Starving for fuel, can NOT figure it out!?

[Turmoil]

Lets me start by saying I have done extensive research and also searches on this forum and many/many others with no luck. I'm reluctant to post as I love the challenge but I'm simply out of ideas.
I have a 1926 Fordor with a fresh 1925 engine. I have had it running for a few weeks. I'm running a NH carb. The engine starts and idols flawlessly. When I first started the engine I noted the intake would frost up and drip. I did not have a hot air pipe at the time. I drove the car after it was warmed up for about 15-20 minutes and it would start to sputter and then die altogether. I could get it to restart with full choke applied but once I released the choke it would die. Clearly starving for fuel. I checked several things, including seeing if the bowl had fuel by opening the drain and noted that it was full. So being new to these engines and an updraft carb I suspected it was freezing up? My best guess as after 10 minutes, it would start normal and off I could go. So I found a hot air pipe and installed it. Just like that, no more frost and I assumed problem solved. Wrong. I would again drive 15-20 minutes and same deal, cough and sputter and die. Full choke and would restart but die once choke was released. Again THE BOWL IS FULL of fuel! I wait 5 minutes and the engine would restart and off I'd go but the problem would reoccur in 10-15 minutes.

The tank is pristine clean.
The gas cap has a vent hole.
The carb is new. Float is set correctly. I changed to a float ball valve to rule out a needle valve issue. Jet is clean and correct. low/ high ports clear.
New gas line that does have a steel filter. (i've read many times these cause issues)

So it is clearly starving for fuel but yet there is fuel in the bowl? Again I know this because I open the drain and a steady stream comes out. Oh and after I let fuel out it still doesn't restart. I was thinking vacuum or vapor lock but nope.

I guess I'll take the fuel filter off and try it but I highly doubt thats it. What am I missing? Can't wait for the replies. What would change after 5 minutes that would allow restart?

Thanks very much, Angus

[TWrenn]

Bingo. I vote for fuel filter issue
You don't need one on a T in the first place. Get rid of it and I bet your problem will be over.

[slang250]

I have had worked on a few cars that had fuel flow issues that would not completely drain the carburetor bowl by the time the engine would stall out. If you open the drain valve on the bowl it will drain maybe the bottom 1/4 or 1/2 of what the bowl can hold then slow down to almost nothing.

You might of already checked this but not mentioned it, If you drain the fuel in the carb bowl into a bucket long enough for the bowl to completely empty it will slow down some to show you how well the full fuel system will be able to flow. You want about an 1/8" diameter stream.

Tim could be correct about the fuel filter. performing this style test before removing the filter and after will let you know for sure.

[Scott_Conger]

I am going to suggest that fuel coming out of the bowl is not proof that it is full. It is proof that after the car died, there was some fuel left. And every moment spent climbing out of a stalled car and fiddling to open the drain valve is time spent refilling the bowl and fooling you into believing it was ALWAYS full.

A steel filter is typically a 40 micron mesh, or .0015" hole(s) and with gravity feed, at best you are not much more than "sweating" fuel into the bowl...that filter is meant to be used on a modern car with a fuel pump.

The car will idle and run a bit as the fuel level is modestly keeping up with the consumption, but any kind of increased consumption will slowly run the fuel level lower and lower until the idle and main circuits are not sufficiently fed. Choking the carb introduces a vacuum and a "gulp" of fuel out of the bottom of the carb through the main jet, and that is why it will start but not keep running

I believe you are on the right path by eliminating the filter. After all, what needs filtering?

Once your car is running right, do not be surprised if the ball-style float valve eventually fails either full open or full closed...that is the next in line as far as failure modes.

Only thing that doesn't compute is having an NH but calling it an updraft carb (?)

You will have this thing fixed soon.

[RVA23T]

not applicable

[Oldav8tor]

First of all, I run my NH without a heat pipe in Michigan in temps between 40 and 90+ degrees without issue. Yes, I'll see condensation on the intake but that's all.

I'd dump the filter for sure.... you don't have enough fuel pressure to push thru a filter. I also question the carb float adjustment...might want to double check it.

I also suggest you consider buying a Full-flow float valve from Scott Conger (on this forum). It is a needle valve but the passage is much larger than those available from the vendors. Your valve may be limiting the fuel flow...a real problem when your fuel level is low. Scott's valve is on the right.

Float Valve comparison.jpg (34.07 KiB) Viewed 2157 times

[bdtutton]

I had that exact problem on my 1914 Touring....I had to remove the fuel filter. Worked perfectly after that.

[Norman Kling]

If I understand correctly, the 26 fordor still has the tank under the seat. If so, the tank must have enough gas to flow to the carburetor. The original "filter" was a sediment bulb under the fuel tank. There is a fine mesh screen in that bulb with the output above the bulb. So any water or sediment in the gas will go to the bottom. If you have any sediment in the tank, you should drain that bulb from time to time to allow the water and sediment to go out instead of into the carburetor. From that bulb the fuel line should go down and then up to the carburetor. There should be no high place in between the bulb and carburetor. That way any vapor or air in the line will flow to the high high points and not compress causing "vapor lock". There should be no other filter between the sediment bulb and the carburetor. Most of us put a shut off valve next to the carburetor so we don't need to crawl under to shut off the gas. I have not had good luck with a ball valve float valve. The needle and seat work best.
I don't know whether you have any mountains or steep hills on your route you drive, but especially going uphill you need the fuel level in the tank to be higher than the carburetor.
If your car has a cowl tank, you would have better fuel flow, but still a filter would starve things because you have no fuel pump. Just gravity flow.
Norm

[Harvey Bergstrom]

I too seem to have a problem with my engine starving for fuel. I have an NH carb on mine. I thought a filter would be a great idea, but after reading everyone’s posts, I guess I’ll be removing mine. At high idle I would get spitting & popping and I suspected fuel starvation as I have a new timer and fresh coils from Brent Mize. Also engine is nearly all new. At that rate, what else could I do. At high idle without engine pulling the car, it will be running at much faster rpm, thus calling for more fuel than necessary and there is not enough flow. I only have a 1/4 inch fuel line, but that is what was in the car when I got it. I’m sure it run for many years with that size line. Thank all of you good folks for great thoughts & solutions to many problems that we all experience!

[RajoRacer]

You need to verify what needle & seat is in your fuel feed circuit and then remove the inline filter.

[Stu Tomlinson]

Please also consider the route of your fuel line keeping it from the heat of the exhaust pipe.

[TRDxB2]

What updraft carburetor are you running and with what manifold? You need to remove the filter to eliminate or prove it being the problem.

[bobt]

Try loosening the fuel tank cap. The tank has to be vented. Also, NEVER use a paper filter. (ask me how I know). bobt

[TWrenn]

Try loosening the fuel tank cap. The tank has to be vented. Also, NEVER use a paper filter. (ask me how I know). bobt

He did say the tank is vented, so I think that possibility is ruled out. I was so focused for the most part on the needless in-line filter, I did overlook the often overlooked fine mesh screen in the "potato" under the tank, as his car should have the tank under the seat. However, he did say the tank was pristine clean, so one MAY assume (we know what that word means!) that the screen in the potato is clear. I still think it's all in the stupid in-line filter, as another poster mentioned was his problem also. There's just not enough "push" for the fuel to get through it even when it's clean, let alone starting to get gummed up. People forget that when the car is laid up even over winter, fuel laying in that pleated filter starts to turn to gum, especially with the crap for gasoline they sell us nowadays. I'm anxious to hear from him of his results.

[Loftfield]

Not every "clean" fuel tank is really clean. Little nasties can be out of sight beyond the tank baffles. While modern fuel filters will cause problems, such as those discussed above, there is nothing wrong with obtaining an older fuel bowl filter that can provide just that extra little bit of protection that gives peace of mind.

[Scott_Conger]

Something I failed to mention in my previous post is that an NH can digest enormous pieces of junk so long as that junk doesn't stick in the float valve. There are no "jets" as in the sense of more sophisticated carbs such as Zenith and Stromberg, so there is absolutely no reason to be running any kind of a filter that has a smaller mesh than what is already in the sediment bowl on the tank.

If, on the other hand, you are running a Zenith or Stromberg, or any other carb which has very tiny idle jets, the best thing you can do for yourself is install an old-style tractor sediment bowl with a clear bowl immediately prior to the carb as has been suggested above by at least one poster.

[John kuehn]

A Mosel T did not come with a “fuel filter” other than what’s in the sediment bulb. Didn’t have a fuel pump either.
It relies on gravity flow and it’s best with a mostly full fuel tank. Any kind of restriction with gravity flow can’t be good. We tend to think in terms of modern engines with a fuel pump or pressurized gas tank. A Model T is 80-100 technology which is pretty simple and knowing that helps in figuring out problems.

[Steve Jelf]

While I agree that a modern fuel filter is a bad idea, experience has taught me that dirt fine enough to get past the sediment bulb screen can give you fits. The only cure I know for that is to clean or replace the tank.

[J1MGOLDEN]

There is also an internal passageway that is seldom cleaned out with a home rebuild and is used for speeds up to 20 mph.

[jiminbartow]

While modern fuel is clean, the inside of the tank might be rusty or sludgy. Before eliminating the fuel filter, be sure to flush and clean the fuel tank of all dirt, rust and debris. Jim Patrick

[TRDxB2]

Lets me start by saying I have done extensive research and also searches on this forum and many/many others with no luck. I'm reluctant to post as I love the challenge but I'm simply out of ideas.....................................
I have a 1926 Fordor with a fresh 1925 engine. I have had it running for a few weeks. I'm running a NH carb. The engine starts and idols flawlessly. When I first started the engine I noted the intake would frost up and drip. I did not have a hot air pipe at the time. I drove the car after it was warmed up for about 15-20 minutes and it would start to sputter and then die altogether. I could get it to restart with full choke applied but once I released the choke it would die. Clearly starving for fuel. I checked several things, including seeing if the bowl had fuel by opening the drain and noted that it was full. So being new to these engines and an updraft carb I suspected it was freezing up? My best guess as after 10 minutes, it would start normal and off I could go. So I found a hot air pipe and installed it. Just like that, no more frost and I assumed problem solved. Wrong. I would again drive 15-20 minutes and same deal, cough and sputter and die. Full choke and would restart but die once choke was released. Again THE BOWL IS FULL of fuel! I wait 5 minutes and the engine would restart and off I'd go but the problem would reoccur in 10-15 minutes.

The tank is pristine clean.
The gas cap has a vent hole.
The carb is new. Float is set correctly. I changed to a float ball valve to rule out a needle valve issue. Jet is clean and correct. low/ high ports clear.
New gas line that does have a steel filter. (i've read many times these cause issues)

So it is clearly starving for fuel but yet there is fuel in the bowl? Again I know this because I open the drain and a steady stream comes out. Oh and after I let fuel out it still doesn't restart. I was thinking vacuum or vapor lock but nope.

I guess I'll take the fuel filter off and try it but I highly doubt thats it. What am I missing? Can't wait for the replies. What would change after 5 minutes that would allow restart?

Thanks very much, Angus

I think its necessary to refresh the description of the problem. Many useful comments were already taken care of by Angus or are not applicable to his configuration and have caused a some drifting. I'm sure it would help to know what updraft carb is being used and in conjunction with what manifold. He also indicated that

[jab35]

Angus: You mention that the fuel bowl is 'full' and you determine this by opening the carb drain. If you leave the drain open, what is the sustained flow rate after the bowl volume is depleted? Is steady state flow sufficient to feed the engine at max demand?

[George Mills]

Just because I have been there, done that...

You 'might' want to check the screen in the sediment bulb.

Same symptoms, years ago..everybody local baffled, until I had absolutely nothing else to check! Screwed off the front plate and...there it was! A thin 'Brillo pad' of decades of accumulated dust on the tank side of the screen! Soaked the screen clean, put it all back together, ran and has run strong ever since

My take? The 'fluff' was dense enough it would not allow fuel to flow at the flow rate needed...let it sit for 15-20 minutes, enough fuel would trickle through and into the bowl to let it start and run 'a bit'.

[Turmoil]

Thank you all very much for your thoughts and replies.
I have removed the new fuel line and filter. I bent up a new fuel line and ran it as indicated on this forum and others. Just for discussion I measured the the bottom of the new line to the floor in many locations down the line. It has a nice downward pitch and only a very slight (1/4") up right before the carb. I checked the fuel flow out the bottom of the carb before and after removing the filter. I can see an increase after removing the filter but it is not drastic. Maybe just enough? Fuel valve sediment bowl and screen are clean.
It has been pouring rain here all day, so I'm not able to test out the new filterless line. Hopefully tomorrow I'll be back with good news.

Best,
Angus

I miss spoke in my original post, I meant I was not very familiar with an updraft intake manifold. My carb is a standard NH style.

[Tmooreheadf]

I had a fuel starvation issue for many years in our 24 touring, but only climbing hills in Ruckstell and low pedal. Put one of Scott’s larger flow float valves in, problem went away. Thanks Scott!

[Scott_Conger]

.... ....

[Allan]

A couple of mentions of tractor type, glass bowl filters were made. Scott correctly called this a sediment bowl. It is meant to trap sediment/water in the glass bowl, that clear bowl allowing visual inspection. While they can assist in checking problems they are simply doing what the tank sediment bowl does, but giving a visual clue. At least they are not likely to add to fuel flow problems like a true filter does.

Allan from down under.

[Turmoil]

Success!!

45 minutes straight driving after warming up in the driveway. Mixed in every hill I could find. Put it at max speed for 5 miles. That GD filter was screwing me up all along.
'
Regardless, I'm happy to report zero issues and damn this engine runs strong.

Thanks,
Angus

[Aussie16]

Thankyou Angus for the update. This thread has been a classic example of how folks can be very generous with their advice but it can be a distraction. Tim nailed the problem in the very first response! Remove the non standard Henry Ford part or modification (the extra filter) should be the standard procedure before going ahead with any other checks! This situation repeats itself many times on the forum before pictures or a better description reveals the problem is with non standard Ford parts or modifications. Have fun driving and enjoying you Fordor. My 26 Fordor is pretty much stock with the exception of a straight through Carb, high volume inlet manifold and Z head. These additions are either standard Ford production or proven mods and help to make it a very enjoyable Tour car.