| Fuel Sending Switch and valve near tanks [message #285659] |
Sun, 23 August 2015 13:08  |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Probably depends on how the last person hooked it up but my sight of it looks like the lower one feeds the main tank. I got rained out while working out my problem but did discover that my fuel pump was sending gas to the carb much stronger (Pulsating stronger) when I ran a direct line into a gas container in front of the coach. Once I rehooked everything back to original my idling was worse and I stalled out again. My coach ran fine until I depleted the gas in the gas container. I got an idea from another member on line/phone discussion to bypass the switch/valve and see if the main tank would supply the gas needed by directly bypassing the valve. I couldn't get that far (rain). If the switch is properly installed the lower inlet looks like it goes to main tank. Also, I am slightly perplexed as to why there is so many fuel lines for each tank. Is one for the gas delivery and the other for the vapor cannister? Where two line T together to feed the second connection on the vapor cannister?? I obviously know one line goes directly to the carb (vapor line to cannister). Thanks gentlemen I feel like I might be getting somewhere NOW!
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: Fuel Sending Switch and valve near tanks [message #285668 is a reply to message #285666] |
Sun, 23 August 2015 16:38  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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budworks521 wrote on Sun, 23 August 2015 16:05Is that I told ya so Mr. Hamilton! LOL Sort of.
In communications problems there are a couple of processes for troubleshooting called the "expanding loop" and the "contracting loop".
The first means you start at one end and you loopback the closest device. If that works, you move out to the next device and loop it back. When you get to the one that doesn't work, that is your problem device. Contracting loop starts at the distant end.
When I said to gravity feed the carb, or feed it from a separate electric pump, it was to include only one questionable device (the carb).
So first gravity feed the carb, or feed if from a separate electric pump. If it runs, expand the system to include the system's fuel pump. If that works, add one tank by bypassing the selector valve and feed off the main tank. If that works...
What you did was skip a step and add another questionable device to the system. If it hadn't worked, you still wouldn't know, is it the carb, or the fuel pump? You were "lucky" in that the problem is farther upstream so it ran.
Now add ONE potential problem component at a time until you find the culprit.
[Updated on: Sun, 23 August 2015 16:41] Report message to a moderator |
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| Re: Fuel Sending Switch and valve near tanks [message #285802 is a reply to message #285659] |
Tue, 25 August 2015 06:41 |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Senior Member |
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Thanks for the post of pics.... maybe I can work on it today. Appreciate the help. I do have the new replacement switch/Valve and the OEM one is long gone. It looks like I'll try one line at a time starting off with the main tank. I'll just throw a splice line to connect the dots and bypass the valve and see if it is valve is stuck or dirty. Thanks again
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: Fuel Sending Switch and valve near tanks [message #285831 is a reply to message #285659] |
Tue, 25 August 2015 16:05 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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DCS rule - troubleshoot from the receive end - he sees the problem first.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Fuel Sending Switch and valve near tanks [message #285924 is a reply to message #285659] |
Wed, 26 August 2015 16:20 |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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Senior Member |
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Not sure what DCS means but upon deeper inspection of the switch and valve unit it is marked with a M high side and A bottom side. P in the middle. I ended up by passing the valve/switch and just spliced the two lines together (main tank). Same symptoms! I decided I would buy more gas and try filling the tanks more since the gauge now reads 1/4 tank on the main and empty on the aux. I also decided that I would try running the coach off a gas can in the back just after the switch and see if it runs better. That way I can isolate the issue to tanks or lines to the tanks or anything after the switch/valve. I don't see any obvious wear in the gas lines and the socks were replaced in 2006 and less that 3k miles on fuel system repairs from Cinnabar. ?? Always something... thanks for the help gentlemen
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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