312-8 won't start

[ScottR 5]

I'm new to this forum. Bought a 1995 312-8 two weeks ago.  Used it once, then decided to change all the fluids, plug, lube job. The intake to the fuel pump was lose so I tightened that. 

 

Now the engine won't start, just cranks. It has good spark.  There is gas to the fuel pump, but with the line to the carb disconnected I don't see any gas coming out of the pump when I crank the starter.  This is the limit of my small engine knowledge.  Any ideas? 

 

Thank you,

ScottR

 

[Martin 2,131]

either you have an airlock, the line is blocked from tightening it or the pump is no good. since it already has run, i would be leaning towards the first two, especially the airlock. pressurize the gas tank and see if that makes any difference. i wouldnt recommend it, but i do it all the time, rag on the gas tank, stick your mouth down there and blow. or you could use a plumbers plunger on it. i didnt tell you to do the mouth thing though, so thats up to you......

any time you mess with gas lines you run the risk of introducing air into the system.

dont discount the possibility that the pump has crapped out too. but i would work on making sure there is no air in the system first. you need to keep pressurizing until you hear gas going into the carb bowl.....

[ScottR 5]

I figured I did something stupid. I'll try pressurizing the tank tomorrow.  I'm sure the line isn't blocked.

 

Thank you.

[ScottR 5]

One other question.  Can you confirm whether this model is supposed to have an in-line fuel filter?  The manual only mentions a filter on the 416 and shows the gas line running above the fly wheel.  This unit has a fuel filter (which I replaced and operated the unit after replacement) and the fuel line runs below the fly wheel. 

 

Thank you.

[Martin 2,131]

Most people run a filter even if the tractor originally didn't come with one. Cheap insurance, just in case you get some junk in the gas.........

Sent from my iPhone using Tapatalk

[ScottR 5]

Martin,

 

The toilet plunger did the trick.  I haven't used it since the kids moved out, glad it still has a purpose. 

 

Changed out the fuel line and installed a Kohler fuel filter while I was at it.  Now I can get after my overgrown field.

 

Thanks for your sound advice,

 

Scott

[ScottR 5]

Well, took it out to mow today, mowed about 40 feet and it quit.  Wouldn't restart.  Checked for spark, that's good.  Pulled the air filter and it's soaked in gas. Cranked the starter and watched gas blow out of the carb bore.  No leaks to or from the fuel pump.  Any ideas on what's wrong now?  I have not touched any of the carb adjustments.

 

Thanks for any help.

 

ScottR

[ScottR 5]

Update - After letting it sit for about 30 minutes and letting the air filter dry out, I got out the Kohler Magnum M12 manual and adjusted the needle settings on the carb, Let it idle for 5 minutes and did the final adjustment and everything was fine.  Started mowing with it and it ran well for about 3-4 minutes and then the high speed idle started fluctuating and eventually it flooded out.  Same condition as before.  Hope someone has some ideas.

 

Thanks.

[953 nut 55,046]

   My guess would be that some trash had been holding a check valve in the fuel pump open and the old plunger trick disloged it and now it is moving around near the needle seat, may need to pull the float and needle valve and remove the carb fuel line, and blow some carb cleaner in the needle seat and then the fuel inlet. IMHO Seafoam is the best carb cleaner, but use what you have if you have some on the shelf.  Good luck and keep us informed.

 

 

 

[ScottR 5]

After my last post I played with the carb adjustments again and the engine ran fine while I mowed for about 30 minutes.  Your idea about the floating trash makes sense, I'll try it if and when I have more trouble. 

 

Thank you.

[ScottR 5]

Ok, time to try the SeaFoam.  I've had to use the plunger again to get it running and when I shut it off and try to restart it won't start.  Knowing nothing about carberators, I'm not sure what's meant by pulling the float and needle valve.  This is a Walbro WHG carb with adjustable lo and high idle jets.  I can't find a parts diagram. I assume I unscrew the bowl and can then remove the float.  How does the needle valve come out?

[pfrederi 17,646]

It will fall out when you remove the float

[ScottR 5]

I removed the carb bowl, float and needle valve.  The bowl had a fair amount of black junk in it, but the needle valve and float are in good shape.  Sprayed SeaFoam up through the needle seat and the fuel inlet, cleaned the bowl and reassembled.  I had to pressurize the tank again to get it started.  Seemed to run ok, I only ran it for about 5 minutes and not under load.  This morning I went to start it up and I have the same old problem.  No fuel coming out of the fuel pump.  Had  to pressurize the tank again to start the engine.

 

Do I have a bad fuel pump?  Is there anything else I need to look at?  The fuel filter was filled with gas before I pressurized the tank, there is very little in it when the engine is running. Does fuel line inside diameter make a difference?  The lines that were on it before I replaced them have a 516" ID, outside diameter is almost 9/16"  The replacement lines Toro sold to me are 1/4" ID and are a little over 3/8" OD.  The fuel line runs under they flywheel and up to the fuel pump, is this the right way to run it? 

 

I appreciate any advice.

 

Scott

 

 

[gwest_ca-(File Mod) 11,031]

Mine does the same thing but found if I give it about 3 short cranking periods with a pause inbetween it will start on the 4th crank. Steady cranking it takes forever and hard on the starter.

 

Another thing to check - remove the air filter and see if the choke is fully closed with the knob pulled all they way out. It is possible the cable is adjusted so it will not fully close. When you get that make sure it is fully open with the knob pushed in.

 

Garry

[ScottR 5]

The culprit was a bad fuel pump.  Bit the bullet for a new Kohler pump and all is well.  Thanks for all the advice.

 

Scott

[DoctorHfuhruhurr 137]

At least you know the fuel system and carb are cleaned out now too.  The black gunk in the bowl would have given you grief eventually so that's one less thing.  I clean out the bowl every spring and maybe once during the summer.  Even with a fuel filter in line I seem to get "stuff" in the bowl over time that will eventually cause it not to start.  I like to add some Seafoam to the gas also.  You'll fine lots of threads on that.  

[ScottR 5]

Adding Seafoam to the tank was one of the things I did before replacing the fuel pump. Now to find somewhere that sells gas with 10% or less ethanol. Hard to find here in corn country. 

[Martin 2,131]

Sort of lost track of your thread here, glad you got it sorted finally.

There are ethanol free gas stations in the corn belt, search for www.puregas.org I think and enter your location .

Edited August 19, 2013 by Martin

[953 nut 55,046]

   Glad to hear you whipped the problems.

 

Try buyrealgas.com to find ehanol free gas. It costs about $ .35 a gallon more, but not having to add anything to it makes it about the same.   

 

 

 

Edited August 20, 2013 by 953 nut

[ScottR 5]

Great info guys; looks like there is a station near me.  I'll be heading over there tonight.  Thanks for the links!

[ScottR 5]

Well, sad to say I'm still having problems with this 1995 M12 and looking for advice as to whether I should rebuild the carb or look elsewhere for the problem. The carb is a Walbro WHG, marked 71-3424.

 

Previous symptoms, surging and missing.  Adjusting the high speed jet would usually sovle the problem temporarily but it would always come back. Two days ago, I pulled the carb bowl, fuel line, inlet needle and the adjusting needles and sprayed the carb liberally with cleaner and blew out with compressed air.  After doing this the surging and missing went away but the engine wants to stall when I hit a particularly bumpy spot or turn on a bank (I use it to mow a field and fence line, it's pretty rough in some spots).

 

The fuel pump, lines, filter, air filer and spark plug are new. I use ethanol free fuel and Sea Foam.  The tank is clean.  Any ideas?

 

Thanks all.

 

Scott

[posifour11 723]

Is the float adjusted properly?

[bitten 134]

Scott

I would rebuild the carb if it was me, just to make sure.  Its really not to hard to do. I use Berryman carb dip. Remove the carb take everything apart put in the dip for the recommended time remove clean when you think you have it cleaned do it again to make sure.assemble and go.

Good Luck.. 

[ScottR 5]

I'm not sure about the float.  Everything I know about small engines has come from surfing the web after I bought the WH.  My understanding is that I'd have to pull the carb and flip it over to determine if the float is sitting level, correct?

 

On the rebuild, the kits I see for the WHG look like they have have an o-ring for the bowl, gasket for the nut that mounts the bowl, an enging mounting gasket, two welch plugs, inlet needle and clip and what I guess are high and low idle inlet seats. Is this all I need?

 

Thanks guys.

[Fordiesel69 259]

Scott, now that you did all that, is the air filter still getting soaked?  When the engine wants to stall is it running out of fuel or flooding?

 

The old carter carbs were very beastly in tolerating crud.

 

It would be wise to completely tear down the walbro you have and rebuilt it.  Use a good brake / carb cleaner or soak the body in a gallon of digestive carb cleaner overnight.