[raboley]

There was a discussion a while back around using a primer bulb to prime up an Onan to reduce the excessive startup times. I finally had a chance to put a check valve in and plan to wait about a week to start it.


http://www.usplastic.com/catalog/item.aspx?itemid=32233


http://www.wfmachines.com/discus/messages/335/270439.html?1388748527

 

[Hammerdown-7]

Hello Richard
I am Not a fan of plastic part's that come in contact with gasoline but perhaps' the plastic used in those check valves is made of material that will not be harmed by gasoline over long period's of time ? I have a similar check Valve in my gas line of my 318. I used a Metal PCV valve the style that goes into an older Vintage Car or truck valve cover. It was only a couple of buck's and will not allow the fuel to drain back as they only work one way as well. Regards, Kurt

 

[mikeduwe]

Fuel filters, fuel tanks, fuel pumps, fitting in carburetors etc on todays engines are all plastic. Just need the right type, a blanket statement that plastic is not a good option is not true.

And being carbureted, even if the fuel leeches some stuff from the plastic with the big hole sizes in a carb it will likely just go right through the system.

Looking at the link above, Viton should be good for ethanol fuel. Dont know how the plastics listed like fuel.

The 0.5 psi cracking pressure could cause problems though as the pump need to overcome that with its vacuum, should be interesting to see hoe it works.

 

[akaothermick]

Question? do the Onan fuel pumps have no reverse flow check valve in them making an additional check valve necessary? or does the fuel pickup strainer have one built in also? Thanks,
Mick

 

[knottyrope]

fuel pump is a check valve but it will seep by with the low pressure isn't enough to keep it closed and that goes for the tank check valve too.

Carb is only like a foot higher than the tank.

2.3 feet of head is 1 PSI, so by math its less than .4 PSI to keep the check valve checked and only a small tiny piece of dirt will keep the check valve from closing fully.

best to use a squeeze bulb primer like they do on boats and ebay has em for less than 10 bucks

 

[bo2009]

So, --- asked this question 12/31/13 (no answer): where to actually install\put the primer bulb? Bobo

 

[mikeduwe]

Or go electric pump so you don't need open the hood to start.

Have to find one thats 1-2 PSI, NO more.

 

[dave_thompson]

I'm with you Knotty as I have pinched the fuel line at the carb and let sit overnight and that didn't help. The carb itself leaks down a little. I think the squeeze bulb would probably be the best answer. Dave

 

[boomers_influence]

club
my onan manuals call for 1.7 PSI MINIMUM
fuel pressure.
thank you. boomer

 

[Hammerdown-7]

Hello Guy's
It is sometimes good practice to take the factory Onan fuel pump apart to clean it. They do get crud built up in the port's of them. I use Gum-Out carburetor cleaner to flush mine and gently apply compressed air to blow it out with. When you disassemble your Onan fuel pump Be careful not to damage the rubber diaphragm inside of them. Since the Pulse vacuum is low on these Onan's it is not hard to have starving fuel issues with the pump once they get crud in them. I elected to go with two clear see through gas filter's in my 318 fuel system. I have one before it hit's the fuel pump and another in the line that feed's the carburetor and it does not effect the cold or hot starting of my Onan nor the engine's over all performance. It is normal to see the gas filter's only half full or a little less when operating the engine, that is just how it work out. I located both of the see through Gas filter's on my inboard engine side of the fire wall area out in the open they are very easy to see or check on and now my chance of getting any trash from the gas tank into my carburetor is zero, I don't enjoy taking my Carburetor apart to clean it



By placing Twin filter's I also eliminated any further issue's of plugging up my idle jet tube holes.I Put all new fuel lines on my Tractor and eliminated the Internal gas tank filter as it is not easy to check or get to & shortly after I changed out the fuel lines I had to spend Three Very frustrating days chasing a Plugged idle jet tube and drove Poor Robert Kummer who is the forum Onan Expert known as Boomer Nut's with phone calls chasing this problem. It turned out to be the Main hole down through the idle jet that was plugged solid making the engine surge wildly and not run without the choke being fully on The metal PCV valve that I placed is in the main gas line under the floor pan that can be gotten to from underneath the tractor should I ever have trouble with it. Placing the PCV Valve in my main gas line has cured the fuel drain back issue that I was having. I am Not a fan of electric fuel pump's they put out much too much pressure and will eventually wear down the small rubber tip of the float needle valve where it seat's and will cause the carburetor to boil over flooding it, Plus if there is very a Punctured or ruptured fuel line there is a chance of burning down the Tractor before the leak get's noticed with the Pulse line if it looses vacuum from a gas line leak or rupture your tractor engine will simply quit. I hope this helps, Kurt

 

[jw332]

Hello
Got a tip about the fuel pumps.
My wife's 318 went bad and was not feeling the extra cost with some of the other pumps put there.
Looked around and it was right in front of me !
My Gravely hydro walk behind has a 15 hp Kawasaki twin and has a pulse pump on it.
For $ 15.00 dollars a new pump ,a small shop made bracket and some new hoses and clamps and a new fuel filter while everything was apart
Done and just a few turns of the crank ,fires right up.
Wife is Happy ! Works great for me
Thanks - JW

 

[Hammerdown-7]

Hello James
I ran a Briggs & Stratton made fuel pump on my 1983 John Deere 318 until I could get a replacement Onan fuel pump. it worked fine but there is no way to take it apart for cleaning it or to replace any part's so that is why I went back with the Onan factory fuel Pump that I bought from forum Onan Expert Boomer, as it can be disassembled and cleaned should I need to in the future. Regards, Kurt

 

[knottyrope]

"So, --- asked this question 12/31/13 (no answer): where to actually install\put the primer bulb? Bobo"

Put it inline any where you want that wont rub and you can access

 

[dan_hosler]

I, too, have had this problem on my 420 repowered with a new 23 B&S Vanguard. Even though we have different engines, our problems are probably very similar. It always takes about 10 seconds of cranking before fuel hits and engine starts. I have tried a few things in my attempts at an improvement:

1. I have tried turning off the fuel valve after after shutting down the engine. That doesn't help at all.

2. I replaced all the fuel lines, gas tank grommets, gas tank pickups, and fuel filter. The entire fuel system is new. This, too, has not helped starting performance.

3. I have tried to keep the hood open after shutting down to quicken cooling and lessen gasoline evaporation. That doesn't help either.

Just recently, I bought a marine-grade squeeze bulb with internal check valve. While spacing is tight, it's installed under the battery tray. I know an optimal mounting attitude is vertical for the internal check valve to prevent backstreaming over time, but there wasn't room for mounting in that position. Nonetheless, it can push fuel up to the carb after 2 or 3 squeezes. I can hear fuel move, and the bulb hardens after those 2 or 3 squeezes.

Guess what - this doesn't work either. Starting still takes the exact amount of cranking time as before. In my opinion, the fuel primer bulb didn't help a bit in my application.

Perhaps you will have better luck than I. I would be interested to know if your check valve eliminates your hard starting problems.

 

[knottyrope]

Dan you might have that solenoid on bottom of carb bowl which prevents you from priming it unless the engine is cranking.

or

maybe you need to turn on the ign key and prime it

 

[raboley]

OK, I couldn't wait any longer so I went and tried starting the 318 with the check valve. And....cranking...more cranking...lot more cranking...extra cranking...vroom. So didn't solve anything. I only put it BEFORE the fuel pump, so I will try another location as well. Glad I bought a few

 

[akaothermick]

Richard, possibly your float level is too low, that could effect starting,

 

[torino]

I also wonder if something else is going on. I have read where others have had success using a check valve. I installed an electric pump on my 318 and the engine starts right up.