engine stall at very low rpm

[kevin hoy]

Usually when I am motoring down the channel to dock, as the engine is at idle or close to idle, it will start to sputter and then stall. I can usually re-start it but not always. I find my self shifting to neutral and revving the engine to keep it going. Any thoughts ....?

[ILikeRust]

My first thought would be to focus on the carb. When was it last cleaned or adjusted? Also check the fuel filter and make sure you've got clean, full flow.

[Dave Neptune]

Check first!

Kevin, welcome to the MMI Afourian Forum. It's probably just an adjustment and a few things to check. First question is how long since the last tune up and what was done then? Second is what do the plugs look like, just pull a couple and advise us. If they're black and sooty It could be as simple as an idle adjustment or the choke. Third question is is your choke fully functioning~open and closed? And did you try the choke while it was sputtering~~worse or better. If the plugs are pretty clean and a brown to whiteish color we would look at fuel delivery or cleaning the carb. The carb may be fine and the tune is due or the carb is dirty and the tune is ok or both.
If you have any mechanical skills it is no big deal with the help of the forum!

Fair winds _/) _/)

Dave neptune

[bigal]

We had this problem and it turned out to be the oil pressure being too low for the oil pressure switch that controls the electric fuel pump which would cause the engine to stall. Of course, if you have a mechanical fuel pump this would not be the problem.

[Jesse Delanoy]

I had the same issue as bigal for a number of years, until I figured out what was going on. I got real good at jumping into the cabin, when idling into the marina, to put a jumper cable around the oil pressure safety switch to get the A4 running again in a hurry. First time I tried it, the Admiral was duly impressed!

[lat 64]

My first thought would be to focus on the carb. When was it last cleaned or adjusted? Also check the fuel filter and make sure you've got clean, full flow.

Ditto!
I cleaned my carb last year and it stopped all that nonsense. I took it apart and just blew out all the fuel/air passages. If you've never done that, Get a bud that has done it before to help. You may lose some tiny bit that is critical. Read up on specific details about your carb before you just tear it apart though. Like all things in life it's easy if you know how, but you can mess it up if you are just working in the dark.

Russ

[sastanley]

I had the same issue as bigal for a number of years, until I figured out what was going on. I got real good at jumping into the cabin, when idling into the marina, to put a jumper cable around the oil pressure safety switch to get the A4 running again in a hurry. First time I tried it, the Admiral was duly impressed!

HA ha..Jesse, I can see you doing that in a C-30. I have cushions flying all over the boat all the time! "Please don't put anything there, I may have to open the engine compartment any second!"

Ditto!
I cleaned my carb last year and it stopped all that nonsense. I took it apart and just blew out all the fuel/air passages. If you've never done that, Get a bud that has done it before to help. You may lose some tiny bit that is critical. Read up on specific details about your carb before you just tear it apart though. Like all things in life it's easy if you know how, but you can mess it up if you are just working in the dark.

Russ

Russ, I just took my spare carb apart yesterday evening and it is happily soaking in a can of Chem-Dip! I do not think it was ever taken apart, but what do I know. That stuff usually takes the paint right off the outside too!

[edwardc]

Hi Kevin. Welcome to the forum!

Assuming your carb is clean, it sounds like you might be running a little too lean. Try turning the idle screw a quarter of a turn closed (reduces air at idle) and see if the problem gets better or not.

[jhwelch]

Idle speed is usually set to 800RPM -- is this where yours is set to? Any lower and you may have "iffy" results.

[tenders]

> That stuff usually takes the paint right off the outside too!

And makes the house smell minty fresh, too.

[kevin hoy]

The carb was last rebuilt and cleaned , I think 5 years ago by the previous owner. I did remove the carb last Saturday, not too bad of a job getting it out. I don't mind the challenge of cleaning it, and I do have the MMI Service and Overhaul Manual....hate do do all that if it just needs some adjusting though. From the book, I can tell I have the later model, series 68, page 4-2.

[Mo]

It's any easy job to take it apart and clean it out. You have it off and they should be done occasionally anyway...just may save yourself some more trouble down the road. Takes me about 30 minutes to remove, clean and blow it out, and re-install. The first time is the learner...after that it's a breeze.

[bigal]

What is recommended as a solvent for cleaning the carburetor parts? I seem to remember using alcohol.

[sastanley]

bigal - I would use a spray can of carb cleaner with the little red tube..it is the only way to get at all the jets. I don't think alcohol (even 90%) is strong enough.

IMPORTANT SAFETY TIP - Always wear safety glasses..you never know where the other end of the jet is and it might come shooting carb cleaner back at you.

I soaked my spare in Chem-Dip this weekend to prep it for rebuilding & that didn't even get all the brown goo out. I used a full can of carb cleaner on the carb in that Sabre down the way when we cleaned it (it runs now! )

Carb Cleaner.

[kevin hoy]

I'll give it a shot; done this as a kid with autos....how hard could it be?