I'm new here I have a JD 310c backhoe the motor is a 4239D I'm having trouble when I start it sometimes it will only Idle when I try to give it fuel it makes a slite try to rev up but it won't if I fluther the fuel pedal it slowly starts to rev up but when I let off the pedal and try to give it fuel again it won't rev up, before it would clear up and run fine for a while the fuel filter has been changed and the Orings are ok I thought I saw a few air bubbles in the fuel filter.
Disconnect outlet line at lift pump. Operate lift pump with manual primer lever, see if it puts out fuel flow. If not, disconnect inlet line at lift pump, blow back through line with compressed air to clear line of obstructions at fuel tank fitting. Be sure to take fuel cap off before doing this. When you hear air bubbling in fuel tank, reconnect inlet line to lift pump. Operate lift pump lever again until you get fuel flow. If you don't get flow, probably have a failed lift pump.
Thanks for the reply...
OK while I was checking what atco sugested, it was still doing the samething I started the machine I was on the left side were the fuel pump is I noticed behind the pump were the linkage is there's a small screw with a spring that ingauges the linkage to the pump the screw had backed out and the pump was not giving the motor fuel when I would pump the pedal it would catch a little and the motor would rev up so I'm guessing as the screw started to back out it started to get worst... it's going to snow tonight so I was stressing about not having the old JD not running right.
Well, that's good news.