

To grhuck,

Removing the fuel tank cap was my step #3. There was no difference in flow with or without the cap.

To Caryc,

You are correct that we did not remove the plug at the bottom of the carburetor bowl. We will do that next.

We've had that brass elbow off before, and I don't remember ever seeing a filter screen in it, or in the carb when we rebuilt it last fall. I wouldn't be surprised if it was missing. We'll remove the carburetor to look for the screen.

To R Geiger,

We had about 1.5-to-2.0 gallons of fuel in the tank when we did that fuel-flow tests through the fuel line. Thanks for the 2-3 minute metric.

To all, I will report back after checking the carb for flow and filter.
 
(quoted from post at 16:02:53 08/06/18) Thank you for the quick responses!

To grhuck,

Removing the fuel tank cap was my step #3. There was no difference in flow with or without the cap.

To Caryc,

You are correct that we did not remove the plug at the bottom of the carburetor bowl. We will do that next.

We've had that brass elbow off before, and I don't remember ever seeing a filter screen in it, or in the carb when we rebuilt it last fall. I wouldn't be surprised if it was missing. We'll remove the carburetor to look for the screen.

To R Geiger,

We had about 1.5-to-2.0 gallons of fuel in the tank when we did that fuel-flow tests through the fuel line. Thanks for the 2-3 minute metric.

To all, I will report back after checking the carb for flow and filter.

That screen is attached to the elbow. If you buy a new elbow it will have the screen on it.
 
Welcome to the forum.
You need a minimum of 2 gallons of gas in the tank to run it with the
fuel valve opened to it's normal operating position of two full turns.
Opening it all the way gets into the "reserve" which is almost
always plugged with sediment if not rust from the tank.
But, as others have said, your fuel flow looks sufficient to me.
I'd hook it back up with a new elbow and screen, check fuel flow
through the carb and if that's good, check for good spark.
 

I just drained a tank with the line removed for the carb just like you pix and many others Something is wrong with yer flow from there up...

No guarantee it will fix it but I would solve that problem first...

Install a fitting in the crab drain with a clear plastic hose and run it above/along the side of the carb seeing is believing and takes the guess work out of it...

Redneck engineer"N is hard to beat...
 
I don't see your video, only pictures, but probably a browser issue on my end. No matter, from what the others say, it doesn't sound like a fuel flow issue. Listen to Bruce(VA) and Royse and Geiger and the others. I'll just add this: Perform the fuel flow test at both the drain plug and the fuel line inlet brass elbow. If both pass, it isn't in the Sediment Bulb nor carb. Chances are your gas tank is full of rust flakes, dirt, and other debris that, when the fuel valve is open and especially when the tractor is in motion, the fuel sloshing around causes the junk to get sucked around the fine mesh screen on the inlet port. This is the portion that is up inside the tank. You may not see any debris in the glass bowl meaning the two screens in the Bulb are doing their job. You may still see debris flow into the glass bowl when you first open the valve 2-Full Turns. Use caution blasting compressed air into the brass elbow and Bulb. These screens use to be soldered on but nowadays they are simply glued on and can easily be dislodged. On the Sediment Bulb Assembly, unless the fuel line threads in the outlet port to the carb are boogered up, the only other part that needs to be maintained is the fuel valve stem. It uses a rubber seal on the stem and will wear out and get chewed up over time. If the special brake line/fuel line threads, 7/16-24, are not stripped out and the top screen isn't missing, then you do not need to buy a whole new assembly. A new valve stem is only about $5. It contains a new knurled knob and the #8-32 screw to fasten it with. One procedure I always do when replacing a valve stem is to apply a dab of thread locking compound on the screw to help ensure the screw and knob won't fall off when working in the field. Permanently fastening the knob won't affect anything. It doesn't ever need to be removed except when it's time to replace the entire valve stem, and then you get a new knob and screw in the package anyway. just toss out the old valve stem. I concur about buying anything from TSC or other bargain-house parts suppliers. It is pretty much a given that many parts are now made in Cheena, but some of the reliable suppliers do have some quality control in place and use the better manufacturers. Most others are simply cloning parts that have probably already been cloned and have no idea on engineering and manufacturing methods. Buying and just replacing any part without first performing a root cause problem solving procedure to determine if the part is defective or not is not the logical way to proceed. Also be sure there is sufficient gas in the tank to start with. Tank capacity is 9 Gallons plus a 1 gallon reserve. Fuel Valve knurled knob stamped: "OPEN 2 FULL TURNS <-&#390;" with the 1 gallon reserve FULLY OPEN. The reserve is intended to be used only when the main is depleted and one needs to get back to the barn before dark. It may be in your near future to pull the tank and have it cleaned and coated -that's your option. Some radiator shops will boil the tank and coat it, there are specialty gas tank shops that will also do it. Some guys opt to do it themselves. I've tried myself using a few dozen nuts and bolts inside and rotating around but that didn't work so well. Some have done a similar method only attaching the tank to a rear tractor wheel and driving around the barnyard a few times to try and loosen the crud then flush good and coat with POR-15 or equivalent. If you choose something like this, be sure you account for all the nuts and bolts when you remove them.

FORD TRACTOR SEDIMENT BULB & VALVE STEM:
5kg5WXLh.jpg
m1VbxJCh.jpg

VALVE STEM ASSEMBLY, p/n APN-9194:
SC9Vznlh.jpg

Tim *PloughNman* Daley(MI)
 

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