| [GMCnet] Heat, pumps, and the gas tanks. [message #332380] |
Mon, 21 May 2018 16:17 |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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With our two coaches I found re-plumbing the fuel tanks helped a lot. By removing the tank selector valve and mounting two electric pumps outboard of the frame rails, one for each tank, you can plumb the gas lines to remain outboard the frame and around the front of the coach where it is relatively cooler before entering the carb, mechanical fuel pump, EFI surge tank or directly to the EFI fuel rail depending on the pressure of the pumps. You can use the the dash tank selector switch to flip a relay from the normally closed to the normally open posts on a five pin relay to select which electric pump you want to run. The fuel gage will still register the tanks individually. I always filled the tanks, ran 200 to 250 miles and filled again so was always pulling off of one tank. You can access around 40 to 42 gallons this way without switching tanks so the second fuel pump is just a backup. The fuel in the tanks will still get hot from radiated road heat but you can easily baffle between the exhaust pipe and the tanks to reduce that heat load. No need to cover or coat the tanks. I tried that and could see no difference.
The EFI guys will seldom have any vapor lock issues doing this and really none if they use a front mounted surge tank or they put the pumps inside the tanks. The carb guys are going to continue to have issues, although at a slower rate, simply due to the fact that the gas today is formulated to atomize when pressure fed through a fuel injector instead of drawn into the air stream via venturi effect inside the carb.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
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Message: 1
Date: Mon, 21 May 2018 10:05:17 -0600
From: Chris S.
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Heat, pumps, and the gas tanks.
Message-ID:
Content-Type: text/plain; charset="utf-8"
I was really close to installing the aluminum panels under the tanks as well. I'm not a fan of the high amount of pressure that builds up in the
tanks on hot days. This write-up was one that I found very interesting:
http://minniebiz.com/gmcmotorhome/2017/02/25/insulating-the-fuel-tanks/
I'm particularly interested in it due to the fact it seemed to help with the tank pressure issue that we see often.
I too have seen pics of the diamond plate aluminum, similar fashion to above, but cannot find it.
I researched reflective coatings, but did not find anything that seemed promising or proven to actually work. I found that some had tried to coat the
tanks with thermal coatings (including Jim B) but the conclusions seem to indicate it did not help.
I also tinkered with the idea of installing a deflector to direct the hot engine air down below the tanks but so far have not revisited. That would
be much easier to install but would probably not help the issue with road heat. We did install the side air vents from JimK to vent the engine box,
and so far I'm convinced those are well worth it. I figure getting any hot air out of that area can only help.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
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Jerry & Sharon Work
78 Royale
Kerby, OR
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