fuel pump madness

I have a 1956 CJ5 with a stock 134 F head engine. It will run smooth for awhile then start wanting to stall. I have to pump the gas and pull choke in and out for about 2-3 minutes. Then it will smooth out again. I thought it was dirt in the fuel tank, so I took it out and drained it and put in fresh gas. I'm suspecting the fuel pump. But what are all the lines going to the pump for. I know I have the one from the tank to the pump and then to the carb. But there are 2 other lines going to the block. I wanted to put in a electric pump, but I have a 6 volt positive ground sys. What do you suggest? Thanks

 

are those lines for vacuum-actuated windshield wipers?
i bought a $30 mechanical pump for the slug.
it works fine and was an easy install.
i still have the original pump.
in a box in the shed.
i got sick of tinkering with it.

 

2X UncleBill, I agree, the mechanical pump I have works good to. Make sure your lines are new, solid, not copper.

 

Those other lines are vacuum lines for the wipers, as said above. If there is a big enough leak in the vacuum lines, that could also cause the JEEP to run badly. I have a similar system, and retained the old vacuum wiper motors. You can hear the motor running differently when the lines to the wipers are unplugged.

 

Thanks for all the help guys. I'll take a closer look tomorrow. But why would one of the lines go to the block?

 

When I replaced my gas lines up to the fuel pump the lines had rotted from the inside looking fine from the outside throwing specs of visible small rubber particles into the fuel pump, there was also a small section of rubber gas line on the outgoing side of my fuel pump attached to some old bent up stainless gas pipe going to the carb. When I replace the outgoing side to the carb with new metal gas line all the trouble stopped. My guess was fine pieces of rubber was breaking down or air was going into the carb. I do not have a fuel filter right before the carb. Only fuel filter I have is between the fuel pump and the tank. That total fix was around $10 bucks and well worth it. The F134 runs like a dream. My old mechanical pump doesn't have any lines to the block.

 

It's kinda weird. I've have a fuel line from tank to pump and line to carb, check. Then there's a rubber hose for the wiper coming from the bottom of the pump, check. And there is a line from the bottom of the pump that goes to a tee, then one line goes to the base of the intake manifold and the other goes about 6 inches back and into the side of the block. When I pulled the pump off there is two 90 degree bent tubes for the wiper and for the other one that goes up to the tee. Both tubes fell out. They looked like they were pressed in at one time, and oil drained from both of these holes. Well that's about it for the confusing stuff. Any ideas guys?? New pump or JB Weld for the tubes?????

 

No clew for me, pictures would help, perhaps one of these fellows on this site would know and speak up? Sounds like sometime pre you tried to update the fuel system. If I were you I would go back to basics for a F134 and just put an old mechanical pump on and new fuel line. My intials are ARC so anything electric I hate.....or at least weiry of.

 

The fuel pump is a dual action pump. The upper portion is the fuel pump and the lower portion is the vacuum pump. Sounds like you have that figured out. The vacuum pump is an assist for engine vacuum to operate the windshield wipers. In the stock configuration engine vacuum is taken from a port in the intake manifold below the carburator, a steel vacuum line from that port wraps around the front of the engine to a tee on the pump side of the engine. One side of the tee connects to the vacuum pump and the other connects to a steel bodied PCV valve that is connected to the side valve cover. Without the wipers running the engine vacuum pulls air from the crankcase via the PCV valve and valve cover. Turn the wipers on and the engine vacuum pulls air from the wiper motors to operate them. If you open the throttle quite a bit you loose engine vacuum and the vacuum pump then provides the air suction to operate the wipers.

Here is a view of the pump from the cj3b page;

http://www.film.queensu.ca/cj3b/Photos/Tech/Fuel/FuelPump.gif

Also on the 3b page is good commentary on the PCV system as well as good pictures in the engine re-build write-up by Eric Lawson.

You will have to figure out why the tubes no longer fit in the vacuum pump body and if they can be fixed as you suggested. Also need to find out how oil has gotten into those lines. I'm not sure, maybe a ruptured diaphragm in the pump or oil through the PCV system. By the way the PCV valve is servicable, it is two pieces and unscrews.

If you do not have vacuum wipers you can ditch the dual action pump for a single action pump and plug the vacuum line to the pump.

 

Thanks Willys3B, that answers every question I had about the pump. The wiper have been inopt for quite awhile so I will plug the lines for now. And at least I can take apart the PVC valve and clean it or see if something is wrong. The oil does have me wondering. One last question. The previous owner put on an after market Carter carb. It was leaking very bad and the float was stuck for awhile there. I took it apart and cleaned it, but I'm still having trouble with surging and stalling. What do you think about putting on a Solex carb. I hear they are good. Here's what it's doing. I start jeep, runs for about 15 minutes perfect idle, then starts to die. I have to pump gas and pull choke in and out to keep it running. This goes on for about 2 or 3 minutes. Then its back to a perfect idle. Then 15 minutes later, back to pumping gas and pullin choke. Thats why I thought it was the pump at first. Starving it for gas. What do you think? New fuel lines?, new pump, or new carb? And thank you for all the good info.

 

You might check your fuel pressure, mine did that when the pressure was too high. It would overpower the float/needle. I put in a fuel pressure regulator and all was well.

 

On the subject of fuel pumps. I replaced mine a few years ago with one from Jeep doc. I tried the start the jeep a few weeks ago and the fuel pump is no longer pumping. It's also leaking fuel where the pump bolts together at the diaphragm. I feel it is ethanol related. at one time you used to be able to buy rebuild kits for these pumps. Anyone on here had this problem?

 

I am a pretty poor mechanic so I am not sure how much help I will be but....

Make sure the basics are right first...ignition system is correct, point gap and timing. Might remove the vacuum line from the port below the carb and put a pipe plug there just to be sure you don't have a leak in that system.

You cleaned the tank and put in new gas. Is there a fuel filter? Is it clean? You can check the pump volume by disabling the ignition, direct the discharge from the pump into container and cranking the engine. I don't know how much it should deliver but if it is causing a problem at idle it would have to be pumping very little.

Rubber fuel line is cheap, I would replace any you have if it is questionable.

The Carter YF 938 carburetor was original, is another carter carb installed? I have had pretty good results with the carter YF. If you have a carter YF I would suggest investing some time and money into rebuilding it with a kit and a gallon size container of carb cleaner you can soak the parts in.

Cater YF discussion here:

http://www.film.queensu.ca/cj3b/Tech/Carburetor.html


I have had no experience with the Solex but I see Oldtime just posted one for sale on the CJ3B page.

You are sure it is starving for fuel and not flooding? A needle and seat in the carb that is too large can cause these to flood.

Good luck!