Fuel issues

[SAWCo69]

1950 CJ3a, fuel suppy problems, is the system vented anywhere? gas cap that I have does not seem to be vented...is that correct?

[Carls_jeep]

The cap is vented. What are your problems?

[SAWCo69]

Runs fine when cold, at operating temp, the fuel pump does not want to pump. Glass bowl shows about an 1/8 inch fuel, small bubbles.Seems like a vaper lock, but all lines are in stock position and don't appear even warm.All new lines on suction side,all joints are tight.
After sitting for a hour or so, starts pumping fuel and off we go...
New fuel pump does same thing.No spacer at pump, I think that would get a little more fuel pressure, but don't think new Solex carb needs it.
New tank, I may pull it just to make sure there are no odd bits swimming about.
A bit baffeled at this point.

[athawk11]

Saw,

It really sounds like vapor lock.  Vapor lock has been a topic here and on the 2A page. I have a Solex also.  I'm not sure if that is a factor, but I made special effort to run my fuel lines as far away from the manifold as I could, but as close to the original look as possible.

If it were a clogged fuel delivery, it would probaby react the same way, cold or hot, but more so when you are hard on the throttle.

You could try to re-route the fuel lines further away from the manifold.  Or temporarily install an electric pump.   You could also wrap some cool rags around the fuel line from the pump to the carb, and get it up to operating tempurature and see how it reacts.  These approaches would at least eliminate vapor lock as a possible issue.

Tim

[aboyandhisdog]

Your fuel pump delivers about 3 3/4 lbs. pressure, but the Solex requires 1 1/2 - 2 lbs.  This is why you have to have a pressure regulator in the fuel line before the carb.  Do you have one?  Are you saying the jeep just quits running after it is hot, or is it just hard to restart after you have shut it down when hot?  If it shuts down when running, I would concur with Tim on the vapor lock.  If it is just getting too much heat after being shut down, this is a pretty common problem with the Solex or the Carter.  Mine will fire up with the use of the acc. pedal when hot, but having the right fuel pressure might be necessary for your Solex.

[Carls_jeep]

Try this, run the Jeep until it is warmed up good and stops. Be sure to take a tool kit with you. Pull the fuel line at the carb and turn the engine over to start it. Does fuel come out the line? If it don't then you may be getting vapor lock but if fuel comes out quickly and a good flow then you may have an ignition problem.

BTW, have a can to put the fuel line in so it don't spray fuel on the hot engine.

Or, leave the fuel line connected and check the ignition for fire to the plugs. You could have a bad coil, bad condenser or both.

I only had a vapor lock on my Jeep at 11,000 feet on a mountain with a weak fuel pump and it was not a hot day, just the conditions.

[garage gnome]

Runs fine when cold, at operating temp, the fuel pump does not want to pump. Glass bowl shows about an 1/8 inch fuel, small bubbles.Seems like a vaper lock, but all lines are in stock position and don't appear even warm.All new lines on suction side,all joints are tight.
After sitting for a hour or so, starts pumping fuel and off we go...
New fuel pump does same thing.No spacer at pump, I think that would get a little more fuel pressure, but don't think new Solex carb needs it.
New tank, I may pull it just to make sure there are no odd bits swimming about.
A bit baffeled at this point.

My '49 is doing the same thing too, but I have a Carter. Good fuel supply, good spark, decent compression. Was running fine a few weeks ago and not so well now. �[smiley=angry.gif]

I still need to tear into it and see whats up.

[SAWCo69]

 ï¿½ Sunday afternoon,put a new fuel pump on the little red beast, put tools in and drove in circles around the hood till it got to temp (about 20 min) a couple of sputters and it died, again. Fuel pump is not pumping fuel.At this point makes a regulator rather moot......walked home...a few hours later it fired right up and off we went.
 ï¿½ Current plan is to re-rout fuel lines , maybe install elec pump. Stay tuned.
Thanks for the replies.

[Carls_jeep]

If you disconnected the fuel line and it would not pump fuel out I don't think it's the fuel pump. It may have something floating around in the fuel tank that finally gets sucked over the outlet in the tank.

A vapor lock is usually between the fuel pump and the carb.

[Williamsmar]

I bought a 53 chevy truck would idle great and run good for about 1000 yds and die .  changed out fuel filters even added a secound one due to paticles in fuel bowl.  Took tank out took rubber hammer to it and dumped out $35 of change covered with laquer from old gas.  cleaned tank ran like a charm thereafter.  I think you have something in the tank.

That is my newbie expertise.

Marty Williams

[Macgraham]

When I was a kid in Colorado vapor lock was common because of the high altitude at home. Our 3A never had much trouble but some guys would put a row of clothes pins on the fuel line to dissipate heat. It must have worked cause I remember rigs using them alot. Maybe a guy could figure something else that looked a little better. Mac

[Carls_jeep]

I had a car that would vapor lock on a hot summer day. I cured it by putting a bypass line from the pressure side of the fuel pump at the carb to the inlet side of the fuel pump. It kept the fuel flowing but I did us the 1/8" OD plastic line to restrict the flow.

[SAWCo69]

   I am at 7000 ft in CO, but vapor lock has not been an issue before,not hot weather yet, but that was then and this is now... I am currently rerouting the exhaust line ( PO had it different than stock), then the fuel tank is coming out for a good look see.The little red 50 will run sooner or later,more likly later as I'm off to Moab with the 75 crawler for a week.
Thanks for the tips, if I see some clothes pins I'll give it a try....

[rocketeer]

What would really help are photos of how your fuel lines are routed and how it's connected to the tank.

Larry

[SAWCo69]

 Back from 4 days in Moab, love that town.
Finished up moving the tail pipe this morning.
Pulled the fuel tank, its only two years old, got all the fuel out but a small amount that hides behind the internal baffle.
 Two small bits of junk found, seem too small to clog fuel line. Reinstalled tank, seats, lines etc. Installed 5/16 hose barb in tank drain, ran fuel line up to engine.This will be my back up fuel line if the other still won't act right. Added a elec. fuel pump to the jeep tool box, some wire, and set out on another test flight.
  1 1/2 hours of good jeep driving, around town , up to the airport, out to a buddys pond, up, down, around.Feeling rather smug with myself, great wrencher and all.Headed home thru town and.....sputter, cough, die....dead red jeep by the side of the road.Much screaming, grinding of teeth and pulling of hair, choice words said.No fuel in glass pump bowl, no pumping fuel.
  Unhooked original fuel line from pump, jammed fuel hose from tank drain on and fired right up......drove home bewildered.
Will do another test flight today just running off the drain line.
Stay tuned.......