I have a john deere LT160 mower. I replaced the fuel pump but it does not seem to be pumping as I crank the engine. It acts as though the actuator arm on the pump is not engaging inside the engine. I have tried to find exploded views of the engine with no luck. What drives the pump? Is it the cam shaft, the balancer shaft, or something else? I hate to tear into the engine if I don't have to. Any help would be greatly appreciated.

Hi,
It is the camshaft that runs the fuel pump. Most come with a short sheet (note) extolling the care that must be taken to get the actuating lever on the correct side of the cam. If you feel confident that you have done that, then look for a fuel line with a hole in it, a fuel line unplugged from the pickup or a bad pickup in the tank. Unhooking the line from the carb should yield a strong pulsing of fuel as the engine is spun over. Assuming a healthy pump, the only conclusion for that existing is that the fuel is not picked up by the pump.
Peace,
Clarke

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Thanks so much for the help! I'll check to see if its sucking air through some fuel-line leak. How do I make sure I'm on the correct side of the cam??

Keith

Hi,
If I remember correctly, the curved actuator arm angles toward the rear of the machine so that the proper way would be to both angle the pump to keep the arm rearward. The cam should be forward of the arm and a lobe on the cam should push on the arm. If mounted wrong, it will mangle the arm in such a way as to be unmistakeable.
Once it is verified to be correct, you can fairly easily remove the tank. Two 13mm wrenches or like will remove the bolts and nuts. Two are beneath the rear of the tank and one is beneath the side with the filler cap. It is possible to remove the bolts, the cap and drop the tank downward and very slightly rearward to access the fuel line and clamp on the top of the tank with a long pair of pliers to disconnect it. If not too full, you can slip the tank out with little or no spillage.
Everything can be checked by blowing into/through them. Tank - mouth/face to filler opening to see if something comes out the place where the line attaches. Fuel line - disconnect near engine and do the same; check it unobstructed and have someone reach beneath the seat area and place their thumb over the end of the line. If it is the culprit, you will be able to blow either way. My guess is that something has harmed or pinched the line, rare but I have seen it and it can be innervating.
Peace,
Clarke

Thanks so very much, Clarke. I'll look her over again and get back to you with what I find.

Turns out the problem WAS inside the engine. The actuator arm on the pump was no longer being driven by the engine. A local shop repaired it for $150. For that price, I wasn't going to lose a whole weekend tearing into the engine. So for now, problem solved.