Until recently, my Universal M25XP produced 2,700 rpm under way. Now it tops out at 2,100 rpm whether in neutral, in gear tied at the dock, or under way. The power is too low to safely leave the dock against tidal currents and wind. It starts easily and the exhaust is clear. The change seemed to have occurred abruptly. That is, I didn't notice with each sail less power than the sail before.
Without causing any change, I've done the following:
- dove below and ensured that the prop and shaft were clear and spun freely while in neutral
- changed both fuel filters
- removed the air filter (temporarily to make sure it was getting enough air)
- checked the low pressure fuel supply at the engine (plenty)
- backed out the throttle cable stop
- messed with the governor adjustor under the cap (This changed the rpm almost not at all, although it got to 2,250 rpm with dark black smoke and oily exhaust discharge); (I didn't measure what I did, so I readjusted by feel and it's back to 2,100 rpm and clear exhaust) Does this seem normal? Should it have changed the rpm more?
What do you suggest I do in what order? Here are some possibilities:
- Mixing elbow
- Fuel delivery at injectors one by one while running the engine by backing off the high pressure supply line to see if I might detect no change, which could indicate a bad cylinder/fuel issue
- compression check
- test injectors
- fuel injector pump system
- governor system
Is there a way to watch the injector mist/spray/dribble there by the engine?
I'm also interested if anyone knows how to properly adjust the governor.
Thanks!
Joe Houska
Luanna
1990 C36 Mk "1.5"
(first year with walk-thru transom?)
Hull 1071
Joe, I'm not sure I understand that you checked the linkage, but I recently had an issue where my engine wouldn't rev over about 1800, a quick check revealed that a clamp on the accelerator cable had worked free and the machine screw was laying in the bildge. Quick fix. That wold be my first check, the linkage.
If you can manipulate the cable by hand to hit 30000, then that's the issue. Next, I'd check fuel filters, then air filter, Then I'd be at a loss.
Capt. Sam Murphy
1994 Catalina 36, Hull 1327
Shoal draft, two cabin model.
Panama City, Florida
Are you sure the Tac has not changed. How is your SPOG compared to before?
Bill Miller
S/V Lorraine
Pacific Northwest,Sound Sound
Grapeview,Wa
1990 Mk1
It's not the accelarator cable, filters, etc.
Is "SPOG" speed over ground? Anyway, it's not a tachometer issue, as the boat is too underpowered to safely manuever the boat around the docks against currents and wind.
I appreciate all ideas
Joe Houska
Luanna
1990 C36 Mk "1.5"
(first year with walk-thru transom?)
Hull 1071
Joe
I'm no expert on our engines.
If I were you I would try and see if all the cylinders are firing. Might try cracking open each injector one at a time to see if they are all equal? If there is a no change, at least you know what cylinder isn't working. I have found dead injectors this way in the past.
If you can measure the exhaust temp somehow for each cylinder, that will also show a dead cylinder. I use one of those IR temp guns. It's going to be harder on our engines because it uses a water cooled manifold.
Do you have a lot of crankcase pressure? Blow by?
Does the engine start well when cold, or due you have to crank it a while? Low compression shows up quickly during cold starts.
Good luck
Chuck
Edit: Just to be clear, When I suggested cracking the injectors. I speaking about the "B" nut attached to the injector. Not removing the injector. There test labs that can test your injectors. If you do buy new, buy Kubota parts. half price of uni's.
Chuck Lennox
97 MKii Ventura Ca
Island Girl Hull #1611
Joe-
Be careful if you remove an injector to visually check- they produce very high pressure fuel streams.
It sounds like a fuel delivery system to me;
-Electric Fuel Pump working?
-Obstruction in the line between the tank and filter?
Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B
Joe
I'm sure you have checked this but I have one of those snap on drink holders on the front of the pedestal.guard. It had slipped down a bit and limited the forward throw of the throttle lever.
Gary Smith
93 MK I, Hull #1231
Std rig; wing keel
M35A Oberdorfer conversion
Assuming your tach is accurate AND you're getting full travel on your throttle cable, concentrate on these components in this order:
Sorry, I have no idea how to adjust the governor. For the most part, they limit the upper end of how much fuel can be dumped into the cylinder based on RPM, but also regulate fuel somewhat to compensate for varying loads. Again, I think when you adjusted your governor you enriched the air/fuel mixture at wide-open throttle without a corresponding increase in RPM. Kinda says to me "not enough air" or "fuel injected at the wrong point in the piston travel". The suddenness of your symptoms makes me lean a bit towards the latter.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Hopefully, you've already checked this, but just in case, did you check the compression release lever for cold starting on the rear of your engine? (it's near the rear of the valve cover and near the air cleaner) It isn't cabled/connected, and it could have gotten knocked open when someone was working on the rear of the engine/changing hoses. I found mine in the incorrect position about 3 months after I bought the boat... There's also a "too far" position, which is past the stop point on the lever, so I think if it's too far over, it also may reduce power. So, make sure it's correct before you start pulling injectors!
Ellsworth Wente
S/V Wind Dancer, C-36MkI hull #256