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Ok fuel system is pretty easy, you have the two pickup lines in the tank, they go to the fuel switch on the left pedestal, that line goes to the fuel pump. The other line you can see goes to the carb. The line you cannot see is is the vacuum line on the backside of the fuel pump and goes to the crankcase, this is where the pulse is gotten to pump fuel. So if there is a hole in that line you won't get any fuel. I highly recommend that you replace any original fuel and vacuum lines first. Start with the pickup lines in the tank and work your way forward!
 

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ams
if the flywheel is bad, about 425.00 ( new prices )
the ring gear about 65.00. (cummins/ onan list )
IF you purchase the SAME parts from J.D. expect to add at least 35/45 %
for the SAME part????
thank you boomer ( the used onan engine parts guy )
 

· Three of my friends
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Why I asked about the engine is a p218g model bolts on the side of the engine frome the front ( mine did) and you cant go farther back with the starter.it must have been hitting the flywheels just enough when it was new to work foe a while.like pa318 said the fuel is simple.
 

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As I posted many times before;;; Here goes. 318 starter;; Sometimes the boss on the engine block get worn or out of shape by tightening the starter mounting Bolts.. . If you do this step by step . your starter will sound sweet and will out last you/and the machine;;With the engine out of the tractor. I lay it with the flywheel UP... Measure the distance From the starter boss on the block to the flywheel teeth;;; LOG that demention for future Use also The Back of the flywheel teeth. It may be 3/8". ;;; Now take your starter Measure the distance from the threaded bosses on the starter to the bendix. In /in state; Now take the starter (I disconnect the wire that spins the starter) Engage it so the Bendix kicks out, Measure that distance... That distance is changed by removing/replacing shime between the starter and the Solenoid . Now you can determaind how much you will have to shim the starter . I have made up the 1/4 moon shims in.025 .062 .125 . I shim it so the Bendix is about .030 away form the flywheel, And when the bendix is engaged it goes through the teeth on the flywheel. With t6he bolts snug I use a wooden block to adjut the Bindix at a true 90 Deg to the flywheel.... Now as starters. Weather you buy one for$69.00 or $485.00 Your choice. But remember the $69.00 is a high speed starter with a gear reduction. Basicly NOT rebuildable. My words of advice;; When you go to buy a tractor and they have a box of parts they will give you.. Run don't away.. (drive fast) Don't buy someone alse is problems;;;
 

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Discussion Starter · #46 ·
Ok, i've got the starter working good enough for now. Might need some fine tuning later. But i want to get this thing running. So again, it seems to be the fuel not getting through. I'm going to start replacing lines. However, is there any other things i should be looking for. That solution just seems to simple for me. Is there a filter on the lines in the fuel tank i should be looking at? Can the fuel pump go bad? Is there anything that can go wrong in the crankcase that i should look for? Also, is there a way to test the main tank, reserve tank, no fuel switch? It's definantly not creating a vacuum because we tried to get it started by pouring a little fuel in the carb, and it wants to start, but its just running out of fuel.
 

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Does your 318 have a B or a P Onan?
I have a Onan service manual from Gravely for the B series if you are interested.
Onan parts are crazy expensive now here in Canada since Cummins took over.
I ended up scrapping my old faithful Sears GT18 ( it had a B48), when it needed a lot of rejuvenating at 3000hours, because of that.
 

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Ok, i've got the starter working good enough for now. Might need some fine tuning later. But i want to get this thing running. So again, it seems to be the fuel not getting through. I'm going to start replacing lines. However, is there any other things i should be looking for. That solution just seems to simple for me. Is there a filter on the lines in the fuel tank i should be looking at? Can the fuel pump go bad? Is there anything that can go wrong in the crankcase that i should look for? Also, is there a way to test the main tank, reserve tank, no fuel switch? It's definantly not creating a vacuum because we tried to get it started by pouring a little fuel in the carb, and it wants to start, but its just running out of fuel.

There is only a screen on the end of each pickup line (one for main and one for reserve) in the tank. The fuel pump can go bad but so can the line to the rear where it gets the pulse from the crankcase. To bypass your fuel system you need to run a fuel line from the carb to a container of gas and hold it above the carb. If it runs then you know the lines or fuel pump are bad.
 

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The fuel pump on my B48 crapped out at 1400hours run-time when the neoprene diaphragm ruptured. It took me a long time to find the problem. I made a new one out of nylon reinforced silicone rubber sheet which lasted until the Onan's BIG END OF LIFE POOF.

By the way, that Onan manual is a PDF but too big (2.5M) to attach here.
 

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Discussion Starter · #51 ·
Sorry again, another long time with no post. Have gotten some work done though. I have determined it is not a vacuum issue. Put a funnel in a fuel line straight to the carb. Still doesn't want to start. However, while cranking over again and again, eventually got fuel coming out of the fuel filter. So at least i know its not fuel. now, im pretty clueless where to go from here. The next thing i guess i was going to try was taking apart and cleaning the carb. Spark plugs seem ok, but im going to replace those anyway. Is there any other suggestions? i might try to post a you tube video of trying to start it if you think that would help.
 

· Three of my friends
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Had to go back and see what model you have and you said 218 so there are no points so you need to take the top off the carb and clean it out good and remove the idle jet and make sure there is a hole ALL the way through the jet.replace the plug wires AND plugs,these motors start really good when all is well
 

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OK AMS4LIFE, I'm still assuming that your Onan is a B series and your fuel pump is on the carburetor run by pressure pulses from the crankcase.
Remembering my woes, that pump is not very strong even when new and a bit of icing in the fuel filter (screen) would give grief. As the machine ages and the fuel line rubber dries out little cracks develop and the connections at the fittings is no longer as tight. All this can add up to the pump sucking air instead of gas. Of course, if the diaphragm in the pump is also as old, it can have some unseen pin holes which further diminish its effectiveness. Try a bit of vacuum on the hose when disconnected from the the crankcase and see if you get some fuel coming through the diaphragm.

P.S. That PDF of the Onan "B" manual is still available and waiting only for an email address to go to.
 

· Three of my friends
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Should have said P218 engine.
 

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Discussion Starter · #57 ·
well, got good news! She's running again. Although i do need a new starter. I want to THANK everyone who helped me out. I learned alot about this machine from you. now my last question would be this, wheres a good place to go for maintenance parts? oil filters, air filters etc.? any good websites out there? and any opinion on aftermarket vs. john deere parts? ive almost always gone with aftermarket parts for anything fix up. John deere parts just seem so ridiculously expensive that the aftermarket parts seem to be the better option even if they aren't as good. any advice? any parts websites out there?
 

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Discussion Starter · #60 ·
To be honest, we are not totally sure. I think the big factor was new plugs. We tested for spark initially with both plugs and got spark. However, i think the spark must have been weak because that was really the only thing that we changed. However, the starter cashed out so its still not running for sure. The starter might have been part of the problem too, but we had that tested at an auto parts store and that passed too. So hopefully when someone types in "won't start" and sees this, the one piece of advice i can give is replace the plugs, even if you get spark! for a couple bucks, it's worth it even if it is not the problem.
 
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