Offshoreonly.com

Offshoreonly.com (https://www.offshoreonly.com/forums/)
-   General Q & A (https://www.offshoreonly.com/forums/general-q-20/)
-   -   Rpm issue ideas.... I'm lost.... (https://www.offshoreonly.com/forums/general-q/340112-rpm-issue-ideas-im-lost.html)

Full Force 08-10-2016 07:13 PM

Same tank, 1/2" pick ups, no screens, monitor fuel on dash and also at rail it's good, also running rich on wideband, still leaning to ignition/wiring


Originally Posted by monster12valve (Post 4469532)
Anyway it could be a fuel flow issue... After the reg... Or where ever your reading pressure? And maybe the load difference from the dyno and the boat makes the problem occur? Sorry if this all sounds dumb.. Just sounds like you covered most everything... So just trying to think of the oddball things. Do both motors feed from same tank? Maybe anti siphon?


Full Force 08-10-2016 07:14 PM

Can't remember exactly but we barely had heat in them just like boat, we also did a a good 10 pulls each engine along with a sustained 4200 pull for at least 3-4 minutes to simulate a cruise speed.


Originally Posted by phragle (Post 4469537)
Again, different motor stuff but a thought.... How warm did you get the motor on the dyno?? full heat soake operating temp like sustained running?

I have seen things manifest themselves, airleaks, casting pourosities etc only after the motor is completely and totally at operating temperature.

Something like that might not show up after a quick warmup and dyno blast, but after 10~15 minutes of actually running with a load would show up.


Full Force 08-10-2016 07:14 PM

Correct, I am one of the few that run a wideband full time in a boat, especially with N/A

Originally Posted by Mr Maine (Post 4469534)
If it was that, wouldn't it show lean on the Afr gauge at wot?


phragle 08-10-2016 07:22 PM

Your engines are simply cursed. You either need to sacrifice a pool party chick at the alter of purgatory or start over with merc 1350's and let the warranty deal with it.

Full Force 08-10-2016 07:31 PM

I don't think this boat or even my Baja ever ran 100% more then 6 times combined, it's getting old!!!!


Originally Posted by phragle (Post 4469550)
Your engines are simply cursed. You either need to sacrifice a pool party chick at the alter of purgatory or start over with merc 1350's and let the warranty deal with it.


bck 08-10-2016 07:32 PM

Any chance there is nothing wrong at all but one of the tachs is screwed up?

Full Force 08-10-2016 07:55 PM

I swapped tachs, also since I swapped I have a new set.


Originally Posted by bck (Post 4469562)
Any chance there is nothing wrong at all but one of the tachs is screwed up?


Mr Maine 08-10-2016 08:13 PM


Originally Posted by Full Force (Post 4469543)
Correct, I am one of the few that run a wideband full time in a boat, especially with N/A

Yes I have a wide band as well

bck 08-10-2016 08:19 PM

Is the motor that is down in rpm the one that was making a little less power on the dyno?

Full Force 08-10-2016 08:32 PM

no, port made 632, star 629 the port is down.

Just came in, swapped Dist and put a new coil just because I had it, brand new one...

after doing that, I checked voltage on port coil + to ground and it was 15.6, seems AWFUL high, was getting late so wife was *****ing about revving engines out back, so I did not check against starboard.... but I found notes from when I did a check a few weeks ago that I forgot I did, that note shows at coil + to ground Star=15.8 and port=16.8!! now, maybe for some stupid reason they were not charging that high on Dyno but do on boat? and even with starboard at 15.8, that engines runs great right to 5500 all the time, so I am even more lost now, but feel I am heading into right direction... what a F-in pain!!!!!


Originally Posted by bck (Post 4469587)
Is the motor that is down in rpm the one that was making a little less power on the dyno?



All times are GMT -5. The time now is 04:59 AM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.