Mercruiser 3.0 low wot rpm... Yes another thread

[achris]

Don't remember how many times I have heard "calibrated" but suggest need to remove the term. Next to no regular user will use a calibrated unit. They will use another unit and compare it to the one at the helm. A timing light is no more calibrated then any other unit once it leaves the factory. Only way to get calibrated units is to have them on a predetermined re-calibration testing time line

Hmmm. A digital tacho requires no calibration (like the ones in timing lights), because it's working against an internal crystal (or circuit designed to operate like a crystal) and it becomes just a math/computational solution. As opposed to an analogue tacho (the dash tacho), which converts the frequency to a voltage, which moves a voltmeter needle (and the 'voltage' scale is re-worded to read RPM)... The frequency to voltage components, which is an analogue system, have tolerances, the meter is a moving coil, which is also subject to variations, and will drift with age, and being bounced around, like in a boat...

Agree with you on 'calibrated'.... Let's use 'digital', much more accurate...

Chris.........

 

[aimlow]

That's a nice 'quick check'... I was going to say that the dash tacho is not reliable to check revs. Use a calibrated tacho, or one in a timing light...

The light trick also works for adjusting speed on an gas generator..just don't use the generator to run the light.....

 

[bfeils]

Well I checked the fuel pressure and it seems ok. It bounces between 6 and 7 at idle. I couldn't check higher rpm because it was on the muffs. I wouldn't think it would drop at higher rpm though if anything I'd imagine it would climb although I don't have much experience with carburated engines.

 

[alldodge]

With your pressure being in the 6 to 7 psi (7 is max), and your carb bowl being low, then I would say your float is set to low

 

[bfeils]

With your pressure being in the 6 to 7 psi (7 is max), and your carb bowl being low, then I would say your float is set to low

Plot twist. I wasn't sure which way the inline filter went on after taking it apart so I looked it up. I can't remember which way I had it in before but it may have been backwards. I remember looking it up previously but I think the pic I found had it in opposite of the way I found this time. Anyways after checking the fuel pressure I opened the top half of the carb and the fuel level was a lot higher than before. Didn't take a pic because I didn't want to remove the linkages but it was well above the shelf in the bowl. Probably a good 3/8-1/2 inch higher fuel level. I won't be able to see if it runs any different until next weekend if I can get it to the lake. Fingers crossed.