1992 Evinrude 140 V4 Running Rough

[laminaytrap]

Wow - I thought I lost his post, but apparently the forum just decided to post it. I almost walked away.

This is my first post, so I will introduce myself before I explain my problem.
My name is Jon,
I live in Canada.

I have a history of motor hobbies dating back 15+ years, but not too many 2-Strokes besides basic snowmobile stuff, chainsaws etc.

I recently acquired a 17' JCraft complete with what appeared to be a nice 140 Evinrude motor and trailer for a fair price, with the understanding that both the hull and motor would need some amount of attention to operate properly. It was sold as a 1 year stored boat, with some indication that it was running rough when stored, but good compression.

I have been reading and Lurking quite a bit around here in trying to solve my problems over the past few weeks.

The Problem:

The boat came with an installed plastic 75L (20Gal) fuel tank, with some old fuel remaining.
First order of business was removal and rinsing of the tank with fresh fuel, replacing all lines to the motor (did not replace primer as it seemed to operate OK, checked vent/supply and found no check valves/restrictions) Inline Racor style fuel filter with water separator, deleted original fuel filter on the engine (which appeared very dirty) replaced water pump (preventative - old one looked used but not failed) filled with fresh fuel and premix for a test run. The motor came with the VRO disabled - no tank in the boat. The story was that the motor was bought from a marina and there was no tank - so they always ran premix 50:1, which seems to be a pretty common thing on these motors.

Replaced plugs, Engine fired up ok, so we went to the water for a test drive.

Took the boat out for maybe 20 minutes, idled rough, did not have much power, returned to the dock.

Removed and disassembled carburetors, cleaned all jets and passages with carb clean and compressed air, no significant deposits found in the carbs, though the port and starboard idle jets were different (checked parts listing, this is normal). Reassembled, continued to run similarly, perhaps slightly better (maybe placebo effect)

Ran through <1L of Seafoam and Mixed Gas mixture.
Noted that one side of the motor was running cool, while the other would warm up. Swapped coils port>starbord, no change.

- Checked spark w/>7/6" gap - Strong spark all cylinders
- Battery is charging when running - 14+V
- Re-Test Compression - 125,120+,125,130- (gauge has very small markings) but that should be ok
- Timing Light at Idle - ~6* on 1&2 - They were both the same, and I figured it was too early to start messing with timing.

Starts ok if you prime it, then inject on start, does not Idle well right away and sometimes will require a restart - but once it is warm it will restart right to idle.
It does Idle along without stalling in neutral once it warms up a bit, though there are persistent stumbles and misfires, it smooths out a little if you get the RPMs up - but definitely hesitant to increase RPMs. Will tolerate a significant stab to the throttle and rev up (cannot report rpm as tach is not currently wired)

Visually inspected the tops of the cylinders for washout, all appeared black and sooty?

Plugs are always black and somewhat wet/oily. I assume this is better than dry with a dead cylinder, but at what point do they not run from fouling? How much of a difference does small gap adjustments make to running performance?

I think that is all I have done.

Next steps I imagine are:

- Pull the thermostats and check operation and or replace.
- Check Carb sync visually - I haven't specifically looked at that yet. though I did note that one of the stops had been adjusted from the factory position slightly.
- Hook up the tach as another tool for diagnosis
- Replace or bypass the fuel pump with electric to test operation?
- Check Reeds???
- Carb rebuild kits? - Maybe some of the little gaskets in there are not 100% - or the floats aren't correctly set? (seems unlikely)
- Dropout test - I forgot to do this the other day while it was running


I do have a feed water setup so I can run the boat at home for testing.

I do not have an FSM - Should look into that

Also looking at the pics I remembered that I had a bit of trouble with that exhaust gasket when installing the lower unit, ended up affixing it with bellows adhesive.

-Edit for pics and video link - taking too long, will follow-up with video

Replaced plugs with same as installed



Filter setup


Came with a nice stainless Raker
Pump replacement

Compression Check

Definitely Rough

 

[laminaytrap]

Video of engine running

 

[Bosunsmate]

You should check thermostats as you say, one side should not be cool.
And i wouldnt rev it up like that when not in a tank, thats how they break not being under any back pressure load

 

[Riley C]

Good compression numbers for the engine though. I feel your pain on this engine, I too have a 140hp and Christmas I purchased. With the help of these guys it turned me into a outboard looper cadet mechanic from not much experience previously. Especially with help from Bosunsmate .

Does it idle horrible at around 2k? What's the max revs when you are in the water?

What happens when you are running no thermo's temporarily? Uneven temps? You may need to flush calcium from the jackets.

Regarding your different jet, it's because you may have 397908 stamped on side of carbs as opposed to the 431883 models.

I had a massive issue with bad fuel lines, bad lync and sync previously, I was getting Lean Sneeze from broken reed gasket and the mid range jet sitting on the reeds. It was crazy, I went loco and my wife was pretty keen to get rid of me lol.

 

[racerone]

Where in Canada ?----Have you looked into crankcase compression issues ?----Orange / blue stripe wire on the top cylinder coils ?

 

[laminaytrap]

In Muskoka,

I have not done anything that has not been listed. Will try to take a look at the thermostats this week, though I am not optimistic that they would cause that level of idle issue on their own.

I have not investigated crankcase compression - do you mean like checking the pulse to the pump? Or is there some other diagnosis with regards to that?

Orange blue stripe wire? Is that not just the signal wire to #1 coil? I have checked the spark on all cylinders, is there something more to investigate there?

Thanks for the responses so far, if I don't make much progress in the next round of tests and can confirm that there is good fuel delivery to all cylinders I may try to get it back on the water with a tach and see what I can report.

 

[racerone]

Orange / blue stripe wire goes to # 1 cylinder and #2 cylinder.------Orange / green stripe goes to #3 and #4 cylinders.-----Sky is blue and grass is green so to speak.----There have been issues with sealing rings on the crankshaft on the loopers.

 

[laminaytrap]

My motor has blue, green, pink, and purple leads it seems.

I didn't have much time but I did find this...



I did try stretching them to see if I could extend them, but it only resulted in more pieces.

Therefore I didn't do a drop test or go for a cruise

I'll put in a call tomorrow and see if I can find springs/stats/gaskets

I guess I could try it without thermos and see if I can figure anything else out. I would be shocked if this was the source of my issues.

 

[Bosunsmate]

A cold motor on one side will cause some very weird issues amongst the many that motors can do.
Im too tired to write right now but those thermostats might be vernatherms
So inspect and test thoroughly.
Yeah toying with springs has never worked out for me ever

 

[KG ON]

Common problem on these, lean cough, I believe they sell a thermostat kit that allows it to warm up quicker. They dont usually lean cough quite as bad as yours, sounds to me like you need to do a link and sync. Check the timing but also visually check to see if the cam follower on top of the carb is lining up with the line on the stator plate when the carbs start to open. That'll give you a rough idea of how far out the link and sync is.

Goodluck

 

[laminaytrap]

Thanks for all the replies. Figured I would need to wait for the thermos regardless, put it all back together without them, to see if it as much better, also cleaned/sanded/regapped plugs and ran it. Didn't seem much different,but I decided to take it to the lake to test, as it hasn't been run in the water since before the carb cleanup, and I had a feeling that there was more to be learned under load.

Also noticed the fuel had a pretty strong brown colour to it, must be cleaning out the tank of all the varnish and gunk.

Anyways, put it in the water, idle is still poor. Noticed that my shift rod is out of adjustment, though I tried my best not to turn it when the lower unit was off for service.

Puttered around warming up a bit, then gradually increased throttle. Trimmed up till the porpoising scared me and let off. Almost immediately my feet were wet!
Thought i was taking on water and headed for the launch, but the boat just had a bunch of water in it, must have been from the rain this week. I gave myself quite a scare.

Acceleration was great, jumped right onto plane, did a few passes of the bay over 30 minutes, ran very well up to about 50mph (GPS) where the trim makes it unstable, could also be a bit of transom flex that isn't helping. Jack plate might fix it, or maybe a higher mount when I do the transom work.

Anyways, seems good at speed, will look into the link and sync issue, I did take a quick look and noticed that the port side is opening just the tiniest bit before starboard, but I figured a higher throttle positions this would be less of an issue.

Never got the OMC tach working, I do have a universal unit I will try to get into it this week for testing.

Thanks again for everyone's input!

P.s. I really thought I had a video to show, but I guess I only took a picture looking back.

 

[laminaytrap]

Thought I would bump this thread. Still have not picked up thermostats/springs, but the inlaws wanted to go for a ski this weekend, so I took them out.

Put in new plugs then we skied for about an hour or so before they all got tired out, so we packed up and did a quick blast around the bay while we waited for the trailer to pick us up. Ran fine for a bit, did one pass at about 40mph then picked up my mom and we went to tour another bay. Ran fine on the way out, but when we turned around it started to bog and lose power. Seemed to idle fine and ok up to mid throttle, but wouldn't wind out. I guess I'll do another compression check and pull the carbs again to make sure I got everything.

Need to do brakes on the truck before I do more testing though.

Jon

 

[Bosunsmate]

Yep with that brown fuel you talk of id be starting there and draining that tank

 

[oldboat1]

and replace the racor filter element. Is there water at the bottom (can't quite determine from the pic). The motor sounds normal to me on muffs. Would guess it's much smoother (and quieter) in the water. The water depth to test idle should be a few inches above the water pump.

Repairing and renewing the t.stats should allow it to operate at proper temps all around (about 60C), assuming the passages are clear.