Pump on dual carbs.

[slowboatn]

Ok. I need to know how this thing works. I've got a 98' GTX Limited. it has the 947/951 engine. Have dual carbs. There is a pump on the PTO carb. It seems that it is working correctly but I'm real curious how it works. When I pull on the throttle it gets activated but won't return all the way back. If you know what I mean? There is a cam on the PTO that moves the arm on this pump. When the cam is back at no throttle the arm on this pump doesn't quite go all the way back out. Is this a problem? When it does move, I can hear air going into the carbs. So I put some gas in the lines and tried it and gas gets squirted into the carbs when I push the arm in. It just won't pop all the way back to the cam on the PTO carb. I appreciate all of the help. I'm trying to get this thing back together so we can run it soon. Thanks.

 

[Dr Honda]

If you give the pump arm a little push, will it go back more???? If it is mechanically stopping, then no... it is fine.

With an accelerator pump, you have a few tuning parameters. Pump timing, pump dwell, and pump volume. On the pump that is on some of the SeaDoo carbs... the pump timing is set with the physical length of the rivet on the pump diaphragm. So, there is a good chance that the pump arm will stop, and the throttle arm will continue to close.

The reason for this is... at idle, if you hit the throttle, you don't want raw fuel squirting in, until your engine has enough RPM to proses the fuel.



With all that said... if you can reach in, and push the arm back... then there may be some junk in it, and it may need cleaned. (but it's probably fine)

 

[slowboatn]

Ok. When I push it it will move the plunger. Then only come back out a little. Not all the way out. It is the arm. Thanks. Sorry it took me so long to get back to you.