70 Hp Evinrude fuel pump

[wrmdunker]

1974 70Hp Evinrude Model 40473M. I have been chasing an issue with rough idle. Good compression, spark and fuel. Carbs rebuilt.
Thought I might have a ruptured diaphragm in the fuel pump. If so, then the pulse line could draw fuel right into the crankcase and run rich. I also admit to the infrequent occasions when I did not vent the old style portable 6 gallon tanks with the thumd screw vent.
Pump was replaced on vacation in 2010 so not that old. Does this diaphragm look normal or is it stressed or degraded from Ethanol?








The pump is right for this motor according to the references I have. Got a rebuild kit for it and the diaphragm is clearly wrong.Top hole does not line up. Got a Sierra 18-7820. But now that I back reference that kit it does not list my motor. A local shop said there is no kit for that pump.




Should I replace the pump for $75? Did the "blow test" on it and no leaks from the outlet.

 

[racerone]

That diaphragm looks just fine.------What are your actual compression values.-----Checked reed valves ?---------Checked flywheel key ?.

 

[boobie]

The local shop was correct. BRP doesn't list a kit for it.

 

[wrmdunker]

Ok glad you think disphram looks fine. Compression is 132-133-125. I looked at the reeds as best I could when the carbs were off. Also did a "spit test" holding white cardboard in front of carbs and reving motor looking for blowback. Read this on iBoats.

Think flywheel key is OK. Had a mechanic look at the timer base for coil leaks last year. I stood there and watched him remove and replace the flywheel.

I have the idle set at 1200 rpm in a tank or it wont run.

Thanks boobie. Bought kit on Ebay from a marine dealer and clearly listed the kit would fit this pump and 4 others. What are you going to do........?????

 

[wrmdunker]

double post by me. hate these glitchs