Fuel pump diaphragm failures

[Cvijr]

Hello all, I have a 1968 seaking with a chrylser built montgomery wards outboard.

My question is this: what can cause multiple diaphragm failures? I installed a diaphragm 2 years ago when i first got the boat. Recently i experience another.

1)Can pressure buildup from tank connected over time cause the failure when the tank swells in the heat?

2)Can over squeezing a primer bulb cause it?

3) is there another possible cause?

Thanks in advance
Chuck

 

[roscoe]

a backfire can do it in an instant

 

[jerryjerry05]

Like Roscoe said a backfire could do it.
​The airscrew not set right can cause the backfire.

​The non vented tank could help split it.
Why isn't it left open?
The tank should be left full and in the shade of some sort.
​Over squeezing could contribute to the problem.
​Ethanol can hurt it too.
​Being as the diaphragm is on a 50 year old motor the parts might be OLD from the dealer?
I've seen using 2 diaphragms at one time. Might help? Might not?

 

[gm280]

I have to concur with the above suggestions. I would first open the tank vent for starters. Then no pressure builds up and applied to the fuel pump diaphragm.

And like jerryjerry05 stated above, probably the replacement diaphragms you are buying are vintage and not designed to handle Ethanol fuels offered today. So they get eaten up and not lasting as long. I would check to see if newer parts could be swapped in and solve that possible issue. JMHO

 

[Cvijr]

Thank you to all. I am new to the boating scene and left the fuel lines connected. It was after I discovered the split diaphragm that I recalled the swollen tank . Live, pay and learn. Thanks again.