Full throttle to start

[JBob]

I have a Grasshopper zero turn with a Kubota 22HP diesel engine. I think it's a D902. Currently has a just under 1000 hrs on it. It has gotten to the point that I must open the throttle wide open for it to start. This did not happen all at once. I have had to gradually increase the throttle to start it. Fuel filters are replaced religiously. After started it runs fine. Throttle response is good. If it's cold it's even harder to start. It's garage kept so it never that cold. Any suggestions appreciated.

 

[RalphVa]

I'd try some Seafoam in the fuel. Saved me some carburetor removals on a number of gasoline engines when I had some (all battery now). Just started putting in it the Isuzu's 60 gallon underbelly tank and use it for the tractor, too.

 

[JBob]

I'd try some Seafoam in the fuel. Saved me some carburetor removals on a number of gasoline engines when I had some (all battery now). Just started putting in it the Isuzu's 60 gallon underbelly tank and use it for the tractor, too.

I'm a firm believer in Seafoam. I have ran it several times in the mower. Never saw a difference in the mower. I have gotten great results elsewhere.

 

[thepumpguysc]

I said it once and I’ll say it again..
All mechanical injected Diesel engines, SHOULD BE started at OVER 1/2 to FULL THROTTLE..

 

[JBob]

I said it once and I’ll say it again..
All mechanical injected Diesel engines, SHOULD BE started at OVER 1/2 to FULL THROTTLE..

Bought the mower new in 2004. Never did have to go wide open to get it to start. I would be happy with half throttle.

 

[ROUSTABOUT]

I said it once and I’ll say it again..
All mechanical injected Diesel engines, SHOULD BE started at OVER 1/2 to FULL THROTTLE..

I'm sorry but I'm not cold starting any diesel with the throttle open that much. They start fine as it is with a little throttle.

 

[RalphVa]

All our old Benzes needed about 1/2 throttle to start them in really cold weather. Also the 3 Yanmar JDs. You just start them and as soon as they quit shuddering, you bring the throttle back to idle. You don't let them race above idle speed cold.

Or get an Isuzu, VW or Kubota diesel. They will start without shuddering and not much or not throttle.

 

[lmichael]

I said it once and I’ll say it again..
All mechanical injected Diesel engines, SHOULD BE started at OVER 1/2 to FULL THROTTLE..

Why? My G2160 rarely needs to start at more than fast idle. In warm weather I can leave it at idle setting and it fires right up. Cold weather maybe 1/3rd but that is it

 

[KennyG]

I said it once and I’ll say it again..
All mechanical injected Diesel engines, SHOULD BE started at OVER 1/2 to FULL THROTTLE..

My JD owners manual says just open the throttle slightly. It will start no matter what but they want it just off idle. An engine that requires open throttle has a problem IMO.

 

[5030]

I said it once and I’ll say it again..
All mechanical injected Diesel engines, SHOULD BE started at OVER 1/2 to FULL THROTTLE..

...and I'll say again that of the engine has a Bosch style injection pump (which all Kubota diesels are equipped with), when starting them, the pump will automatically advance to full throttle and as soon as the engine starts will ****** to the preset throttle position.

I never advance my throttle, don't have to if the pump is operating correctly. I never ,never use Sea Foam in my diesels. Sea Foam is a solvent and as such, breaks down the boundary layer that the pumps and injector pintles require. The ULSD fuel is hard enough on micro honed pump surfaces and pintles as it is. Why reduce it even more.

 

[neverfailyou]

My Ford/New Holland 1720 (1990’s vintage mechanical Diesel, cable throttle ):
Power the glow plugs for a count of “10” and then turn key to start. No throttle applied. Starts every time unless freezing cold or weeks since last start (then repeat glow plug/ignition). After start, apply throttle to normal rpm till warmed up.

 

[etpm]

The manual for my Yanmar YM2310 says to open the throttle all the way and as soon as it starts to reduce the throttle setting. When it is warm out it will start easily at less than half throttle but when cold it starts much easier at full throttle. It bugs me to start a cold engine at wide open throttle setting but I guess Yanmar knows more about their engines than I do.
Eric

 

[5030]

All depends on what injection pump you have. My Bosch pumps advance the fuel to 100% and when the motor starts. immediately reduce the fuel to whatever the throttle is set at. How they work. What your pump does or don't do, I have no idea. Lots of different injections pumps out there.

 

[JBob]

All depends on what injection pump you have. My Bosch pumps advance the fuel to 100% and when the motor starts. immediately reduce the fuel to whatever the throttle is set at. How they work. What your pump does or don't do, I have no idea. Lots of different injections pumps out there.

Mower has always started with throttle all the way down. This started the last couple years. Began as just a small bump up, now has to be full to start and it will crank a few seconds to start even at full.

 

[RalphVa]

The Isuzu starts at full throttle and immediately has to go to work (on generator) at that level, only about 1,800 rpm; I'm guessing.

 

[90cummins]

I’ve never heard of a (rule) that diesels need full throttle to start. Some diesels such as the p-pumped dodge Cummins need some throttle to start but not full.
My 1990 dodge starts at idle position except in very cold temps which requires some throttle.
I have some small diesels, Yanmar, Farymann & kubota that start at idle or slightly above.
The fact that your kubota is slowly needing more throttle to start tells me you have a developing issue.
Worn rings (low compression) or a defective glow plug are possibilities.
Injection pump or injectors may also need attention.
90cummins

 

[thepumpguysc]

Could b several different things..
Have u been changing the fuel filter 2x a year.?
Have u checked the flow out of the supply pump (if equipped)
The pump/throttle linkage most likely has a “start spring”.. it’s a very thin, what we call a hair wound spring, to pull the pumps control rack to the start position “excess fuel”..
If said spring is weak or broken or the pumps control rack is sticking, overcoming the strength of the start spring, moving the throttle to wide open will most likely compensate for that condition, allowing the engine to start..
Or.. the pumping plungers inside the pump itself are worn from dirt/contaminates that they simply won’t pump the fuel to start the engine..
Or the injectors spray pattern is off, not allowing a complete fuel burn..
It’s anybody’s guess until u put a wrench on it..

 

[5030]

I’ve never heard of a (rule) that diesels need full throttle to start.

You lead a sheltered life then. Mechanically injected diesels all start at 100% fuel then immediately revert back the the previously set throttle position. Always been that way on Bosch style pumps. Don't know about others. Read the previous post. Pump Guy knows his chit. You don't. No clue on the new ECM controlled common rail diesels. Don't have any, don't want any.

 

[thepumpguysc]

Lol.. I was biting my fingers trying not to respond.. I’ll leave it at that..lol

 

[5030]

Lol.. I was biting my fingers trying not to respond.. I’ll leave it at that..lol

Thus forum is full of armchair experts that really don't know but always assume. Like my comment on the mis aligned pin bosses on Kubota backhoes and how I 'should' fix them. Gee, I've repaired at least 5 of them for my dealer. All the same, all repaired the same too. Don't need anyone's input, I know what is necessary and what is the most expeditious and easiest method and that is exactly what I do. I get paid to fix them, not use any method that entails excessive time and effort on my part.