87 Johnson 50 hp VRO - Rough Idle & Stalls

[skelly]

This motor runs pretty good on the top end ,But Idles rough for 1 or 2 min and then STALLS. I have been having a problem with this motor for about 5 years I cant seem to fix It, Here is a list of the things i have allready tried. had carbs rebuilt twice- rebuilt carbs my self - changed plugs-decarb engine lots of times - check for air leaks - replaced fuel hose & ball - new fuel - New fuel tank - sink & link - replaced that valve that you put the engine tune in on the choke - check for arking spark at night,looks good - I have not checked the reeds yet. I also have one Question ,When I squeez the Primer Ball and hold pressur on it ,I can hear a small amount of air escaping from the end that plugs to the motor when It is unpluged, My Question is , Is this normal ? Thanks.!!

 

[fireman57]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

It shouldn't leak. If it is leaking at the hose connection remove the clamp and use a good automotive radiator clamp to reseal. If it is leaking at the connection to the engine then I would get a whole new line with primer bulb and all. One more thing, don't get the cheap aftermarket from Sam's We Sell Everything Cheaper. Get an OEM setup.

 

[skelly]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

Thanks for the advice Fireman57, The one that i have now is a new one but it is an aftermarket, so i will get a OEM I will keep you guys posted, I an sure this is something simple Thanks.............

 

[rauletta]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

I'm not an expert, and I know nothing about the 50hp but just a few ideas.<br /><br />have you tried to isolate the problem to a single clyinder? one at a time remove the spark plug wires (don't forget to ground them) and see if it is a particular cylinder causing the problem. If it is try swapping the carbs between cylinders to rule out that carb as the culpret.<br /><br />- have you checked compression. don't forget that despite "good compression" in each cylinder, uneven compression between cylinders will cause a rough idle. By definition (per. SELOC) more than 5 lbs difference between cylinders suggests a problem that may need to be investigated (although I don't think.I would consider a lower end rebuild for 5 lb diff)<br /><br />- I know the carbs have been serviced but air/fuel mixture problems will cause a rough idle. are you sure that<br /> *the float level is correct. High float level in the bowl, leaking needle & seat <br /> I know this well ... I allowed my 10 year old to rebild 2 of my 4 carbs. one seat was not tightened, and another carb had the wire clip for the needle wedged into the retaining screw for the float pin. both caused a high fuel level in the boal. But there was a gas leaking out of the carbs from the overflow and it may leak into the engine.<br /><br /> * defective choke- check choke solenoid - see manual will need ohmmeter.<br /> *I'm not sure which carb you have but improper idle orifice or inadvertently interchanged idle and intermediate orifices (if applicable) could cause the problem.<br /><br /> * If your VRO is disconnected, and you mix your own - to much oil will cause a rough idle.<br /><br /> - it's pretty easy to visulize the reeds. remove the throttlebody, and the reeds should be visible. see if they are visibly messed up, and squirt some seafoam deep creep into them. they should hold it for a few seconds without leaking. then manually rotate the motor clockwise and watch the seafoam get sucked in. for about 30 bucks per cylinder, and gaskets replace them if in doubt.<br /><br /> - lastly have you checked your check valve in the cylinder drain. If it stuck open it would cause a rough idle (see manual if your engine has one)<br /> <br /> - that is about all I know, hope I didnot confuse you with a lot of jibberish. Good luck.

 

[skelly]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

Thanks Ray for responding - I forgot to mention that both cylinders have 145 lb PSI. I think i did the check right.As for the carbs they are the ones with the set orfices.I also replaced the thermostat and it was stuck open,Engine was not reaching correct temp, that helped a little but was not the fix. I will keep you guys posted............ - Thanks

 

[fishnfiend]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

Hey - I have an '88 40 horse - I'm pretty sure they are the same configuration (idle air bleed at top of carb).<br /><br />Mine idled rough and had low power at idle for years. Had to speed shift into gear and give gas to keep'er going.<br /><br />Finally got serious about fixing the problem. Got a manual, read Iboats posts. My problem was a clogged pickup tube in one carb. The idle circuit has some small openings, and if boat sits for more than a couple months or so, the openings could easly clog with varnish. Used a syringe with alcohol - just squirted it in the pickup tube until alcohol flowed freely.<br /><br />FIXED the idle problem. Idles all day long now.<br /><br />Hope yours is something as easy.

 

[tomil]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

Hey Fishnfiend - I've VRO 40 -87. Probably same congiguration as well. Yours problems sounds a bit similar than I've. Please, could you kindly descipe a bit more in detail what you ment with "idle air bleed at top of carb". I'm a Finn carb only remains me about a fish
Cheers
Tomi

 

[tashasdaddy]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

air leak can cause your problem, there are several aftermarket connectors that look like Johnson/Evinrude connectors, but fit other brands. these are not the correct size connectors. one is too small, the other is too large and leaks air. make sure you have a J/E connector, or if the hose is long enough, remove the connector, and connect it directly to the fuel pump.

also read the carb cleaning in TOP SECRET FILE, most do not properly clean a carb, and a rebuild kit is required, i have several of these motors. also the timing has to be almost perfect on them, as they age.

this past Friday, i did a 70hp your vintage, would not idle, the timing was off 2 degrees, the linkage was off just a little, all complicated into a big problem, of not idling, and being able to shift.

i was the third person to work on this motor for this problem, all of them certified Mechs. none of them fixed it.

 

[aprilia rsv4]

Re: 87 Johnson 50 hp VRO - Rough Idle & Stalls

Have just spent a few hours on carbs, spark and compression at 130 psi on a friends 50hp vro Johnson with the bad idle problem, We found the top pot to be the lazy one. We finally found about .4 of a mil (15-20 thou) side to side play at the fly wheel Which leads us to believe the top crank bearing and seal has failed? Allowing air into the top chamber and leaning it out.