50 hp merc dies at idle still repost after trying to fix need help

" 93 merc three cyl. tiller,

" 93 merc three cyl. tiller, LS, TT, oil injected. So far I have relaced every gas line and fitting from the tank(new) to the fuel pump. I saw air bubbles in the plasitc T right before the fuel pump that appeared to be coming from the fuel line not the oil sender. So I took the fuel line off at the cowling ( so that there was only fuel line to the fuel pump T, which was about 12" of line) and dropped it in a cup of gas, trying to eliminate any thing from there to the tank, same results air bubbles... idles down and dies...
I have a rebuilt kit for the fuel pump, but I replaced it 2 years ago. to no avail.

It has had this problem for some time, I troll with the motor and therefore it is at idle a bunch. If I take my had of the tiller handle, it drops RPMS and dies. If I pump the bulb it will continue to run or if I pump the tiller trottle handle by rotating to more gas a couple of times.

At HIgh RPM (WOT) right after I get on plane, the motor will occasionally die until the bulb is pumped then it will run fine forever at WOT.

Thanks in Advance! It has me stumped!

dan "

Check for fuel pump pressure

Check for fuel pump pressure 5-7 psi. Also check the connector to see if AIR is getting in and causing the air bubbles...thus leaning out the engine.

Check the alignment of the Throttle plates.

Generally if you have to pump the primer bulb to keep an engine running the fuel pump is the culperate.

Something to take note of. If you turn off the engine and let it sit for a few mins...do you have to pump the primer bulb to get it to restart..or activate the choke?

If any of these happen...dissassemble the fuel pump and check the MYLAR disks. One could be stuck open.

I doubt that the settings on the carb are out of whack..ie Low speed fuel jets as a quick sqeeze of the ball will not fix that.

It is also possible that you did not put the pump back together properly...or you could also have poor primary compression...the stroke that draws the fuel in and drives the pump. Just because you have adequate compression it does not mean you have the suction to operate at low speed.