The Ford Barn

JMFL36 · 01-31-2021, 03:42 PM

Hi guys. I have an all stock '34 with mechanical fuel pump. The car runs great but I have run out of gas on several occasions. On each occasion the car took less that 5 gallons to fill up. At first I thought I had a vapor lock issue, but uncorking the cap has no effect. I also checked and blew out the vent holes in the sending unit but they were all clear. I also tested for vapor lock by adding different amounts of gas to the tank after it dies. Add a little gas and it will run for a little while then die. Add a gallon and it will run for 20 miles or so and die. So then I thought I might have a small hole in the sending unit pick up tube about half way up or so. I pulled the sending unit today and no holes or leaks in the pick up tube. An easy test was to put my finger on one end of the tube and blow into the other end to see if it would hold pressure, which it did. Now I'm wondering about the tank itself. I had it cleaned and lined last year. I have never seen any photos or drawings of the inside of a '34 tank, but I assume there are baffles in the tank. I'm wondering if when the tank was lined, the liquid lining may have plugged the bottom equalizing passageways between the baffles? Then once the gas level gets below the top of the baffles, the sending unit sucks the center baffle dry and dies. When I then fill the tank it only takes a few gallons to fill the center baffle and top off the tank. Is this far fetched? Has anyone cut open a '34 tank? Does anyone have any photos or drawings of the tank innards? Any other theories? Thanks in advance

JimG · 01-31-2021, 04:36 PM

Here is a thread that shows the inside of the tank with the top removed, the baffles, and the holes in the baffles. Seems hard to believe these holes could all be plugged.

https://www.fordbarn.com/forum/showt...hlight=34+tank

cas3 · 01-31-2021, 04:42 PM

i have cleaned a 34 tank on a rotating fixture with BB's inside. they roll under all the baffles. hard to imagine gas could be held up there

JMFL36 · 01-31-2021, 05:00 PM

Thanks Jim. I assume the fuel sender sits in the larger middle baffle section? I wonder if those 2 bottom holes in the baffle nearest the filler tube could be plugged? That liner material is pretty thick and gooey stuff before it hardens.

DavidG · 01-31-2021, 05:30 PM

While not stated, I assume that you verified that the fuel pick up tube extends to nearly the bottom of the tank.

JMFL36 · 01-31-2021, 06:49 PM

Sponsored Links (Register now to hide all advertisements)

Yes, the end of the pick up tube sits about 1/4" above the bottom of the tank.

Terry,OH · 02-01-2021, 10:12 AM

If the two holes in the baffle nearest the filler neck were blocked it would be difficult to refuel the gas tank! Have you tried to remove the bottom drain plug. Some people that have tried to seal a tank find the sealer does not adhere properly and falls off.

DavidG · 02-01-2021, 10:17 AM

An anemic fuel pump, per chance?

Karl · 02-01-2021, 04:34 PM

Quote:

Originally Posted by Terry,OH

If the two holes in the baffle nearest the filler neck were blocked it would be difficult to refuel the gas tank! Have you tried to remove the bottom drain plug. Some people that have tried to seal a tank find the sealer does not adhere properly and falls off.

Terry you are so right -I POR15 sealed my 34 and currently have the tank cut open trying to remove the (small) proportion of sealer that actually stuck to the inside of the tank.

I had no end of problems after I sealed the tank - Which were patiently worked through by the guys on this forum and I am very grateful ! -In the end some if it was condensor but some of it was also fuel contamination from the flaking POR -15 -Bypassing the tank and fuel line by feeding direct to the fuel pump didn't help as in retrospect I must have had crud between the pump and the carb. All so obvious now but at the time frustrating beyond belief

Lawson Cox · 02-01-2021, 05:34 PM

Sounds like a coil problem to me.

JMFL36 · 02-03-2021, 08:07 PM

I doubt its a fuel pump or coil problem because of how the car reacts to the different amounts of gas I have put in after it dies. If I add just a little gas after it dies, it will run for a few miles and die again. If I add a gallon it will run for about 20 miles before dying. If I fill the tank every 60 miles or so the car never dies. This direct correlation between how much gas I've added and how long it will go before dying makes me think its a supply issue. I've ruled out vapor lock and a blocked or broken sending unit. This is why I suspect the tank baffles may be blocked. I plan to drain the tank in the next couple of weeks so I can get a peek inside at the fist baffle (nearest the filler tube) and the holes at the bottom of that baffle.

tubman · 02-04-2021, 09:26 AM

I had a similar problem with a '36 I had years ago. It turned out to be the remnants of a rag that somehow got into the gas tank. When the car had half a tank or more it ran great. When the fuel level got low, the rag would get sucked into the fuel pickup and starve the car. Sometimes I could run the tank down quite a way; other times I'd sputter to a stop at anything less than half a tank. If that happened, I'd unhook the flex-line and blow into it, HARD. You could usually sense the crap getting blown out of the fuel pickup. I finally spent the time and effort and got the crap out of the tank.

01-31-2021, 03:42 PM	#1
JMFL36 Senior Member Join Date: Oct 2017 Location: Venice, FL Posts: 227	34 Fuel Tank Baffles? Hi guys. I have an all stock '34 with mechanical fuel pump. The car runs great but I have run out of gas on several occasions. On each occasion the car took less that 5 gallons to fill up. At first I thought I had a vapor lock issue, but uncorking the cap has no effect. I also checked and blew out the vent holes in the sending unit but they were all clear. I also tested for vapor lock by adding different amounts of gas to the tank after it dies. Add a little gas and it will run for a little while then die. Add a gallon and it will run for 20 miles or so and die. So then I thought I might have a small hole in the sending unit pick up tube about half way up or so. I pulled the sending unit today and no holes or leaks in the pick up tube. An easy test was to put my finger on one end of the tube and blow into the other end to see if it would hold pressure, which it did. Now I'm wondering about the tank itself. I had it cleaned and lined last year. I have never seen any photos or drawings of the inside of a '34 tank, but I assume there are baffles in the tank. I'm wondering if when the tank was lined, the liquid lining may have plugged the bottom equalizing passageways between the baffles? Then once the gas level gets below the top of the baffles, the sending unit sucks the center baffle dry and dies. When I then fill the tank it only takes a few gallons to fill the center baffle and top off the tank. Is this far fetched? Has anyone cut open a '34 tank? Does anyone have any photos or drawings of the tank innards? Any other theories? Thanks in advance __________________ Document your car with CollectorCarCompanion

01-31-2021, 04:36 PM	#2
JimG Senior Member Join Date: Aug 2016 Location: Hamburg, NY Posts: 244	Re: 34 Fuel Tank Baffles? Here is a thread that shows the inside of the tank with the top removed, the baffles, and the holes in the baffles. Seems hard to believe these holes could all be plugged. https://www.fordbarn.com/forum/showt...hlight=34+tank

01-31-2021, 04:42 PM	#3
cas3 Senior Member Join Date: Jan 2011 Location: sw minnesota Posts: 4,577	Re: 34 Fuel Tank Baffles? i have cleaned a 34 tank on a rotating fixture with BB's inside. they roll under all the baffles. hard to imagine gas could be held up there

01-31-2021, 05:30 PM	#5
DavidG Senior Member Join Date: May 2010 Location: southeastern Michigan Posts: 10,101	Re: 34 Fuel Tank Baffles? While not stated, I assume that you verified that the fuel pick up tube extends to nearly the bottom of the tank.

01-31-2021, 06:49 PM	#6
JMFL36 Senior Member Join Date: Oct 2017 Location: Venice, FL Posts: 227	Re: 34 Fuel Tank Baffles? Sponsored Links (Register now to hide all advertisements) Yes, the end of the pick up tube sits about 1/4" above the bottom of the tank. __________________ Document your car with CollectorCarCompanion

02-01-2021, 10:12 AM	#7
Terry,OH Senior Member Join Date: May 2010 Posts: 4,751	Re: 34 Fuel Tank Baffles? If the two holes in the baffle nearest the filler neck were blocked it would be difficult to refuel the gas tank! Have you tried to remove the bottom drain plug. Some people that have tried to seal a tank find the sealer does not adhere properly and falls off.

02-01-2021, 10:17 AM	#8
DavidG Senior Member Join Date: May 2010 Location: southeastern Michigan Posts: 10,101	Re: 34 Fuel Tank Baffles? An anemic fuel pump, per chance?

02-01-2021, 05:34 PM	#10
Lawson Cox Senior Member Join Date: May 2010 Location: Above the gnat line in Georgia Posts: 7,009	Re: 34 Fuel Tank Baffles? Sounds like a coil problem to me. __________________ Life is like a roll of toilet paper. The closer to the end, the faster it goes. It is better to be seen, than viewed. "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm".

02-03-2021, 08:07 PM	#11
JMFL36 Senior Member Join Date: Oct 2017 Location: Venice, FL Posts: 227	Re: 34 Fuel Tank Baffles? I doubt its a fuel pump or coil problem because of how the car reacts to the different amounts of gas I have put in after it dies. If I add just a little gas after it dies, it will run for a few miles and die again. If I add a gallon it will run for about 20 miles before dying. If I fill the tank every 60 miles or so the car never dies. This direct correlation between how much gas I've added and how long it will go before dying makes me think its a supply issue. I've ruled out vapor lock and a blocked or broken sending unit. This is why I suspect the tank baffles may be blocked. I plan to drain the tank in the next couple of weeks so I can get a peek inside at the fist baffle (nearest the filler tube) and the holes at the bottom of that baffle. __________________ Document your car with CollectorCarCompanion

02-04-2021, 09:26 AM	#12
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,319	Re: 34 Fuel Tank Baffles? I had a similar problem with a '36 I had years ago. It turned out to be the remnants of a rag that somehow got into the gas tank. When the car had half a tank or more it ran great. When the fuel level got low, the rag would get sucked into the fuel pickup and starve the car. Sometimes I could run the tank down quite a way; other times I'd sputter to a stop at anything less than half a tank. If that happened, I'd unhook the flex-line and blow into it, HARD. You could usually sense the crap getting blown out of the fuel pickup. I finally spent the time and effort and got the crap out of the tank.