The square fuel pump, pros and cons

[pcrussell50]

Beginning to wrap up readying a 2.4/200 for service. Going through pretty much everything.

Anyway it’s a late 1990 build and has the square fuel pump. I have two other motors in family both mid-eighties xr2’s.

Anyway, I plan to open it up and clean/inspect, re gasket. Any tricks or is it pretty straightforward. The manual has some check valves with a hokey sounding installation process. Do you have to change them with every servicing? Or just if they look leaky or damaged?

Also, what are the pros and cons? Are they better worse or about the same as the old “figure-eight” pumps?

Thoughts?

-Peter

[XstreamVking]

They are easy, just take your time and do it on a clean surface. Pay attention to the valves and how they are placed. Take it apart and place it in order to make it foolproof.

[pcrussell50]

They are easy, just take your time and do it on a clean surface. Pay attention to the valves and how they are placed. Take it apart and place it in order to make it foolproof.

would you classify them as more or less the same reliability as the figure-eights?

new diaphragm every couple of years/100 hours?

-Peter

[pcrussell50]

So, I changed only the gaskets and diaphragms.

The springs and plungers looked fine.

The check valves looked fine.

Is this what you guys do?

-Peter

[XstreamVking]

Old type dia. would blow if the engine sneezed. The new square ones are better to me. I usually go thru the whole thing and replace all the parts. You may get lucky with only gaskets.

[pcrussell50]

Old type dia. would blow if the engine sneezed. The new square ones are better to me. I usually go thru the whole thing and replace all the parts. You may get lucky with only gaskets.

I did gaskets AND new diaphragms. But I left all the hard parts (springs and the plastic discs all looked fine)

-Peter

[25two.stroke]

The check valves are the most common thing that goes bad in there. The plastic cups over time and then the check valves dont check. I always change them. Even if they look ok I change them. Many times I have an engine running out of gas at idle and I just change those check valves and the problem is solved. Did one yesterday and one on Tuesday.

[Dave S]

Most fun is doing it on the water.................

[25two.stroke]

Most fun is doing it on the water.................

Those damn plastic retainer pins lol
Can't imagine doing that on the water. They are sometimes difficult on land. Especially when its 100 and they just wanna bend over rather than slide in.