Model A dies over 45 mph

R

Rondo1

Junior Member
I recently restored my 29 A.
Over 45mph for extended drives the car runs out of fuel. If I slow down it catches itself and drives fine.
What I have done to date:
Drained & flushed the tank twice
Added stand pipe to new shut off valve
New feed pipes
New fuel glass filter assy
New zenith carb
Things I have tried:
2nd known good carb
2nd known good distributor
2nd known good coil

Really out of ideas now.
Any thoughts?
 
What if you leave the gas cap loose

Is the fuel system stock, or does it have modifications--- xtra filters, valves
 
Sure sounds like your fuel line is going too far into the carb and it is hitting the side of the screen and the only flow you get is through the screen within the diameter of the tube. Just circumcise the end of the tube. Happens all the time.
 
I would check and adjust points gap and timing . When trying to get a higher top speed , be sure to be running full advance . The owners manual states full advance at speed . Some are so afraid of full advance that they run retarded . Running retarded isn't a good thing and doesn't save anything . I would check to see if the carburetor was opening all the way at full throttle . Check for brake drag . Sometimes opening the GAV a bit can add a little speed so I've been told .
 
Purdy Swoft said:
I would check and adjust points gap and timing . When trying to get a higher top speed , be sure to be running full advance . The owners manual states full advance at speed . Some are so afraid of full advance that they run retarded . Running retarded isn't a good thing and doesn't save anything . I would check to see if the carburetor was opening all the way at full throttle . Check for brake drag . Sometimes opening the GAV a bit can add a little speed so I've been told .
Click to expand...

X2 - Should be easy to rule out timing and GAV. Could be insufficient advance.
 
I have run the car with the gas cap on, loose, and off. Same results.
Fuel system is stock.
Initially I notched the fuel line going in to the carb inlet but then I cut it off near the ferrule to prevent that from touching. Also at the fuel filter. Same result.
I have not only set the points and timing but also changed out the whole dist from a car that runs well. Same result.
Carb is opening fully, Timing is a hair advanced, brakes are not dragging.

So you know, this car WILL run over 45mph. I have had it over 50+. It is just that after running at that speed for just a mile or so, it starts to die, coughs, and slows down, catches itself, and if I continue on at 35-40 mph it will drive fine.
 
Oh, also. I do have a keyed fuel cut-off switching valve(from Snyders) installed but I have put the "new" one piece pipe back on thinking the valve may restrict flow but the car still dies out.
 
Rondo1 said:
Oh, also. I do have a keyed fuel cut-off switching valve(from Snyders) installed but I have put the "new" one piece pipe back on thinking the valve may restrict flow but the car still dies out.
Click to expand...




pet **** plugged a little not letting enough fuel in

because it sure sounds like it is running out of gas
 
Perhaps hang a small tank from the radiator support rod and run a line straight into the carb.


If it runs OK then you would know it is fuel supply issue.


If it does not help possible carb, intake, electrical. Since you have replaced the carb with a known good one, that should not be it, most likely not intake. That leaves electrical. Flakey condenser or coil? Wireless distributor plates can cause a lot of odd/unusual issues. Could try bypassing the wireless connection by adding a wire. I realize some of this should have been addressed by replacing the distributor, just a double check.
 
I agree !! Rust or trash in the tank will cause the petcock to get plugged and cut off or restrict flow . I would install a stand up filter in the cut off valve . I use the stand up filters in all of mine .
 
Just remembered, had some odd problems. Distributor points did not ground properly even though it looked good with an ohmmeter. Cleaned up the distributor cable sheath to head stud clamp connection (head was painted under the head nut/clamp). Found the distributor base was painted, sanded off the paint and sanded off the paint under the distributor on the head. Most of the grounding was only through the distributor hold screw in the head/block. One of symptoms was intermittent missing at higher speeds was solved.


Added - Unscrew the ignition cable from the distributor, make sure the thread for the ignition cable are clean and not painted. Insure you do not screw the cable in too far, can short or intermittently short the ignition.
 
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Okay, so I did just run the car with a small gas can connected to the carb and it ran just like it should! hit 50 mph and even ran up a long hill on the way back.

Now what? I have already checked and cleaned the tank, cleaned the new valve, and have new line and filter all the way to the carb.

Something is restricting it but just haven't found it yet. Starting over with checking everything.

I am bothered by that shut off valve from Snyders. I took it apart and it only has about a 3/32" hole that fuel comes out of past the solenoid. (but remember, I bypassed that with a straight pipe earlier with no change.) Will try again.
Anyone had luck using one of these?

Hey all, thanks so much for the quick responses!

Yes, I did check the float level.
 
take the gas line off by the carb and gently blow backwards up the line with the cap loose or off
you need to check each section of line to make sure it has good flow
what about the filter in the carb?
 
1st check your sediment bowl screen, you said you replaced the bowl, but did not mention replacing or cleaning the screen.


Run/test without the screen the car. If runs OK replace the screen, if you do not have a spare clean it with brake clean or something that will dissolve varnish/etc.) and try it again. You may be able to see buildup by shining a flash light through the screen from the back side, even if you do not see anything clean it anyway.


If removing the screen does not help, run a gas line direct from the sediment bowl to the carb and test.


Then it has to be filth blocking up your standpipe or in the shutoff. Instead of a stand pipe, use a pencil "standup" filter in the inlet of the shutoff.
https://www.brattons.com/fuel-tank-filter-screen.html


The Model A has an atrocious electrically noisy ignition system, do not know if it is possible it could be interfering with your gas supply solenoid, rapidly causing it to turn on /off. I do not think so, but never say never.
 
I pulled off the inline solenoid and line and replaced it with the new solid fuel line. This time it continued to run well above 45-50mph.

I cannot explain why this test failed previously unless there was some debris in the main shut off valve.

Yes, I have replaced the bowl screen, checked and rechecked it. Have many in stock.

Regardless, I am calling this fixed! I will definitely add that stand up filter.

Thanks for all the input!!

 
A friend of mine who is new to Model As was complaining of a similar problem. He asked a very experienced vintage car guy to come for a drive to see if he could find it. It didn't take him long to ask - "You are turning the fuel tap all the way, aren't you?" Turns out, he was not turning it till it hit the stop so the car was starving for fuel.
This is not one of the things that most would check but it takes nothing to do so. Maybe you should check he valve is all the way open.
 
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