2003 75hp 2-stroke ELPTO Rough Idle with Video

[Texasmark]

That's what I found in my engines, the 90 hp I had and 115 I currently have. Nobody has nailed, with proof, exactly what it is. It isn't Ethanol because the 90 I bought 2 years old and kept for 10 years I ran on E10. The year ago purchase of the same 2002 year model 115 had been run on Gasoline (E0), which is all I ever put in in it, and had the same kind of crud, choked my fuel filter and cost me a bundle of time and money before I found out my main problem was just a clogged fuel filter.

Confusing thing is that the fuel tank fuel line inlet usually has a screen of fuel molecule size, so I personally can't nail it as tank crud besides I don't have metal tanks, keep my boat in my shop, only buy fresh fuel from respected dealers.

On fuel lines, both engines were running the OEM grey slick (silicone maybe) hose and upon cutting it open on the 90, I found circular pieces that fit the ID of that fuel line but cutting the line itself and bending it back looking for degradation, I found none, no cracks, no splits, nothing but slick hose.

 

[MonkeyBird747]

When I bought the motor the PO included the old fuel line and primer bulb. I didn’t need it because I bought brand new tanks and lines. It was the same smooth grey stuff, and was full of this junk. That’s why I ordered the rebuild kits. The black lines in the engine look clean.

My new hoses are the grey ones also. Might look at some better line. These seem prone to kink and memory deformation.

 

[Watermann]

The new OEM lines are gray, the bad gray primer bulb lines are the cheap Attwood you get at WalMart are the ones that turn stiff in a year or 2 and come apart on the inside.

I now build my own primer bulb lines from good quality parts and see no need for the lined low permeation lines on a primer that is not below deck on my boat.

 

[MonkeyBird747]

Ah, I see. I’ll look in to replacing my cheap ones with something better.

 

[Texasmark]

The new OEM lines are gray, the bad gray primer bulb lines are the cheap Attwood you get at WalMart are the ones that turn stiff in a year or 2 and come apart on the inside.

I now build my own primer bulb lines from good quality parts and see no need for the lined low permeation lines on a primer that is not below deck on my boat.

My question is do you use the old diamond shaped Mercury bulb? If so, what is your source? Recall numerous posts on here over the years about that Merc. OEM at the time vs the football shaped Attwood where they work and the other didn't. Know not why Merc. OEM now has the latter.....cost? EPA......what was the problem?

 

[Watermann]

My question is do you use the old diamond shaped Mercury bulb? If so, what is your source? Recall numerous posts on here over the years about that Merc. OEM at the time vs the football shaped Attwood where they work and the other didn't. Know not why Merc. OEM now has the latter.....cost? EPA......what was the problem?

Not sure where one would find the old style bulbs, I use the Moeller max flow 3/8" primer bulb

.

 

[MonkeyBird747]

Ok, we have a lake test under our belt!

The good news is the motor starts easily, and stays running when I put it in gear. I have great hole shot with the 13-3/4 X 15 aluminum prop that came on the boat. Actually more hole shot than I think I really need, and might look at a new TP SS prop. The motor runs very smooth between 1/4 and 7/8th throttle. The remote trim system works great. I have a very small trim range of adjustment before i start porpoising. Hit 32mph on the gps. Cruise at 28-30 with 3/4 throttle, which is great for us.

Current issues:
The first shot out of the hole had a little hesitation. I enriched the idle mixture, which cured that. However, the idle is back to being rough with lots of sneezing/popping or knocking. Not sure if this is maybe some detonation or pre-ignition? Once I get above 1/4 throttle it smooths out. No manner of adjusting the idle mixture seems to smooth out the idle, until it is too lean and causes hesitation out of the hole.

Around 3/4 or 7/8th throttle is the sweet spot for max rpm and smooth running. At WOT the engine bogs down a bit and I loose a few mph. Pulling it back slightly there is a noticeable increase in power/speed.

I bought an ELING digital tach, but I don't think I have the setting correct, because I was getting crazy readings on the lake at cruise throttle. I'm on setting 1, which I think is incorrect. This makes it hard to tell if my idle RPM is in the proper range. I need my "speed ratio", and the chart they have in the manual doesn't make sense for 3-cyl 2-stroke. Perhaps this is the wrong tach for this application?

https://www.amazon.com/gp/product/B0755JF9FK/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1

The sweet spot for speed on the trim is right where the boat starts to porpoise. I've since raised the jack plate 1.5 inches and will retest. The ventilation plate was still well underwater on plane. A link to video at (almost) WOT.

Boat pulls pretty hard to the right when trimmed on plane. Adjusted the trailing edge of the trim tab toward starboard and will retest.



Motor video:

https://www.dropbox.com/s/h8cmpqw7110nv93/Video Aug 29, 15 23 01.mov?dl=0

https://1drv.ms/v/s!AmWdpg_AjC1qgrEtbZ78RWJRpsckbQ?e=4knBv4

https://drive.google.com/file/d/1K8o68zJ8VQNKAkevvdxJSDdLHJxg1C9A/view?usp=sharing



Tach weirdness:

https://www.dropbox.com/s/3zxfye43hldc06e/Video Sep 14, 18 08 34.mov?dl=0

https://1drv.ms/v/s!AmWdpg_AjC1qgrEr7RPGUur7oMeIcQ

https://drive.google.com/file/d/1zfLv6UEh6H2gwokdYa7qs-oMA3X2DWrS/view?usp=sharing

 

[Texasmark]

Some comments:

A more than required fast hole shot means you don't have enough pitch in your prop and if you had a SS ported prop, either that or the ports were too large allowing the engine to rev up too high too fast. Props like the newer Mercury Laser II has plugs of different diameter holes for getting the right hole shot and WOT performance.

Having your performance fall off at ⅞ throttle setting indicates "to me" that you have an "overrev" module which deliberately cuts out some triggers as you advance the throttle, keeping the rpms "limited" to a certain number. On my 2002 115 2 stroker that number is 5250 and when I was getting used to my newest old boat and running too shallow a pitched prop, you could clearly feel it start cutting out. You need to get some reliable tach information so that you can get the right pitched prop dialed in.

Your (jack plate) height is ok for what you want to do. It's better to have the plate in the water than out unless you are after top speed (on smooth water) as your only concern.

I think 6 is the correct number for these engines on tach setting.

You might get some sea foam and do a "decarb", explained herein or just Google the word. I run premium gasoline (91) in the engine mentioned and what I thought was pre-ignition has stopped....along with Mercury #1 fuel additive available at WM. The other thing I do, since I have a 2+2 engine, only running on 2 cylinders at low rpms, is to tilt the rear of the engine up about 10-15* when going slow. It's amazing how that little trick makes for silky smooth performance and when it's time to punch out of the hole, no hesitation, and no having to clean up the plugs before rpms will run on up to the max available.

 

[MonkeyBird747]

Ok, I'll take a look at that procedure. Interesting on the over-rev protection. Didn't consider that, but sounds reasonable. I've had good luck with the prop wizard on Turning Point site. I'll take a look at the mercs too, because having that adjustment is appealing.

Tried 6 on the tach setting in the driveway with muffs just to get an idea. It was showing around 1200, which could be right if the idle is set too high. The problem I'm having is anything from about 15 to 4 looks reasonable since I don't really know what the actual idle speed is set to. I'll need the manufacturer to give a definitive setting, which is hard because I have to go through amazon. Or get a better tach. I don't have a lot of dash room, and was trying to avoid cutting a 3" hole in the dash.

Tried the multimeter hack to measure rpm, but readings are too unstable. I might try again and see if I can get some verification. Is there a way to determine idle speed with timing light? I think the one I bought has some type of inductive RPM reading feature. I'll have to check when I get back to the shop.

 

[Watermann]

On the SS prop I personally don't think it's a good idea to experiment with pitch using a prop that costs hundreds more than an AL prop and I believe that SS is best used on higher HP motors with performance hulls. The Turning point hustler props have all the latest features and will eat up some RPMs with the substantial cupping, aggressive rake and they have venting to help holes shots.

Have you done the link & sync yet after cleaning the carbs of that gunk? Most of the issues you're chasing sounds to me like a result of not being set up properly. The sneezing is normally caused by a lean condition as is the bogging.

 

[MonkeyBird747]

Link and sync is next. I just have to sort out my rpm gauge first. Other than that it’s trying to find time to drag to the lake for engine run and testing. My understanding is the entire procedure cannot be performed on muffs.

 

[Texasmark]

I bought a little "Digitach" I think is the name of it I think it was 30 bucks off ebay new. You put a strip of reflective tape on the flywheel and shoot it with the enclosed laser pointer getting a digital rpm readout. Just takes a second. The 675 rpm idle setting is a Merc. SWAG for a number which will keep the engine running when shifted and not be so fast as to crunch the gears when doing so.

 

[Watermann]

Link and sync is next. I just have to sort out my rpm gauge first. Other than that it’s trying to find time to drag to the lake for engine run and testing. My understanding is the entire procedure cannot be performed on muffs.

I'm not sure of the exact procedure for your 3 cyl but my 4 cyl Merc just about all the settings are done off the water except for the fine adjustment of the idle air mixture. It ran so well after those adjustments that I didn't even need to make any on water carb adjustments.

 

[MonkeyBird747]

Performed link and sync per manual. The idle stop, wot stop, and cam roller were all adjusted. My oil pump linkage just has a single line, and a notch. The line is in the middle of the notch. I don’t see any other reference mark to match up to the single line. The notch is maybe 1/8” wide?

The WOT timing check under max cranking was quite a bit off. So much that I’m doubting my own adjustment. Lake test next.

Just to be sure - the TDC reference mark is on the port side of the engine. When using the timing light, I’m looking for 20 degrees to be to the left of the zero mark for BTDC, as opposed to ATDC. Does that sound right?

after adjustment I ran it at idle and check the idle timing again. It’s around 6 degrees BTDC. The manual lists a. Rand of 2 atdc to 6 BTDC. Adjusting toward the atdc side lowers the rpm, while adjusting more toward btdc it starts coughing.

on the carb idle mixture screws - the middle carb has significantly more control over the quality of the idle, followed by the top carb. The bottom has a small effect, but engine runs with the screw fully closed. The middle carb has to be more rich than the top and bottom. It is about 2 - 2 1/4 turns out, compared to about 1 1/2 turns on top and bottom.

lots of carbon on pistons when looking though plug holes. Completely black. Looking into decarb today.

 

[Texasmark]

I wouldn't run with any carb screw fully closed. You need fuel mixture to lubricate the moving parts for each cylinder supplied by it's respective carb. 2 ½ open seems to be a bit much. I'd open the lower to at least 1 ½ prior to the decarb process. Don't forget to replace the spark plugs when finished with the decarb.

 

[Watermann]

Yeah in the 20 degrees area is pretty common, sounds right. The oil pump on my Merc has 3 lines on the linkage to line up but if your's set in the middle of the only mark you have then it's good.

With the disparity in your idle air mixture screws I'm inclined to think some of that gunk has gotten in the circuit and needs cleaned out.

 

[MonkeyBird747]

I wouldn't run with any carb screw fully closed. You need fuel mixture to lubricate the moving parts for each cylinder supplied by it's respective carb. 2 ½ open seems to be a bit much. I'd open the lower to at least 1 ½ prior to the decarb process. Don't forget to replace the spark plugs when finished with the decarb.

Thanks for the tip. FWIW, I didn't leave it screwed all the way in. I just noted it during carb adjustment.

I did three cycles of the DUNK method decarb today. Cylinders still look nasty inside. I'll keep running seafoam in my tanks too. Will monitor and maybe repeat.

I repeated the compression check because last time i did it the motor was stuck in forward gear without me knowing. This was also after the decarb. 122 all cylinders now.

Lake test - mixture was too rich. Sputtered out of the hole and eventually caught. Leaned it up about 1/8th and all good. Also, I forgot to mention I believe you were correct about the RPM gauge setting of 6. During the timing adjustment i checked the rpm readout on the timing light with it set to 2-stoke. It was reading about 980, and agreed with the tach with setting of 6. Armed with that information I could now check RPM on the lake at WOT. I hit 5250 about 7/8th throttle as before, and then it started surging/bogging down. So I think you and watermann are right about the prop and the over-rev protection. Fined tuned idle rpm under load at dock in forward gear.

Jackplate was adjusted up 1.5 inches prior to this outing. Now the smaller plate directly above the AV plate is just skimming the top of the water on plane. No blow out in turns. Think I'm good on that now.

Any prop recommendations? I saw mercury laser II and TP hustler mentioned.

 

[MonkeyBird747]

Well I thought I’d make one more post to wrap this up. I ended up putting a 17 pitch aluminum TP prop on, and that eliminated the over rev issue. Wot no longer surges, and RPMs at 5150. Max for this motor according to Merc is 5250. I could probably go up one more pitch, but I’ll run this till next season. Cruising now at 35mph. The last 1/8th throttle travel doesn’t really get me anything more. I plan to check wot timing on the lake, as there could be a small tweak need. But really it’s running so well I will likely wait until next spring to do anything else.

The motor is running well. Easy to start, doesn’t die at idle.Lots of punch out of the hole, and whole lot of fun.

Many thanks to all that chimes in with great advice. One last idle video...
View attachment trim.C4D68F14-A2F5-47B9-819B-683934349B05.MOV

 

[guitarplaya39]

Well I thought I’d make one more post to wrap this up. I ended up putting a 17 pitch aluminum TP prop on, and that eliminated the over rev issue. Wot no longer surges, and RPMs at 5150. Max for this motor according to Merc is 5250. I could probably go up one more pitch, but I’ll run this till next season. Cruising now at 35mph. The last 1/8th throttle travel doesn’t really get me anything more. I plan to check wot timing on the lake, as there could be a small tweak need. But really it’s running so well I will likely wait until next spring to do anything else.

The motor is running well. Easy to start, doesn’t die at idle.Lots of punch out of the hole, and whole lot of fun.

Many thanks to all that chimes in with great advice. One last idle video...
View attachment 326857

My motor acts exactly like your did in the first video. What do you think helped the most as far as smoothing out the idle?