Backfiring and spitting gas thru carb

[tuscola4x4]

87 jeep 4.2 Any ideas on what's going on with this? My jeep would run great and then die like it was running out of gas. Let it set for a few minutes and it would start and might not do it again for miles or might do it in a few 100 feet. I changed the fuel pump I put a electric pump on it now it's worse than it was now it want even run just idles extremely rough and spits gas back thru the carb when I turn key off, nearly acts like its out of time but haven't messed with the timing.
Thought about getting a new carb but have read so many bad things about webber and good things to?

 

[TerryMason]

Does it always idle rough, or just sometimes?

I'd start by cleaning the venturi out. It's not very hard and doesn't cost anything:

Neither removal of the carburetor nor a complete rebuild is necessary to fix the problem. To fix the problem, start with you Jeep off and parked securely:

1. Remove the air cleaner cover and air cleaner. You may need to remove a few hoses and wires to get the air cleaner out of the way. Make sure you tag them all so you can put them back in the right spot. It's often easiest not to remove the heater hose that goes to the exhaust manifold, if you have one.
   Remove hoop that holds air cleaner.
2. Remove the two screws holding the choke plate with a 3/16" socket or small flat blade screw driver depending on what screws you have holding it. Be careful not to drop the screws down the manifold unless you enjoy fishing. Remove the choke plate.
3. If your carb has one, remove the plate on the side that covers the choke linkage so you can access the screw holding the choke rod. It may be necessary to drill out a rivet to get it free.
4. Remove the little snap ring and screw (1/4" socket) that holds the rod that holds the choke plate and remove the rod. A screw driver will normally push off the snap ring.
5. Remove the two screws with holes in the middle of them and carefully remove the venturi cluster with the two little gaskets. There should be two idle pickup tubes pushed into the venturi sticking out of the bottom. If they have fallen out, that could cause your idle problem.
6. Blast the venturi and inside of carb with lots of carb cleaner. Be sure not to dislodge the check ball in the center.
   With a long thin pin or piece of piano wire, make sure the idle tubes and nozzles are clear. After you have run them through, spray with more carb cleaner.
7. Put the cleaned out venturi cluster back with the two gaskets and two screws.
8. Replace the choke rod with snap ring and screw and replace the choke plate. Make sure all the screws are tight that hold together the carb body at this time. Often the screws will loosen up and dirt will be sucked into the carb.
9. Replace the plate covering the choke linkage with a sheet metal screw, or leave it off.
10. Replace the air cleaner.

From the guys at Jeep Tech

 

[Syko]

If it's spitting gas out of the carb, the pump might be putting too much pressure/fuel into the carb, causing it to flood itself, literally. Try dialing the fuel pressure down on the pump, or see if you can install a pressure reg in line.

 

[Jester32]

To much pressure. Stuck needle and seat. Improper float adjustment. Will all cause fuel to spit out.

 

[tuscola4x4]

Thanks guys the fuel regulator worked I have it set a 4 and seems to be running great now

 

[Gronk]

The Webbers/EMPI setups are VERY sensitive to pressure and being off camber. I replace as many Webbers (and all the so called webber knockoffs which is the majority) as I do Carters with my Motorcraft conversion business. I have a pile of them on the side of the shop as I don't even resell them any more. It was too much of a headache and they were never jetted right.

If intreted in more info on a Motorcraft, send me a message.