#1
IP: 69.123.242.143
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Mechanical Fuel Pump: Diaphragm issue
Experienced what seemed like a fuel-related shutdown this weekend an started trouble shooting. After some cranking (yes, thru-hull was closed ), I removed the flame arrester from the carb expecting to see some fuel puddled -- bone dry. Operating the priming bail on the fuel pump, I could hear fuel moving, but when I removed the main passage plug on the carb, it was dry. Replaced the plug, moved the the priming bail and gave it another shot -- started this time, but needed to keep rpms high -- figured I might be moving some crud through... Same thing again on Sunday. Removed the fuel pump this morning and found pieces the diaphragm coming off (and I'm sure ending up in the carb). Anyone seen this before (see pic)? Ethanol related? I just replaced the diaphragm 2 years ago.
Cleaned it all up, brought home the carb, tore it down and cleaned it with carb cleaner and compressed air. Hopefully case closed, but I was very surprised to find the debris I found (it was all from the textured center section of the diaphragm). |
#2
IP: 107.215.189.93
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I think the rubber corrosion is somewhat normal. This is why you must have a polishing filter BETWEEN the pump and the carb. If you have a polishing fiter maybe it has done its job and is now clogged.
dvd |
#3
IP: 24.152.131.153
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Now would be a good time to check the oil level for overfill and sniff it for gasoline fumes. Just sayin' . . .
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#4
IP: 76.122.168.101
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Quote:
__________________
Mike |
#5
IP: 69.123.242.143
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Part is from here as part of a mechanical pump rebuild kit (Product No. - FPMP_13_320).
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#6
IP: 69.123.242.143
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I have a polishing filter in place and just replaced it in April of this year (I write the date on them as I do my Racor). Hard to believe it's clogged given that the I've put maybe an hour on the engine so far this season.
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#7
IP: 69.123.242.143
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Quote:
Chris |
#8
IP: 24.152.131.153
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Sorry Chris, I figured I'd harped on it enough that . . .
The USCG has a specific requirement for diaphragm type fuel pumps for inboard gasoline engines that they do not leak fuel in the event of diaphragm failure. The way the requirement is met is to deliver errant fuel into the engine's crankcase thereby keeping it contained and not in the bilge. The two things I mentioned (elevated oil level and gasoline smell) are indicative of a breached fuel pump diaphragm. edit: I can't say if fuel was dumped into the crankcase but under the circumstances I think it merits checking.
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others Last edited by ndutton; 06-23-2014 at 10:22 PM. |
#9
IP: 69.123.242.143
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Quote:
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#10
IP: 142.136.107.234
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Bit o' hose
Those look like hose chunks cut out by barbs to me!
Dave Neptune |
#11
IP: 69.123.242.143
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No - they were all loose and coming off the textured center portion of the diaphragm. The largest piece was barely attached -- I rubbed with very little force and what came off is what's in the first photo. In this photo, you can see the rough edges around the perimeter of the textured portion of the diaphragm.
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#12
IP: 142.136.107.234
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Hmm
How old is that diaphragm? The diaphragm should not breakdown like that. Are you using any additives? The diaphragm looks like it sat in the sun for a while too.
If it is a very old diaphragm OK but if not what ate away at it? That's what we need to know. Save Neptune |
#13
IP: 69.123.242.143
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Quote:
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#14
IP: 161.213.49.150
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Betcha the rubber is not ethanol rated.
I sure would talk to MMI about this. Maybe soak the replacement diaphragm in a jar of gasoline for a while to see how it performs before you instal it? TRUE GRIT Last edited by JOHN COOKSON; 06-24-2014 at 12:34 PM. |
#15
IP: 71.118.13.238
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Old style perhaps
The diaphragm for these could sit in a warehouse for years before being sold. If they were built before the E in the gas they should be discarded however not all suppliers are goi8ng to toss them out.
Soaking for a while in gas may be a good check. I doubt the "diaphragm" itself is suspect but the rubber disc under the spring support could well be the offending party. Dave Neptune |
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