Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

whatasteal

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Jun 7, 2009
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First I would like to thank everyone on this forum for all the great info. I have not posted much because from searching and reading I have solved most of my issues. ie bad starter, dist sensor, etc.

Current issue started a few weeks ago (weekend boater) with low rmp, 3700, at WOT. Should be between 44 and 48. I have covered almost everything on the wot issue list in the adult section. Replaced cap rotor wires plugs 2 fuel filters, anti siphon valve, added fuel/water separator, boat never had one, fuel pressure/vacuum ok, timing ok, compression ok, oil level ok. This past weekend I also noticed it was overheating at very slow speeds.

So, would these two issues, low wot and overheating, lead to impeller/shutter issue? Not sure if I would tackle these as my BYM skills may not be good enough for dropping the drive.
 

jerryjerry05

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Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

Sounds like the points might not be opening or the dwell not set.Did you change props?
Overheat at low speeds could be the impeller(easy fix)J
 

Don S

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Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

I have covered almost everything on the wot issue list in the adult section.
What you haven't checked, is pobably what is causing the problem. Keep checking.

The impeller in the drive is the first thing to check in any kind of overheat situation. Too many things can damage them.
 

jtybt

Senior Chief Petty Officer
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Aug 5, 2009
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Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

Yeah! No special tools needed to do the impeller. The work you've already done shoes you can handle the water pump. Alpha II?

Try doing a vacuum test. connect a vacuum gauge to the port on the intake manifold.


This one of the best sites for vacuum readings. there are two pages.

http://www.users.bigpond.com/ergoff/vac1.htm
 

IVAZ

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Jan 6, 2009
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Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

Sounds like the points might not be opening or the dwell not set.Did you change props?
Overheat at low speeds could be the impeller(easy fix)J
There are no points on his dizzy.


I do agree that the impeller is a likely cause for a low rpm overheat.
I would definitely go thru the whole list like Don suggested.
Just out of curiosity, what pitch prop are you using?
 

IVAZ

Master Chief Petty Officer
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Jan 6, 2009
Messages
816
Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

Yeah! No special tools needed to do the impeller. The work you've already done shoes you can handle the water pump. Alpha II?
Alpha II wasnt out until the 1990's. The title also says Alpha I.
 

whatasteal

Cadet
Joined
Jun 7, 2009
Messages
13
Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

I will work on finishing up Don's list this weekend and check/replace impeller.
Prop is 14x19. Thanks for the feedback and suggestions.
 

Evinrude Boater

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Jul 6, 2004
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1,144
Re: Impeller and/or shutters? What do you think? 1988 4.3 Alpha 1

Is the throttle cable actually opening the carb fully?
 
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