Fuel pump trouble ? need some help

[gunnerb17]

Jeep was running good-Then it just wont start one day.Did some checking on normal items.Ignition,Compression-All ok.Got to fuel pump and it wasnt pumping any fuel.Removed fuel pump(orginal type later style with the priming lever).Disassembled pump and put back together -----It pumps fuel real good when clamped in vise on bench.I installed back on engine and it still doesnt pump.Used suction gun and pulled fuel from gas tank through fuel line to pump no trouble.I had the priming lever pushed down which I believe is correct.I need some help,ideas,etc ------Iam missing something but I dont know what.Thanks in advance

[OKCM38CDN]

Going to ask, what size spacer under the fuel pump where it bolts to the block? To my understanding needs to be a certain size (thickness) depending on if Military or civilian. If not the correct size pump does not work properly... Something to look at...

Sorry cannot remember the correct size. but 9/16" comes to mind...

Hope this helps...

[wesk]

If the pump passed a thorough inspection using the manual TM 9-1828A and you have not altered or switched the spacer that was between it and the engine then I would check the drive cam on the front end of the cam shaft.

[gunnerb17]

Thanks Hal and Wes for fast reply.Yes I have the correct spacer somewhere 1/2 inch plus thick. Wes Thanks for great pictures of the fuel pump drive cam.This could very well be the problem and also the most work to repair.I dont know how common it is for it too wear that much but there isnt much else left.Just my luck//////Believe I will try to make a fixture to see how much movement I have .thanks again for the help.

[wesk]

Just remove the pump and attach a dial indicator to the pump mounting pad and let it's plunger ride on that lobe of the cam. Rotate the engine to determine total lift available at the lobe.