Revisiting "hard to start after sitting".

[RED-Z06 2,415]

Its not something ive experienced, but I see alot of others experiencing it, and it has always left me confused as to why.  The consensus is always.. install a check valve in the line because the pump loses prime, or a boat tank pump bulb to fill the bowl, or an electric pump.

 

I always come back to, if the engine was running when parked then the bowl was full..a bowl should remain full for a couple months at least...meaning when the engine is cranked next, fuel should already be present, the engine catches and in a moment, the pump reprimed and the system full again.  My contention is a full carb cannot backflow through the lines, kohler with its top fill system, the fuel is below the inlet, Onan with its bottom up system, the fuel is below the inlet..it just cant get there.

 

So hard starting must be related to the bowl emptying much faster than normal evaporation through the bowl vent. I filled an Onan carb to its "fill line" stain on the casting and let it sit with no needle installed..no fuel runs out anywhere.

 

Any further thoughts?

[JCM 9,931]

[Handy Don 13,112]

  

[RED-Z06 2,415]

37 minutes ago, JCM said:

I know...its like asking about what oil to use, but.

[Handy Don 13,112]

5 minutes ago, RED-Z06 said:

I know...its like asking about what oil to use, but.

The only times I’ve had long cranking have been after leaving an engine to over-winter. 

Prior to leaving it, we shut off the fuel petcock and let it run until the choke cannot keep it running so we expect that the carb will need replenishing. 

 

A thought to add, perhaps, is whether the fuel level in the bowl must be at or near “full” to successfully get fuel into carb’s throat? If yes, then some “pumping” would be needed. How long? Good question.

 

Darryl did a couple of videos where he left a number of fueled engines (new, all the same, loaned from the manufacturer) in covered outdoor storage for many months and then tried to start them. The test was about fuel additives, but NONE of the gravity-fed, recoil engines started on fewer than five or six pulls.

[Blasterdad 2,800]

2 hours ago, RED-Z06 said:

 

So hard starting must be related to the bowl emptying much faster than normal evaporation through the bowl vent.

I've often scratched my head about this too. The K341 in my dedicated snow beast gets grouchy after just sitting a week. Last time I tried to start it I had to use a squirt bottle of gas to get it to fire & keep it running until the fuel pump took over. I've since put a primer bulb in the line, I'm about to go try it here shortly.

My theory is the engine wants the fuel "pushed" through the jets rather than "pulled". 

I'll report back, hopefully happy, Lol. 

[JCM 9,931]

10 minutes ago, Blasterdad said:

 

I'll report back, hopefully happy, Lol. 

Again,        

[RED-Z06 2,415]

26 minutes ago, Handy Don said:

The only times I’ve had long cranking have been after leaving an engine to over-winter. 

Prior to leaving it, we shut off the fuel petcock and let it run until the choke cannot keep it running so we expect that the carb will need replenishing. 

 

A thought to add, perhaps, is whether the fuel level in the bowl must be at or near “full” to successfully get fuel into carb’s throat? If yes, then some “pumping” would be needed. How long? Good question.

 

Darryl did a couple of videos where he left a number of fueled engines (new, all the same, loaned from the manufacturer) in covered outdoor storage for many months and then tried to start them. The test was about fuel additives, but NONE of the gravity-fed, recoil engines started on fewer than five or six pulls.

Run dry thats definitely reasonable, you've at minimum got to get fuel into the bowl.

 

I keep about 15 generators in dry storage in case we get a hurricane, ill cut a few loose here and there if someone i know is in need, i run them dry and choke them until they are dry, then let the tank evap a couple days.  Most of the time, after i add fuel...1 or 2 pulls and its running.  I try not to let anything sit with fuel over 3-4 months, even with Stabil360 it starts to congeal.

 

I do see an abnormal amount of 10hp Briggs OHV generators that after 2-3 months will not start...and thats on a new carb, unless you give it a shot down the breather, once it hits..its fine on its own.  I see evidence in these where the fuel has already started to sour and leaves a micro thin film that covers the main jet, and the EPA compliant chokes dont make enough vacuuming to clear it out.  But once it hits on fuel once it sucks the film out.

[RED-Z06 2,415]

20 minutes ago, Blasterdad said:

I've often scratched my head about this too. The K341 in my dedicated snow beast gets grouchy after just sitting a week. Last time I tried to start it I had to use a squirt bottle of gas to get it to fire & keep it running until the fuel pump took over. I've since put a primer bulb in the line, I'm about to go try it here shortly.

My theory is the engine wants the fuel "pushed" through the jets rather than "pulled". 

I'll report back, hopefully happy, Lol. 

Do you see any evidence if a slow seep around the bowl or bowl nut?

[peter lena 8,984]

@Blasterdad  personally have , vertical fuel check valves in place , on my 3 units ,looking at held standing fuel , those primer bulbs work , long ago was a regular issue , went after  cause / reason , eliminated fuel hose break down , from tank , sta bil in all my fuel , keeps my fuel filters clean , no fuel hose break down , add 1 1/2  oz to each tank , zero debris in filters or carb , my generator  has the same  sta bil  in its fuel , sits for months  , starts right up  , fuel filters  are clean / clear , no debris . just my vuew of a used to be problem , pete

[Blasterdad 2,800]

10 minutes ago, RED-Z06 said:

Do you see any evidence if a slow seep around the bowl or bowl nut?

No, but the plastic replacement mechanical fuel pump has seen better days, I'll be putting on an electric one come spring.

[ebinmaine 69,813]

47 minutes ago, Blasterdad said:

I've often scratched my head about this too. The K341 in my dedicated snow beast gets grouchy after just sitting a week. Last time I tried to start it I had to use a squirt bottle of gas to get it to fire & keep it running until the fuel pump took over. I've since put a primer bulb in the line, I'm about to go try it here shortly.

My theory is the engine wants the fuel "pushed" through the jets rather than "pulled". 

I'll report back, hopefully happy, Lol. 

 

 

I'm in the same boat with my '74 C160-8 Cinnamon Horse.

 

I'd say after 1 week to 2 weeks it's very resistant to getting back to work.

 

I will say that I am aware both of my own Kohler 16 engines have a carb throttle shaft that is a little looser than some folks would use them. Perhaps too much air is getting through at initial startup?

 

I tried to find a time frame online for roughly how long it takes Plain no booze gasoline to evaporate in a certain quantity but I couldn't really come up with something accurate.

[pfrederi 18,201]

The fixed main jet on my M16 snow plow tractor can be hard to start after she sits in the winter.  The Adjustable main jet K301 fires up almost instantly.  (both have fuel tanks up high) Not being terribly inquisitive i leave the A/C off the M-16 and hit her with a wiff of carb cleaner...fires right up. Heck snow blowers do not have air cleaners...

[RED-Z06 2,415]

1 hour ago, ebinmaine said:

 

 

I'm in the same boat with my '74 C160-8 Cinnamon Horse.

 

I'd say after 1 week to 2 weeks it's very resistant to getting back to work.

 

I will say that I am aware both of my own Kohler 16 engines have a carb throttle shaft that is a little looser than some folks would use them. Perhaps too much air is getting through at initial startup?

 

I tried to find a time frame online for roughly how long it takes Plain no booze gasoline to evaporate in a certain quantity but I couldn't really come up with something accurate.

Its affected by a few factors like temperature, warm fuel will evap faster.  Another factor in the field is tank pressure, if a tank gets hot in the sun it can pressurize some, and push fuel through the system, if there has been enough evap in the bowl to drop the float...people question how a carb can be loaded with varnish with a pump type system...thats how.

[lynnmor 7,497]

1 hour ago, ebinmaine said:

 

 

I tried to find a time frame online for roughly how long it takes Plain no booze gasoline to evaporate in a certain quantity but I couldn't really come up with something accurate.

Usually the engine is hot when shut down and that will certainly increase evaporation for some time.  Also, the float will take up a fair amount of volume, so factor that in as that reduces the quantity of fuel that needs to evaporate to cause the delayed starting.  I believe that the issue is simply evaporation.

[ebinmaine 69,813]

1 minute ago, lynnmor said:

Usually the engine is hot when shut down and that will certainly increase evaporation for some time.  Also, the float will take up a fair amount of volume, so factor that in as that reduces the quantity of fuel that needs to evaporate to cause the delayed starting.  I believe that the issue is simply evaporation.

 

 

I can see the logic there. 

 

My Automatic K341 with a marine primer bulb is DEFINITELY easier to start after extended periods. 

Couple light squeezes and off she goes!

 

 

[ri702bill 8,769]

26 minutes ago, ebinmaine said:

 

 

I can see the logic there. 

 

My Automatic K341 with a marine primer bulb is DEFINITELY easier to start after extended periods. 

Couple light squeezes and off she goes!

 

 

Agreed - I added one on the C81 - hardly ever have to use it. It puts a small quantity of fuel above the rear mounted tank.... Easier starts even after sitting 2 weeks...

Edited Thursday at 11:13 PM by ri702bill

[Blasterdad 2,800]

3 hours ago, JCM said:

Again,        

 

Started second crank!  Here she is ready to eat some snow...

 

[Racinbob 11,507]

I hear what you are saying and it makes sense but there's still something. My 05 liked to bulk at starting after it sat a while. In the summer it wasn't an issue because it never sat for extended periods. I tried the check valve thing but that didn't help and I don't like them so they were removed. As an experiment I backed the tractor up some ramps one winter. Problem all but eliminated. So I went with an electric. Problem eliminated. All my tractors now have electrics regardless of tank location. Maybe there's another way but they work. 

Edited Friday at 12:25 PM by Racinbob