2 Outings - Way Different Results

[Evinrookie]

Took my 67 80HP Evinrude out for the second time this past weekend and the motor acted way different from the first time out. Here is what changed and how the motor acted.

1st Run
Engine ran great. Idled good. Went very fast at WOT and did very well putting around the lake. Just my wife and I in the boat (approx 350lbs combined). Gas was probably mixed too rich because wasn't sure of ratio at the time and a bunch of unburt 2-cycle dripped out when done.

2nd Run
Ran ok. Idled good. Very good putting around the lake. At a little over 1/2 throttle started to sputter a little. From 3/4 throttle to WOT sounded like it was going to stall until I backed it down. Wife, both parents, and I onboard (approx. 850 lbs). Mixed 50:1. Just a little unburnt 2-cycle coming out. I also changed the LU gear lube but I don't think that would have given me the problem I experienced.

My boat is a 15' Crestliner Tri-Hull and I was pretty much at the weight limit. Would the added weight cause the engine to sputter? I know a carb clean is an obvious next step but I doubt the carb would get gummed up enough in that short amount of time. Is there something I'm missing?

 

[iwombat]

Re: 2 Outings - Way Different Results

What were your RPMs with a fully loaded boat? With that much load on the engine any kind of tuning problems are going to come forward. I'd check timing and maybe do a link and sync before rebuilding the carbs given the first run.

 

[tashasdaddy]

Re: 2 Outings - Way Different Results

also have you checked the compression on the motor, the additional load may have shown a problem the lighter load didn't.

 

[Evinrookie]

Re: 2 Outings - Way Different Results

I don't have a tach. How can I check the timing, and forgive me but as the name states I am a rookie to outboards, what is a link and sync? Sounds fun! I checked the compression when I first got the motor and all 4 were just a bit over 100.

 

[tashasdaddy]

Re: 2 Outings - Way Different Results

recheck to be sure, link and sinc, is a step by step, procedure, outlined in the manual for your particular motor. it sets the electrical timing in sinc with the linkage of the carbs, so everthing works together, at the same time. also check the position of your plug wires, the can come in contact with the metal lock on the cowl, and short out, arc across, if the insulation is cracked, or arc to the block. also it cold be clogging high speed jets in the carbs, and it never hurts to rebuild carbs if in question.

 

[Evinrookie]

Re: 2 Outings - Way Different Results

I don't have my manual handy but it is a Seloc. Is the link and sync procedure outlined in that manual? I'm sure I'll find out when I get home but if you know for sure that it isn't I can start looking for a real repair manual now. Any way to unclog the high speed jet port without carb rebuild? I know this motor only has adjustable low speed needles.
Thanks for your help guys.

 

[Silvertip]

Re: 2 Outings - Way Different Results

Have you pulled the plugs to see what they look like? It may be one of them is simply fouled. It costs nothing to look and if they were not changed when you acquired the engine, that would be a good time to replace them, the thermostats and the water pump impeller. As for cleaning the carbs without a rebuild, the process is the same with one exception. If you do not use new kits (gaskets, o-rings, needle and seat etc) you only "cleaned" the carb. Sort of silly to go through the trouble and then put all the old stuff back in.

 

[iwombat]

Re: 2 Outings - Way Different Results

I guess a decent follow-on question is. Does it run well w/o a full load now?

 

[Evinrookie]

Re: 2 Outings - Way Different Results

Plugs are new. I replaced them when I got the engine. I guess by "cleaning" I was thinking more along the lines of using Sea Foam or Deep Creep. Wouldn't a dirty carb manifest itself at WOT even without a really heavy load?

Very good question iWombat. That's exactly what I thought. I was going to drop the family off and take it back out to the speed zone by myself but it was starting to rain so we had to just pack up and go home. If it does run fine with a lighter load your guess about a tuning issue is probably correct. How can I check to make sure the timing is set properly?

 

[iwombat]

Re: 2 Outings - Way Different Results

It could also be that you're overpropped and lugging. You'd check that with RPMs at WOT. Might want to consider investing in a tach.

 

[HighTrim]

Re: 2 Outings - Way Different Results

Engine performance depends on the accuracy of ignition timing and carb link n sync. If major power head components have been replaced, or disturbed the timing pointer, the pointer should be re checked against the Top Dead Centre mark on the flywheel. To check it and adjust:

1. Disconnect the spark plug leads and remove plugs.

2. Temporarily set timing pointer mid way in its adjusting slot. There is a piston stop assembly tool that you can use in number 1 cylinder hole but there are other homemade tools you can use that ppl will jump in and mention how to make. Anyways, install the tool, or whatever, and turn the flywheel clockwise until the piston contacts the end of tool. Adjust the tool to the proper setting (as per your manual) and lock it.

3. Mark a line on rim of flywheel adjacent to timing pointer. Now turn flywheel counterclockwise until the piston contacts the tool. Mark a line on the rim of the flywheel opposite pointer.

4. Using a scale or tape measure, measure the mid point between the two lines. Mark the mid point line on the rim of the flywheel. If the mid point line and the cast in TDC mark on the flywheel are in agreement, the timing pointer alignment is correct. If not, turn the flywheel to align the mid point mark with pointer (hold flywheel in this position). Loosen pointer adjustment screw and move pointer to align with cast in TDC mark on flywheel. Tighten adjustment screw.

5 . Check timing with a timing light on spark plug wire number 1 as per the manual you have. Ill assume you have those directions in there, but if not just ask and someone will be able to help you out.

 

[iwombat]

Re: 2 Outings - Way Different Results

How's the hole-shot w/ just you in the boat? Right up on plane, or does it take awhile?

 

[Evinrookie]

Re: 2 Outings - Way Different Results

I actually just finished looking around the tinytach website that I learned about from another thread on this site. It appears those are for 2 or 3 cylinder engines and I see no mention of using one on an OMC. Any suggestions on where I can find one for my engine?

I also just read HighTrim's reply on a different thread about setting the timing. I'd love to hear about how to make one of those home made piston stop tools.

It appears you guys have dealt with people like me before.

 

[Evinrookie]

Re: 2 Outings - Way Different Results

Got up on plane pretty quick with my wife and I in the boat. The day we had it out there were some other bigger boats in the speed zone (small lake). I caught some air a couple times off their wake. Pretty scary for the first time out, but fun as Hades too. It actually got up on plane a little bit with the parents in the boat too but that's about when it started to surge. It almost felt like it wasn't getting enough gas but the tanks were more full than when I took it out the first time.

 

[HighTrim]

Re: 2 Outings - Way Different Results

1 way to make a homemade one is to gut a sparkplug and install a rod of sorts in it (at a predetermined lenght) to stop the piston against. Not sure how "technical " that is but it works. I have heard others mention other techniques that im sure will jump in.

 

[iwombat]

Re: 2 Outings - Way Different Results

For a piston stop . . .

You can just take a 3/8" bolt and put two nuts on it. Jam the nuts together. Put the end of the bolt down the hole, and shoulder the nut against the outside of the spark plug hole.

You can also use the back end of your dial calipers. All you need is a depth gauge.

 

[Evinrookie]

Re: 2 Outings - Way Different Results

Sounds like a plan. I'm going to try and take it out on the water this weekend to see if it is acting up with a lighter load and then I'll begin the timing check. Thanks for all your help guys.

 

[iwombat]

Re: 2 Outings - Way Different Results

You need the tinytach for 2-strokes. Makes no difference how many cylinders on a 2-stroke since they fire every revolution anyway.

 

[Evinrookie]

Re: 2 Outings - Way Different Results

Okay,
It has been a while but I finally got back on the lake with just my wife and I and it was doing the same thing as with my parents (fully loaded). This time it actually stalled when I had the throttle up. It's very strange but after I've putted around the lake for a little while and then move into the speed area of the lake, she seems fine for a few seconds at high throttle (gets up on plane real quick) but then begins to lose power. It did this 3 times Saturday.

It almost seems like that all that low throttle cruising allows fuel to build up and once I open it up and use that fuel, she isn't getting the gas fast enough to sustain high throttle operation.

As I mentioned before the previous owner installed an electic fuel pump in lieu of a primer ball.

Could this pump not be powerful enough to supply the gas needed for higher throttle or does it sound like something else?

 

[F_R]

Re: 2 Outings - Way Different Results

Good Grief!!! The only timing to do on that motor is the distributor/magneto belt, whichever the case may be. Your seloc manual should tell you how to do that. And the throttle linkage, if somebody has messed with it. Seloc will tell you that too.

Look on the bottom, front of the carburetor. You will see two hex-head plugs. Take them out and look at the ends. If they are shiny bright clean, put them back in, there might not be anything wrong with the carburetor. But if they have a coating of varnish on them, the high speed jets are probably varnished too. They are deep in the holes behind the two plugs you just removed. You need a special screwdriver to get them out. Make you own screwdriver.
http://i155.photobucket.com/albums/s311/frankr_photos/FixedJetScrewdriver2.jpg?t=1191856974

Your problem probably is somewhere between the fuel pump and gas tank. Restricted or sucking air. What's the deal with the dumb electric fuel pump anyway? Do you know if it works and supplies enough fuel?