1986 50 HP Evinrude "bogging down"

[weylthing]

Hey guys. First time user, having "bogging down issue" with my 1986 50HP Evinrude.

Getting good spark, replaced primer solenoid, took apart carbs and they are very clean in the main chamber areas. Engine idles with a bit of "jerking" and won't confidently run at low speeds (makes docking boat parallel in the lagoon a real pain) also bogs at WOT (like starved fo fuel). If I manually move that red lever to the rear position on the primer solenoid it will run WOT fine but then stall out when reduce throttle. I read all the stuff related to what this solenoid does and think I get why using this manual adjustment works at WOT.

Timing? Not idling smoothly or at low speed might be timing right? But would timing be an issue if I can get it to run ok at WOT with this manual adjustment?

Carbs? Should I take carbs completely apart (I have seen this small brass orifice/jet being refered to in the float bowl area) and clean again?

Great forum, been quite informative so far.

 

[jtexas]

Re: 1986 50 HP Evinrude "bogging down"

Manually operating the primer floods the engine with gasoline and should kill it immediately(except during cold starts when the rich mixture is needed). Fact that the motor runs like this tells you that gas is not getting from the carb bowls into the cylinders. Because your motor gets it lubricating oil from the fuel, one or both cylinders is not getting enough oil. Continuing to run it like this is guaranteed to result in catastrophic piston failure.

You to rebuild the carbs, but first do some basic troubleshooting.

Make sure the fuel is fresh, fuel line holds pressure, tank is free from water/debris, and the vent is open & clear.

Compression test, PSI should be about the same (within 7% or so) on both cyl.

Spark test (not a "spark plug" test): get an inline spark tester (couple bucks at autozone), set the gap for 7/16", clip it to the engine block, attach the plug leads (one at a time) and look for a strong blue spark while cranking. If it can't jump a half-inch gap in the open air without a spark plug, it's not firing in the hole under heat & compression.

Then rebuild the carbs.

Click on the "top secret file" at the top of this forum and follow the link to "carb cleaning and rebuilding" for good tips including how to fabricate a jet removal tool. Don't use a regular screwdriver, it's too easy to mar the brass jets. Install carb kits, those orings, gaskets and especially float valves & seats do wear out eventually.

Get yourself a manual, to walk you through the "link & sync" (process of syncronizing carbs and spark timing). The idle timing and WOT timing are set separately -- you won't have to reset WOT timing.

 

[chadpcb]

Re: 1986 50 HP Evinrude "bogging down"

So you are saying that you are bogging down at WOT.
Then you turn the primer selonoid and it runs better.
But then it stalls out in the same position when you let off the throttle.

You have a fuel flow issue. When you turn the red handle on the primer selonoid you are bypassing the carb and dumping fuel into the cylinders.

That is why it runs better at WOT with the lever turned and not at idle becuase it is flooding out the motor.

Personally I would take and rebuild the carbs kits cost about $20 each.

 

[weylthing]

Re: 1986 50 HP Evinrude "bogging down"

jtexas, thanks for the info. Definitely going to get a manual. I am going to try your suggestions Friday when I get back to the boat. I will be in touch.

 

[weylthing]

Re: 1986 50 HP Evinrude "bogging down"

chadpcb, yeah you got it, that's what is happening. Got the carb kits and will replace them. Thanks for the help.

 

[Scottycat]

Re: 1986 50 HP Evinrude "bogging down"

had a similar issue, spent 100.00 on kits and carb acid (shipping, etc..)

It was the gas, which was not that old.
Gas went bad, very cloudy.

Runs good now!!

 

[weylthing]

Re: 1986 50 HP Evinrude "bogging down"

ThanksScottycat. Got fresh gas in there so should be okay. But you are correct, the ethanol gas these days can go bad very quickly. Gonna do an in-line sprak test and rebuild carbs Friday.

 

[weylthing]

Re: 1986 50 HP Evinrude "bogging down"

Sucess!!!
Well, first off it's a 1996 Evinrude (not a 1986)...but the carb kits are identical so when I replaced them it was fine.

Here is what I did and I post this in hopes to help someone else doing it for their first time.

1.) Spark test over 7/16" gap--GOOD
2.) Compression test--140psi on both cylinders-GOOD
3.) Cleaned and rebuilt carbs---still had boggin down at WOT
4.) Took apart fuel pump--replaced diapram/gaskets--still had WOT bogging

NOTE: when I would push in electric shoke on key she would run WOT no problem. If I pumped ball while bogging it would NOT solve problem (indicates fuel pump was okay). Asked resident expert at marine repair shop and he said CLEAN CARBS AGAIN.

5.) Took apart carbs again--this time I used a fine piece of wire to poke the casted channels of the carbs themselves to be sure there were no blockages in there (the orifices/jets were easy to inspect and confirm they were clean because they can be removed). Durning one of my "pokes" of the casted channels I felt a restriction and then release..something was in there but it was so small I couldn't even see it when trying to find it after the wire was able to move freely through the channel. Assembled the carbs back together and VOILA!!! Runs better than ever!

Thanks to everyone for their insight and help. It was a great learning experince and I no longer intimidated to get in there and figure this stuff out.

 

[jtexas]

Re: 1986 50 HP Evinrude "bogging down"

yup, it's that last step #5 that gets 'em every time.

Thanks for reporting back with your final results...........