Intermittent poor running

[Phil Greetham]

Engine can run fine one day and not the next, Last Sunday ran for an hour on test in my garage and appeared fine (although she did have a tendancy to cut out when at higher revs after about 10 seconds), the next evening started first pull on full choke then within minutes started to run rough on all choke and throttle settings and on occasions would cut out altogether.
Full choke and half throttle were then required to get her started again (even when at operating temp), this starting, and cutting out, continued several times until I gave up on her, switched the lights out and went for a cup of tea. Plugs are also picking up carbon diposits and are a little sticky after running.

Fuels fresh, naturally one suspects fuel so the carbs been taken to bits & cleaned out several times, Engine Oil is now clean after water ingress last season due to a degraded filler neck o-ring seal. have a good spark with measures of 190 volts at each lead.

I'm thinking possible CDI unit problem, would others agree?

[Ciao Bye]

Hi

I was reading your post and after a while I tought you had the same problem as I had 2 years ago.

I dipped the carb in GUNK for 3 days (the minimum) then the problem was solve. But you said you did cleaned it. Hum!!!

How about your float and it's level?

I doubt the cdi will act like that. It would not have anything to do with your choke and the rest. I really suspect the carb.

Some coil had a tendency to break, check it. Use the manual and make all the check that are listed in it related to electricity. It is easy to do.

It's only my guess, let us know of your finding. I will relay your message to one of my friend and see what he thinks about that.

Good luck

John
Quebec city
Canada

[Howard]

John, I hate to disagree with you but I have known the CDI or coil unit to become intermitant. However I agree that the problem is more often feul based.


If you like I could ship you a set of CDI & coil so that you could test them by substitution, Howard

John, many thanks for all you contributions. Its great to have someone so active on the forum.

[Howard]

Phil, the actual output from the coil should be many thousands of volts but It is impossible the get full understanding using just a volt meter. The CDI unit provides a fast spike (.05 of second ish) to the coil that can only be tested with more sophisticated equipment. The simple tests in the manual are useful but only a basic guide. The wires can become fractured within the insulating sleeve and the electronics can also fail in an intermittent fashion. But if you would like to give me a call I could go over the possible electrical issues with you, Howard

Email me with your tell number(not on the forum please) and I will call you back.

[Ciao Bye]

Howard.

Thanks for your kind words.

When he write: Full choke and half throttle were then required to get her started again (even when at operating temp),

This and to my buddy mechanics, suggest fuel problem, intake or carb wrongly torqued.

An electric problem would cut sharply and would not have any relation with choke. I am anxious to find out the real problem.

Let's find it.

Cheers

John

[Phil Greetham]

Gents,

I have to say that i'm feeling confident we'll crack this before the sun starts shinning again in the spring and without throwing too much money at it. I daren't tell you how much my father has spent on this little engine over the past 5 years, nearly half as much as the little boats worth! Of course winterisation wasn't his thing and one little problems soon turns into several little problems.

I stripped the carb down again (completely) and washed everything with a brake cleaner from our Aircraft stores, all the engineers swear by the stuff as the best degreaser and cleaner there is. Once back on the engine she started second pull. I ran her for 30 mins but it took about 15 mins before she would idle by herself and I had to catch her on the throttle a couple of times to avoid stalling. After a while I also found myself thinking that she's running perfectly some of the time and then thinking that she wasn't on odd occasions due to a slight increase in vibration which seemed to come and go. Now I'm not sure whether this is simply as the engine is not under load or the odd lack of combustion now and then. Something tells me I still have a little problem, I'll continue the weekend tests over the the next few weeks and see what developes. This engine has not really even been ran-in since new rings and bores 4 years ago and a second overhaul 2 years ago.

Many thanks Howard for the kind offer of substittute CDI & Coil, i'll continue the running trials over the next few weeks and get back to you. And thank you John for your excellent carb advice.

Just one final question for Howard though. What did you mean by 'intake or carb wrongly torqued'? I simply torqued it up to 10nm as I do with most of the 6mm threads!

Phil.

[Ciao Bye]

Hi Phil.

The "wrongly torqued" info was from me.

My friend told me that if the intake or the carb is not well secure to the engine, air will pass and it will run poorly. I still think that the problem was the carb even though you said it was clean.

Those jets are so tiny and only a good carb cleaner and a well soak carb for 3 days in it will come to clear the passage away. I suggested GUNK because we use it a lot in our city garage.

I am a senior buyer for the city here in Canada and have bought a lot of product but this one has been recognized as "the master cleaner of all carbs".

As soon as you have to play with choke and mixture control, you can be sure that the problem usually come from there.

Take care.

John.

[rasmuslund]

This sounds like the problem we have with our MB2. It runs very unstable. If we run it without the choke, the engine speeds up and down as if someone pulled the handle. Often it stops by itself. If we use the choke, we kan keep it running, but only at high speed.
Last season it ran much better, so it seams that the engine has gone poor during the winter, where it hasn't run that often.

Another problem we have is, that the engine dosn't alter the battery we use for all the electronic equipment. We kan alter the battery if we do it with power from land.
Is it possible that these problems are connected? The altering problem started several months before the motor problem. (the motor has always been a little unstable, but fare from what we now are experiencing.)

We are know seeking all over the internet to find someone, that can guide us to a solution.

In this thread you mention to solutions:
1. Degrease and clean the carburettor
2. Replace the coil (both?) and the CDI

Solution no. 2 could maybe solve both our problems? Or maybe an combination of the two solutions?

What do you experts think?

/Rasmus

[Ciao Bye]

Ok here is my humble opinion.

Take the carb completely apart and let it sink in GUNK for 2 days and pass the air in all the holes. Make sure the float is level and the gasket are perfect. It should work.

As for the charging of the battery (if I understand corectly) first check if it is charging at the end of the 2 wires when connected to a battery (very important).

If not check the fuse. If not then you have 2 solutions. The first one is the magneto but I Highly recommand checking for AC output directly at the wire near the plug in front of the engine. My plug has rusted inside and the wire were corroded. No way to find out unless you cut the big rubber boot. I did so and connected the wire directly without the boot and now it work perfectly. By the way my 2 engines had the same problem.

Hope this will you. Let us know please.

John
Quebec Canada.

[rasmuslund]

Thank you John, for your reply.

I am a motor mechanic rookie, so I have some extra questions.

1)
Are there something I should be aware of when I take the carb apart? Do you know I can find a manual or tutorial somewhere on the internet?

2)
How do I ensure that the float is level?

3)
When I check if it is charging the battery, how much power should it charge with?
3A)
How much power should I be able to measure from the output on the engine?

In this upcoming weekend I will start "operation fix the engine", and of course I will tell you the outcome afterwards.
/Rasmus

[rasmuslund]

...some extra questions...

4)
Could it be possible that some water or condensation has come into the fuel system? If so, shouldn't I clean and dry the entire system? (tank, pipes, filter, carb, etc?)

5)
Do you think I can use something like: Redex fuel system cleaner? (http://www.4wheelplay.co.uk/redex-fuel-s...0173.html)
Or won't it do the job as good the a manually cleaning you suggests?

6) You recommends me to use GUNK. What GUNK product do you prefer to this task? And do you know a substitute for GUNK. I can not find a GUNK reseller i Denmark.

Once again, thank you for your help. I am very grateful.
/R

[billyjmcd]

rasmuslund Wrote:Thank you John, for your reply.

I am a motor mechanic rookie, so I have some extra questions.

1)
Are there something I should be aware of when I take the carb apart? Do you know I can find a manual or tutorial somewhere on the internet?

2)
How do I ensure that the float is level?

3)
When I check if it is charging the battery, how much power should it charge with?
3A)
How much power should I be able to measure from the output on the engine?

In this upcoming weekend I will start "operation fix the engine", and of course I will tell you the outcome afterwards.
/Rasmus

rasmus
for q.1 try http://www.leisureowners.org.uk they have a manual on there site you can download that will answer q.2.
q3 measure the two leads from the charge coil with a ohm meter they should read 0.13ohms if it reads 0 [open circuit] the lead may be cut where they come between the casing and the flywheel this a common fault.
q4
the output depends on engines normal is about 2 amp

hopes this helps
billyjmcd

[Ciao Bye]

Hi again Rasmus

1)Are there something I should be aware of when I take the carb apart? Do you know I can find a manual or tutorial somewhere on the internet?
====not really a big thing. Just take your time to take the screws under the bowl. There is nothing to worry, just note the place where the parts goes. Do not immerse any rubber or gasket in the GUNK. Take the mixture screw out but count the turn to close it before you do and give back the same number of turn when you'll replace it. Approx 1.5 turn. As for a manual I do not know of any one on the net but maybe if you make a search you should be able to find something on that subject. I use SELOC printed manual for Honda outboard repair manual 1978-99 (it cover 2-130 hp 4 stroke engine). ISBN: 0-89330-048-9 http://www.delmarlearning.com/Browse_Cat...at4ID=7E1A

2) How do I ensure that the float is level?
=======Make sure first that the float is not full of gaz because it would mean that she is no good. it should be empty. Usually it should not be out of level if it was running well befor the problem arise, I would not worry but be cautious as not to force anything during the operation.

3) When I check if it is charging the battery, how much power should it charge with?
==== no sure I understand. Take a small 12 volt battery and measure the voltage. Plug the motor, run it and compare the reading. It should rise and so specially if the previous voltage was around 11 volt the it will show a big difference.

3A) How much power should I be able to measure from the output on the engine?
==== read above. The charger is not powerfull, 5 amp at the max full throttle. It it does charge a bit at normal speed this mean that it is working at all speed.

4)Could it be possible that some water or condensation has come into the fuel system? If so, shouldn't I clean and dry the entire system? (tank, pipes, filter, carb, etc?)
===== empty everything and start with fresh gaz everywhere.

5) Do you think I can use something like: Redex fuel system cleaner? (http://www.4wheelplay.co.uk/redex-fuel-s...0173.html) Or won't it do the job as good the a manually cleaning you suggests?

=== I do no think it is the righr product beacause you put it in the gaz. You need something strong to clean that carb. I know that GUNK is hard to find now. Chryler of America as a product in their MOPAR line that clean carb. I usually empty the spray can in a plastic container and dip the carb in it for 24 hours. Visit you local small engine shop in your town and they should be able to tell you what product work best for their chainsaw, snowblower or else. Blow air in the little holes in the car afterward without being to genrous about it in order not to break anything.

6) You recommends me to use GUNK. What GUNK product do you prefer to this task? And do you know a substitute for GUNK. I can not find a GUNK reseller i Denmark.
======= read above or visit http://www.gunk.com/menu_CD.asp and check for M4814
Carb Medic
- Powerful solvents quickly go to work to remove dirt, varnish, gum, carbon deposits, and sludge from the carburetor and combustion chamber of gasoline engines.
also M4816 The product you are looking should be able to perform this task as described above.

Good luck to you and be confident. If I find something else I will post it here.

John
Quebec Canada

[quaich]

hi to all members i have allmost but given up with my engine i have had a mechanic working of and on for allmost 9 months the longest i have it running was 3 minutes one day i have had a spark the next time no spark? I would willingly give the engine away for a compatable replacement diesel engine does anybody know of one (fed up person) quaish.

[Ciao Bye]

Where are your from.?

There is a saildrive 330 that fit perfectly over the bed of your existing MB2A but, I would suggest to buy a rebuild one from Howard here on the forum. Futhermore, you would have all the spare parts you need with your old. engine

That is exactly what I've done. Found one by pure accident at 5 kilometer from my home 10 hours on it. A pure luck.

Hope you find the right motor that will give you peace of mind.