Chasing demons, getting confused. Why would a pump do THIS?

[nj-boatbuilder57]

So here I am, back for more advice. The engine (in case you had forgotten) is a mash-up of a ’59 Gale Sovereign and a ’57 Golden Javelin.

With last week’s magneto plate error corrected, I’m happy to report that the engine is running quite well! I ran it all morning, went to do a load of laundry, and when I came back it wouldn’t run right. In the short time I was gone it went from running great to idling with sneezing & stalling.

Run…sneeze…stall.

It was more like it was running out of gas than too lean. Squeezing the priming bulb would get it to restart, but in short order it would sneeze & stall. And every time I repeated this, the bulb felt empty, like the pump hadn’t been sucking and the line was empty.

So I unscrewed the pump cover to discover that the diaphragm was bulging out of the little fuel window in the plastic plate. Disassembling the pump revealed that the diaphragm had "grown" 50% in size and torn itself apart.

What would cause this? I’m perplexed….

[dan-in-tn]

Welcome to ethanol! That is more than likely what irritated the old rubber. The newer rebuild kit should tolerate newer fuels better.

Dan in TN

[nj-boatbuilder57]

But it’s not old rubber.

This is a brand new pump with less that 1 hour on it….

[david-bartlett]

quote NJ-boatbuilder57:

But it’s not old rubber.

This is a brand new pump with less that 1 hour on it….

Brand new from where?

[nj-boatbuilder57]

…and that may be the crux of the issue.

An OEM pump from OMC is about $90. But, hey!….you can get the "same" on eBay for 20 bucks! See?…I "saved"…….

So now I’m thinking that I’m being kicked in the arse by "you get what you pay for", and if you all can confirm that, then I’ll buy an OMC pump & move on. Just as long as I know that a.) I didn’t do anything to cause this and b.) the engine didn’t do anything to cause this. If it’s simply a cheap pump, then I’m fine with that.

Is that the root-cause analysis?

[bill-loveland]

Not sure how available it is down your way, but I don’t buy anything for the boathouse or the barn that isn’t sold as "ethanol-free". And I always add fuel stabilizer to it at the point of purchase. Cheap insurance.

[jerry-ahrens]

I’ve had a couple of those ”cheap” fuel pumps on motors that have come through my shop this year. The diaprhagms are junk…. very thin compared to a good one. The check valves aren’t great either. Time to step up to OEM.
Maybe the old saying ”if it isn’t OMC Systematched it could be Mismatched” is still true? I would suspect ethanol or something in your fuel accelerated the failure. BTW, the two cheap fuel pumps that I replaced this year on a customers V6 were only 2 years old.

[nj-boatbuilder57]

Is the new, modern OMC-BRP 438556 pump ethanol-tolerant? Anyone know?

I can’t imagine it’s not…..it’s running in about a million engines world-wide. Anyone know?

[jerry-ahrens]

I would say yes. I haven’t had any trouble with the ones I’ve installed anyway. I’d say it should last a long time.

[billw]

I wonder if they have ethanol in China?

Long live American manufacturing!

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