Starting problems when hot - Suzuki 2.5

[ash2020]

Hi all,
I have a Suzuki 2.5 four stroke outboard. It starts every time, first pull from cold, with a little bit of choke and runs well. However, sometimes, not always, after it's been running for 15 or 20 minutes it will strangle and stop, as if it's got fuel starvation. Then there is no possibility of starting it and I end up rowing. Next day it will start perfectly. I've refilled with fresh fuel, stripped and cleaned the carb several times, changed the plug. Any ideas?
Cheers. Andrew

 

[prv]

Mine's a 2-stroke, but I had similar symptoms that were resolved when I replaced the ignition system. I don't know what part of it had failed, since on the small Suzuki 2-stroke the replacement part is a single unit from magneto to plug cap, but the ignition system is definitely where I'd look next on yours.

Pete

 

[duncan99210]

As per PRV, I’d look at the ignition circuit. Given that it starts and runs then dies suggests that there’s a loose connection somewhere. A fouled plug is suggestive of an intermittent wiring fault affecting the lower plug, so check everything in the ignition circuit carefully: undo and remake all the connections so as to make sure that they’re secure.

 

[prv]

A fouled plug is suggestive of an intermittent wiring fault affecting the lower plug

I don’t think a 2.5hp motor has a lower plug ?

Pete

 

[ash2020]

Mine's a 2-stroke, but I had similar symptoms that were resolved when I replaced the ignition system. I don't know what part of it had failed, since on the small Suzuki 2-stroke the replacement part is a single unit from magneto to plug cap, but the ignition system is definitely where I'd look next on yours.

Pete

Thanks Pete. I will look at that, trouble is, because it's so intermittent, it's difficult to diagnose without actually replacing the CDI unit.

 

[ash2020]

Thanks Duncan. I have checked the wiring but haven't found a way of testing the ignition unit. Next time it does it I will whip the plug out and see if theres a spark.

 

[prv]

Yes. Same reason mine showed the fault for quite some time, and through a number of carb-fiddling efforts and plug changes, before I finally bit the bullet and replaced the ignition. It’s been trouble-free since.

Pete

 

[duncan99210]

I don’t think a 2.5hp motor has a lower plug ?

Pete

Indeed you’re correct. Been looking at something else where it was a twin cylinder engine..... Confused of Falmouth.....

 

[CAPTAIN FANTASTIC]

It would be good to replace the spark plug so to eliminate one thing, if no cure, then most likely to be the CDI which its an expensive item as I found out few a few years ago.

 

[ash2020]

It would be good to replace the spark plug so to eliminate one thing, if no cure, then most likely to be the CDI which its an expensive item as I found out few a few years ago.

I've already replaced the spark plug so I guess the only thing left is the CDI. I just don't understand how it works 75% of the time and then, just when you need it - nothing. Then you leave it and it starts perfectly the next day.

 

[Buck Turgidson]

is the tank vent ok?

 

[RAI]

The Suzuki is sensitive to old fuel. So my first move with mine is new fuel and a new spark plug.

 

[steve66]

When was the last time it as serviced. You have valves that can close, cylinder heads gaskets that can fail. Check the basics first like a new plug

 

[MonniotC]

Am I alone in wondering why so many people are suggesting things like fresh fuel and a new plug, which he stated that he had done in the first post?

 

[steve66]

Am I alone in wondering why so many people are suggesting things like fresh fuel and a new plug, which he stated that he had done in the first post?

He hasnt said he put a new plug in. He said he changed the plug

 

[seadog30]

Hi

I had the same problem with my suzy 2.5 four stroke. It was the fuel tank vent, try removing the srew in plug to expose the hole fully.

Good luck

 

[ash2020]

Hi

I had the same problem with my suzy 2.5 four stroke. It was the fuel tank vent, try removing the srew in plug to expose the hole fully.

Good luck

Thanks, I will check it but if the vent was blocked it would stop way before 20 minutes.

 

[ash2020]

He hasnt said he put a new plug in. He said he changed the plug

I wouldn't put an old plug in. When I buy a new plug I throw the old one away.

 

[ash2020]

Thanks for all the suggestions. i think the most likely is the CDI. As mentioned in the original post, I've changed the plug, changed the fuel, stripped the carb.