engine stalls

Ross · Sep 7, 2009

Engine warms up and something expands and then the engine won't idle? Bled the injector lines ? Idle speed too low? Tweak the idle screw setting? Stop cable retracts all of the way?

Douglast · Sep 7, 2009

was there an idling problem with the contaminated fuel before all your work...??..if not then just possibbly loose fitting/element housing etc on your new installs that is introducing air...higher rpm etc overcomes the air problem but not idle...its just a thought

John Dezzutto · Sep 8, 2009

Filter location change?

I also have a 1996 Hunter 29.5 with I assume the same Yanmar engine. It appears there is not enough fuel getting to the engine when at low rpm. I'd be concerned with the new primary filter mounted above the fuel tank. The original position under the rear bearth allowed a gravity feed to the secondary filter on the engine. It's possible there is to much lift for the fuel pump at low idle rpm or you could have an issue with the fuel pump. The engine runs 3-5 minutes when you first lower tom idle due to the fuel in the line to the engine. If you have no black or white smoke I'd doubt it's an injector issue.

Deadline2 · Sep 8, 2009

Fuel is still the problem

Mechanic I know charges hundreds to pump the fuel out and hundreds more to recyle it. He laments that despite his best efforts there is still contaminated fuel in the lines. If you can keep her running long enough to flush the lines with new fuel, should be okay.

Recommend Fuel Power by FPPF for emulsifying any future water so it burns through the engine. Just a little, per instructions. Good luck. Your patience has been tested.

fredr · Sep 8, 2009

Do I understand correctly that, if you brought the throtttle back slowly, not all the way to idle, but tried to run the engine at 1000 or 900 RPM it would stall?
Is the engine reaching max RPM when at 150 D under load?
Is the engine kill lever COMPLETELY in the run position?
Is the tank vent restricted?
Did the idle screw or cable hold down at the engine come loose?
Are all cylinders firing? I am wondering if accidently one of the compression release levers is activated
If it is getting engouh fuel to run at 1100 RPM and above all the way to 2800 - 3000 , it is getting engough to idle.
It could be nozzles are not atomizing, I doubt it though.

fred

Ron Chappell · Sep 8, 2009

One thing I do know for certain ...

is that a 2 micron primary filter is much too fine. Yanmar recommends a 30 micron filter in that position and a 10 micron filter in the engine mounted canister. Too fine a filter puts a lot of pressure on the lift pump diaphragm and definitely will eventually cause failure - even with a clean fuel system. At higher rpms the lift pump may be supplying enough pressure to force fuel through the filter but at idle may not have enough. Doesn't seem logical but I have seen this happen. There could still be an injector problem etc. as well but I would first change out that primary filter. The fact that it first ran fine at the dock tells me there are still some impurities in the fuel

Ron20324 · Sep 8, 2009

Ditto, that 2 microns is too small. At a seminar last year, the Mack Boring guy that sets up the engines for local new-boat dealers says that unless you have an electic fuel pump, you should not use a 2-micron filter. I take that to mean you could likely blow your on-engine pump.

Benny · Sep 8, 2009

The 2 micron filter and the location of the filter are probably the culprits. Last year we switched to 30 micron filters from 10 micron for the Racor and have done away with fuel starvation problems. Let us know the solution when you find it. Good luck.

Dan Johnson · Sep 8, 2009

Ron & Ron...

(Boy, this is going to stir things up!) The two previous owners ran a 2 mic filter on my boat for over ten years and I continue to do so for the five years I've owned it as well. There have been no lift pump problems in doing so. The only time I've seen the vacuum gage go up is when my fuel became contaminated over a winter and I had to polish it and change filters that next Spring. I cruise all day at 2,700 RPM without a problem, and it idles smoothly when docking.

I would rather have the 2 mic clog and change it than the engine filter clog and try to change it when hot.

The idle problem in the thread seems to me to be a function of fuel not being in sufficient quantity at low engine speed, possibly pointing to a lift pump/filter placement issue already mentioned. It may be time to replace the lift pump diaphram. It seemed to run strong at speed in the slip as tested.

Try removing the return line and capturing the flow in a jar to see how much is passing through the pumping system and not being used by the injectors at idle RPM's.

jcela · Sep 8, 2009

I had similar problem with my 29.5

I had the same problem and if you review the archives I am sure that you will encounter my experience.
I received many recomedations and I expend a big deal of time and money following all types of good suggestions trying to fix the problem, the engine will run perfect at the dock but just to go out in the bay and as soon as the boat will started moving by the waves, the engine will die.
Finally someone from our knowledgable pool of hunterowners friends, wrote to me and said, jorge you can do many things but you will continue to have problems until you get rid of the dirt inside your fuel tank and removed the clogged strainer at the bottom of the fuel intake tube of your 29.5.
Take the fuel tank out and clean it very well and take the strainer out from the bottom of the fuel intake tube, and the problem will be solved. For some reason they placed that small strainer at the bottom of the intake tube that with years gets clugged and it restricts the passage of the fuel.
It would take a little time and effort but you will fix the problem for good. I did it and never had a problem again. Change the filters as recomended and be sure you get good fuel and you will be OK for many years (at least 10 yrs).
Empty the fuel tank as much as possible. It takes time to remove the tank from its limited space, but laying on the afterbirth armed with patience and with the help of a good fan keeping you cool, you will remove all the hoses and the clamps that hold the tank in place and you will remove the tank.
Once you remove the tank, take the intake fuel line out of the tank and take off the small strainer made out a fine mesh at the end of the fuel intake tube. In fact when you pull the intake tube the stariner will come off because it wont go through the opening of the fitting, so you will have to remove the stariner from the bottom of the tank after you are able to pull the intake tube.
Do not worry about not having the strainer at the bottom of the tube, most boats do not have that strainer and if they do tey have a stariner with 2" or 3" diameter. The dirt that will be sucked by the pump will be eliminated by the two filters in the 29.5 fuel system. The clogged strainer will keep the fuel from going into the line and through the filters.
Use a flexible extension attached to a power washer, introduce it through the opening of the fuel gage, use some detergent or soap and clean the inside of the tank until all of the dark spots attached to the inside of the tank are gone and the tank is perfectely clean as when first was placed into the boat.
Allow the tank to dry out completely. Install the fuel intake tube WITHOUT STRAINER, with the bottom of the tube about 3/4" to 1" from the bottom of the tank.
In my case I installed the tank back into the boat without the fuel gage installed, reason to avoid damaging the gage while moving the tank around during its installation. Insure that you have enough room to install the fuel gage from the top after installing the tank in its place.
Replace all clamps.
Fill up and start enjoying you 29.5.
Happy motoring!!!!!!!!!!!!!!!!!!!!!
Jorge

John Howitt said:
My Hunter 29.5 has a 2 cyl yanmar engine that will not idle. I checked the fuel and it was really uglly.It had water in it ( a bad O ring on the filler cap). We drained the tank and put in clean new fuel , and I put on a new raycor filter system in the locker about 10 inches above the tank with a 2 micron filter.in place of the factory original below the aft bunk. I also changed the filter at the engine. I ran the engine under load at the dock for about an hour everthing seemed fine so off came the lines,and away we went. Long story short it is doing it again.
The engine runs fine above 1100 RPM The engine temperature is about 150 and oil pressure is around 50lb. no black or white smoke.
Docking with this problem is exciting to say the least.
could it be the injectors?
I thought about the throttle cable, but it will idle properly all the way up to operating temp, and then about 5 min of operating temp and it will no longer idle.
Has anyone else had this happen to them?
Any help will be appreciated.

RichH · Sep 8, 2009

John Howitt said:
My Hunter 29.5 has a 2 cyl yanmar engine that will not idle. I checked the fuel and it was really uglly.It had water in it ( a bad O ring on the filler cap). We drained the tank and put in clean new fuel , and I put on a new raycor filter system in the locker about 10 inches above the tank with a 2 micron filter.in place of the factory original below the aft bunk. I also changed the filter at the engine. I ran the engine under load at the dock for about an hour everthing seemed fine so off came the lines,and away we went. Long story short it is doing it again.
The engine runs fine above 1100 RPM The engine temperature is about 150 and oil pressure is around 50lb. no black or white smoke.
Docking with this problem is exciting to say the least.
could it be the injectors?
I thought about the throttle cable, but it will idle properly all the way up to operating temp, and then about 5 min of operating temp and it will no longer idle.
Has anyone else had this happen to them?
Any help will be appreciated.

The fuel delivery lines are usually the lowest portion of a fuel delivery system, water will collect in the very lowest portion. Did you blow-out the fuel delivery lines between the filters and between the first filter and the tank? Probably 'slugged' your new filters with water that was trapped/settled in the fuel lines. Suggest that you 'validate' that the fuel lines still dont have water in them.

Ron Chappell · Sep 8, 2009

Regarding 2 micron

Dan Johnson said:
(Boy, this is going to stir things up!) The two previous owners ran a 2 mic filter on my boat for over ten years and I continue to do so for the five years I've owned it as well. There have been no lift pump problems in doing so. The only time I've seen the vacuum gage go up is when my fuel became contaminated over a winter and I had to polish it and change filters that next Spring. I cruise all day at 2,700 RPM without a problem, and it idles smoothly when docking.

I would rather have the 2 mic clog and change it than the engine filter clog and try to change it when hot.

The idle problem in the thread seems to me to be a function of fuel not being in sufficient quantity at low engine speed, possibly pointing to a lift pump/filter placement issue already mentioned. It may be time to replace the lift pump diaphram. It seemed to run strong at speed in the slip as tested.

Try removing the return line and capturing the flow in a jar to see how much is passing through the pumping system and not being used by the injectors at idle RPM's.

Hi Dan,

LOL, you are exceptionaly fortunate in being able to run that 2 micron for so long without incident. The only other case I have heard of was a fellow who had an inordinately large filter setup and was running an electric pump (can't recall the Racor model but it was twice the size of mine). The 2GM20F is my favorite Yanmar (and I have worked on a lot of them) invariably running a 2 micron filter has been problematic for most people. There is always the exception that proves the rule

Sfleischer · Sep 8, 2009

No Engine Idle when at Operating Temp

If the fuel injector throttle is not sticking open, then the the injectorbody discharge to the fuel return line is limiting the fuel return at idle. Hence the higher rpm at throttle idle. You may get lucky and find that all you need to do is blow out the fuel return line, but I doubt that because your problem is temperature related, My guess is the injector body fuel return check valve is sticking when hot. My two cents anyway good luck.

alan83054 · Sep 8, 2009

I had it last year...same problem...had a blown head gasket....My engine is a 1GM...

chuckwayne · Sep 8, 2009

Hey John,
I had the same issue on my 29.5 and it was the strainer at the bottom of the pickup that was clogging. You don't have to remove the tank, just take out the pickup and remove the strainer

Dan Johnson · Sep 9, 2009

Ron C...

Two previous owners ago was an Air Force pilot on SR-71's. He was a fuel fanatic, which may explain the 2 mic filters.

When I had my fuel problem (couldn't get above 2,000 RPM and engine would die back done to below 1,000, when evidently enough fuel got through to power up some), I took an old Perko water separator and an "Algae X" unit out of the fuel lines before the Racor. Both had ugly black goo build-ups in them.

I built a fuel polisher and used it to remove all the fuel in the tank into jerry cans. I cut an access port into the tank, rubbed, scrubbed and otherwise removed any offending material that had built up there (the last quart of fuel removed was almost black in color!) over the twenty some years of age. There was no screen on the pick-up tube. I refilled the tank from those same jerry cans using the fuel polisher once again. I haven't had a problem since.

Based on discussions on the forum over the past few years (and especially from Rich H's insights), I am now stocking in my spares a couple of 10 mic Racors in addition to two spare 2 mic ones I carry.

I've put less than 20 horus on the engine so far this summer so it's not had a heavy workout like the past couple after the problem was solved. Four three hour motor-only runs recently didn't produce even a hic-cup.

Maybe I'm an exception, but I make sure that everything about the fuel system is in the best condition that it can be. I estimate fuel useage at about .4 gallons per hour at cruising revs. That's less than two quarts going through a 2 mic filter in an hour (it's surely more, but I don't know the amount of excess fuel that gets returned to the tank at cruising revs). I doubt if that volume taxes the 2 mic's flow rate. I don't think I can pour it through by hand that slow, which may explain why I haven't had a problem with the 2 mics!

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John Dezzutto

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Ron Chappell

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Ron Chappell

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