Define "Cold motor". or Cold start

[MassillonBuckeye]

As in, when do I need to use the choke? Having some issues with my 1975 Merc 7.5 Thunderbolt motor being a bit hard to start after running for a bit then shutting down. When I do that, I can pull it a couple times and it wont start. If I choke it, it'll sound like it starts to fire but doesnt start. I unchoke and pull a few more times and it starts. The motor itself feels warm at that point so why am I needing choke to get it going? Too lean?? I've adjust the idle screw as low as it'll go without stalling. So its on the lean side. I want a nice slow troll out of it so haven't richened the mixture with the idle screw.

 

[bnicov]

Re: Define "Cold motor". or Cold start

Probably since you've leaned it out to slow troll. Try richening the mixture a bit to see if it helps at all. A Cold Start is usually the first start of the day with a cold motor, after it's run for a while, it's warmed up and SHOULD be easier to start (not always the case esp. with older motors). Also, give it a bit of throttle, with a really low idle setting, it will also make it harder to start.

 

[Texasmark]

Re: Define "Cold motor". or Cold start

"Also, give it a bit of throttle, with a really low idle setting, it will also make it harder to start" comment from bnicov:

I had a 7.5 and my annoyance was that they had the starter handle recessed in the cover and it made it hard to get a hold of it. Starting for me was to put the engine in N and advance the throttle to "fast idle" where it stops. If cold, i.e. first start of the day (as mentioned) or if you have been fishing and the engine has been off for an hour or so, then I'd ensure that the bulb was firm, add some choke and crank. Otherwise just fast idle (in N) and crank.

Obviously once the engine has settled down to running smoothly, you reduce the throttle to idle and then shift.

HTH,

Mark

 

[SalmoTrutta]

Re: Define "Cold motor". or Cold start

Im definitely not a outboard pro, but a harder warm start is usually a sign of worn rings. If you check compression cold vs. warm this may help explain why it's harder to start warm. Just a thought

 

[DavidAK]

Re: Define "Cold motor". or Cold start

Is the engine tilted forwarded? Do you have it tilted to the top pin location for shallow running? If so, the gas is running out the front of the carb and requires the choke on to start a warm engine. It will require some throttle above idle to start properly. Warning, leave the carb fuel mixtures alone unless you know what you are doing!

 

[MassillonBuckeye]

Re: Define "Cold motor". or Cold start

Not tilted up, its all the way down. Last pin setting. I can get it now in about 3 pulls. I just choke it every time unless I've only sat for 10-15min. I pull it, it sort of fires, I unchoke and pull about 3x and it starts. And yeah, I start in in N with the throttle as far as it will go, which is fast idle I guess. Hmm. Doesn't seem like I had this problem before changing my float. I *think I have it set right heh. Didn't even have to do the float as it turned out to be a bad venturi. Thing was stuck sideways in the carb.. Thanks for the info guys.