Twin 1989 Evinrude 140's Rough Idle & Stalls

Maybe Later

Cadet
Joined
Sep 18, 2009
Messages
21
I will try to make this as short as possible but I have been fighting problems for a couple of months now & I have tried almost everything.

I purchased the boat a year ago and there were no fuel filters on the port motor and only the in-line filter on the stbd motor. I have removed the screens on the tank fittings (clogged), added water separators/fuel filters and replaced all of the fuel lines including the small carb lines. used metal clamps on the 3/8 line and zip ties on the small lines. Here is what I have done to each motor per the omc manual:

Port Motor: "Idles very rough until 1500 RPM runs fine after that"

Rebuilt Carbs twice (used new kits 2nd time, 2 carbs had #50 intermediate jets instead of #54 so I replaced them with #54. Didnt help)
New Spark Plugs
DeCarbed motor
Swaped fuel pump
Checked compression (all at 130 psi)
Checked Spark (7/16 gap blue spark)
Synched linkages (Idle timing was at 4 deg btdc had to back timing screw all the way to get it to reach 8 deg atdc then it started to backfire so I turned it back to 0. I assume I have to fix whatever is wrong with the motor to sync properly.)
Checked recirculation system
Checked Primer system
New thermostats (both were bad now Idles at 140 deg)
Swaped Power Packs

Stbd Motor : "stalls at idle have to rev up quick and shift into gear will run at 1500 rpms and fine after that"

Did the same as the port motor except 2 carbs had #46 jets so I replaced them with #54. I synched the linkages fine and set the Idle timing at 8 deg atdc (was at 6) motor still stalls.

Anything I have over looked?
 

bktheking

Vice Admiral
Joined
Jul 29, 2008
Messages
5,057
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

Ever inspected the reeds?
 

Maybe Later

Cadet
Joined
Sep 18, 2009
Messages
21
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

visually look at them today through the carb throat. Seem ok, I sprayed some decarb on the reeds and turned the motor over and it got sucked in. Do I have to pull the reeds to inspect? I forgot to mention on the stbd motor 1 cyl has 115 psi instead of 125 to 130.
 

marinemech1

Chief Petty Officer
Joined
Mar 26, 2005
Messages
623
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

Have you cleaned throttle bodies??
Sync and link is critical on these motors check again don't skip step 1 set timing pointer.
Champion spark plugs QL-78YC ( I think) others may make engines run poorly.
Wayne
p.s. don't get to hung up on idle timing as you can increase it to improve idle speed.
Also air boxes should be on for motors to run.
If engine is coughing at idle try plugging air jets to see which cylinder is lean.
 

Maybe Later

Cadet
Joined
Sep 18, 2009
Messages
21
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

I have not cleaned the throttle bodies yet, do I need to remove the metal plug to clean them properly? I did step 1 and set the pointer. I have ql77jc4 plugs gapped at .030 per the manual. I have the air boxes installed when I run it on the water. What will happen when I cover the air jets?
 

marinemech1

Chief Petty Officer
Joined
Mar 26, 2005
Messages
623
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

Yes remove core plugs thats the idle passage part of the carburetors .
Plugging air jets should richen up the cylinder.
Wayne
 

Maybe Later

Cadet
Joined
Sep 18, 2009
Messages
21
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

ok another week has gone by and I think I am getting closer. I used a syringe to add gas to each carb ad it ran. Cyl 2,3 & 4 all bogged down after I added fuel and cyl 1 did nothing even after I gave it a bunch. Pulled 1 & 3 carb and throttle body. everything looked good so I put everything back and swaped 3 & 1 carb. I still had the same problem. I noticed if I put my palm over the carb throat one at a time 2,3 & 4 would suck real hard and gas would flood into the throat bogging down the engine. Cyl 1 it would take 5 or 6 rotations before it would bog down and it felt like it was pulsing in and out, not just in. Does this sound like the reeds have gone bad? I have checked compression and spark and all is good. Is there anything else it could be?
 

Maybe Later

Cadet
Joined
Sep 18, 2009
Messages
21
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

Port Motor: Fixed! problem was port temperature switch, the quick start sensor was bad. this caused the idle timing to be advanced by 10 deg. Bypassed the swith and everything ran fine idles like a charm now.

Stbd Motor:
re did link and sync and the problem was fixed!

Thanks for the help.
 

BenJ-

Recruit
Joined
Dec 26, 2008
Messages
2
Re: Twin 1989 Evinrude 140's Rough Idle & Stalls

Hi "maybe later"
I have 1988 Evinrude 140 which runs very rich on idle. Looks I have similar problem. My question is: how you "bypass" quick-start, grounding white/black temperature switch wire, or?
Thanks in advance,
Ben.
 
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