2GM20F Starting?

[steveebryant]

Dear Boaters:

It has been hot here in Oklahoma with 100 degree weather. It takes 4 or 5 attempts on the starter for a couple of seconds each before my 2GM20F picks up. Once running, it sounds good with plenty of power. If the weather were cooler, it would be a little more difficult to start.

Does that sound like an issue with air in the fuel system?

My friend has a boat/engine just like mine except his starts with the slightest press of the start button.

Thank you for your comments,

Steve

 

[anchorclanker]

Diesels begin to show signs of air starvation at full power, anything so restrictive to make it hard starting would cause severe smoking and running problems.

When was last time it had a tune up? Clean injectors, check/adjust injection timing, check fuel system for leaks, filters, check compression....thats where you start.

 

[steveebryant]

I've only owned it a short while and it operates for me now just as it did when I bought it; I have no knowledge of previous maintenance. I have thoroughly cleaned the fuel tank, and replaced all filters. Once running, there is no visible smoke or any smell out of the ordinary. Since I have opened the fuel line, the engine starts a little slower than it did before I changed the filters but not much slower.

I am focused on what one would see in engine performance if there were a little bit of air in the fuel system.

If there were air bubbles anywhere in the system, wouldn't they go away if the engine were to start and run nicely?

I have not bleed the system at the injectors; I don't want to do that never having seen it done before.

If the symptoms I have described do not sound like an "air in the line" issue, then I could try to find an experienced and current small engine mechanic (that will be hard to do in OKC) to do a tune up for me.

So, I am still back to my original question:
"The engine will start and when it does, it will run nicely; on a cool spring or fall day, the engine is difficult to start. On a hot day, it will take 5 or perhaps 6, three second pulses on the starter, before she kicks over?"

 

[kloudie1]

I have had this on my 3 GMF. It was due to the banjo fitting washers on the intake side of the lift pump. A slight leak in the hose clamp would do the same thing. A very slow air leak will allow a bubble to form right at the intake of the pump and the weight of the diesel in the fuel line will suck in more air .. When you crank the engine, the lift pump takes a few seconds to get the fuel pulled up and pressurized again so the injector pump can function. Check your banjo fittings first . be very careful because they can be easily stripped when tightening too much. Our Yanmar guy here has some elastomer coated washers that can be substituted for the soft copper ones. Those do not leak.

 

[Bill Roosa]

Hard starting us usually a compression problem. Given you are at cranking speed the intake and exhaust really can't be clogged that much or you would notice it at idle and higher speeds. If it preforms well at normal RPM then the fuel system is providing sufficient fuel at cranking speeds to for similar reasons. The biggest thing in getting a diesel started is crank speed (clean connections to the batteries and fully charged batts) and compression. Lower compression results in less heat being generated during the compression stroke and you have to give it a few cycles to build heat in the combustion chamber walls.
Compression problems can be piston rings or the valves. A simple compression test is well within most folks capabilities and the compression checker is available at your local auto parts store.
On way to check if it is the rings or valves is to check the crankcase breather hose while the engine is running. Lots of blow by gasses is a sure sign the rings are going. No blow by and hard starting is more likely the valves..

 

[seadaddler]

Mixing elbo

Back in 2005 my 2GM would not start at all and so after many different things to try I removed the 4 bolts holding the mixing elbo and removed it and it started up like a race horse,I cleaned out the mixing elbo with ice pick type of tools and got cleaned out and the egine ran better than when new.
I does not cost much to try it first to see if that is the problem.
Nicck

 

[navigator97]

One other quick thing to check on is the position of the throttle leaver before pushing the start button. It should be at roughly 3/4 open to start then once it "catches" drop the throttle down to idle speed for engine warm up period (about 5 minutes). If you are already doing that, then follow the other guys advice.

 

[Stu Jackson]

You don't need to "warm up" a diesel engine.

You should also check all of your electrical connections including the ground wire at the engine.

If it runs fine after it starts, your starting problems are most like poor electrical connections. It is rarely the start button.

Other advice specific to your engine as provided is valid, too.

 

[kloudie1]

If the starter is turning the engine over, then there are no electrical problems. The lift pump on this engine is mechanical and it would take some engine cranking (as noted by steveebryant)) to get the fuel pressurized, if there is an air leak anywhere between the HP pump and the tank. Messing with the filters etc probably installed a tiny air leak that is allowing the fuel to bleed back toward the tank when the engine is shut down. fix this leak and bleed then things will get lots better. Good Luck

 

[anchorclanker]

You don't need to "warm up" a diesel engine.

Not at 100 degrees you shouldnt, but you cant say that across the board. Diesels become very hard starting as temperatures drop below 50F. Engines without glow plugs (direct injection), start having real trouble near 40F. By 30F most diesels begine to have real difficulty without a block heater, and by 0F its pretty much a necessity.

I was able to get a 300D Mercedes to start at zero once, but once it started it was so rough and noisy I vowed I would never do it again. It is extremely hard on the engine.

They also need to warm up before being put directly to work. The engine should be at operating temperature before asking for anything exceeding minimum power. Working too hard from cold, the pistons can heat too fast and swell to full size ahead of the cold (contracted) cylinders and cause scoring/seizure damage.

 

[steveebryant]

If the starter is turning the engine over, then there are no electrical problems. The lift pump on this engine is mechanical and it would take some engine cranking (as noted by steveebryant)) to get the fuel pressurized, if there is an air leak anywhere between the HP pump and the tank. Messing with the filters etc probably installed a tiny air leak that is allowing the fuel to bleed back toward the tank when the engine is shut down. fix this leak and bleed then things will get lots better. Good Luck

I need to thank each of you for what I consider excellent attention and response to my question. Thank you very much. Each of your responses has prompted in me at least one more to ask; however, I have chosen one of kloudie1's responses for my first two questions:

When I was changing the two separator filters and primary fuel filter, I noted that, try and I may, the little mechanical lift pump would not push fuel to the primary fuel filter. That distance was no more than one foot away and perhaps six inches higher than the lift pump itself. So, at a convenient place between the fuel tank and the little mechanical pump, I installed a fuel squeeze bulb. Then I was able to push fuel to the fuel filter thus clearing out all the air to that point. It was at that juncture that I stopped any additional attempt to "purge" the system of potential air bubbles.

So my slightly retro-question now is this: "Because this little mechanical fuel pump has been the source of a small leak between the two halves at the gasket interface, and because when I attempted to prime the primary fuel filter by operating the mechanical fuel pump manually and was unable to deliver fuel to the filter, should I replace it?" PS. I was able to tighten the screws on that mechanical fuel lift pump and it stopped the wetness observed to accumulate at the gasket interface. I know one of you have already posted, in an earlier and related message, a source for the mechanical pump so I think I will search it out to see if I can still get one.

And now the next question here is: "Just how difficult will be the replacement of that little mechanical fuel pump be anyway; have you any little bits of insight into the uneventful installation of such a pump by a novice mechanic wannabe?"

Oh, yes, and kloudie1, I am very much intrigued by your comment concerning the banjo fittings and washers. I'll likely come back to that later. Thanks!

Steve

 

[kloudie1]

Ya welcome, Steve. Lift pump.. It operates off the cam shaft in the engine and if the cam is positioned to compress the diaphragm, you can't operate the lever. Engage the decompression lever on top of the engine then rotate the crankshaft front pulley 1/2 turn.. then try the pump again.. rotate another half turn and another if necessary. You will be able to find a spot where the finger lever will work. The cam turns at half crankshaft speed, so when you rotate the crank a half turn, you are rotating the cam a quarter turn. When you get to the low spot, the finger lever will work. again, happy hunting

 

[heritage]

Yanmar is using Dowty washers instead of a copper ones for the banjo fittings on their new 3ym30 diesels. These washers fit the gm series and were recommended to me by Laborde Diesel, http://www.labordeproducts.com/default.asp?page=parts&ID=21&ID2=21&ID3=24. I installed them last year with no more leaks. They seem to handle the vibration of the engine without unseating.

 

[s sauer]

Bleed screw washers

one main culprit on the 2GM20F Yanmar are the two bleed screw washers on thr top of the primary filter at the front of the engine.

When you replace the filter element, you should replace the bleed screw washers, the nylon one is usually the worst one and can let air back into the system, causing your fuel pump to need to go a couple rounds before fuel is delivered to the high pressure pump. After the engine has been running awhile, shut it down and wipe it around the filter bleed screws and lift pump with toilet tissue and see where you find fuel....you should find the possible air leak that way.

 

[Bill Roosa]

There is a HAND LEVER on the lift pump that bypasses the engine cam operated part.
It is put there expressly to bleed the fuel lines.
You do not need to crank the engine to get the lift pump to pump. You just need to locate the hand lever and work it.

 

[Dan Hill]

Bill is spot on about the manual lever. Id like to add that if the fuel pump's internal arm is on the high spot on the cam you won't feel much at the manual lever. The trick is to toggle the compression releases open then while operating the manual lever rotate the motor by hand at the crank (lower) pulley on the front of the motor. You will feel the difference at the lever when it's off the top of the cam lobe. Only rotate clockwise as you view the motor from the front and don't forget those compression releases when done. Good luck

 

[Granfalloon]

2gm20f

Bill is spot on about the manual lever. Id like to add that if the fuel pump's internal arm is on the high spot on the cam you won't feel much at the manual lever. The trick is to toggle the compression releases open then while operating the manual lever rotate the motor by hand at the crank (lower) pulley on the front of the motor. You will feel the difference at the lever when it's off the top of the cam lobe. Only rotate clockwise as you view the motor from the front and don't forget those compression releases when done. Good luck

I have a 2GM20F - from what I gather the wire from the Start Switch to the Starter Solenoid is under sized. A simple way to check this is to connect a remote start switch directly to the Start Solenoid. If it cranks immediately in indicates poor connection or under sized wire.

I removed the alligator clips that came with the remote starter and permanently mounted the wires.

Coast Awhile
Hunter 310

 

[Dan Hill]

I think the OP was about cranking over too much before firing due to possible air introduction into the fuel system. You are correct that many of these model yannys have no/slow crank situations. Some replaced the main harnesses, some installed remote relays to handle the load. I opted for the relay system and added a remote start button in the engine compartment. Works great at either button.