New pump not pumping to carb - why?

[fixitdad45]

Very first thing to check is the tubes at the pump.
Most people plumb them together wrong despite the fact that there are generally arrows cast into the pump.
The one on the circle is the impulse line it blows & sucks on the diaphragm the ones on the side are the fuel lines.
Usually the in line is the one nearest the the impulse line and the out line is the one furthest away
Look closely and you should see an arrow on the body or tube somewhere.

Blow & suck on the impulse line, it should only move a little bit both ways if the diaphragm is in a good condition.
With the other two, there is a one way valve inside the pum so you should be able to blow but not suck on the in tube and suck but not blow on the out tube.

See pic with current configuration. I tried swapping the lines that aren't running to the carb and got the same result - no fuel pumping.

I tried the blowing/sucking thing and the new pump worked as it was supposed to. The configuration I have it in now matches the way the diaphragms allow the air to move.

I did find a little gas in the fuel pump which means it may have worked a little bit at some point. It's still not moving fuel though and it's brand new.

Now what?

 

[BlazNT]

Remove pulse line and put finger over hole. Crank engine and see if you have a pulse.

 

[fixitdad45]

I disconnected the pulse line from the fuel pump, put my finger on the end of the pulse line and cranked the engine. I felt no real tugging and even that could have been the shaking of the engine. I put my top lip to the pulse line and thought I felt a little something but it definitely didn't feel like enough to suck fuel from a tank and shoot it into a carb.

Could I have a leak somewhere besides the valve cover gasket, which appears to be solid? Even if that cylinder isn't firing (I've no evidencenyet that it's not) it should still be building up positive and negative pressure when the piston moves, right?

 

[fixitdad45]

I took it a step further by disconnecting the pulse line from the fuel pump and putting a dab of grease on the end of the line, completely covering the hole. When I cranked the engine the grease didn't move at all. This tells me the engine isn't generating a pulse as it should be.

Another piece of information... when I got the mower there was a lot oily residue on the engine and the oil level was at the bottom of the dipstick. Could this mean that the engine has a leak in a gasket somewhere that's bad enough to disallow compression to build up?

 

[Don in Mystic]

I am not familiar with this specific model but will offer some general suggestions. Put the pre pump hose in a container and let some fuel out while removing the fill cap - deturmines a venting issue if fuel flow increased with cap off. Take the pump off and bench test it in a vise with a small can of gas and supply hose. Put some fuel into BOTH sides of the pump in case a check valve is hung up then re test. Don

 

[NorthBama]

have you check compression or did I miss that in a post

 

[BlazNT]

Possible problems are Head Gasket, Valve cover gasket(Just because its stuck on does not mean it is not broken in one spot), Valves out of adjustment, and sump gasket. I would start with valve cover gasket and while it is off adjust the valves.

One more thing I just thought of is hole in engine block.

 

[Don in Mystic]

Also re my post bench test you can replicate the vacuum pulse with a turkey baster and length if fuel line....

 

[fixitdad45]

Don - I've already verified fuel flow from the tank right up to the inlet of the fuel pump. It dribbles nicely with just gravity.

NorthBama - I haven't checked compression - I don't have the tool to do that.

BlazeNT - The things you suggest are beyond my capabilities so I'm probably going to cry uncle on this one and tell my friend to take the mower to a shop for further diagnosis.

Thanks very much for the help here guys, I really appreciate it. I was hoping for a quick fix on this one but it sounds like my friend is going to have to shell out some coin to get this fixed.

 

[Boobala]

I guess nobody told him to give it a shot of gas into the carb to see if it would attempt to run briefly....