73, 125hp evenrude doesn't idle

[paperdesk]

Hi everyone! I've got a 1973 125hp Evenrude outboard on my 16' Rienell tri hull. I just bought the boat, and have had it out a couple of times, and am looking forward to a great season.<br /><br />However, it starts hard, and I have to sometimes keep the starter going for a few seconds after the motor starts or it will die. I keep the warm up lever high for a while and then try to quickly slide the throttle forward to engage the drive, and get the rpm's up again or else it wants to die.<br /><br />Even when it's warmed up I can only idle for a little while and then it dies. I've noticed that when the drive is engaged at low rpm's it always wants to die, but when I increase the throttle it does fine. Kinda annoying in a no wake zone because it forces me to have high rpm's or let it die and paddle in (also embarresing).<br /><br />Supposedly the carbs were professionally rebuilt just before I bought the boat. I've run a couple tanks of gas through it and it seems do a little better than when I first bought it. Any ideas on what is causing this?<br /><br />Thanks,<br /><br />Ted

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

By the way, I'm sure that this kind of thing has been discussed, but I didn't find it in my search. Maybe I used the wrong keywords. Anyway, if anyone can point me to a useful link I'd really appreciate it!

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

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[Solittle]

Re: 73, 125hp evenrude doesn't idle

Use the choke/primer when starting. Most of the OMCs, particularly the older ones, seem to like a lot of fuel to get going.<br /><br />On the idle - I had this problem with my 1987s (110 hp). Turns out that a wrench pulled the thermostats and the motors never got to the specified operating temp. New t-stats solved it. You can also tilt the motor up a tad - this changes the level of fuel in the float bowl to give it just a tad more.

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

I do use the choke when starting (as well as the cold start throttle).<br /><br />How can I find the thermostat? I'm ok at automotive mechanics, but I'm new at working on boats.<br /><br />Thanks.

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

BTW, I started it with muffs the other day to see if I could figure out anything. I got it going, but it died fairly quickly. I pulled several of the plugs and found that they were very wet with oil/gas. I was able to start it again no problem, and with high rpm's it keeps going well.<br /><br />Also, the former owner told me the battery was no good. It does seem weak, but still starts the motor. Would this play into it?

 

[R.Johnson]

Re: 73, 125hp evenrude doesn't idle

Do you have a 1973, 135 HP or a 1972 125 HP, These are two different animals, give us a model no. they did not make a 125 HP in 1973

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

Do you have a 1973, 135 HP or a 1972 125 HP, These are two different animals, give us a model no. they did not make a 125 HP in 1973 <br /><br />I was looking for a replacement prop, and found this discrepency as well. I'm only going by what the former owner told me, so evidently he got something mixed up. I'll go check for some numbers and let you know.

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

Thanks for your help so far! Here's the info I pulled from the motor:<br /><br />Model: 135383M<br /><br />Serial Number: J 05207<br /><br />Rpm's 4300-5500<br /><br />Would that make it a 72' or 73'?

 

[R.Johnson]

Re: 73, 125hp evenrude doesn't idle

Your engine is a 1973, 135 HP. The first thing I would do is take a compression test. Then check the sync. & link. That engine in 73 was a hard running motor, I have seen any number of them go "Bang" that's why check the compression first. If that proves to be all right. My guess would be Sync. & link, or dirty carbs.

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

Wow, you'r fast! Thanks. I'll get the compression checked ASAP. What do you mean my Sync. & link? This is my first boat, so I'm still learning the terms.

 

[SCO]

Re: 73, 125hp evenrude doesn't idle

Ive got the same motor, and had the same problem. May or may not be your problem, but on mine, the engine throttle cable was mal adjusted. On that motor, you must start in neutral, and the only way to advance the throttle for start is with the pull up lever. Because of the misadjustment the throttle was in effect "spring loaded" against the closed throttle screw. THe effect was that when I pulled up the neutral throttle lever, the throttle flapper linkage stayed pressed to the closed throttle screw and didn't open. Idle throttle..little air..little fuel..hard start. To rule this in/out, figure out where the throttle flapper is on the carbs and make sure they begin to open as soon as you begin to pull up the neutral throttle lever. All carb/cable linkages should be checked also for proper adjustment against the service manual as a first step. BTW, with the neutral throttle lever up all the way, you should be revving way too high for comfort.

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

Thanks for the advice Sco. I know what you mean about the rpm's getting high. I can get there no problem so maybe I have a different issue. I don't seem to have any trouble with the motor when the lever is up, it's just when I bring it down to go into gear. I have to throw it into gear and give it lots of throttle fast or it will die (sometimes it will no matter what). I'm going to try to get a compression test today or tomorrow. I live in the boonies so don't have many mechanics to work with

 

[SCO]

Re: 73, 125hp evenrude doesn't idle

MAybe your lever down idle rpm is just set too low. I had that problem too. Also if you run it on the muffs too much, the engine will not idle well in my experience.

 

[Joe Reeves]

Re: 73, 125hp evenrude doesn't idle

Sorry... Encountered a error here. Reply was not intended as it would have been repetitious.

 

[R.Johnson]

Re: 73, 125hp evenrude doesn't idle

By sync. & link! this is the relationship between ignition, and throttle opening. On your engine the throttle plates should just start to open at 5 degree's before top dead center. If the plates open to early, you will have the condition you discribe. A service manual discribes this much better than I. If you don't want that old 135, can I have it?

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

That is a thought. How can you know what the proper idle rpm's are? I'm assuming that if the idle is too high you either can't engague the gear, or else it may damage it. My tach is broken, but I'm going to see if I can find the problem with it tonight and fix/replace it.

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

News! I got my compression checked. Now what?<br /><br />Here are the numbers, I don't know which cylinder is number one, but starting from the top left cylinder going clickwise, here are the readings:<br /><br />1. 108<br />2. 112<br />3. 110<br />4. 99<br /><br />So can anyone tell me what this means and if it might affect my current problem?

 

[paperdesk]

Re: 73, 125hp evenrude doesn't idle

Just saw your reply Johnson. Thank's for the explination. I'll have to see if I can get a hold of a manuel, especially since I'm not at all sure how I'd know how to find 5 degrees before TDC on this thing.<br /><br />I'd gladly give you the motor too, if I had another to replace it (lol). I'm guess I'm pretty well attached to it at the moment, and am going to give it as much TLC as I can to get it going.

 

[ledgefinder]

Re: 73, 125hp evenrude doesn't idle

I've had three V4s from that era (1973-77 have a common ignition system & carbs), and they all did what I think you're describing. <br /><br />Your case sounds a little worse, but let me see if I've got it. Hard to start when cold. When cold, have to set the warm-up lever pretty far forward, and may start for just second or two several times before it really catches. Starts instantly when warmed up, but still stalls sometimes if run in gear at idle. Sound right?<br /><br />By the way, my current motor does this (though not as bad) though the carbs are spotless & the motor pulls very well on the test prop.<br /><br />Here are some things to think about. The idle setting is 600-700 rpm, when in forward gear, with the motor warmed up. I'd run 700. <br /><br />You said the carbs had been cleaned. Did you leave old gas in them over the winter, or run dirty/gummy gas through them from an in-boat fuel tank?<br /><br />Your compression figures sound a little too varied, but that may be technique or a dirty solenoid. In any case, they're not way out of the ballpark. I'd give the motor are real good decarb (that may be the problem right there). <br /><br />RJ's right about checking the synch of advance versus butterfly opening (in fact, I'm going to check my motor's this weekend).<br /><br />You should be running Champion UL77Vs (flat tip surface electrodes) in that. If you let anyone talk you into running the L77Vs (regular protruding electrodes), please check the motor to see if they're hitting the piston tops. If you are running the L77Vs successfully, I think Joe Reeves said there was a service bulletin changing the gap to 0.040 (from 0.030), which might help. <br /><br />Does it sound to you as if you're running on less than 4 cylinders intermittenly, when at idle(cutting in and out)? The timer base sensors on that era ignition tend to be flaky, in my experience.