Starving for gas at highway speed

[Chris Haynes]

Today is the first time I took my car onto the highway. Runs great but it is starving for gas at highway speed. Gas filter is clean. New fuel line. What should I look at?

[Railcarmover]

pull your strainer and look in your fuel tank

[fordcragar]

I was thinking fuel pump, but forgot most Model A's are gravity feed.

[Charlie Stephens]

Check to be sure the vent in your gas cap isn't partially blocked.

Charlie Stephens

[H. L. Chauvin]

Hi Chris,

Per your post: "Starving at highway speed. Gas filter is clean. What should I look at?"

1. First, what kind of gas filter? If you have an in-line gas filter, many in-line fuel filters are designed to be used in vehicles with pressurized fuel pumps and many said in-line filters do not allow enough constant fuel flow with the Model A non-pressurized gravity flow of fuel.

2. Second, have no idea how clean is your fuel tank; however, even if it is immaculate, if you ever fill up at a pump in the future that has poor fuel filtration, you will wish you had installed a Cylindrical Vertical Gas Tank Screen, Model A Part No. A9193-T 1928-31 like those from Model A parts suppliers. Please install one if one is not installed to help prevent "any" type of fuel blockage between the fuel tank and the intake manifold.

3. Maybe try opening your carburetor's GAV when starving for fuel and let us know what happens .... could also be a leaking intake manifold providing more air and not enough fuel.

[Mike V. Florida]

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What exactly do you mean "starving for fuel"? What is the car doing?

[Patrick L.]

All good info, especially about the gas cap vent [ open gas cap and drive it].

Also make sure the new fuel line isn't pushed too far into the carburetor. End of line should be about 1/16" from end of ferrule.

I use an in-line filter with no issues.

[steve s]

Remove the filter--at least give it a try.

[Dick Steinkamp]

Remove the fuel line from the carb with a pan under it to catch the gas. If you have a nice steady flow of gas, the problem is in the carb. If not, the problem is a restriction somewhere from the tank to the carb.

[Kurt in NJ]

On my car I found the pencil filter in the tank was the fuel flow problem---i removed it and flushed the tank several times ---after a 1000+ mile trip I no longer collected debris in the sediment bowl

I did look at the ends of the bowl to carb line, what the tubing was cut a dull cutter must have been used, the end was 1/2 closed off----like the tip of a hamster water bottle ----after both those things I could get a strong full diameter of the pipe constant flow

[Jacksonlll]

The dredded new fuel line. Hapens all the time. I bet Patrick is right. Just give the end a little circumcision. Let us know.

[clo2jim]

A few years ago with my 1930 Roadster I was having some issues running at highway speed and acceleration where the car was cutting out, like I had problems with fuel starvation. Once I got the car warmed up after startup and running well, I usually ran with the spark lever fully down. One day while I was experiencing the engine cutting out, I moved the spark level up a few notches and it smooth right out with no cutting out.

So could your issue be too more spark advance?

[henry's 31]

Chris:

All the solutions given should solve the problem. Make sure the in line filter you placed is a free flowing filter (not dependent on fuel pump). A good example is the ones used on Lawn mores. I use a John Deere filter available on the box stores #GY20709. Can you let us know what fixed the problem?

[western77]

90% of fuel problems are electrical. Check your gas cap vent! JB

[Chris Haynes]

Originally Posted by Mike V. Florida

What exactly do you mean "starving for fuel"? What is the car doing?

The carburetor runs out of gas. I back off the throttle a bit and the gas flow will then keep up with the demand.

[Chris Haynes]

Originally Posted by H. L. Chauvin

Hi Chris,

Per your post: "Starving at highway speed. Gas filter is clean. What should I look at?"

1. First, what kind of gas filter? If you have an in-line gas filter, many in-line fuel filters are designed to be used in vehicles with pressurized fuel pumps and many said in-line filters do not allow enough constant fuel flow with the Model A non-pressurized gravity flow of fuel.

I have the stock screen and bowl filter.

2. Second, have no idea how clean is your fuel tank; however, even if it is immaculate, if you ever fill up at a pump in the future that has poor fuel filtration, you will wish you had installed a Cylindrical Vertical Gas Tank Screen, Model A Part No. A9193-T 1928-31 like those from Model A parts suppliers. Please install one if one is not installed to help prevent "any" type of fuel blockage between the fuel tank and the intake manifold.

Mine is installed.

3. Maybe try opening your carburetor's GAV when starving for fuel and let us know what happens .... could also be a leaking intake manifold providing more air and not enough fuel.

That worsens the problem.

[Chris Haynes]

Originally Posted by Charlie Stephens

Check to be sure the vent in your gas cap isn't partially blocked.

Charlie Stephens

I'll remove the cap and see if that helps.

[H. L. Chauvin]

Hi Chris,

Usually while driving, after further opening the carburetor GAV makes one's Highway Speed engine sputtering worse, this is many times a sign that your air/fuel mixture is already too rich with fuel when the GAV is completely closed, and/or when the GAV is only 1/4 turn open.

In your statement, ("Today is the first time I took my car onto the highway."), does this mean that this is the first time that this carburetor has been tested on the highway; e.g., this carburetor was never observed by you where it formerly functioned properly.

Brief history of this carburetor may help to try to diagnose a possible carburetor problem.

[J Franklin]

Keep an eye on this thread also for more info on carb problems.

https://www.fordbarn.com/forum/showthread.php?t=223907

[P.S.]

Chris: Is the car at your Pine Grove home? If so, make the trip down the hill and bring it by my shop and we'll fix it.

[jpcouture]

Make sure your float valve is not sticking or partially open. On a trip my A was stalling out over 30 MPH. We looked at everything on the road, including checking gas coming into the carb. I later found that my neoprene needle and seat was partially disolved due to Minnesota alcohol gas. There was gas coming in, but a dribble not a full stream. I now have an NOS needle and seat, best 12.00 I have spent on that car.

[Dick Steinkamp]

Originally Posted by Chris Haynes

The carburetor runs out of gas. I back off the throttle a bit and the gas flow will then keep up with the demand.

To follow up on Mike's question...

What is the actual SYMPTOM (not your guess at the cause)? Be as specific as possible. Did it just start happening and run well a week ago? Did you change anything or do anything (even as simple as filled with fuel) just before it started happening? Does it always happen at a certain speed? Certain RPM in any gear? Can you make it miss just bringing up the RPM with the car at a stand still? What test have you performed that shows the carb float bowl empty when it starts running badly?

This could be a fuel flow problem or a carb problem, but a high speed miss could also be just about any other factor that can effect drivability (coil, condenser, point gap, timing, intermittent electrical short, bad ignition switch, valve clearance, dirty spark plugs, plug gap incorrect, vacuum leak, etc)

It's tough to diagnose a drivability problem over the internet, but more info might help. It's also tough (or counterproductive) to start implementing "solutions" before the cause is known.

[Chris Haynes]

Originally Posted by henry's 31

Chris:

All the solutions given should solve the problem. Make sure the in line filter you placed is a free flowing filter (not dependent on fuel pump). A good example is the ones used on Lawn mores. I use a John Deere filter available on the box stores #GY20709. Can you let us know what fixed the problem?

The only filter is the stock Ford unit on the firewall.

[Chris Haynes]

Originally Posted by H. L. Chauvin

Hi Chris,

Usually while driving, after further opening the carburetor GAV makes one's Highway Speed engine sputtering worse, this is many times a sign that your air/fuel mixture is already too rich with fuel when the GAV is completely closed, and/or when the GAV is only 1/4 turn open.

In your statement, ("Today is the first time I took my car onto the highway."), does this mean that this is the first time that this carburetor has been tested on the highway; e.g., this carburetor was never observed by you where it formerly functioned properly.

Brief history of this carburetor may help to try to diagnose a possible carburetor problem.

H. L.,
I have no history on the carburetor. I recently purchased this non running car. I got it running and I'm working the bugs out of it. I had the head off and was pleasantly surprised surprised to find clean chambers with new pistons and valves. The light carbon wiped off with a squirt of Kroil and a rag.
Evidently a previous owner of the car didn't have much mechanical ability. I do know this car changed hands a few times during the last 12 months. In addition to not running the juice brakes were inoperative. Loose wires everywhere.
The warped exhaust manifold had blown a gasket. I R&R'ed the manifold and put the gland rings in the number 1 and 4 port with a new gasket and all is well now. A new manifold is on the way.
Speaking of the fuel line it was leaking at the strainer on the firewall. Inspection found the ferrule was barely on the end of the line. I pushed it on the new line far enough in to seal properly and that problem was solved.
The reason for the dry hydraulic system was a cross threaded "T" on the rear axle.
It had been converted to modern points with the Nu-Rex assembly. The plate adapter was grounding out on the distributor body. A little tweak and some shrink tube fixed that.
I am enjoying this car and I am having fun finding and exterminating its many bugs.
You should buy stock in Snyder's as this car is making them rich.

[Bruce Adams]

ALL OF THE ABOVE are right on the mark.
Just for kicks, use a tire pump with a pointed nozzle (Harbor Freight) and stick it in the fuel line, cap off, and gurgle some air into the tank to clear any of the usual suspects out of the way.
The "too long" fuel line would be my first check, though. Call a MOIL to help out.

[Chris Haynes]

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Originally Posted by Bruce Adams

Call a MOIL to help out.

I have no idea what a MOIL is.

[H. L. Chauvin]

Hi Chris,

This one (1) most wonderful statement:

"I am enjoying this car and I am having fun finding and exterminating its many bugs."

is a Revelation in itself that your Model A "will" no doubt run great, "Come Hell or High Water!"

Never a bad idea to try to obtain a spare carburetor to overhaul while you keep your Model A running at maybe a little less than highway speed ...... for example, this way, you don not have to remove your existing carburetor and experience the agony of "Model A Down-Time".

I'm be calling Snyder's on July the 5th to inquire about their stock quotes ... thanks for the tip.

[Chris Haynes]

I started tearing apart the fuel system to check things today. The first step was to drain the tank. I disconnected the fuel line from the carb. and stuck it in a container to drain the fuel. While it was draining something in the glass strainer bowl caught my eye. There was about 3/8" of water floating on top of the bowl. I am sure this was slowing down flow through the screen. Road test will tell.

[wmws]

That could be the problem. Won't run very well on water. Check out all the other good tips to be sure all is in order.

[JBill]

What do you consider "highway speed"? Highway speed around here is seventy to eighty mph.

[Dick Steinkamp]

Originally Posted by Chris Haynes

There was about 3/8" of water floating on top of the bowl. I am sure this was slowing down flow through the screen. Road test will tell.

???

Gas floats on water. Not visa versa.

It's good you drained the tank and got the water out. Continue checking for water in the float bowl. It will be on the bottom of the bowl if there still is some.

[Chris Haynes]

Originally Posted by JBill

What do you consider "highway speed"? Highway speed around here is seventy to eighty mph.

I can travel 40 MPH but can't go over that without starving. I have tried with the gas cap off and it made no difference.

[Chris Haynes]

Originally Posted by Dick Steinkamp

???

Gas floats on water. Not visa versa.

It's good you drained the tank and got the water out. Continue checking for water in the float bowl. It will be on the bottom of the bowl if there still is some.

All I can tell you is that it was a clear liquid floating on top of the yellowish gas.

[Chris Haynes]

Originally Posted by wmws

That could be the problem. Won't run very well on water. Check out all the other good tips to be sure all is in order.

Whatever this clear liquid was is wouldn't penetrate the screen. So it was blocking the flow of gasoline.

[wmws]

So is it full speed ahead now?

[Chris Haynes]

Originally Posted by wmws

So is it full speed ahead now?

I'll let you know as soon as I have it back on the road. Replacing generator and wiring now.

[Chris Haynes]

Back on the road today. Still starving for fuel at highway speed. :-(

[jm29henry]

Could your float be set to low ? If you turn the gav to the left making it run richer .?

[BILL WILLIAMSON]

With 1/2 tank of gas in Minerva, she would flow a 6" stream of gas at the disconnected gas line. I was using only a Pencil Filter & a Cast Iron Sediment Bowl.
Bill W.

[wmws]

With all the good advice and guesses about your problem I don't think anyone has mentioned your main jet. It could be partially blocked. You could try taking your carb apart and giving it a good soaking and blow job especially the main jet. Just a thought.

[barnstuf]

A friend purchased one of the new Zenith carburetors that have been on the market for quite a few years, and up to 45 mph everything was fine, over 45 he experienced hesitation and starving for gas. He tried to find the problem without result and turned the carburetor over to a professional Zenith restorer. After serious testing he found the secondary well side opening was a tiny bit too small so he enlarged it to proper specs and the problem was solved.

[kinggrr]

Chris - I was reading through this 4-year-old thread of your problem with cutting out above 40mph or so. I was saddened to see the thread end with no solution as I am having same issue. I have rebuilt carb, new ignition, checked fuel, etc, etc. Did you ever resolve yours? Thx...

[Jacksonlll]

King, if you put a new fuel line on check that you don’t have more than 1/8 inch of tubing beyond the ferrule. Common problem. Good luck.

[nkaminar]

Sounds like a carburetor problem. Try a different one and if that works take the old carburetor apart to check for good flow through the float valve, the correct float level, correct jets with no clogs, jets tight in their threads, vacuum leaks at throttle arm or flange, etc.

[nkaminar]

By the way, the water will be yellow because of the rust it has picked up and the gasoline will look clear with the small volume. Keep emptying the water out of the sediment bowl.

[CWPASADENA]

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several years ago, there were some poor quality carburetor float valves made with a very small hole for the fuel to pass thru. The car would run fine around town but get it on the highway and it would starve for fuel. When this would happen if you would let up on it for a little while it would get enough fuel to run for just a little more and then start starving again. I ran into this on a Model A of one of our club members. Took the carb apart and found a float valve with a very small hole in it. Replaced the valve, car then ran just fine.

If you have a good steady stream of fuel with the fuel line removed from the carburetor, you may want to check the float valve.

My experience, Chris W.

[Chuck Sea/Tac]

Originally Posted by CWPASADENA

several years ago, there were some poor quality carburetor float valves made with a very small hole for the fuel to pass thru. The car would run fine around town but get it on the highway and it would starve for fuel. When this would happen if you would let up on it for a little while it would get enough fuel to run for just a little more and then start starving again. I ran into this on a Model A of one of our club members. Took the carb apart and found a float valve with a very small hole in it. Replaced the valve, car then ran just fine.

If you have a good steady stream of fuel with the fuel line removed from the carburetor, you may want to check the float valve.

My experience, Chris W.

Do you know the office size on the float valve? I’ve seen the spec somewhere, but sure where.

[Patrick L.]

Since he hasn't answered must be he got disgusted and sold the monster !

I still think he just had a gas cap issue.

[CWPASADENA]

Do you know the office size on the float valve? I’ve seen the spec somewhere, but sure where.

I am not at my shop where I could measure an original and off the top of my head, I do not know the size of the opening in the float valve but if you take it out and look at it, it is obvious that it is a very small hole.

I know Brattons has good valves and I am sure other of the parts suppliers also do. I would not recommend Mac's as most of their stuff comes from China.

Chris W.

[redmodelt]

Originally Posted by Patrick L.

Since he hasn't answered must be he got disgusted and sold the monster !

I still think he just had a gas cap issue.

Probably not as he was online here today around 9:30 Pm.

[jimTN]

Just fixed a similar problem with my 28. Ordered a pencil filter for the tank and when I drained the gas and pulled the tank valve, found that valve was only about 1/3 open when turned to open. Removed the valve core and drilled the passageways out larger, ground and amount of the lever stop arm and put a metal ship in the lever opening to tighten it up. Problem solved!

[Patrick L.]

Originally Posted by redmodelt

Probably not as he was online here today around 9:30 Pm.

That was said ' tongue in cheek ' since he didn't bother to let us know what he found.