no rpm

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Oct 7, 2013
3
catalina 36 port isabel tx
I have a M-25 universal engine,it idles fine,and starts fine ,when I accelerate in gear it hos no power maybe 1500 rpm max.i replaced the electric fuel pump,and two fuel filters,i have checked all the fuel lines,any suggestions
 

jviss

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Feb 5, 2004
7,089
Tartan 3800 20 Westport, MA
More info, please.

Will it rev up in neutral? How high?

Is the bottom of the boat clean? Prop clean?

A couple of first things to check:

1. shut off cable all the way in;
2. speed control moves freely, all the way up and down;
3. fuel leaks from high-pressure pump up.
 
Oct 7, 2013
3
catalina 36 port isabel tx
Re: More info, please.

it will rev up in neutral to 2200 or so,it all started after I filled up with fuel,no water in filters,i checked ,all controls are fine,no leaks.
 
Nov 6, 2006
10,093
Hunter 34 Mandeville Louisiana
No black smoke? Sounds like a classic fuel supply shortage. Does your pick-up tube in the tank have a screen on the tip of it, inside the tank? all fuel lines thoroughlly bled up to the injectors?
 

Johnb

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Jan 22, 2008
1,461
Hunter 37-cutter Richmond CA
Twice after changing fuel filters and bleeding the system it has started and ran fine under no load but had no power - stalled on being put into gear. A second bleeding fixed it in each case.
 
Oct 2, 2008
1,424
Island Packet 31 Brunswick, Ga
I'll tack my question onto this thread since I have a similar problem:
My Yanmar 3GM 30 revs up to 36K RPM's when not in gear, but only around 2100 in gear. She starts fine and runs smooth. She does not run hot. I have changed the fuel filters (both for inlines, but not the screen in tank). There also is grey exhaust smoke that I have not noticed before. I have cleaned the prop, but there was very little growth on it. It did not make any difference. I have been told that it could be and exhaust problem, but I don't understand why it could rev up when out of gear, and not rev up in gear if it were an exhaust problem.
This is a recent problems as she was running fine in the spring.
So to summarize, does the fact that the engine revs up well out of gear but not in gear eliminate some of the possibilities with exhaust issues or fuel line issues?
 

Blitz

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Jul 10, 2007
708
Seidelmann 34 Atlantic Highlands, NJ
it will rev up in neutral to 2200 or so,it all started after I filled up with fuel,no water in filters,i checked ,all controls are fine,no leaks.
A guy in my marina had a similar problem of not getting higher rpms whether it was under load or not. After struggling with it over the season now he's on a hard so he checkd his pickup tube in his fuel tank and it was partially clogged thus restricting the quantity of flow for higher RPM's. It might be an easy check for you to eliminate this as a cause.

Also, be sure your tach is reading accurately.

Good luck. Let us know when you determine the problem.
 
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