1955 cj5 won't stay running

I just purchased an all original 1955 CJ5. The jeep hadn't been run for about 15 years. Put new plug wires on, new rotor, cap, points, condensor. Changed oil and put in new spark plugs. Reset the points. Jeep starts to run and would run for about 15-30 Seconds and then stop. Cleaned out the entire gas tank (it was very dirty with almost like a varnish at the bottom). Pulled the top off of the fuel pump and the screen was pretty clean. Tried to start the jeep again. It would run longer now, 2-3 minutes but then eventually it will just start to lose idle and then eventually stop. It seems that the carb is running out of fuel. If you press the accelerator 10-15 times, the engine will then start right up and run again for 2-3 minutes and then will eventually stall out again. Just before the jeep was put away 15 years ago, it had a new fuel pump and carb was rebuilt. Any help or advice would be appreciated. I hate to have to try to rebuild the carb if it is not necessary. Thanks.

The Jeep has a little surface rust and all original canvas tops. The canvas tops are in great shape and the jeep is very solid. Does anyone have any guess what this may be worth. Even the tires are original as it only has about 13,000 miles on it. I am thinking about getting it running and then do nothing else with it as it may be worth more as original.

 

Fuel filter plugged? Float sticking? Wonky coil that opens the circuit when it warms up, then cools down and the circuit closes?

 

As Red mentioned there could be a number of issues after setting that long but it sounds like you have done quite a bit to eliminate many of the common problems.

Lets focus on fuel delivery for a starting point if you know you have ignition and you know the oil bath air cleaner is not plugged, After setting that long something could be plugged or the fuel pump may not be up to the task.

First it may pay to remove the fuel line at both the pump and fuel tank, Blow it out to make sure its not partially plugged with fused/solidified rust & varnish deposits.

Second,If the tank is rusty install a fuel filter between the pump and tank, Get the clear kind and buy several as they will plug quickly when the fuel starts sloshing around knocking rust loose.

Third, Place a pressure gauge ( most vacuum gauges can be used to measure fuel pump pressure ) between the pump and carb and see what the output pressure is, It should be between 2.5 and 3.75 psi for the F-Head.

Fourth,If the pressure is good and the problem persists get into the carb and check fuel valve needle and seat for corrosion that could cause sticking ( the early needles were spring loaded steel, if spring is corroded or broken it could contribute to sticking or flooding ), float level, float drop and make sure there is no sediment in the bottom of the bowl or under the main jet. Make sure the low speed/ idle jet is open.

Note; With a YF Carb thats been setting that long it would be wise to replace the pump diaphragm as they get brittle and can allow fuel to leak directly from the float bowl into the intake manifold. I would recommend replacing the diaphragm even if its not leaking at the moment, They usually dont last long after drying out like that.
Your problem could also be influenced by flooding at high manifold pressures ( idle and part throttle ), This is directly related to a leaking diaphragm.

 

gonna vote either fuel pump or carb rebuild or both. stuff dries out when sitting that long. also check out whats been talked about already, good advise and cheep too

 

When it dies, look down the throat of the carb and hit the throttle.
If you have fuel in the bowl, you should get a GOOD squart of gas spraying from the accelerator pump.
If not, take the top of the carb off and see hoqw much gas is in there.
Crank it and see if you got gas comming outta the fuel pump before the filter.
If you crank the engine with the line off, you should get oh, maybe a qt. of gas in no time.
Take the line off the pump BEFORE the pump to see if you got fuel there.
Take the gas cap OFF and try to run it, (might be sucking the tank into a vacum)
If'n you got fuel to the carb............
Put a timing light on a wire and see if the spark is there all the time as it's running.
When it stalls, check the points, open them with the key on really fast and you should see a tiny arc.
Feel the coil, see if it's hot.
I'll bet it's a fuel dilevery problem..........
Joe
It's a jeep, it'll run no matter what!

 

disconnect the fuel line between the fuel pump and the tank.
Put compressed air to it and blow it clear.
You may have to consider a new tank.
And maybe a new pump and a new carb.
Being a 55 it should have a dual chamber pump.

one side (or end) is plumbed for fuel, the other is plumbed for vacuum.
Follow the lines and see where they go.
The vacuum one will go to a spot high on the firewall and then to the wiper motors.
The fuel one will go back under the body on the inside of the drivers side frame rail.

Buy a can or two of SeaFoam.
Run a long piece of fuel hose from the inlet side of the pump to the can of SeaFoam and have your assistant start the engine. In neutral, with a block in front of and behind one of the back tires.

It runs for 15 to 30 seconds you say? This will be enough for the SeaFoam to get into the idle circuits and start cleaning them out. The SeaFoam will get rid of the varnish.

It'll take 3 or 4 minutes to empty the can. SeaFoam can also be used as starting fluid.
Only takes a capful or two in the throat of the carb. Or pop the top of the carb and fill the fuel bowl with it, then replace the top.

 

Thank you all for your comments. Some additional good ideas. I really like trying the Seafoam and see if that works. I really hope to not have to try and tackle a carb rebuild. I will try some of the other ideas and report back after the weekend. Where can you buy this Seafoam and what exactly is it?

 

A carb rebuild isn't THAT hard!
If you look closely at the carb as you take it apart, keep the parts kinda together, and assemble the reverse order of disassembly, you can't go wrong.
Decades ago, when I was wet behind the ears, my instructor at trade school had us take a spray can straw and when we had the carb in little pieces, blow into each port to make sure thay were open.
He also had us go through the path of the fuel from when it entered the carb to the exit, through all the circuits.
You can learn a heck of a lot that way!
Seafoam??? Is that like a carb cleaner??
Joe
Sure it's my jeep, can't you tell by the way it's NOT running??

 

The mechanics shop book has the blown up view of every Jeep carb used.

To make sure it is super clean, drop it in a solvent tank for a day.






Todd