2cyc "Loading up" ?

[jerrypark1]

Sorry for the dumb question, but what exactly is loading up a 2 stroke? I ask because ever since a fishing trip a month ago, (where we did a lot of trolling at low speeds) my 1976 75HP evinrude is acting up a bit. It is slower to take off, idles poorly, and has a bit of a knocking sound. Compression and spark are still good, and carbs are clean. When finally up on plane, I'm now running ~200RPM or so lower than I used to, which tells me that it's not enough for a missing cylinder, but something is wrong. Ideas? I'm planning a de-carb this weekend to see if all that trolling just coked up the engine, but any other thoughts would be helpful. Thanks.

 

[ken1313]

Re: 2cyc "Loading up" ?

loading up to me is the clyinders are not burning all the fuel being supplied ---therefore leaving extra gas in the cylinders causing plugs to foul--rough idle then motor finaly dies--hard to start after this occurs.<br />for whatever the reason too much fuel left in combustion chamers not being burned--<br /><br />sounds like a decarbon for you --<br /><br />mine runs fine on top speed--just rough idle then loads up cylinder w/left over fuel(loading up)--but mine is only doing this on the left two cylinders???<br /><br />hope your decarb works...

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Thanks, Ken. I'll give the decarb a shot....not looking forward to doing it in the driveway since I live in the Rockies....(anytime there's even a little smoke from a tractor or something, the wildfire HotShots are called in. Since I've got a day to work on this thing, I'm planning to finally change the impeller (5-10 yrs old at least!) and the thermostat which I've been procrastinating. Anything else I should do as a preventative maintenance (carbs are already done). Any other possible causes for the symptoms described above....rough idle, loss of 200 RMPs, etc.??

 

[DJ]

Re: 2cyc "Loading up" ?

Anything else I should do as a preventative maintenance (carbs are already done)

Yes, service the lower unit. Make sure and replace the fill/drain plug seals.<br /><br />The decarb is a GREAT idea.

 

[fireman57]

Re: 2cyc "Loading up" ?

In your area you might give the local fire station a call before you decarb with your address because I will almost guarantee the someone will call. Just let them know what you are doing.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

So.....the decarb didn't help, and I'm a bit stuck now. To recap: 1976 75hp Evinrude that was running perfectly, but after quite a bit of trolling at low speed, it runs very poorly....very rough idle to the point of stalling most of the time. And a very slow take-off and a loss of ~200 RPM at WOT, now turning 5200 max vs 5400-5500 usual. Compression is good (110-115 on all 3 cyl) decarbed, new thermostat and pump. Fuel is good and carbs and fuel pump were rebuilt less than a year ago by me (anal engineer). Power pack is only 6 months old and have tried new plugs. Any ideas on next steps? I'm not too thrilled by having to take it to a mechanic....not that I'm cheap, nor do I distrust them, just that I did have it running like a top on my own, and it's a bit of a pride factor now.....Any help is greatly appreciated!

 

[Paul Moir]

Re: 2cyc "Loading up" ?

What plugs and gap are you running?<br />EDIT: Sorry, I just saw where you have tried new ones and you're still loosing 200 RPMS. Still, would be good to know.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

I'm using the Champ QL77JC4 (# from memory but I know it's close to that) Gap at 35. Manual says 30 and I've read in other places that 40 is preferred....I split the difference and went with 35.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Sorry to bump back up, but I'm hoping to get some advice to help me along with troubleshooting. Thanks

 

[joe_morgan]

Re: 2cyc "Loading up" ?

Hi fallen,<br />I have read where users have gone out and everything has been OK, then the next time they go out they have problems. I would say that I doubt the trolling has caused an issue (maybe you could have used hotter plugs for the trolling to prevent loading) but as you suggested the decarb didn't help. Maybe step back from the problem, forget about the trolling (it may be confusing the matter) and just say "OK this thing isn't idling the way it used to, and I have lost a bit at WOT". Maybe a change in approach might give you a break thought. Go back to basics. <br />Sorry there isn't much here for you in this post but I thought it might help you to take a step back and "go back to basics";<br /><br />fuel-ignition-compression.<br /><br />Just one point I picked up - you said the Carb was clean; how do you REALLY know how clean it is. Mighten hurt to strip it let it soak in some fuel (or what ever anyone may suggest as being better) for a day or so then blowing it out with compressed air. The problem sounds fuelly to me.<br /><br />Hope this helps.<br /><br />Joe

 

[Solittle]

Re: 2cyc "Loading up" ?

Take it out again with the hood off and bring a spray bottle of pre mix with you. Bring it up to WOT and when you notice the 200 rpm drop spray some of the pre mix into the carb throats. I'll bet it picks up which could indicate a bit of crud in one of the carbs.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Thanks for the advice. I'm already planning to rebuild the carbs and pump. Cheap and easy way to rule them out. I'll post the results next week when I get them done. I'm not really holding my breath though....rough idle and a bit of top end loss I can understand being associated to fuel delivery; but this "knocking" sound has got me a bit stumped (and worried)

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Well.....carb cleaning/kits and a fuel pump rebuild didn't help. I also pulled the reeds for a close look, and all seems fine there too. Now I'm really stuck. Good compression and good fuel. I got it to idle up to 4kRPM in a tank, and pulled the plug wires one at a time, and each cylinder dropped the RPMs about 1k or so, so I know all are firing. The symptoms are: bad idle to the point of dying, loss of power while throttling up, lowered top-end of about 200RPM. Generally running poorly. This spring, it ran great. When I pull off the cover, it does appear to run a bit better, like it's a bit starved for air (I do live at 8k+ feet), but as I said, it ran great last fall and this spring. Any ideas of what to try next? Is there a clue in the "starving for air" somewhere? The physical setup has not changed at all, and I did confirm that all airways are free of obstruction...

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Forgot to add....plugs are L77JC4 and not QL77JC4...but these same type were used while it was running well too.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Some more data:<br />New carb kits, new fuel pump kit....no change. I'm starting to think it is something to do with air-flow. With the cover off, I can rev up to ~3000 RPM or so, but it is a bit smokey, and some of that is getting back into the carb intake. So when I blow clean air by the carb throats, to keep the smoke from getting in, it will rev up to about 4000 RPM. This is the same when the cover is on too....so when sitting idling, it runs really rough, but when it moving along at speed, it smooths right up. Also, it's still a bit more noisy than it used to be.......with all of this, my thinking is now that there's an exhaust leak under the cover that's causing some problems....has anyone ever heard of this? Is there a place to look for a leak? Or am I way off and missing the boat all together? Thanks, and I'm still looking for some help, so anything is appreciated.

 

[K Hultgre]

Re: 2cyc "Loading up" ?

Have you tried running the engine off a different tank and a known good hose? <br />Try spraying some carb cleaner around the fuel connections to locate a leak.<br /><br />Exhaust leak<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=034354#000001 <br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=034262#000024 <br />look where BassCat starts posting<br /><br />Also, it is bad to rev the engine without a load

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Thanks much. I have been testing in either a barrel or the lake, don't even have muffs. (Barrel is just as easy and you can rev it up that way.) I'll dig through my Seloc manual for some ideas on exhaust leak locations. This motor has always been a bit smokey, but lately it seems a bit excessive.....expecially in a barrel with the cover off, you can easily see smoke making it back into the air intake. I can just blow on it through my mouth and get higher RPMs. Is this something you'd need to remove the powerhead for, or can it be worked on from below?? Thanks again, and I REALLY hope this is the ticket.

 

[lark2004]

Re: 2cyc "Loading up" ?

Just a point, You really shouldn't rev your motor too high without a load on it. If you need to rev it up, you should put in gear, which really means you need to be on the water. I know it's a pain, but if you keep reving it up with no load, you'll be rebuilding the whole engine from the ground up not what you really whant to do yet...

 

[K Hultgre]

Re: 2cyc "Loading up" ?

In a barrel the smoke seems to always be excessive. I use a fan to keep the air clean going to the carbs.<br /><br />What did the old plugs look like when you took them out, were they wet, black and sooty, clean and shiny, light brown, does it look like they have been hit by anything? How about the new plugs?<br /><br />Can you explain the knock? is it rythmic: does it happen when each cylinder fires (exhaust leak) or would you say its related only to one cylinder. Pull plug wires one at a time and see if the knock follows a particular cylinder. <br /><br />I remember reading about a gasket that fails on some it can let water into they cylinder and on another where the manifold is prone to cracking. If you haven't tried use the search (just under the "Post" buttons) and see what you can find.

 

[jfm1]

Re: 2cyc "Loading up" ?

try to regap your plugs at 30. may just be those plugs