Logo
FULL SITE MENU

omc 3.8 low rpms

R

rogers57

New member
need help! I bought a 1983 sun ray with an omc 3.8. It had been sitting for 5 years. Put fresh gas in, changed plugs, rotor points and condenser. Checked timing and it's at 10 degrees tdc(as engine plate and manual state). Rebuilt the carburetor, checked fuel filters and lines. It will not go over 2000 rpms. When pushing throttle farther, after 2000 rpms, it sounds like it's trying to suck air into carb and starving for air. Then the rpm indicator goes down to 1000 and engine bogs. What else can I do? Also, it does it on the river and in yard with earmuffs. Disconnected out drive so ball gears weren't engaged so I could rule out the outdrive gears and it still does it. Runs perfect at idle and does have a miss while at 2000 rpms. Water was in engine oil when I got it, changed oil and filter twice, no water in it now. Figured water got in thru carb while sitting, no water in oil under valve covers and was not mixed when I drained it. Any suggestions? Is it the timing?
 
start with compression test of the engine, then I would remove the points plate from the distributor and do a visual check on the advance weights and springs under there - common for them to gum up and rust and stick at the 10 degree setting instead of advancing properly.

triple check the firing order and verify throttle linkage working through full range. Observe ESA switches under way to make sure the ESA isn't staying engaged due to a shift cable issue.

was the distributor ever removed during the work?
 
hystat said:
start with compression test of the engine, then I would remove the points plate from the distributor and do a visual check on the advance weights and springs under there - common for them to gum up and rust and stick at the 10 degree setting instead of advancing properly.

triple check the firing order and verify throttle linkage working through full range. Observe ESA switches under way to make sure the ESA isn't staying engaged due to a shift cable issue.

was the distributor ever removed during the work?
Click to expand...

The distributor was never removed. I'll check what u said today. Ohms on coil were good last night, 1.7 on primary and 9.6k on secondary. I did notice the nut on top of distributor shaft that moves points contact is rounded on 4 of the 6 peaks...taking boat to mechanic friend to look at it and the advance weights and springs this morning. Thank you.
 
Just pulled carb to take to mechanic friend. I took boat to him this a.m. and ran it for him. He showed me that one half the carb is not getting fuel, just dripping into throat. He says because it sat so long it's probably plugged, going to drop it into parts tank to clean it up. Will give update. He told me I didn't "rebuild" carb, just replaced gaskets and spray cleaned. Know better now!
 
3 of the distributor lobes should be rounded and 3 sharp- that's why I was asking if it had been removed - there's a 50/50 shot of indexing #1 TDC to the correct lobe. (the 229 is a bit of a weird motor)
 
Back
Top