HDS2155 Fuel Problems

[MowerMike]

Hey, you're expert enough for me! I know slightly less than 3/5 of nothing, and that seems to be just enough to get me IN trouble

[Ozcub]

I got all embarrassed when I read your post , I am just sorry i did not have my service manual ( it went with the HDS2155 I sold) when you first posted your problem

[kbhonline]

HI All
Brand new to the forum and after helping my friend with his HDS2155 and reading this post, I had to jump on it and see if I can get his issue resolved.

I'm reasonably handy with engines but haven't worked on this one before. He bought it used and it is in reasonably good shape, but it was clear it was not maintained regularly so we've done all the basics...new air filter, spark plug, oil, oil filter, fuel filter, fuel lines around the engine (from the tank is still original and I would leave that one to someone with a lift).
Same problem as Mike, it runs for about 30 mins great (great now that we changed out all the basic parts) and then just stops. The fuel filter is hardly full and after a bit it fills up again and he can run it again for a while.

I've blown air down the fuel line to the tank and can get bubbles in the tank with relative ease, and don't see any signs of any fuel leaks (or air) getting into the lines.

I took the fuel pump off and manually moved it and saw good fuel flow all the way to the carb. With the plug uncapped we even cranked the engine a few times and saw the pump pumping fuel to the carb.

I checked several times to make sure I have the pump installed correctly against the cam lobe (as I think it should be and by the image in the service manual), since Mike discovered he installed his wrong (I'm still having a hard time seeing how there could be 2 ways to install it, but he's helping me with that just so I know I'm sure I have it in the right way)

So my question is how do you know when your fuel pump needs replacement? If I had to guess the pump is original and the serial number shows the engine was built in 1999. My one theory in this situation is that the pump works at a slow speed, but when the pump arm is moving against the lobe at full speed, the action of the lobe is so fast, the pump cannot retract fast enough (due to its age) against the lobe to return to position for the next push from the lobe, thus the movement is limited and the pumping at high speed is minimal.

I'm determining this by when running the engine at full throttle and the blades engaged, I can see the fuel level drop in the fuel filter and watching the flow of fuel coming into the filter (the filter is made of clear plastic) is very slow, even at times it seems that air is coming in (which I doubt) or more likely there is back pressure somehow going back into the fuel filter and some of the air in the fuel filter pushes back down into the fuel line. This happens a few times in engine cycle, then I see a little drip of fuel come into the filter.

In all of this, when the engine does stop running after this happens, it seems the gravity feed of the fuel line fills up the fuel filter again fine, and he can then run it again fine for a while longer.

Oh and by the way, this happens the same with the gas cap tight or loose, or off, so I've ruled out a gas cap vent issue.

Thanks in advance for your help, all.

Kevin

[Sam Mac]

Change the line from the tank to the pump. They can collapse inside.