Sits a week, won't start

GB SISSON

GB SISSON

Well-known member
If you looked at my thread about picking up a bunch of flatheads and having to leave my panel out in the rain and snow, you will feel my pain. I have two jailbar trucks that sit in a shed next to my shop and I don't use too often, but when I need to move them or haul some lumber it is like pulling teeth to start them. One, the two ton has an 8ba and the tonner panel has a 59 ab. One is 6v pos and the other is 12 v neg with a gm one wire. Yesterday I couldn't start the panel so I rolled it out because I live on a hill. Tonight it still wouldn't start and it was hailing and snowing and I wass pissed off. I got my wife to tow me to the top of a hill and I rolled it but no dice. The panel ended up in a mud hole up to it's hubcaps and would start and run 2 seconds with ether but never pick up it's fuel. As I woild not leave it out all night in that dead condition in a mud hole I pulled the rubber fuel line between the fuel pump and carb and cranked engine with that awesome button on the bottom of the solenoid. The tank was 7/8 full, but no fuel came out. Next I sucked on the line until I got a mouthful of fuel which I still have. The very next cranking brought even spurts of fuel from the line to the carb. Hooked up the line and it started and ran perfectly. Good thing I have excellent mud and snow 7.5 x 17s and I drove out of the deep mud hole and parked in my shed. I then proceded to clean what I could with an old towel. My question this evening is why does this keep happening? I have rebuilt both carbs with modern kits and both fuel pumps are fresh stock, coming from my local napa store. I am thinking tonight I will order 2 electric fuel pumps on line. A six and a twelve volt. These will have a momentary switch in the cab. Do others have to do this? Does this 'new fuel' evaporate from our old school carbs? why doesnt my new mechanical fuel pump deliver fuel to the carb even when I am coasting down a 1/4 mile hill with ignition on? Manualy sucking on the fuel line through the fuel pump seemed to succesfully prime the fuel system, but nothing else did. Electric pump for a primer???
 
I have a good mechanical pump on my '47 59 AB which works fine. However, I always prime the gas system with my 12 volt Airtex electric pump located at the gas tank. I let it run for about 10 seconds. Both pumps put out 3 psi pressure.

It seems that when my car sits more that a day or so that the gas is siphoned back to the tank. The Airtex flow-thru design allows this. I don't think that this is a "new fuel" thing problem .... if it was a vapor-lock problem then maybe. You may have an air leak between the carb or pump that's allowing the siphoning to occur. I've never done any mechanical pump work but understand that some pumps have a valve or valves that should prevent the siphoning so if my glass bowl pump is suppose to do that, its not. Regardless, what I have and how I use it works okay for me.
 
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How old is the diaphragm in the fuel pump? Maybe the check valves are gummed up and not sealing. (Even with old time gas things could get gummed up when sitting for long periods of time and diaphragm do wear out)
 
I never have that severe an issue but I do find after mine has sat for a week or more it takes a while to get it fired up. 6 or 7 days seems to be the limit, after that it's a bit of a pain but always pulls enough gas with the mechanical eventually. Probably has some thing to do with the ethanol in the fuel too. I had an occasion to fill mine up towards the end of last season with fuel with no ethanol and it could sit for a month and fire up fairly quickly, went back to the ethanol and again hard to start after a week or more. I'll add some additional info supporting the ethanol fuel may be the culprit. I had the same problem and even worse in my snow blower with the ethanol fuel. I didn't fill the car up with the ethanol free again because the station round trip is almost 100 miles and burned half a tank going and coming but did fill a 5 gallon container when I was in the area again and always use it for my snow blower and it fires up immediately every time with it no matter how long between snows.
 
redmodelt said:
How old is the diaphragm in the fuel pump? Maybe the check valves are gummed up and not sealing. (Even with old time gas things could get gummed up when sitting for long periods of time and diaphragm do wear out)
Click to expand...
The napa fuel pumps are two years old and 3 years old. I will add I had a '47 jeep CJ2a about 5 years ago. Kind of a beater but ran excellent, but same hard start issue. I ran a outboard motor fuel line from the tank forward. This had the rubber squeeze ball. Couple good squeezes it got firm and then started. I don't think I want that crude, but seems it did the same thing. I know the electric should be frame mounted and close to tank. They always seem expensive, but anybody recommend a good one? Actually need two, one six one twelve volt. I love amazon because I have prime 'no pun intended' and I don't have to fill out a bunch of credit card and address stuff. Will a 12 volt pump work, but not as fast as a six volt pump if I used both 12 volt. That way if I convert the panel to 12 volt it can stay. Thanks, GB
 
Mechanical pumps do not pump air to well, if there is some fuel in them it tends to seal things of and make it work better ,In the day theses cars were started every few days so it wasn't such a problem ,If you want to set it up properly get a vacuum gauge and do the tests to make sure the air line and pump is sealed .Check the join into the tank its a good source of air ,Run a filter at the carb to fend of any rocks coming from you 80 year old tank ,I am more and more in favour of electric pumps for priming ,On one carb I drilled and taped a thread the same as the brass plug on top of the bowl then used a plastic squirt bottle to fill the carb it worked good , We tried to start a (34 )today the owner went from a 8Volt to six but all the cables are now to small to carry the current so he now has opted for a 12 volt fun projects generator conversion ,we poured a cup full of gas down the carb in 4 stages and jumped it direct to the starter to get it to go ,Ted
 
My 52 Merc is a little reluctant to start after sitting a few days too. It needs a lot of gas. Sometimes pumping the pedal , then full choke as I hit the button will be enough for it to fire up. If I want to make it easy I will lift the air cleaner and pour some gas down the teapot carb. I don't think we have much ethanol in gas here in Canada. It is just a characteristic of the old fuel systems. This one needs a few pumps on the pedal even on a hot start.
 
I found Airtek pumps on line at RockAuto. They were almost half the price anywhere else.
Both 6 and 12 volt.
 
I started having fuel pump issues and eventually found the flex line from the rigid steel line to the pump was cracked inside the metal braid covering. The pump was mostly pumping air. On top of that the old pump diaphragm was also beginning to crack.

My baby got a new pump and flex line plus an added 6V Airtex back at the tank. The electric pump helps with summer Georgia vapor lock and ethanol gas. We just got a new station nearby with non-ethanol gas which is a welcome development.
 
GB,
As part of a carb rebuild when I complete work on the bowl I fill it with corn gas
to check for any leaks, overnight 1/2 the fuel will have evaporated, it is astounding.
I'm guessing that thruout the fuel system this is happening to a lesser extent, but
still happening. Most motors have the f/p sitting low and this enables the suction
(inlet) to be flooded which in turn guarantees, usually, the pump will never be sucking
air. You know where a flathead pump is situated........way above the tank.
OK
The pump must be 100% efficient and zero air leaks in the system.....if this so
on your vehicles they'll start after an acceptable amount of cranking. I like the
antiquainted fiber style valves in Ford f/p's because they seem to hold up better
than the newer 'rubber' valves. When new, in my experience, the newer valves
allow the f/p to develop pressure a bit quicker but the fiber valves last and last.
It's been mentioned here many many times..........the flex hose between the hard
line and the f/p will/can draw air in but won't leak fuel out. I use fuel inj hose on
my vehicles but the Bob Shewman hoses with or w/o the check valves are what
I prefer for customers cars, they look more correct for sure and are trouble free....
Bob Shewman......gadgiteer@aol.com....
Charlie ny
 
I believe Charlie NY has hit on something: the fiber check valves. Back in the 50s we had a '48 ford truck on the farm that would sit for a month sometimes without being started. Then by choking it, it would start right up. Are these fiber valves available today? Nowdays with corn gas this just doesn't work. An electric fp with or without the origonal pump is just about a necessity. Another thing that helps is to run a circuit that bypasses the resister while the starter is cranking. I might add: All the other threads here have good advice.
 
Our '47 has the same problem. We put on an electric pump to prime but eventually it wouldn't even run on the mechanical at all. I checked the pump push rod length and it is ok and even put on a different pump I had laying around to no avail. One day on a whim we checked the line volume and found that the line must have been down to a pinhole size in places. (we cleaned up the original and used it on restoration). It runs better now but not perfect. I suspect for me there are several things going on. I wonder if the cam lobe is worn so the push rod doesn''t move enough. Additionally though upon testing found the condenser voltage to be a bit low (Chinese repo). Next task on that car is new coil and wires.
 
get the airtex and get a toggle switch just use to prime carb, it will pull fuel through your mechanical pump besides if your mechanical dies out you have a backup, I broke down with my 41 w/8BA bad pump had to be towed home, I have installed electric backup pumps on my 41 and 46 merc since .
 
Thanks all for so many great responses. My fuel lines are brand new steel and new fuel injection line. Not stock setup. I will do some checking and get some electric pumps.
 
Add an electric pump in line near the fuel tank operated by a toggle switch hidden under the dash. Use this to prime the fuel system. When primed shut off the pump and start the engine. Also you need to make sure your ignition system is in top notch condition. No weak coil and poorly adjusted points.
 
I agree with CharlieNY on the Bob Shewman hoses that go between the hard line and the fuel pump. I bought the one with the check valve and have had only one time when I had to crank more than a few revs before she fired. Usually it fires immediately, even after two weeks. It seemed an easier solution than an electric f/p, at least for now. Bob Shewman advertises in the V8 Times.
 
My 47 sits for a week then I use the electric pump to prime it. If I leave the pump on too long gas gets forced out around the top carb gasket !! What is going on?
 
cc,
Elec pump probably putting out over 3 psi and overcoming the float/needle and seat. Many of the brass seats (that thread into the air horn) have outlet holes on their
sides. These particular side holes allow fuel to spray out sideways pretty much in the
same plane as the air horn to bowl gasket . As you can imagine this scenario is much
the same as a lawn sprinkler. Couple the lawn sprinkler effect with what ever pressure
your elec pump is putting out and there is your situation.
Lectric pumps........I never use 'em.
Charlie ny
 
Charlie ny said:
cc,
Elec pump probably putting out over 3 psi and overcoming the float/needle and seat. Many of the brass seats (that thread into the air horn) have outlet holes on their
sides. These particular side holes allow fuel to spray out sideways pretty much in the
same plane as the air horn to bowl gasket . As you can imagine this scenario is much
the same as a lawn sprinkler. Couple the lawn sprinkler effect with what ever pressure
your elec pump is putting out and there is your situation.
Lectric pumps........I never use 'em.
Charl

ny
Click to expand...

The last couple of carb kits I bought had some type of one piece 'caged' affair instead of the normal needle and seat. Do you know how these will fare with a 'low pressure' elec pump putting out 2.5 - 4 psi? Just for occasional priming of course....
 
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