'77 Evinrude 25 - Idles Low in Neutral

[LaqueRatt]

Starts right up and runs well. Once warm. Only issue I have with it is when it first starts it idles very low and when I twist the tiller the revs just go up a little bit. Think it should be limited at 2-3k, but I'm not even seeing 1k.

I want to go out tomorrow, but it's a pain when it dies while warming up and is cranky about restarting. Have a generic Johnny Rude manual that says it's adjustable, but I don't have anything on mine that looks like the pic in the manual. If somebody can point out what I need to fiddle with I'd appreciate it.

 

[flatheadsteve]

Been awhile since I've messed with one but the idle adjustment screw should be on the carb. Right at the front of the little linkage rod in your Pic. Adjust while running a little at a time .

 

[LaqueRatt]

The idle is not the issue, the ability to rev it up in neutral is the problem. It's like the throttle barely moves until I put it in gear.

 

[Pappy]

The idle may indeed be the problem. Usually your issue is caused by a rich running engine.
There should be an idle mixture adjustment on your carburetor at the top front of it. Also there should be a reddish plastic bushing that goes into the carb and surrounds that needle. Very often that plastic piece has deteriorated and is missing. When this happens the owner usually richens the mixture. A rich mixture will drop idle RPM down to the point it may not want to stay running when shifted.
Secondly there is a chance your thermostat is either stuck open or someone has removed it. This also has an effect on idle quality. When operational you can further lean your engine and raise RPM with a good warm block temperature vs a cold running engine.
The P/N for that plastic part is 315232.
Start here first and we can go from here if necessary.
There is an idle speed adjustment screw and spring under the lower motor pan on the port side. May be broken off by now. May help a little.

 

[LaqueRatt]

Thanks Pappy I appreciate your thoughts. The motor seems to be operating very well other than this cold start issue. Could it be something with the tiller? Like maybe it's not installed properly? The pointer does not seem to be where it should be. Either in N or in F. I just took some pics that I'm going to upload. The first 3 show the limits on the handle. Both fast and slow. Plus the position on the stop. The last 3 show it in Forward gear.

 

[LaqueRatt]

There should be an idle mixture adjustment on your carburetor at the top front

Slow speed adjustment = Idle mixture adjustment? I have adjusted it to the best of my ability and the adjuster fits snug in the bushing.

 

[MDCrappie]

Not sure about those "older" motors but I think there would be an adjustment on either the connector that attaches the cable to the handle or the cable retainer itself. One or the other screws to adjust the length of cable.

 

[thill]

Sounds like your linkage needs to be adjusted so the marks on the handle read correctly, and it advances the timing a little IF the cable isn't stretched out too much.

You probably also need to adjust the idle mixture. As Pappy says, it's probably set a bit too rich. IF so, it's loading up with fuel and that's why it's hard to restart.

I don't remember that particular motor without seeing it in person, but you have some very good helpers chiming in.

I hope you figure it out.

 

[LaqueRatt]

Pretty sure this model pre-dates the ones with cables. I agree it looks like something with the tiller needs adjusting. This is the first 'rude I've had where you can actually see the nos, but yeah, they look out of whack. Guess I'll try adjusting the low speed jet again, but I still think something is wrong. This motor will not accelerate beyond idle. Even with the carb being off that can't be right can it? I'm about to take a dremel to that cam. Who needs it? I'm not so stupid to go to WOT in N and then go have a sandwich!

 

[MDCrappie]

Pretty sure this model pre-dates the ones with cables. I agree it looks like something with the tiller needs adjusting. This is the first 'rude I've had where you can actually see the nos, but yeah, they look out of whack. Guess I'll try adjusting the low speed jet again, but I still think something is wrong. This motor will not accelerate beyond idle. Even with the carb being off that can't be right can it? I'm about to take a dremel to that cam. Who needs it? I'm not so stupid to go to WOT in N and then go have a sandwich!

If no cable then I'm guessing it's 2 spider gears? If so maybe someone took it apart and put it back together a tooth off?

 

[LaqueRatt]

I was thinking the same thing. Is that possible to do? Not sure though if that would account for not being able to throttle up in N.

 

[MDCrappie]

I was thinking the same thing. Is that possible to do? Not sure though if that would account for not being able to throttle up in N.

I think it would account for the restriction as long as the "stop" is prior to the "joint" where the arm is that actually advances the carb.

 

[Pappy]

Tiller handle.
If you simply tilt the handle up all the way and look at the junction where both gears meet you will see one wide tooth on one gear and one wide space on the other gear. If these mate up it is timed properly.

 

[LaqueRatt]

Thanks, I'll check that out.

 

[Pappy]

Tower shaft gear should line up as well. With the engine off and in gear just throttle it up and take a look at the horizontal to vertical mesh and you will know if it is a tooth off with a bit of common sense.

 

[LaqueRatt]

I'll try to check that out today. Spent yesterday messing with the Mercury. Little by little, making progress with both! Couldn't do it without you guys. Kudos to you all.