onan marquis 5000 bgm gen shut off valve/gas pump

Discussion in 'Class A / Diesel Pushers' started by TOMBOMB, Jul 20, 2008.

  1. TOMBOMB

    TOMBOMB New Member

    Can anyone tell me if there is a way to check the fuel shut off valve and the fuel pump seperately after they're off the generator. also, instructions on how to check the voltage at the generator. thanks.
     
  2. Guest

    Guest Guest

    RE: onan marquis 5000 bgm gen shut off valve/gas pump

    welcome to the forums ,, what kinda probs are u haveing,, that makes u think the fuel pump is bad , or the valve???? also are u not getting any power form u'r set??? ;) :) :)
     
  3. TOMBOMB

    TOMBOMB New Member

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    730, thanks for the reply. i got all kinda probs! The onan marquis 5000 gen in a 96 bounder won't start. took off the fuel line just below the carb and filter and no gas when cranking. gas tank's full. oil level is good. put my hand on the fuel pump and couldn't feel or hear anything when cranking so took it out along with the shutoff valve. hooked it directly to a 12 volt battery and it made no sound/no spark-completely dead. wasn't sure if this was correct way to test it so i posted the above. then found a thread pretty much answering my question. hooked a meter to the pump wires on the gen and it is getting 12 volts when cranking. got a new onan fuel pump yesterday and put it on last night and cranked about 15 minutes and still no gas. :angry: the pump is working - at least i can feel and hear it thumping when cranking. put a new rubber line between the pump and the metal line goin to the tank. blew in it before before hooking it to the pump and could here bubbles in the tank. today after work will try to syphen gas thru the metal line to make sure gas will flow thru it. what do you think? is there something else i should do? thanks!!! any help would be appriciated.
     
  4. Pillaz

    Pillaz Senior Member

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    Do you have more than 1/4 tank of gas? On most models the fuel pick up is not on the bottom of the fuel tank tank. Most Generators will shut down (not draw gas) if you get below 1/3 -1/4 of a tank of gas. You said you blew bubbles so that may not be it but, its worth checking
     
  5. Pillaz

    Pillaz Senior Member

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    whoops sorry U said you had a full tank of gas. :(
     
  6. C Nash

    C Nash Senior Member

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    if the pump is running and still no fuel with the tank full you have to have a hose or pipe that is getting air between the pump and tank Does yours pump have a filter on the pump inlet? Mine has one of the ford type filters on the pump and carb inlet. You might try applying pressure to the filler cap at the tank to see if fuel will flow through the hose to the pump. have the hose off at the pump when doing this test. You can do this with a small air compresser by holding the air nozzle in the filler with a rag wraped around it. Do not apply a lot of pressure to the tank.
     
  7. TOMBOMB

    TOMBOMB New Member

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    last night i tried to syphen gas out thru the gen fuel line but couldn't get any. the line is 1/4" metal tube in fairly good shape. there are no splices as it's been bent and curved to follow the frame and rear axil to the top of the tank which has 1" clearance so there's no seeing or feeling beyond that point. is there a splice where it goes down into the tank? otherwise i don't see where it could be leaking. while crawling around the tank i noticed an extra gas inlet and air vent inlet with rubber caps (like the tank can be used with filler spouts on either side of the vehicle) so i bought some fuel line hose and tonight will route it to the extra air vent inlet to replace the metal fuel line. does anyone think there is any problem doing it this way? thanks for the input.
     
  8. C Nash

    C Nash Senior Member

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    Are you planning on this being a perment fix are just a test to ck the Gen? The air vent tube will not go to the bottom of the tank and the extra filler hole will be to large unless you are just planning on punching a hole in the rubber plug to run the hose through. I would not do it if I am understanding you. there is probably a rubber hose connection at the top of the tank or where the gen supply goes in the tank. if you are just testing the gen why not just run fron a extra gas container?
     
  9. Guest

    Guest Guest

    Re: onan marquis 5000 bgm gen shut off valve/gas pump

    there u go Nash ,, :approve: i think from what it sounds like ,, he might have either a stopped up line to the set or a plugged up sock in the tank ,, most tanks have the sock for the main fuel and one for the set ,, that way the really small stuff don't get to the main filter ,, i myself would blow back thru the line for the genset ,,, toward the tank ,, and listen for a pop in the main tank ,, that will mean the sock is stopped up ,, i know that now the sock is in the tank ,, but so what ,, just change the main ff for the set more offen ,, at least it might solve the prob :approve: :approve: :approve: :)
     
  10. barluis

    barluis New Member

    RE: onan marquis 5000 bgm gen shut off valve/gas pump

    We have an Onan 5000 in our motorhome. I would replace the fuel filter and also check closely at the line that feeds the fuel. It is possible to have a broken line and not know it.
    I would also avoid starting the engine for a long time. The gears on that starter are made of some kind of nylon and they will brake!
     

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