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Mechanical Fuel Pump needs an overhaul
- Thread starter N941WR
- Start date
Bill,
I regret that I don't know of a rebuild kit source for you.
However, do you mind saying how your fuel pump is acting?
Just wondering what a potentially failing pump does?
Thanks,
Lorne
I wasn't able to find a rebuild kit either several months ago, but replacement was fairly simple. Mine had failed to a high-pressure state, putting out 6-8 or more psi sometimes. The new one is rock solid at 3 psi.
Chris
koupster
Well Known Member
Failure Modes?
Anyone here familiar with the failure modes on these mechanical pumps and their causes? Mine will put out 1.5 psi or 4 psi with no discernible pattern to the different pressure outputs.
Anyone have a junk one that could be dissected for the cause of greater system knowledge for the RV community?
Cheers, David
RV-6A O-360 A1A KBTF
Anyone here familiar with the failure modes on these mechanical pumps and their causes? Mine will put out 1.5 psi or 4 psi with no discernible pattern to the different pressure outputs.
Anyone have a junk one that could be dissected for the cause of greater system knowledge for the RV community?
Cheers, David
RV-6A O-360 A1A KBTF
I know I remember somebody here took one apart, but I can't find the thread in any of my searches. There is a really good video from Tempest that describes their operation:
https://www.youtube.com/watch?v=PYKoLUsTJU4
It seems that Tempest doesn't think that they can fail to high pressure, but my case is not the first I have heard of. The resulting overpressure caused carb issues and overflowing fuel.
Chris
https://www.youtube.com/watch?v=PYKoLUsTJU4
It seems that Tempest doesn't think that they can fail to high pressure, but my case is not the first I have heard of. The resulting overpressure caused carb issues and overflowing fuel.
Chris
N941WR
Legacy Member
Chris, I found your old posts and was hoping things might have changed since then.
As for the other comments, yes, I could buy a new or rebuilt one but I have two of them and they look to be an old Chevy style pump, which means dirt simple to rebuild, if you can get the parts.
koupster
Well Known Member
Chris,
Thanks for the link to the video. That helps.
The video shows that air leaks can cause a pressure drop. It shows the air bubbles coming in the inlet, but air could also get past the pulsator diaphragm, the fuel diaphragm, a porosity in the valve body, or a leak around the inlet fitting.
Here's the link to the disassembly thread that you helpfully mentioned:
http://www.vansairforce.com/community/showthread.php?t=73721&highlight=fuel+pump+disassembly
I'll be looking for air leaks to solve my fluctuating pressure.
Cheers, David
RV-6A O-360 A1A KBTF
Thanks for the link to the video. That helps.
The video shows that air leaks can cause a pressure drop. It shows the air bubbles coming in the inlet, but air could also get past the pulsator diaphragm, the fuel diaphragm, a porosity in the valve body, or a leak around the inlet fitting.
Here's the link to the disassembly thread that you helpfully mentioned:
http://www.vansairforce.com/community/showthread.php?t=73721&highlight=fuel+pump+disassembly
I'll be looking for air leaks to solve my fluctuating pressure.
Cheers, David
RV-6A O-360 A1A KBTF
rv7charlie
Well Known Member
Hi Bill,
I spoke with one of their tech guys several years ago, asking the same questions (primary reason for calling was to ask about mogas damage). He basically said that assembly required special jigging to properly tension the diaphragm; etc. He was very helpful in other areas, but on the subject of field overhauls, he was much more vague & said they wouldn't sell overhaul kits; we must do the overhaul/exchange thing with one of their vendors.
I think they look a lot like Chevy pumps, too. Have you considered just buying a Chevy pump to see if the parts fit?
Some of the stuff he told me about alcohol compatibility & upgrades to their materials due to the original materials no longer being available, made it sound suspiciously like auto components might be involved....Aren't you near Charlotte NC? You ought to just pay them a visit. They're not that far from you (somewhere near Burlington, IIRC), and the guy I spoke with said I could come and take a tour any time.
Charlie
cajunwings
Well Known Member
Fuel pumps
Just be careful out there. This is one of those components that needs to be as perfect & reliable as possible. I've built numerous engines including my own but will buy a new pump when the time comes.
Don Broussard
RV-9 Rebuild in Progress
Piper Pacer
Just be careful out there. This is one of those components that needs to be as perfect & reliable as possible. I've built numerous engines including my own but will buy a new pump when the time comes.
Don Broussard
RV-9 Rebuild in Progress
Piper Pacer
Hi Bill,
I spoke with one of their tech guys several years ago, asking the same questions (primary reason for calling was to ask about mogas damage). He basically said that assembly required special jigging to properly tension the diaphragm; etc. He was very helpful in other areas, but on the subject of field overhauls, he was much more vague & said they wouldn't sell overhaul kits; we must do the overhaul/exchange thing with one of their vendors.
I think they look a lot like Chevy pumps, too. Have you considered just buying a Chevy pump to see if the parts fit?
Aren't you near Charlotte NC? You ought to just pay them a visit. They're not that far from you (somewhere near Burlington, IIRC), and the guy I spoke with said I could come and take a tour any time.
Charlie
I would expect that. I thought the early Lycoming pumps were actually stamped with the AC logo. Before fuel injection, AC was the primary supplier of fuel pumps to US auto manufacturers. That said, I wouldn't be surprised to find that the unique dimensions and specs for the arm and it's movement to be unique to Lycoming.
Larry
Bill---call Don Rivera at AirFlow Performance. Bet he has the answer.
Tom
Tom
