Idle speed ?

[Jcris]

Should there be a difference between idle rpm in neutral and in gear?
Jcris

 

[Bondo]

Ayuh,.... Please don't be postin' in antique threads, the one I pulled this post from is dated 2010,.... 6 years ago,...

Please read, 'n follow our postin' rules, 'n guidelines,...

After 90 days, a thread is an antique, unless the original poster brings it back up,...

Thank you,....

My barge idles 'bout 650/ 700 rpms, All the time, but spec is idle in gear, in the water,...

 

[tpenfield]

Should there be a difference between idle rpm in neutral and in gear?
Jcris

Generally, yes, in gear will be lower RPM's . . . is there a problem related to that that you are inquiring about?

 

[bman440440]

my fresh rebuilt 1997 mercruiser 4.3 LXH (220 HP) in gear 650 and out about 775... now my buddy's 1995 OMC cobra 5.0 AKA Volvo Penta (cross over year) in gear 700 and out 850

 

[SkiDad]

Should there be a difference between idle rpm in neutral and in gear?
Jcris

Yes it's normally 200-300 lower in gear than in neutral. It depends on what prop you have. The speed in gear is the most important number.

 

[achris]

No difference with mine. The MPI ECM takes care of that for me....

Ok, for a carbed engine, yes, lower in gear than neutral. In gear adds load to the engine, so of course that will slow it down (everything else 'remaining equal'. ie, no throttle position change).... Although, that said, some engines are equipped with 'idle stabilizers'.... Older outboards, and the later Mercruiser TB-V also has an idle speed control circuit. As you have a 4 cylinder (not running TB-V) then what you are seeing is to be expected and completely normal....

Chris.......

 

[Jcris]

So it appears a reset of the idle rpm will be in order once I get her back on the water.
But I'm unsure what that rpm should be. This is a 4.3 LX Gen+ with Thunderbolt 5 ignition. The idle rpm should be 650 in neutral not in gear (no load). What rpm should I set it to while in gear?
This whole scenario began when I was having trouble with cold starting. Turned out the fuel bowl was draining down when the boat sat for a couple days between outings. This led to the install of a momentary switch to allow manual filling of fuel bowl, which I will say corrected the cold start issue. I also did a tune up, which included replacement of the water separator, inline fuel filter, spark plugs, cap and rotor. I'm new to boats and marine repairs but not to mechanical work.
All that said, this forum has been very helpful getting this old fisherman up to speed and is very much appreciated.
Jcris