Rough starting 3GM30F

[Levin]

Hello all...

So I have been having some problems with my Yanmar 3GM30F on my Hunter 340. Basically the problem is that when I go to start the engine it is very rough starting and seems to require that I give it a lot of throttle to get it to catch and start running. I never needed to do this in the past but recently I have had to. If I don't give it some throttle (around 50-75%) then it either turns over but doesn't catch or starts and shudders and then violently shakes until it dies. However once started it does take some time to get it to run up to full throttle and it will "power cycle" (where I give it full throttle and the RPMs don't go to full easily and then drop back to about 2200 and then up to full and back) for a few minutes before finally smoothing out for good. Now once it is fully started and has stopped this power cycle then it runs smooth from then on out.

From reading previous posts and doing some research here I think the problem I'm having is fuel related and likely related to the engine being starved of fuel at start-up. I've had the engine act like this before when I have replaced a fuel filter and not fully bled all the air out of the system. However I've checked filters and they are not the problem (plenty of fuel and just changed them again) and I've bled the system of air all the way through to the secondary fuel filter on the engine. It also seems that this problem is worse the longer I'm away from the boat or the longer between starts (although it will still happen to a degree even if I wait just 30 mins between starts... but not as bad).

So if I do have a slow air leak into the system how do I find this? And where might be a culprit? Or could it be something other than the fuel? Any help would greatly be appreciated.

Thanks,
-Levin

 

[Warren Milberg]

Assuming you are using fresh, clean fuel without and water in it and the right cetane rating (45), it sounds to me like a clogged or clogging mixing elbow.

 

[kloudie1]

Still sounds like air getting in, Levin.. Your observation is a good one..The prime (no pun intended) suspect would be the banjo fitting on the inlet of the fuel pump but it could be any of the fuel banjo fittings as well as the air bleed screws themselves on the injector pump and the secondary filter. The gaskets on the primary and secondary filters are next to check if the banjos don't do it , as well as the fittings on each side of the primary filter.. Hope ya find it.. they are hard to discover sometimes..

 

[Barnacle Bill]

Could be just a bad glow plug.

 

[Scott]

rough starting

Try bleeding the engine at the injectors. If that doesn't solve your problems, then check for air leaks as others have suggested. I don't believe your engine has a glow plug.

 

[heritage]

I agree with kloudie1 that it is likely caused by a slow air leak somewhere in the fuel lines and probably between the fuel tank and the fuel pump. The most likely suspect is the fuel filter area,,, gasket, clamps, etc. It could also be at the banjo fitting on the low pressure side of the fuel pump. There are several banjo fittings between the fuel pump and the injector pump, but you should see some fuel leakage at those fittings.

The banjo fittings have a copper crush washer on both sides. The fuel pump has 8mm washers and the others are 12mm. Yanmar has stopped using the copper washers and now have a rubber bonded-to-metal replacement. The stock numbers are 22190-080002 for the 8mm, and 22190-12002 for the 12mm. The old crush washers have a greater tendency to leak, especially if they are tampered with.

 

[tkanzler]

I had an H340 with the same engine up until last year. It had exactly the same problems - you could have been describing my boat.

Bleeding the fuel lines up to the injectors solved it, but it would come back when it sat for a while. Replacing the crush washers at the fuel pump and injectors seemed to solve it, but I sold it before it had enough sit time to see if it was fixed for the long run.

Next stop would have been rebuilt injectors, but it ran very smoothly without smoking once started, and was very fuel efficient, so I don't think they were the problem.

 

[Levin]

Hello again all...

Ok sounds like I need to go get some of those new washers. Thanks Heritage for the parts numbers. I know a good guy just down the road who can get almost any Yanmar part especially if I have the part number... so that shouldn't be too much of an issue.

After I get this done if I still have problems I'm sure I'll be back around asking more questions.

Thanks again,
-Levin

 

[Levin]

Better but not fixed

Hello again...

Figured I would just add to the original post rather than start a whole new one as this is still the same problem I'm battling. So since I last posted I bought some of the new washers and installed them on all of the banjo fittings I could find (4 in all... 1 coming from primary fuel filter to low pressure pump, 1 on other side of pump, 1 before the secondary fuel filter, 1 on the other side of the fuel filter) and this seemed to make a bit of difference. The "power cycling" that I described in my original post has gone away entirely. However the problem with being able to start without giving it a lot of throttle has not resolved.

I then read more in the archives (always try to do this before asking new questions) and noticed that someone said there were 5 banjo fittings with copper washers and started looking for the one I missed. Figured it had to be the fitting on top of the high pressure pump and took off this bolt (BTW... don't EVER do this unless absolutely necessary... it took me a day and tearing apart half the engine including removing the radiator hose above it to get the bolt to go back in) only to discover that the special washer was already on this fitting so all these heroics were for not. Since I had that apart I bled it for air too as well as cracking the tops of the injectors and bleeding these for air. Yet still the engine will not start without some throttle.

I have also cleaned out the mixing elbow since I last posted on the off chance this might be part of the problem. It was a mess inside there, but still no change in getting the engine to start up quickly. I figure this needed to be done anyway (about 750 hours on the engine and the mixing elbow had never been inspected) but as I said no change.

Anyway any other thoughts on what could be causing this? I'm really getting stumped over here. Oh and BTW... even after bleeding all the air all the way up to the injectors the engine still would not start without throttle, even right after this was done. Perhaps it's not fuel related?

Thanks for reading,
-Levin

 

[sailaway78]

Air leak

Look for an air leak before the lift pump, not after. On the suction side. If you have an air leak on the pressure side of the pump, you will probably be able to spot a little diesel around it. I had a very similar problem with mine a couple years ago. Timeline on mine was approx. two weeks. Finally found a splice the PO had put in the fuel line, behind and under the sink. Made me crazy for a long time. I replaced the entire fuel line, and installed an electric pump at the tank. End of problem. The electric pump makes it much easier to bleed, and can be useful to pressurize the entire system to look for leaks.

 

[py26129]

What is the temperature where you are? My 3GM starts gmer long but in the spring and fall, when its cooler it takes some throttle to get it to start and it takes a while until iot runs smoothly.


Matt

 

[Levin]

Not the weather

Hello again...

Pretty sure it's not the weather as we out here in San Diego only have two seasons... cold summer and warm summer. Even right now the coldest it ever gets is 50 F and that is only in the middle of the night. Also I don't think it is the weather because this problem happens even right after I have started up the engine and it is warm. This is what has made me begin to suspect that it isn't entirely fuel related. Even after I have warmed up the engine and have had it running very smoothly (which should mean no air in the lines), if I go and shut it off and go to restart immediately it still will not start without a bunch of throttle. Seems like if it were related to air getting into the lines that it wouldn't be a problem this quickly... because if there were an air leak that bad then I should see some fuel leaking somewhere and I don't.

Anyway thanks everyone for their continued help on this... it's been a head scratcher.

Take care,
-Levin

 

[John T1594]

Bleed the injector pump

I have the same 3GM30F engine in my 2000 H340. When you bleed the secondary filter on the engine you then have to bleed air from the screw on top of the injector pump. It is hard to see and get to. Just follow the hose from the secondary filter to the pump. It is on the starboard side of the engine and below the coolant hose going to the heat exchanger. Open the screw, pump the lift pump a bunch of times until the bubbles stop.

 

[Steve Dion]

Could be just a bad glow plug.

No glow plugs on these Yanmars!

I would replace all of those copper (banjo) washers and bleed it again. Be sure that the secondary (Yanmar) filter bowl is full of fuel.

 

[AbbySedge]

Look for an air leak before the lift pump, not after. On the suction side. If you have an air leak on the pressure side of the pump, you will probably be able to spot a little diesel around it. I had a very similar problem with mine a couple years ago. Timeline on mine was approx. two weeks. Finally found a splice the PO had put in the fuel line, behind and under the sink. Made me crazy for a long time. I replaced the entire fuel line, and installed an electric pump at the tank. End of problem. The electric pump makes it much easier to bleed, and can be useful to pressurize the entire system to look for leaks.[/quo

LOL

 

[AbbySedge]

Look for an air leak before the lift pump, not after. On the suction side. If you have an air leak on the pressure side of the pump, you will probably be able to spot a little diesel around it. I had a very similar problem with mine a couple years ago. Timeline on mine was approx. two weeks. Finally found a splice the PO had put in the fuel line, behind and under the sink. Made me crazy for a long time. I replaced the entire fuel line, and installed an electric pump at the tank. End of problem. The electric pump makes it much easier to bleed, and can be useful to pressurize the entire system to look for leaks.[/quo

LOL

roflmao

 

[jrowan]

Levin, This is something that you've probably already checked, but just in case - have you checked the fuel pickup tube in your tank for obstructions? My old Yanmar had a rolled up piece of mesh screening placed inside the end of the fuel pickup tube. It was designed to act as a pre-filter in the tank, but in reality acts as a pre clog. My old Yanmar did the same thing, hard to start up, because the engine was being starved for fuel from being 3/4 blocked at the pickup tube. I did not notice the problem until it was hightened by getting a lil' air in the lines after replacing fuel filters. It doesn't take much of the junk at the bottom of an old fuel tank to create a clog. My 2 c.