: fuel delivery probs and ?'s


tuckster
04-20-2002, 04:38 PM
Working with a '72 Wagoneer, 360 v8, stock motorcraft 2bbl, stock fuel pump, stock gas tank....
I finally got the motor to start (after previous electrical problems)... but now the motor won't stay running. Once the motor is started it will run for close to a minute, and then it will just cut out and die.. like it isn't getting enough fuel. Pump the gas copiously and she fires up and does the same thing again, if I give her any revs she'll wind up like normal, but eventually will cut out.
I pulled the fuel filter, but I don't know how to tell if it's clogged, I blew gas through it using my mouth so I assume it's alright. While the filter was off I cranked the motor to see if I was getting decent flow from the pump, and it seemed to be doing just fine although I didn't do the test for a full minute to see if it pumps a quart.
Well, I'm looking for any suggestions on trouble shooting this and getting it fixed so I can wheel again. Thanks in advance.

AGGIE_04
04-20-2002, 04:56 PM
Have you rebuilt the carb or was it working before? YellowCJ had this same prob on his 83 CJ. It would run for a while at an idle and for a long time at about 1000 rpm, but then die. He had a clear filter, so we were able to see the fuel level in the filter slowly get lower and lower. Took the pump off and took it apart and everything looked fine, but we got a new pump (14 something dollars at Vatozone) and now it works fine. If the filter is good and there are no restrictions in the lines, then it is prbably the pump. :jeep:

dorfs
04-20-2002, 06:29 PM
You need to perform a proper fuel pump pressure/volume test. The fuel pump pressure is tested on the high side, going into the carb. It should be something like 6 lbs. and hold pressure after the engine is shut off. You may have to pinch off the return line to do this. Then perform a volume test. This is done on the return line. Stick a hose all the way to the bottom of a clear container and count off 15 seconds with the engine running. If the volume spec is 1 quart in 1 minute, you should have 1/2 pint of fuel in the container. The reason you want to use a clear container and put the hose all the way to the bottom is to check for air. If air bubbles are comming up, chances are you have a cracked suction line to the pump. If a suction line from the tank has a crack, it will draw in air and have low volume. This is common on older Jeeps where the line comes from the tank to the steel lines on the frame lines in the back.

For the price of a fuel pump and a couple of feet of line with clamps, you might just want to replace everything with new.