93 Evinrude 50 hp Idle issues

[1648Grumman]

I just bought a 16' Grumman with 93 Evinrude 50hp. Model #E50TLETB. Runs fine at high speed, but the idle is a bit rough and it will stall after a bit. ( I know you've heard this before. lol) Tried adjusting the idle mix and got some improvement in the rough idle but it still stalls. I thinking the carbs need to be rebuilt. What do you think? Also any info. on this engine I.E. know issues, and reliability. Would greatly appreciated. Got A manual on the way. All in all it seems in good shape other than the idle issue.

 

[ob]

Re: 93 Evinrude 50 hp Idle issues

Does it stall while idling in neutral or in gear?Anyway ,some items that could be causing your idle issue are fouled or wrong sparkplugs,restricted low speed orifices in carburetors,or if stalling when placed in gear and attempting to throttle up.....out of adjustment link/synch.

 

[tashasdaddy]

Re: 93 Evinrude 50 hp Idle issues

before spending money on parts, check compression, and spark with a spark tester.

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

Ok, first to answer your questions, Compression approximately 115 on both cylinders, Spark tests good. It stalls either in gear or out, it seems like it's spitting back as if the idle fuel mix is too lean, but it's milder than what I have experienced when adjusting the carbs. I checked the timing when at idle on the muffs and it was 4 Degrees after top dead center. which I can't believe that is correct! But sense the manual has not arrived yet I don't know what it should be. (Anybody know what the correct setting is? ) I adjusted it to TDC and this made a big improvement. I haven't taken out on the water yet sense I adjusted the timing, I plan to tomorrow. Thanks for your input.

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

Ok, thanks for letting me know the error of my ways! NOT!!!
I see now that the timing setup on a two stroke is very different from a four stroke engine. Glad I didn't burn a piston.

Maybe this site isn't that great after all!!!

 

[ob]

Re: 93 Evinrude 50 hp Idle issues

Who said anything about jacking with the timing?You posted that you had an idling issue and that otherwise the engine operated fine.Did you look into the carburetors?Plugs?What made you decide to make the quantum leap to adjusting the engine timing.What's any of this got to do with the integrity of iboats and its members?

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

My apologies to iboats and it's members, I let frustration get the best of me.:redface:

 

[ob]

Re: 93 Evinrude 50 hp Idle issues

Apology accepted.We're still here to assist in any way we can with your issue.

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

Thanks OB,

After going over everything I found that the o-ring in the manual valve on the Primer assembly was bad. Also there were a few fuel lines that the clamps were not seated in the correct place or missing completely. After taking care of all of these issues. I did a link and sync, took it down to the lake , made a minor adjustment to the idle once in the water and it's just about perfect but while idling in gear or out, the motor shutters about every 30 seconds to a minute it not enough to stall it. It's just enough to feel in the steering wheel and see when I watch the motor. well and if I listen I can here a change in the sound of the motor as if it's loading up on fuel. The needle valves are set, if I turn either one a quarter turn in either direction the motor does not Idle as good. I think I'm going to get some "Sea Foam" and de-carb the motor next. Any suggestion will be greatly appreciated.

Model #E50TLETB

 

[ob]

Re: 93 Evinrude 50 hp Idle issues

Good to hear that you've got an improvement on your issue.It sure won't hurt to run some seafoam through the carbs.I've owned two of the two cylinder model evinrudes and neither one of them idled near as smoothe as the three cylinder models.Sorta the nature of the beast.

You can sometimes improve the idle quality as well by increasing the plug gap to .035" or even .040" if they are presently gapped at .030".

Also insure that the engine is mounted to its optimal height on the boat transom.An engine mounted even 2" too low can cause excessive thru hub exhaust back pressure and cause the engine to labor more at idle.Basically you'd like to have the engine mounted as high as possible without experiencing excessive prop ventilation while executing tight turns on plane at aroud 3/4 throttle.A good starting point is to perform a visual with the boat on the trailer and the engine lowered level with the keel.The anti-ventilation plate which is located just above the prop and runs the length of the lower unit,should be even or slightly above the boat pad just forward of the engine lower unit.The hull design of each boat will dictate what the optimal mounting height will be.If you find that you are able to raise yours even one hole,you may even gain a couple of hundred rpm at wide open throttle and increase overall performance.Stay plugged in and let us know how things turn out.

 

[Silvertip]

Re: 93 Evinrude 50 hp Idle issues

Chances are the plugs are gapped at 0.030. Change it to 0.040. If you are adjusting the carb idle mixture on muffs, that's not necessarily a mistake but you need to touch them up a bit after the engine is in the water. On muffs there is no exhaust back pressure and that affects idle quality. Same applies for idle speed which may contribute to the stalling issue. If you dont have a tach, idle speed will be tough to set but 750 in forward is in the ballpark. Do not mess with timing until you get your service manual. There are two timing adjustments -- idle and wide open throttle. Both are adjusted as part of the link & sync procedure. If the carbs haven't been rebuilt in five years or so, disassemble them, soak in carb cleaner, clean every passage, blow out with compressed air and reassemble with new kits. Then do the link&sync.

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

Thanks for the input! Yesterday on the lake I did adjust the idle mxture and the idle a bit to get the result I had , so I guess Im' on the right track it seems. this afternoon I change the gap from .030 to .040 ( I will test it out tomorrow morning.)and also checked the height of the motor, the anti-ventilation plate is about 3/4" to 1" above the bottom of the hull. If I understood you right that is about where it should be.

The boat run fine yesterday other than the what seems now a minor Idle issue. The hole shot is good, WOT is strong and steady. At throttle up there is no hesatation or ruff running. I begining to think maybe the plug gap change and decarbing the motor may take care of it. I did notice when I pulled the plugs today there were what looked like flakes of carbon on them not a lot. I shined a light through the plug hole and could see some build up on the pistons. I going to decarb it in the morning.

Thanks again for your help.
Chris

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

Ok, Thursday night I check the WOT throttle timing using Joe Reeves method. ( Sense I messed with the timing before.) Anyway it checked out fine according to the sticker on the motor. 19*BTC

Friday morning I took her out an decarbed the motor, during the process the motor didn't smoke as much as I have seen, so the carbon build up must not have been too bad.

The spark plug gap change to .040 did seem to smooth out the idle a bit.

After decarbing the motor I ran through four out of the six lakes in the chain and back, so I got to run her through the paces pretty good and everything went well. late Friday afternoon me and a friend went back out and went to my favorite lake in the chain which I didn't go to earlier in the day because the water level in the canal to this lake very low, but not impassable. I had to tilt the motor up a fair bit to get through. This canal is about two miles long. About 3/4 of the way through the canal running at idle the motor started running pretty ruff and smoking more, after getting into the lake I put the motor back down and gave her some more throttle. She struggled for a moment smoking quite a lot then cleared up and we were on are way across the lake all fine again. The motor did the same thing on the way back.
I'm thinking she was starving for fuel but the oil pump was still pumping its normal amount causing the smoke increase. do you think this is a good indicator that the fuel pump needs to be rebuilt or is there something else I should look at?

Again thanks for your input.
Chris

 

[ob]

Re: 93 Evinrude 50 hp Idle issues

Sounds like the idling for two miles in gear put the idle mix setting to the untimate test and began loading up the cylinders causing it to smoke.Not to mention the carb bowls being at an unlevel angle for the duration while the engine was tilted.

 

[1648Grumman]

Re: 93 Evinrude 50 hp Idle issues

So, I take it you think this to be.. (for lack of a better way of putting it.) A normal reaction to the conditions the motor was put under?
Earlier in the day idleing through the other canals in the chain I didn't have to raise the motor and this didn't happen, so that make sense. This is my first engine with a VRO system. So I'm learning a lot about it here. My 25 on my skiff has never done this through the same canal but it runs on premixed fuel. I guess that makes a difference.

Thanks for your response OB