Engine stalling

[Graham]

My engine is stalling and just in time for Canada's long weekend.

It seems to sputter and die and is very hard to restart. It seems to happen when it is both hot or cold. I find it happens under load as it will happily idle for hours.

I have an electric ignition and recently replaced my starter coil.
New spark plugs gaped at 40.
New gas and polishing filters in the spring.

I do not have a fuel pressure gauge, but I can install one tomorrow. Best I can find locally is this one: LINK


Thinking I could also pull and clean my carb. I have the gaskets and the how-to video from MMI. One question... the carb I have does not have the 5th bolt, but the gasket I have does. Picture link.

Any other troubleshooting ideas?

Thanks!

[capnward]

I bet if you clean the carb according to the video, taking particular care to remove any obstructions in the idle jet, the main jet, and the idle ports in the throat of the carb, that will be the fix. Your 'sputtering under load" problem sounds like something got past the filters, so you may want to replace the polishing filters. You can probably get away with using the new gasket with the old carb. Make sure it's tight. Cleaning the carb is in my experience the usual remedy. I often do it in the spring before starting the engine, to be pro-active.You will become quick and skillful at it. Also check for water in the bottom of the water separator filter. Your 'new gas' may have issues. A fuel pressure gauge is a good idea. I hope you get her running for the long weekend.

[JOHN COOKSON]

Try loosing the fuel fill cap. There may be a blockage in the tank vent.
When the engine starts running rough does closing the choke make it run better?

TRUE GRIT

[Marty Levenson]

stirred up?

I agree with the above, and wonder if stalling under load is after a rough sea? If so could have to do with stirred up sediment.

Happy Canada Day!

[Mo]

Hi Graham.

I helped a guy with one of those a couple of weeks back. Water in fuel. So removed and cleaned the carb, sucked out the tank with gas line hoses with the bulb. That went into Jerry Cans...you can take a bit from the bottom of the tank first and you will know right away if you have garbage gas.

So, cleaned carb, changed filters, drained tank, sloshed some methol hydrated around the tank. Had a couple of guys stand on the port side of the boat to get the fluid to the low side and pumped it dry...when the last of the fluid looks clean you are good. New non ethanol gas...fire it up.

It ran poorly for a minute or so until the lines cleared then ran perfect. The person in the above case didn't put the cap on the tank tight. I gave him a new seal. Haven't heard anything since...must be good.

From start to finish, with him helping, total time was just under 2 hours.

[Graham]

Thanks for the quick help everyone! I'm going to head down to the boat and follow the advice you all gave me. I'll report back with my progress

[Graham]

Try loosing the fuel fill cap. There may be a blockage in the tank vent.
When the engine starts running rough does closing the choke make it run better?

TRUE GRIT

I usually have to pull the choke out all the way... engine starts... immediately push it back in all the way.

Currently (as this problem occurred), I have to pull it out 1/2 way... engine starts... immediately push it back in all the way. Full choke out and the engine will not start.

[Graham]

I agree with the above, and wonder if stalling under load is after a rough sea? If so could have to do with stirred up sediment.

Happy Canada Day!

Thanks & no it happened yesterday under flat seas.

[ndutton]

If the problem persists after following the advice that has been offered, good troubleshooting practice is to determine if the issue is fuel or spark related which as far as I can tell has not been done. Immediately upon shut down or during a no-start episode pull the large coil wire out of the center of the coil, with insulated pliers or a rubber gloved hand hold its end 1/4" from a head bolt and have a helper crank the engine. Look for a snappy blue-white spark.

Good quality spark = yes, the problem is likely fuel related
Spark = no or weak, pursue ignition issues and we have quite a bit of experience in that area

Be sure to keep the raw water intake thru hull valve closed during cranking until the engine starts.

edit: please clarify "starter coil"

[Dave Neptune]

Graham, get the pressure gage installed. Then when she stalls you can check for blue spark~done. Then you can look to the fuel side. Check for water in the fuel by draining some fuel from the bottom of the carb AND/OR checking the fuel separator. The gage would of already let you know if it was pressure related, so if you have adequate fuel pressure we now know it is at he end of the fuel hose~the carburetor. About two hours max.

I'm betting the carb is way to rich as she starts easy without full choke!!!!!!!! Water in the fuel will require a great deal of choking when cold in most cases.

Dave Neptune

[Graham]

thanks, everyone. Questions... is they a starting point for adjusting the fuel mixture?

What fuel pressure is too high or low?

thanks!

[Dave Neptune]

Pressure 1 1/2 ~ 4 is just fine. The adjusting screw adjuxts the AIR so in is rich and out is lean. Most A-4's like it somewhere around 1 1/2 turns off the seat as a starting point.

Dave Neptune

[zellerj]

Exhaust hose collapsed?

Could also be a partially blocked exhaust that allows an idle but bogs down and stalls with higher rpms. Test is pretty smelly and wet, but pull the exhaust hose off at the water lift or stand pipe and see if it will more easily achieve higher revolutions per minute.

[Mo]

Graham, did you get at that today ... if so how did you make out with it?

[Graham]

Graham, did you get at that today ... if so how did you make out with it?

I replaced the electric fuel pump and the fuel filter. Then I and pulled the carb and gave it a good cleaning. I'm waiting for the heat to break before I go down and reinstall the carb.

I also installed a fuel pressure gauge!

I'll update with more details after it's all back together. I'm optimistic