| Shut off valve for the onan [message #344419] |
Sat, 22 June 2019 14:49  |
Fipp
Messages: 26
Registered: December 2017
Location: Aledo, Illinois
Karma: -1
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Is it necessary to have a shut off valve prior to the fuel pump on the onan.
Scott
Scott D. Fippinger
Aledo, Illinois
1976 Royale
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| Re: Shut off valve for the onan [message #344420 is a reply to message #344419] |
Sat, 22 June 2019 14:50  |
rjw
Messages: 697
Registered: September 2005
Karma: 4
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Fipp wrote on Sat, 22 June 2019 15:49Is it necessary to have a shut off valve prior to the fuel pump on the onan.
Scott
A lot of people, including the PO of my GMC have removed them.
Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com
Roller Cam 455, TBI+EBL, 3.42 FD, 4 Bag, Macerator, Lenzi (brakes, vacuum system, front end stuff), Manny Tranny, vacuum step, Tankless + OEM water heaters.
[Updated on: Sat, 22 June 2019 14:50] Report message to a moderator |
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| Re: Shut off valve for the onan [message #344451 is a reply to message #344419] |
Sun, 23 June 2019 11:20 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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IIRC the Onan presenter engineer said that was a left over from the Onan engine in lawn tractor duty from whence it came. Some of those may have had higher mounted tanks. I have the audio recording of that on an old phone but it's over an hour long and not easy to listen to as it was in a cinder block fair building
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Shut off valve for the onan [message #344476 is a reply to message #344441] |
Mon, 24 June 2019 03:16 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Matt Colie wrote on Sun, 23 June 2019 07:03Fipp wrote on Sat, 22 June 2019 15:49Is it necessary to have a shut off valve prior to the fuel pump on the onan.
Scott
Scott,
I do not recall much other than it happened and was a good talk, but we once had a speaker at an international that had been part of the PowerDrawer program. When some asked about that valve that some of us do still have, he told us that GM was not the only buyer for these units and some had the fuel tank actually above the generator. As such, the full time pressure on the needle could make it leak.
Matt
You can have a similar problem only in reverse on GMCs that upfitted by someone other than GM. On some or all of those coaches, the onan fuel source was teed into the main engine suction line of the rear (main) tank.
He stopped by here one day and while visiting said, "I sometimes can not run on the main tank. I can only use the reserve." It threw us for a loop looking for things wrong. After about an hour he said, "If I start the Onan and shut if off again, then I can use the main tank for the main engine". It was in the failure mode when he got here because he always left it in reserve. So he demonstrated it to me and he was correct.
He did not have the shutoff valve on the Onan so I disconnected the gas line at the Onan and stuck a bolt in it to seal it. The main engine ran fine on the main tank. Then I removed the bolt and the engine main engine died with fuel starvation. Got it started again and reconnected that gas line and drained the Onan float bowl. Sure enough it failed. What was happening was when the needle valve was open in the Onan carb, the main engine fuel pump was sucking air through the Onan carb if the float valve was not closed and sealed. His fix when he got home was to find and reinstall a shut off valve in the Onan fuel line.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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