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Tankman

Fuel Check Valve

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20 hp Onan seems to lose prime.

Thinking, "Check valve in the fuel line."

Install valve before or after the fuel pump? Thoughts? :wacko:

 

Once Onan is running, no problems. Runs fine.

Edited by Tankman
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My 2000  314-8 does exactly the same thing.  I'm interested in opinions on this as well.

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Just now, cschannuth said:

314-8 does exactly the same thing

my 516h/1100  was doing this too . ( including surging )   Electric fuel pump solved the problem. Might not on yours tho....:twocents-02cents:

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1 minute ago, Jerry77 said:

my 516h/1100  was doing this too . ( including surging )   Electric fuel pump solved the problem. Might not on yours tho....:twocents-02cents:

 

Mine runs and re-starts fine after it starts.  But if it sits for a few weeks it takes a long time to start.

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1 hour ago, cschannuth said:

 

Mine runs and re-starts fine after it starts.  But if it sits for a few weeks it takes a long time to start.

Exactly. That's what is making me think "check valve".

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The check valve or shut off valve has to be before the pump to keep it primed.     A marine primer bulb also works.  They contain two check valves just like the fuel pump.

This is a common problem with the under the seat tractors.   If the tanks are kept full, the Kohler fuel pumps are below the pump and they stay primed.

The Onan pump is above the fuel level even with a full tank.

Edited by Ed Kennell
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I am an advocate for electric fuel pumps. Mount the pump low on the frame so the fuel will flow to it and be sure to put a fuse in the electrical line. You can power it from the ignition coil 12 volt feed on battery ignition tractors and use the accessory terminal of the ignition switch if your ignition system is magneto. 

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1 hour ago, 953 nut said:

Mount the pump low on the frame

I actually mounted mine on the Onan tin below the existing fuel pump..it is lower than the outlet of the fuel tank and works great.  :)

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Yup, common problem is right. I have the issue when my 2005 sits more than a couple days. I wasn’t concerned about it when we lived in Florida but here in Indiana I don’t want to be cranking it that long in the cold. I have the Command motor on it and the fuel pump mounted on the rear of the motor and at a height that basically would be sitting on top of the tank. Keeping the tank full really doesn’t help. I was Skyping with @stevasaurus and throwing some ideas at him. First, as an experiment, he suggested that i raise the rear of the tractor when parked so backed the tractor up on ramps. Geez, i never thought of that. After 8 days it did help but it didn’t totally eliminate the problem. A fuller tank probably would have helped more.  So, I think electric is the way to go but I’m thinking of a twist to it and this is a good thread to see what you guys think. The mechanical pump is very reliable and long lasting. I’m thinking use the electric pump just to ‘prime’ it then let the mechanical pump take over. My 2005 ignition switch is different than most. The first position is run and headlights on. The second is run only then the third is the momentary start. If I want the headlights on when running I turn the key back one notch. Now, I really don’t care for that and have intended to install a separate light switch for, well about 8 years now. :rolleyes: I’m thinking to go ahead and install a separate switch and then use that first position for the electric pump. Jump on the tractor, turn the key to the first position for a few seconds and then start as normal. Sorta like glow plugs on a diesel. I think the mechanical pump will be able to suck fuel through the electric pump when it’s not running but I’m not sure. Probably my best bet is to just try it but I’d like to get your thoughts on it.:)

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Sounds like it should work Bob.  I'm just not sure how much restriction the non-running electric pump will create.   The mechanical pump will have to work  harder to pull the fuel through  the two normally closed spring loaded check valves in the electric pump.

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Yea, I can feel the check valves when I blow through it and wondered that too. I think it's worth a shot. At least I'll have the pump installed and all I would have to do is change the wiring if it didn't work. Do you think there would be any issues with it pushing fuel to the mechanical pump? I'd rather not bypass it.

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If a check valve works with the mechanical fuel pump why bother with an electric fuel pump?

 

The check valve on my 20hp Onan solved my hard start issue (problem). :handgestures-thumbupright:

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