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Mercruiser not getting rpms
Last time I took the boat out 2 weeks ago it ran like a champ. Today
it wouldnt run over 1800 rpms. Talking about a 1990 merc 5.7 260hp -
alpha one drive. The boat starts and idles great. In throttle only it
revs as high as I dare but put it in gear and 1800 max. I think the
ditributor is good with good timing and no wires crossed. The throttle
body has full movement and peering down the carb looked like it was
wide open. The boat wasnt used much last year and of course sat all
winter. Just wondering what you would look at first?I could get much higher rpms in reverse but probably due to the prop
taking less of a bite of water. Any body had something similar?? Thanks Joel |
wuz-up-
Mar 17
2006
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| May be carb jet problem ... without being there ... try coaxing it over
the 1800 ... I had some carb jet (I assume) blockage (could have been
water) that went away with a little coaxing. I store my 4 bbl carb dry
(1983 not yet rebuilt) ... I installed a fuel shut off so I can run the
carb dry. In the spring, I top the fuel bowl up through the vent with
carb cleaner, let it sit, then start it up. I keep saying I'll do this
mid-deason but haven't yet. Parking the boat carb is keeping the float
from becoming saturated, jets from gumming up and so on ... well,
that's the plan. You might try that ... run the carb dry, top up with cleaner, ... You should pull the plugs and check them. This imo is something to be
done every month or so .. especially with an older engine ... as
mentioned, mine's an '83. Your plugs tell you all about your engine
condition including if your risers etc might be leaking water ... very
useful to know before destroying the engine :-) Anyway, you asked what would "I" look at first, and those are it. |
bowgus
Mar 18
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| Oops ... mid-season, Parking the boat carb dry ... |
bowgus
Mar 18
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| A guess, but possibly a weak ignition coil. RCE |
RCE
Mar 18
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| Another guess. Wet distributer. |
JIMinFL
Mar 18
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| Fuel flow. Check that the filter isn't clogged and that the pump is
delivering effective pressure. Fuel filters are cheap, if you haven't
replaced it 'recently' then now's as good a time as any. Consider getting
one that has a clear housing so you can see if there's gunk accumulating. Doesn't take much fuel to crank up the revs when there's no load on the
engine. But put a load on (in gear, moving) and it takes a lot more fuel.
If the pump can't keep up or the flow's being restricted then you get stuck
at lower revs or it stumbles. |
Bill
Mar 18
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| Thanks for the quick replies. When I've figured it out, I'll let you
know..... |
wuz-up-
Mar 18
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| Fast replies ... has something to do with last night ... all that green
beer, and ... geez, don't think I'm going anywhere for a while today
:-) |
bowgus
Mar 18
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