2100V Normal RPM range

[Zzzzz5]

So I have a new to me 1999 2100V that idles at 900-1100 RPM and tops out around 3100 RPM. From what I've read online the range on the Mercruiser 350 MAG should be more like 600-4500. Is this correct?

It looks like the throttle cable has some slack that is limiting the top end, so I'm gonna dig into that more in the future, but it is hard against the stop at idle. How can I adjust it to idle lower? Walters V-Drive and

[boatwakes]

The mercury rpm range says between 4400-4800 for that engine. However, I would suggest you use a known working tachometer as those tend to be worn out. Tap on the dash to see if it drops at idle. We have a timing gun that displays rpm digitally and use it during sea trial to make sure we have correct rpm.

[chpthril]

Improper prop to V-drive ration pairing will also hinder RPM. Whats the v-driver ratio and prop specs?

[freeheel4life]

Also.....is you bilge staying dry?? Seen more than one "low power" issue related to hauling around too much bilge water

[Zzzzz5]

The mercury rpm range says between 4400-4800 for that engine. However, I would suggest you use a known working tachometer as those tend to be worn out. Tap on the dash to see if it drops at idle. We have a timing gun that displays rpm digitally and use it during sea trial to make sure we have correct rpm.

That’s gonna be my first step before I go chasing ghosts. Borrowing a timing gun from my buddy, gonna go verify the actual rpm’s tomorrow.


[mention]chpthril [/mention]

Here’s the weird part. I’ve got a black Walters V Drive with 1.00-1 gearing and a 537 prop.



[mention]freeheel4life [/mention]

And there’s an inch or two of water in the bottom of the bilge that my pump won’t get. Right now the pump is basically under the transmission, but I’m thinking about moving it forward of the v drive to see if that works better


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[freeheel4life]

That’s gonna be my first step before I go chasing ghosts. Borrowing a timing gun from my buddy, gonna go verify the actual rpm’s tomorrow.


[mention]chpthril [/mention]

Here’s the weird part. I’ve got a black Walters V Drive with 1.00-1 gearing and a 537 prop.



[mention]freeheel4life [/mention]

And there’s an inch or two of water in the bottom of the bilge that my pump won’t get. Right now the pump is basically under the transmission, but I’m thinking about moving it forward of the v drive to see if that works better


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Sounds like water isn't you issue. See boats of this vintage with bad shaft seals dragging around a lot of water and end up so overloaded they cant hit WOT.

chpthril woukd know best, and I cant remember....but I think the 1:1 black box recommended prop was a three blade. If that is the case you are overpropped and it's not helping your situation....but could be wrong as usual lol

[chpthril]

The 13.5 x 16 is a bit much wheel for the 1:1 gear to spin. With that said, id still pursue other engine performance stuff to rule them out as well.

[Zzzzz5]

The 13.5 x 16 is a bit much wheel for the 1:1 gear to spin. With that said, id still pursue other engine performance stuff to rule them out as well.

Okay thanks. What prop would you recommend? I’m at sea level and I’m looking to surf, wakeboard, and slalom.

Ps. I hear you’re the guy to call about some ballast bags. Hoping to tackle that project sometime this summer


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[Zzzzz5]

Sounds like water isn't you issue. See boats of this vintage with bad shaft seals dragging around a lot of water and end up so overloaded they cant hit WOT.

chpthril woukd know best, and I cant remember....but I think the 1:1 black box recommended prop was a three blade. If that is the case you are overpropped and it's not helping your situation....but could be wrong as usual lol

Yeah she takes water through the vent every time I slow down too quick but that seems to be the only real issue. I’ve heard there are a couple different ways of minimizing that problem


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[chpthril]

Okay thanks. What prop would you recommend? I’m at sea level and I’m looking to surf, wakeboard, and slalom.

Ps. I hear you’re the guy to call about some ballast bags. Hoping to tackle that project sometime this summer


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ACME 653.

Yep, I do ballast. I do props as well.

[boatwakes]

The stock prop was basically a 4 blade 13X13 so I agree, too much wheel. Working the calculations, prop should have you around 3700rpm full rack in an empty boat so for sure check actual rpm and report back. Fuel injector failure or other issues tend to contribute so lets go about it one parameter at a time. Also, please verify the throttle cable is actually pushing the throttle plate to full open. You can check that without the engine running and moving the throttle to full value. A DTC computer will also tell you if the throttle position sensor is seeing full throttle too but you can't know without using one, point being the throttle may be opening all the way but the computer may be seeing a lesser value. However, again the prop appears to be too big so one thing at a time.

[Zzzzz5]

Took her out yesterday and verified correct rpm’s with a photo tachometer.

Throttle plate is opening fully, however the last 30% or so of travel produces no noticeable increase in power.

Spark arrestor/air filter thingy is clean.

The distributor and wires look fairly new, but I didn’t pull the plugs or anything.

Gonna check/replace both fuel filters, then fuel rail pressure and injectors.

Edit: and I found a ACME 525 prop to borrow.

[chpthril]

The 525 will be prefect for testing.

[freeheel4life]

Cap, plugs, and rotors are cheap. Either Delco MR43LT or MR43LTS plugs...can't remember until I pull one.

If you have a fuel pressure tester you can hook up to the rail and check pressures while running to rule out fuel pumps. You can also pull the connector off of each injector one at a time. If RPMs don't change that's your dead holes(s). Seems like you are already on that train. Need a job??

[Zzzzz5]

She’s good to go!! Or at least way better.

The 525 prop helped a lot, as did new fuel filters, but a new IAC ultimately solved the problem. It was too rough today to fully max it out but I was able to hit >4500 rpm on a launch.

Thanks for all the help guys!!!