1999 Merc 125hp Hot Start Issue

[williamtii]

Hi Everone,

I am trying to track down a hot start issue on a 1999 Merc 125. It starts just fine when cold. For cold start, I normally prime the bulb, advance the throttle in neutral, push in the key to choke for a few seconds then crank. It fires up after 2-3 seconds of cranking every time and warms up smooth.

It runs happy when warm, but when shut off for a minute or 30min it wont starting with just the key. It cranks for a few seconds then coughs. After a few tries it floods and I have to wait.

It starts no problem when hot as long as the throttle is advanced in neutral, but that takes a little more time. I would really like to be able to start it with just the key since I fish around rocks and shallow spots. Sometimes a few seconds of futzing with it gets me a little too close to the rocks! I have been working with it now since last season but would like to know what the problem is so I can address it.

I have heard everything from Carbs to fuel to ignition, or that it's just an old merc and be happy it runs at all! Anyone else have this issue? It's been a great motor with no issues other than routine maintenance.

Thanks,

-William

 

[flyingscott]

Doesn't sound like anything is wrong. A motor that sits for 30 minutes is a cold motor so cold start procedure must be used that includes advancing the throttle. An option I would suggest would be an electric trolling motor for those situations.

 

[wn6ngp]

I have got a 90hp 1999 3 cyl. I've noticed that restarts after not running for a while are much easier if I make sure to put the trim in the full in not out position. I think its something about the float positions in the carb bowl. I had similar problems requiring some putzing around to restart until I discovered this. I also rebuilt the fuel pump lately and that seems to have helped too.

 

[williamtii]

I agree that if it sits for 30min it would be cold. But it does it after 1min - 5min - 10min etc. Before mid season last year it would start with just the key when warm.

We did the fuel pump gaskets a few years back along with a filter. They weren't in too bad of shape so no difference was seen. That was before the hot start issue though so it couldn't hurt to check again, the kits aren't too expensive.

 

[flyingscott]

When were the carbs last rebuilt. The issue would be with the top 2 carbs.

 

[williamtii]

Never under my command, and I've had it for about 5-6 years now. Last three seasons have been the most use.

I would be happy to have the carbs rebuilt at seasons end, maybe even try it myself

Just dont want to go down that road if it something in another direction or a common issue