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kirk
MMT F.E.
Joined: Thu Apr 18, 2013 5:52 pm
Posts: 870
Location: SW LA
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 Pulsing at high rpm Motor has stock carb, heads decked 40 thousands, gutted exhaust, pvt cam. First time on water, ran it for about 30 minutes on trailer getting gas out of line and switching fuel pumps.
Motor will increase in rpm very smooth up to about 4200-4300 rpms. Then it will start pulsing like that, with the prop in the water and out. It has high rev coils and I only hit the rev limiter once so I know what that sounds like and this pulsing is not the same sound.
Is it needing more fuel on top end ? Is the governor causing this?
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| Mon Nov 28, 2016 2:29 pm |
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teammarshmafia
MMT Pro Member
Joined: Tue May 14, 2013 2:18 pm
Posts: 478
Location: southeast, Louisiana
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Re: Pulsing at high rpm Sounds like the governor to me
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Gen III Pro Drive with a JBP stage 2 pushin 18x54 madmancustom
Jus nut up and grab a handful of throttle
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| Mon Nov 28, 2016 5:24 pm |
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ronrogers
New Member
Joined: Tue Nov 29, 2016 4:47 am
Posts: 1
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Re: Pulsing at high rpm Thanks for all the good points/suggestions.Engine pulsing is normal at certain rpms. So please be more accurate with your description of "high speed". the pulsing is hard to describe. it varies in intensity, but about every half second the lights will dim by about 10-20% and then go back up to full bright. it varies each pulse in intensity, and if I back off the accellerator to let the car coast, it goes away. if I reapply power to go back to speed, it wont do it for a minute or two. after sustained high RPMs it will start to do it again.
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| Tue Nov 29, 2016 4:49 am |
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T-Bubba
MMT 1000 Club
Joined: Wed Feb 18, 2009 6:43 pm
Posts: 3958
Location: Centerville, La
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Re: Pulsing at high rpm hitting the rev limiter
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I gave up mud motors
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| Tue Nov 29, 2016 5:14 am |
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banded-mallard
MMT 1000 Club
Joined: Wed Oct 07, 2009 8:18 pm
Posts: 4310
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Re: Pulsing at high rpm
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| Tue Nov 29, 2016 11:23 am |
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MaXXis85
MMT Elite Member
Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
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Re: Pulsing at high rpm That is the mechanical governor doing its job by closing the throttle
_________________
Bayou Surface Drive
337-351-0362
Tarkington, TX 77327
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| Tue Nov 29, 2016 3:24 pm |
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kirk
MMT F.E.
Joined: Thu Apr 18, 2013 5:52 pm
Posts: 870
Location: SW LA
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Re: Pulsing at high rpm Alright.. now what are my options to fix that problem or get around it?
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| Tue Nov 29, 2016 3:59 pm |
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Gunshinestate407
MMT Pro Member
Joined: Tue Dec 23, 2014 1:58 pm
Posts: 216
Location: Orlando
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Pulsing at high rpm
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| Tue Nov 29, 2016 4:07 pm |
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banded-mallard
MMT 1000 Club
Joined: Wed Oct 07, 2009 8:18 pm
Posts: 4310
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Re: Pulsing at high rpm
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| Wed Nov 30, 2016 5:52 am |
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MaXXis85
MMT Elite Member
Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
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Re: Pulsing at high rpm
_________________
Bayou Surface Drive
337-351-0362
Tarkington, TX 77327
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| Wed Nov 30, 2016 6:48 am |
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Smoke
MMT 1000 Club
Joined: Fri Jan 23, 2009 1:27 pm
Posts: 1095
Location: SW Michigan
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Re: Pulsing at high rpm If you've got 4700 coils. Why don't you just remove the internal governor all together? Or is this not possible? I have a rev limiter so when I installed my new cam I removed everything inside for the governor and plugged the hole in the block.Seems like messing around with the stock carb and gov is a waste if you can rely on the coils to do the job. But then again, i'm just a shade tree mm mechanic.
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1854 Prodigy Open
HDR/Stage 3 mods
Prodigy Boats Pro Staff
BPS Swamp Staff Member
Blackwater Marine LLC.
Quote classic by rangerp: "Red seemed to be enjoying herself, and I assume by the look on her face was about to hit the high-note and throw a locate as she treed the possum."
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| Wed Nov 30, 2016 11:23 am |
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MaXXis85
MMT Elite Member
Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
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Re: Pulsing at high rpm
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Bayou Surface Drive
337-351-0362
Tarkington, TX 77327
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| Wed Nov 30, 2016 2:27 pm |
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kirk
MMT F.E.
Joined: Thu Apr 18, 2013 5:52 pm
Posts: 870
Location: SW LA
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Re: Pulsing at high rpm
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| Wed Nov 30, 2016 6:11 pm |
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banded-mallard
MMT 1000 Club
Joined: Wed Oct 07, 2009 8:18 pm
Posts: 4310
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Re: Pulsing at high rpm Yes, wrap up spring AND you will have to readjust. You may only have to adjust the screw, but like I mentioned, if the idle starts to creep up from notmal the more you adjust the screw, then you have hit you spring limit. Then wrap about few coils and repeat.
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| Thu Dec 01, 2016 6:12 am |
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