The Ford Barn

o2bnkc · 03-21-2021, 02:46 PM

Hey guys, I just got a 40 Deluxe Convertible a couple of weeks ago and I need some advice. It's got the original flathead and Holley carb. When I bought it I replaced the battery and inline fuel filter. It was running great until yesterday. Coming back from a short trip it started cutting out and surging like it was starving for fuel. Today I replaced the fuel filter again, but I still have the same problem when I get up to speed. The fuel bowl is full. It starts fine and idles fine, but cuts out when I'm around 25-35 mph. I ordered a rebuild kit, but I'm thinking that may not be the problem. I welcome all suggestions. This is my first flathead. Thanks.

51 MERC-CT · 03-21-2021, 04:09 PM

If you have a glass bowl fuel pump, check the cork gasket to make sure it is tight and check for cracks in the gasket.
If it is sucking air, the symptoms will be similar.

o2bnkc · 03-21-2021, 04:19 PM

Thanks. I will check it out.

tubman · 03-21-2021, 06:46 PM

Also, remember that the coils and condensers on these cars are very susceptible to heat.

Remember the old saying : "90% of carburetor problems are caused by the ignition system and 90% of ignition problems are caused by the fuel system.

o2bnkc · 04-05-2021, 12:23 PM

I have an update on my cutting out and surging problem. My distributor has an adapter plate and a remote coil. I replaced the remote coil and condenser. It still wouldn't start. I then replaced the plugs, which were all sooty and black. It then fired up and idled nicely. I took it out for a spin, but about 15 minutes later it started cutting out and would die. I would start it up again and the same thing would happen. I finally had my friend tow me home. When I finally got it started again, I had to keep the choke fully pulled out to keep it running. I usually don't even need the choke to start it. This morning I pulled one of the plugs to see if I was getting a good spark (It was) and the plug was awful black and sooty for just going a couple of miles. I bought the car in Los Angeles, but I live at 5500 ft. Carb?

o2bnkc · 04-05-2021, 12:24 PM

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Quote:

Originally Posted by 51 MERC-CT

If you have a glass bowl fuel pump, check the cork gasket to make sure it is tight and check for cracks in the gasket.
If it is sucking air, the symptoms will be similar.

Seems to be ok.

Ggmac · 04-05-2021, 12:36 PM

Check if another fuel filter . If not remove the line from the fuel pump and take compressed air to the line (15 to 30 lbs ) with the gas cap removed , you should hear bubbles, if you only hear air it could be low on gas . Have you checked it running without the gas cap ? A non vented cap could play havoc.

o2bnkc · 04-05-2021, 01:11 PM

Quote:

Originally Posted by Ggmac

Check if another fuel filter . If not remove the line from the fuel pump and take compressed air to the line (15 to 30 lbs ) with the gas cap removed , you should hear bubbles, if you only hear air it could be low on gas . Have you checked it running without the gas cap ? A non vented cap could play havoc.

I took the inline filter out when I made this last aborted trip. It has a full tank. I haven't tried without the fuel cap.

drolston · 04-05-2021, 06:48 PM

Symptoms are confusing.
- If the car ran right near sea level and you take it to 5500 feet it is going to run too rich and need jet size reduced about two sizes. That could get you sooty plugs. If the plugs get too fouled the engine could die. Makes sense so far.
- But the part about having to pull the choke out to keep running contradicts that diagnosis. Sounds more like fuel starvation.

Couple of things to try:
- Do a cold crank in the morning. Disconnect the fuel line from the carb; put a cup under it to catch some of the gas. With the ignition OFF, crank the engine; it should spurt pretty strong, about a tablespoon of gas with each stroke of the pump. If weak, rebuild the pump, or install an electric fuel pump back near the gas tank.
- If that looks okay, drive it until it dies and repeat the test. Even if it seems to be pumping okay, pull the top off of the carb and pretty sure you will find the fuel bowl quite low. So why would the pump work when cold but not when hot.
- Vapor lock. I big problem with early Fords, even at sea level, because of the high volatility of the alcohol in modern gas. At 5,500 ft altitude you are probably going to need that electric fuel pump. You can keep the mechanical pump. If you get the right electric pump it will push fuel and vapor right through the mechanical pump, and not block flow from the mechanical pump if the electric pump is off.

03-21-2021, 02:46 PM	#1
o2bnkc Member Join Date: Feb 2021 Location: Carson City, Nevada Posts: 56	running rough Hey guys, I just got a 40 Deluxe Convertible a couple of weeks ago and I need some advice. It's got the original flathead and Holley carb. When I bought it I replaced the battery and inline fuel filter. It was running great until yesterday. Coming back from a short trip it started cutting out and surging like it was starving for fuel. Today I replaced the fuel filter again, but I still have the same problem when I get up to speed. The fuel bowl is full. It starts fine and idles fine, but cuts out when I'm around 25-35 mph. I ordered a rebuild kit, but I'm thinking that may not be the problem. I welcome all suggestions. This is my first flathead. Thanks. __________________ A Proud Navy Veteran

03-21-2021, 04:09 PM	#2
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: running rough If you have a glass bowl fuel pump, check the cork gasket to make sure it is tight and check for cracks in the gasket. If it is sucking air, the symptoms will be similar. __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES

03-21-2021, 04:19 PM	#3
o2bnkc Member Join Date: Feb 2021 Location: Carson City, Nevada Posts: 56	Re: running rough Thanks. I will check it out. __________________ A Proud Navy Veteran

03-21-2021, 06:46 PM	#4
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,320	Re: running rough Also, remember that the coils and condensers on these cars are very susceptible to heat. Remember the old saying : "90% of carburetor problems are caused by the ignition system and 90% of ignition problems are caused by the fuel system.

04-05-2021, 12:23 PM	#5
o2bnkc Member Join Date: Feb 2021 Location: Carson City, Nevada Posts: 56	Re: running rough I have an update on my cutting out and surging problem. My distributor has an adapter plate and a remote coil. I replaced the remote coil and condenser. It still wouldn't start. I then replaced the plugs, which were all sooty and black. It then fired up and idled nicely. I took it out for a spin, but about 15 minutes later it started cutting out and would die. I would start it up again and the same thing would happen. I finally had my friend tow me home. When I finally got it started again, I had to keep the choke fully pulled out to keep it running. I usually don't even need the choke to start it. This morning I pulled one of the plugs to see if I was getting a good spark (It was) and the plug was awful black and sooty for just going a couple of miles. I bought the car in Los Angeles, but I live at 5500 ft. Carb? __________________ A Proud Navy Veteran Last edited by o2bnkc; 04-05-2021 at 01:09 PM.

04-05-2021, 12:36 PM	#7
Ggmac Senior Member Join Date: Jul 2016 Location: Lake worth Florida Posts: 1,101	Re: running rough Check if another fuel filter . If not remove the line from the fuel pump and take compressed air to the line (15 to 30 lbs ) with the gas cap removed , you should hear bubbles, if you only hear air it could be low on gas . Have you checked it running without the gas cap ? A non vented cap could play havoc.

04-05-2021, 06:48 PM	#9
drolston Senior Member Join Date: Jun 2014 Location: Williamsburg, VA Posts: 1,627	Re: running rough Symptoms are confusing. - If the car ran right near sea level and you take it to 5500 feet it is going to run too rich and need jet size reduced about two sizes. That could get you sooty plugs. If the plugs get too fouled the engine could die. Makes sense so far. - But the part about having to pull the choke out to keep running contradicts that diagnosis. Sounds more like fuel starvation. Couple of things to try: - Do a cold crank in the morning. Disconnect the fuel line from the carb; put a cup under it to catch some of the gas. With the ignition OFF, crank the engine; it should spurt pretty strong, about a tablespoon of gas with each stroke of the pump. If weak, rebuild the pump, or install an electric fuel pump back near the gas tank. - If that looks okay, drive it until it dies and repeat the test. Even if it seems to be pumping okay, pull the top off of the carb and pretty sure you will find the fuel bowl quite low. So why would the pump work when cold but not when hot. - Vapor lock. I big problem with early Fords, even at sea level, because of the high volatility of the alcohol in modern gas. At 5,500 ft altitude you are probably going to need that electric fuel pump. You can keep the mechanical pump. If you get the right electric pump it will push fuel and vapor right through the mechanical pump, and not block flow from the mechanical pump if the electric pump is off.