mf 135 diesel lift pump replacement problems

Bigd7400 · May 12, 2012

I just replaced both fuel filters and the lift pump on my 64 mf 135 and now i can not get any fuel flow past the lift pump. When i cut the fuel on at the petcock on the tank i got fuel in the sediment bowl but no matter how long i pump th primer lever nothing reaches the fuel filters. Actually nothing is even coming out of the output of the pump because i removed the outlet line complety and pumpex the le er and not a drop. Please help if you can and i really appreciate any advice.

Bigd7400 · May 12, 2012

One question i forgot about that may seem stupid. When installing the lift pump there is a U shaped actuating rod that goes into the engine block and i assume is moved by the cam shaft. Does that U shaped peice just rest against the cam or does it need to fit under it where it would kind of cup it n the bend? I know its a stupid queation but while i'm sitting here thinking about it i may have figured out my problem cause i dont think i got it under the cam if thats where it goes.

Dieseltech · May 12, 2012

I think actuating lever goes on top of cam, look at old lift pump cam wear pattern on lever to be sure. Some hand primer levers will not work if engine cam lobe is holding lever up, turn engine crankshaft 1 turn will move cam lobe away from lever, then see if hand lever will stroke pump diaphragm. Should get fuel at outlet if pump is working OK.

banjodunn · May 12, 2012

G'day lever sits on top of cam not under ,and as dieseltech suggested roll the engine over 180deg as sometimes when the pump is on the high part of the lobe you can't stroke it with the hand lever.

Jon

Bigd7400 · May 13, 2012

Thank you guys so much! You were 100% right about the cam positioning causing the problem. What i actually did was loosen the nuts holding the pump on so i could pull it away from the cam and luckily i had enough slack in the fuel lines to do it that way but once off the cam within a couple pumps fuel was.flowing beatifuly. I went ahead and primed the system withthe pump loose like that with no apparent problems. Thanks for all the help it is greatly appreciated!