Outboard problems

Jizm · 28 May 2003, 22:47

Can some one help me please......
took the old girl out today but didn't even get on the plane because as soon as I opened the throttle, to anything past tickover, the engine seemed to misfire and would not rev past about 2800-3000 rpm. Just seemed as if it was running on two cylinders instead of three. Fuel getting to carbs ok (filter clean, hoses and pumps all good). New fuel this morning on the way to the slip. Swapped plugs over to new ones, all ok. All electrical connections seem ok. I'm thinking maybe a coil breaking down??? Or some one suggested a faulty rev limiter??? I've owned plenty of outboards before and luckily never had to tamper with any of them, until now. Has any one had a similar prblem to this and can maybe shed some light on the matter? All help greatly appreciated.
Regards
Jiz
The motor is a 1990-1992 yamaha 60hp autolube triple.

jwalker · 29 May 2003, 00:23

I don't know this engine but many outboards have 2 charge coil systems. One for low speed and one for high speed. A failed high speed system will give similar symptoms to the ones you are describing.

JW.

Bilge Rat · 29 May 2003, 06:48

Not sure if this will help much but i recently bought a rib with a 1990 evinrude 2 stroke outboard on the back, first thing i did before taking her out was to have the engine completely serviced and checked by a marine mechanic i trust, then began sea trials and encountered exactly the same problems as you described, she'd get to a certain rev line then die away failing to get on the plain and it sounded as if it was missing.
After lots of jigging about with the carbs and removing the fuel filter from the line they were still stumped, the engine was compression tested and everything was ok, the fuel pump was stripped down again and no problems were found there and new fuel filter added but still the same problem.
In the end it turned out to be the petrol had been sitting in the bottom of the stainless steel tank for God only knows how long and had both gone bad and collected condensation, when it was emptied it smelt both bad and had about a quarter of an inch of water resting on the top, they replaced the stainless tank with a plastic can and the engine runs fine now.
So now i've a stainless steel tank that turns out not to be marine grade stainless steel which they think may have corroded inside, at the moment we are going to cut a hole in the top and take a look inside, if it can be salvaged i'll have a stainless steel panel made and bolt it over the hole with a gasket in between and replace the tank. The tank was made to fit exactly and it would be a shame and a pain to try and replace its size and shape with plastic tanks.

So not sure if this helps much as you say the petrol is fresh, are you using a plastic or steel tank? and could water be contaiminating the fuel?

Richard

Charles · 29 May 2003, 07:23

Had a similar problem with a Yamaha 150. The fuel had formed minute sticky little balls in the carb. As soon as more fuel was injected into the carbs the little balls blocked the needle valves -

Bilge Rat · 29 May 2003, 09:45

Interestingly it was one of the things we did when i had the problem with my engine was to soak the carb in some sort of gunk over night, i'm told there is tiny little holes in the carbs that suck in air and if they get blocked up with muck they stop the carbs functioning properly, apparently this is a common cause of engine problems and if the engines left sitting for a long period of time the problem is prevalent and gets worse.
Hey its interesting, when i got into boats i knew absolutely nothing and slowly i'm picking up all sorts of useful information about outboards, not sure its of any use though.

A while back someone suggested this site below:

http://www.iboats.com/cgi-bin/ubb/ul...ubb=forum;f=17

its a great site for picking up bits and pieces of useful information about engines and anything else to do with boats, of course you need to de code the America talk.

Richard

dgpw · 29 May 2003, 12:03

I agree it sounds like the carbs to me aswell. I have used a 1991 90 hp 2 stroke on a phantom that had the same problem. Old fuel had bloked the carbs and the new fuel was not clearing it.

Jizm · 29 May 2003, 21:10

Thanks for the response guys but after a few hours of tinkering (both in the water and out!) with the lack of a manual, and before I started buying lots of spare parts I didn't need, I decided to give it to a man that knows (with a resonable hourly rate) who promised to have it sorted for the weekend. I am thinking it is fuel/carb related, as you chaps suggest, but I used the boat 6 weeks ago with no problem at all. Prior to that it had sat for 7 months with no fuel in it at all (I always let it run out while flushing). Will let every one know what the problem was, when my RIB returns, by posting at the bottom of this thread.
thanks again
Jiz

Bilge Rat · 30 May 2003, 10:13

Jiz mate i recon you've made the right move, these bits are so delicate that you could be messing with it for ages and ages and still not work it out, i've been told by a few old sea dogs that have a go servicing and problem solving is the biggest cause of problems with out boards especially when like me the person really has no real experience with what they are trying to achieve, ok so really we're not talking about changing a spark plug or a fuel filter but more fault finding more through trial and error rather than years and years of marine engine knowledge.

also worth remember when your up to you eye balls in oil and petrol you could be in the pub drinking beer and your man will call you when its fixed

Let us know what happens

dgpw · 30 May 2003, 12:24

When you are letting it run out when flushing it is possible that their is still fule it the carb. f you manualy drain the carb it will get rid of the last drop or you could let it run out and then start it again with some choke and you will find theat it will prob go again for a few seconds. I drain myn manual if it is going to be left. You can get a spary for the carbs if they are going to be left long term I forget what it is called as I don't use it.

jwalker · 30 May 2003, 16:47

Hey kid, you been drinkin'?

JW.

Jizm · 30 May 2003, 18:22

Do most of you guys drain all the fuel out when you are going to leave the engine for a while, or let the fuel sit in the engine/lines etc? I've looked at a couple of other threads and they argue for and against either option. What are your thoughts?
Personally I've decided that I am going to start the engine at least once a month and let it run for a while each time (with fresh fuel) over winter/lay up period.

Keith Hart · 30 May 2003, 19:31

I drain my little 2s each time.

Keith (this is my small contribution) Hart

DJL · 30 May 2003, 21:25

Quote:

Originally posted by Jizm
Do most of you guys drain all the fuel out when you are going to leave the engine for a while, or let the fuel sit in the engine/lines etc? I've looked at a couple of other threads and they argue for and against either option. What are your thoughts?

Does anybody know how modern fuel pumps used by Fuel Injected engines cope when being run dry?

gavin · 30 May 2003, 21:44

The problem you describe could be either electrical or fuel, it is the case that there is a low rev coil in the stator and high rev coil, if you can start your Yam but the revs wont build it would point to the high rev coil or its pick up, however to be sure if your problem is electrical or fuel try this.See if you can get the fault to occur while the rib sits on the trailer with motor gearcase in the water, run the engine and if it wont rev beyond the revs you describe while on the trailer, turn the motor off unclip one HT lead see if the motor will run on two cylinders, be careful here not to touch the plug cap, if it will run on two cylinders carefully with a spare plug fitted to the loose cap using an insulated pliers hold the body of the plug to earth, rev the engine and if your fault comes in see if the plug stops sparking at the same time the fault occurs be careful not to get shocked from the end of the plug, if your plug keeps sparking as the revs die you may be able to decide if it is fuel or electrical.The motor may not run on two cylinders though so this test might not be possible for you to do. There could be as much as 14000 volts across the plug while sparking, very low current though, but enough for you to get a nice wake up cheers gavin

stuart hedges · 31 May 2003, 23:01

Id try that again david.

stuart hedges · 31 May 2003, 23:01

bet it isn't blocked carbs.

Jizm · 01 June 2003, 17:36

What makes you say that mr H20? Had a similar experience in the past?

DJL · 01 June 2003, 19:20

Thinking about it I had a very similar problem with my Mercury 60 ELPTO. The engine would struggle to rev past 3500rpm while underload - out the water with the muffs on it would just about reach 5500rpm. It turned out to be water in the fuel. The carbs were cleaned and all was ok again.

Rene · 02 June 2003, 08:48

Hmmmm,

I had this problem ones. I was an air leak in the fuel line. At low revs there was no problem, but at full throttle the engine was sucking in air from the leak.

Fortunately the previous owner had fitted an extra fuel line ready to go under the seat. (Nice one Pete).

Rene

Jizm · 04 June 2003, 18:29

Just to let you all know, it looks like it is the cdi unit is at fault and will be confirmed tommorrow. The unit has been metered out and gave the wrong readings to the spec. It also appears to be breaking down when revved and will not allow the engine past 2800rpm.
Will post again when Rib returns fully functional!!!