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

Mercruiser not getting rpms
 

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.

Mercruiser not getting rpms
 

Oops ... mid-season, Parking the boat carb dry ...

Mercruiser not getting rpms
 

wrote in message
oups.com...
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


A guess, but possibly a weak ignition coil.

RCE

Mercruiser not getting rpms
 

"RCE" wrote in message
...

wrote in message
oups.com...
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


A guess, but possibly a weak ignition coil.

RCE
Another guess. Wet distributer.

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.

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.

Mercruiser not getting rpms
 

Thanks for the quick replies. When I've figured it out, I'll let you
know.....

Mercruiser not getting rpms
 

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
:-)

Mercruiser not getting rpms
 

wrote in message
oups.com...
Thanks for the quick replies. When I've figured it out, I'll let you
know.....


I have had that problem and it wasn't the engine--the upper gears in the
drive were binding. Re-did upper gears, ran fine.
Just in case you don't find a problem with the engine..
Good luck. Dan

In addition to all the other great suggestions I would also pull out the fuel line pick up. I had a similar problem on an earlier boat. In my case it would get up to 2100 RPM then die or lose RPM's. In my case it was some fiberglass fibers that were in the fuel tank. They had been picked up by the screen on the end of my fuel line. It was clogged just enough to allow anything below 2000 RPM but no more. The mechanic cleared the fibers from the screen and never again was there a fuel pick up problem.