1894 ELPT 75 HP - Can't get it to idle

[pascoea]

So, here goes. Surprise! An old Merc that won't idle! Serial 6559729.

Backstory, I bought the boat about 2 years ago as "a good runner". Well, long story short, it's not a good runner. Backstory on me, I consider myself reasonably handy, know my way around a garage a bit, but by no means consider myself a pro. I don't have a ton of experience on outboards.

On to the boat:

Last year I was able to get it idle reasonably well, it would idle fairly well, but it was super rough and would occasionally stall. First couple trips this year it was about the same, but now last weekend it just wouldn't idle to save its life. I fiddled with the low-speed jets to no avail.

So last year this is what I did:
New plugs (the ones in the attachments have about a full Minnesota season on them, probably less than 20 hrs.)
New stator and pickup. (Replaced more because the insulation was falling off them)
Replaced any other questionable wiring.
New rectifier. (Wasn't getting a tach signal)
Rebuilt carbs, good cleaning, new needle/seat/gaskets.
Checked timing, this SEEMED ok, but I was struggling to get a consistent reading.
New fuel line, tank to motor, new bulb.

At the end of the season I winterized with sea-foam, the run for a half-hour with a heavy sea-foam mix, then spray sea-foam in the carbs until it dies trick. Bit of sta-bil in 5 gallons of fresh gas.

Prior to the new season, the only thing I did was add a new fuel tank, went from portable to permanent (not sure if that's relevant.)

Beginning of the season, started right up on the muffs. Idled reasonably well, same as last season, rough and would occasionally stall. Topped off the 14 gal tank, and off to the lake. No change in idle quality, but it still ran strong once underway. Then this last weekend, I couldn't get it to idle to save my life.

Cold start seems OK. Set the throttle open a smidge, choke it, starts right up. Let it run around 1500 RPM for a couple minutes. When I pull it back to idle it drops to around 900 RPM, chugs for a bit, then it sputters and dies. Once it's hot, it'll fire right back up, idle for a beat or two, then chugga chugga chugga, dead.

Getting into gear is a fun exercise! But once underway it'll putter around at 1100-1500 RPM just fine, and at wide open it'll get to just over 5000 RPM and push the boat around at 35 MPH on the GPS.

After it started acting up this year I dug into it again:
Compression checked: 130,130,130,120
Checked the bleed hose/check valve (I disconnected the hose at the top, I was able to suck but not blow)
Verified float height was 11/16" (I wasn't able to get a real good measurement, no ruler thin enough, so I'd call it 11/16 +/- 1/16)
Re-set low speed jets, with no success.
Attached are what the spark plugs look like after about probably 20-30 hours.

In a prior thread it was mentioned that the bleed inserts tend to fall out, and that can cause bad idle. I pulled the bypass covers off, see attached pic. I don't know what these are supposed to look like, but to my untrained eye I don't see any sort of nylon/plastic insert in any of the three holes. Prior wisdom suggested an 8/32 set-screw with an .040 hole in it. These holes look to be about the size that you'd shove an 8/32 screw into...

Also in a prior thread, thank you racerone, it was mentioned to "Look at reed valves , labyrinth seal grooves in the reed blocks, bottom crankshaft seals, piston and ring wear, bleed inserts..." From what I understand with this motor, the reed blocks are hidden underneath the bottom of the crank shaft? And others have suggested that the reeds in this particular unit are fairly resilient. Those last suggestions (other than the bleed inserts) would require some serious tear-down that I'm hoping to avoid. Are there any checks I can do to test these that don't involve removing the powerhead? From what I've read about compression testing, the numbers I got seem acceptable, ruling out worn rings?

One last thing that I just noticed... I did the compression check last night, came home tonight and started getting into the bypass covers. As I'm ripping into it, I notice that the starter hadn't disengaged from the flywheel. I have absolutely no clue if that's just the result of me cranking on it without starting it while checking the compression? Or is it possible I just ripped half my engine apart for something as stupid as a stuck starter? I didn't really notice any odd noises while it was running, but I really wasn't paying that close of attention either.

So, there it is. Hopefully the hive-mind of iBoats can offer some insight. (And if any of you are from the Minneapolis/St Paul area, and have some good ideas, I'll ply you with beer and home-cooked steak dinner if you wanna come help me get this running!)

Lastly... My warning to others, when they say "disconnect the battery"... DISCONNECT THE BATTERY ya doofus! See attached pic. This was the wire that runs from the output of the rectifier/regulator down to the start solenoid. This could have ended way worse!

 

[racerone]

Are you sure this is a 1894 model motor ????----Post correct information !-----And look into that wee hole to see if the nylon bleed insert is in there.------Or probe in there with say a match stick !!

 

[jimmbo]

The serial # checks out as a 1984

When you say you checked the Timing, what exactly did you check?
When you reinstalled the carbs, did you ensure both were closed at idle, and did you check the Pickup Timing?

 

[pascoea]

Well, crap. We'll blame that one on being a late night. 1984, not 1894. My bad. Any chance a Mod can fix the title?

As far as they insert, I couldn't see/find anything in there. Probed it a bit with some stainless wire, Couldn't find anything in there. I'll double check again. How deep are these generally installed? I assumed they'd be flush with the casting, or even a bit proud. Or are they typically buried in there? The channels felt like the went back a good distance.

For the timing, went by what was in the Seloc manual. Testing the idle and WOT timing of the #1 cylinder. I did it in a test tank, not on the water though. I don't recall the exact numbers, but they were at what was called for in the manual. When I say I was struggling, at idle I would get a good read on the timing marks, but it seemed like every one of 10 revs would pick up an "off frame" picture. Almost like it was firing on one of the other cylinders triggers.

I've never done timing before, beyond watching a mechanic I worked for set the time on cars. So I don't know if that is expected, or if they should be dead-nuts consistent on properly framing every rev.

And the carbs, I did check/adjust the idle closing and pickup timing. I pulled them off yesterday to verify float height, so I'll double check the timing process when I re-install them.

 

[racerone]

The inserts would be just below the surface.-----If you can touch the piston in the cylinder below with a match stick ( rotate flywheel to feel it ) the insert is MISSING.

 

[jimmbo]

There is no Idle Timing Spec. The idle timing will be whatever it takes to give the required idle speed. There is a Pickup Timing Spec though, at what speed that occurs is really irrelevant, as it is about where the Timing is at, at a particular part of the carb opening

 

[pascoea]

I came across this yesterday while doing some searching. What are your thoughts on this process? Novel approach to setting the timing, quite a bit "off-book" as far as setting the max advance.

https://www.youtube.com/watch?v=wop30aYYqqE&list=WL&index=5&t=0s

 

[pascoea]

Well. Fingers crossed, I think I got it sorted out. But, it would be awesome to get a double check.

I replaced the bleed inserts, and as suggested all 3 were missing. While I was screwing around in there I replaced the fuel pump gaskets and membrane, and cleaned the spark plugs up. (And replaced the wire that I cooked)

When I fired it up I still couldn't get the damn thing to idle. So I started digging through link and sync in the manual and got it to idle as expected. But this is where I'd like the double-check.

Manual references a "primary pickup cam" but the picture isn't super clear. I'm assuming the "primary" pickup would be the first one to actuate the carb cluster pin as you throttle up. (Thereby assuming the "secondary" is the cam that opens the throttle plates to 90 degrees at full throttle) Is that accurate?

From idle, how much should I expect the throttle arm to move to get the primary pickup to touch the carb pin? With the way I have it set up, the idle screw holds the throttle arm far enough forward that I have to back it off in order to get the pickup off of the carb pin, meaning that at idle the pickup is touching the pin. And at idle, timing is set to 7 degrees. Does this seem right? It's the only way I could get it to idle...

I guess a more straightforward question, what should occur first when advancing the throttle? Should the timing start to advance before the throttle plates open, the other way around, or should they be perfectly in sync? Mine are in sync. This is how I see the sequence happening the way I have it:

- At idle, throttle plates are fully closed, timing is at 7-8 degrees.
- As soon as I start moving the throttle, the plates start to open and the timing starts to advance.
- The plates stop opening at about 5-10 degrees, timing continues to advance.
- Timing stops advancing at 27 degrees (plates are still only slightly open)
- Plates then open up to full-open

That sound right?

Again...you guys are awesome. I don't know how you put up with guys like me, but either way, thank you for doing it.

 

[jimmbo]

At idle the carbs will be fully closed. As the throttle is pushed forward, the timing will advance and the carbs will remain closed closed until the primary Timing Spec. After that point, the carbs may open a very slight bit as the timing continues to advance. After all the timing advance is in, will the carbs open fully. A timing-carb relationship like this, allows for high RPM will a closed carb, but full timing, resulting a big gain in fuel economy at speeds around 75-80% of WOT

 

[pascoea]

After sleeping on it, it makes perfect sense. At the point where the primary makes contact the advance should be at the primary spec (now that I say that out loud, I feel dumb, lol.). And the advance at idle should be whatever it needs to be to get the desired RPM.

Which, is exactly what you said a couple of posts ago, Jimbo.

I'll update when I get it out on the lake!

 

[pascoea]

I know you were all waiting around with bated breath to hear if I got things running or not.

I'm willing to bet 90% of the problems I've been chasing around since I got the motor was related to the minimum advance setting. After all the futzing around last year I hadn't touched that adjustment. When I verified it, based on the procedure outlined above/in the manual, it was set around 0 degrees. When I got it set to 6-7 degrees, and the thing idles like a champ. (This took two attempts, as apparently I didn't set the jam nut tight enough the first time and the friggin thing backed itself all the way off, setting idle timing to 4-5 degrees ATDC. Oddly enough, it wouldn't idle at that setting!)

I appreciate your guys time and patience.