27 Marmon fuel issue

[sambarn]

I am trying to get the 1927 Marmon Model L back to reliable driver, I have installed a 6V positive ground fuel pump - I think it may work too well. When I shut off the car the updraft carb begins dribbling gas out of the bottom of the car - not the biggest problem but... the exhaust pipe is directly below. Today as the car got hot, it stalled on the road. Because I had mounted the fuel pump switch under the seat, I have to get out to shut it off. the carb just POURED gas that immediately vaporized - just a little bit of a fire hazard. Is this because of the pump - what shoud I do??. After this the car was very hard to start - I had to push the air valve on the Schebler carb open and crank the starter from under the hood - easier done than said, just pull the levr - It fired but was very uneven idle and harder to rev up, sputtering and coughing then finally running right, jumped in and headed home. died at the next full stop and went through it all again. finally got it home ( I was only a couple of miles away) letting it cool now. I ran a soft copper fuel line from the pump to the carb, it sits about two inches from the exhaust pipe - could this be causing a vapor lock or boiling the gas?? It is right next to and farther from the exhaust than the original line. I feel a bit out of my mechanical league..Any suggestions???

[mrspeedyt]

i put a 6v stewart warner old style on my '23 buick... i put a 'pressure regulator' right after the pump and adjusted it to 1 psi... except for the noise of the pump it works ok...it's mounted on the firewall right where the origional vacuum tank belongs. this i did because when i bought the car years ago (at a kruse auction in scottsdale) the top part of the vacuum tank was missing... and i haven't found a good cheap replacement yet.

[Rusty_OToole]

If the pump floods the carb you have WAY too much fuel pressure. You don't notice when driving because the engine sucks in the extra gas and burns it but you are probably running rich because of it.

Don't Marmons have the fuel tank in the cowl like a Model A? You shouldn't even need a fuel pump.

[nickelroadster]

Sam,

You need a good adjustable fuel regulator. The previous poster who suggested one pound pressure is right. You could also have a vapor lock problem which it seems as if you are taking care of . Todays gas just vaporizes very easily. Its remotely possible that you have a problem with the float needle not seating quite right but chances are that the modern fuel pump is giving four to six pounds of pressure where the float needle is designed for about 1/2 to 1 lb. of pressure. If you cannot find a good adjustable regulator at a local parts store, I can bring one to the muster (I assume you are going). It would take about ten minutes to mount.

David

[sambarn]

David -and all, I will begin looking in the morning for a regulator - I think you are all correct except that the Marmon does not have the tank in the cowl. If I cannot find one then I will have to see about getting you to bring one to the muster, BTW david - I've got an even smaller rumble seat for you this year!! At least when it rains this time, I'll be in a hardtop, you... well.... you still have that hat right??

[sambarn]

It looks like the only regulator I could get before The Muster would be the Holley 12-804 rated for between 1 and 4 PSI. Lou Iaccino says rebuild the stewart Warner but I have some pot metal destruction that is causing me so we'll see - I'll get to the garage on Thursday and leave on Saturday for the Mighty Marmon Muster in Bowling Green so I figure my odds are about 50/50 but I do at least have a back up ride if my work fails. Crossing my fingers!

[Friartuck]

I believe there is a Restoration source in Michigan that reproduces the Stewart Warner lid in cast Aluminum to replace the pot metal version. I too recommend rebuilding the vacuum tank.

Edited September 7, 2010 by Friartuck (see edit history)

[Restorer32]

THE FILLING STATION has repro parts, including tops, for Stewart Warner vacuum pumps.

[sambarn]

So.. I put a regulator on the electric fuel pump, dialed it all the way down runs great- still drips 12 - 15 drips over a course of about two minutes. I am shutting off the pump a minute or so before shutting off the engine and still the drip. Having that done and some free time I tear into the vacuum system -which I would prefer to use. I was able to use a die grinder and drill press to scratch off the flare on the brass pin for the overflow valve that runs through the lid and the dremel tool cut the brass pins to remove the guts of the vacuum fuel tank. I was able to solder the overflow valve pin back together through the new lid and replace the brass pins with cotter pins and assemble the aforementioned guts to the new lid - installed it, primed it with the electric pump, swapped the leads to the tank so the vacuum tank wouldn't have to pull through the pump and regulator and ran the car for three to four minutes before it coughed to a halt. I was able to start it but only for short bursts and sediment - coek looking - chunks appearing in sediment bowl. Out of time and needing the car on the trailer tonight, I swapped back to the electric pump. and loaded it up. The oddest thing during this is that everytime the car shutoff - even under vacuun fuel delivery it dripped it' usual 12 - 15 drips - right on the exhaust pipe. I now use a red shop rag tied with a bit of string as an Schebler updraft tampon. after shutiing her off, I open the hood and insert the rag. remove it when I return to the car, close the hood and off we go - I hope. Off to the Marmon Muster for a week of touring in Bowling Green - lots of hills - so we'll see what happens. More to come....

[mrspeedyt]

carry a large box of baking soda... (a really big box...) good to use as a fire extenguisher (pardon the spelling... ) hopefully it won't be needed.

[Guest downrcd]

HI

I had similar problems with a model 68 Marmon , I installed a electric fuel pump and regulator and it worked fine. I now am driving a 1929 Blackhawk made by Stutz and was having problems with the carb. dripping fuel, I removed the older replacement electric fuel pump and installed a stewart vacuum pump of unknown vintage that I built up from parts of 4 units purchased at swap meets. The system works fine and stopped most of the dripping. My carb actually has a drain line to handle the dripping and route it under the car and onto the ground. I think by design those old carbs did leak a small amount under certain conditions. My carb is slowly failing due to the die cast potmetal and may have some internal cracks, I have a replacement stromberg carb that can be fit up to my engine and it also has a drain line for excess fuel. I am convinced that the original vacuum type fuel pumps will work fine under normal usage but under full throttle conditions such as pulling a long hill the loss of vacuum from the engine can result in fuel starvation but even then if you let up on the throttle for a moment it will catch up. My car actually had a vacuum tank made by Kingston and uses vacuum from a second vane in the oil pump which is somewhat constant to avoid fuel starvation but my original tank is totally shot and I cannot find a replacement.

Good luck

[sambarn]

day two of the muster, and all seems pretty good. Dribbling after shutoff is the only fuel related issue since I've adjusted idle up to keep her from dying at intersections (it was just too low, a turn and a half and we're in a good place) but now the mechanical brakes are not what they were when I set and adjusted them last week. I feel like I set the system up well and corrected a couple of odd angles but must have backed the shoes off too far. Oh Well, breakfast and crawling under the car again. There are truly worse ways too start the day!!! Yesterday we did about 70 miles, today about forty with four stops and then the 140 mile day tomorrow. I'll update this evening after the parking lot tech session (5 of 9 cars at the muster are suffering FORD syndrome, It's a good thing we all seem to enjoy Fixing Or Repairing Daily).