Uneven RPM and Planning issue.

serpico1

I have a 2004 Rinker 312Fv with twin 5.0 EFI Volvo engines and XDP Ocean Series drives.

Both engines appear to be running in-sync at slow speeds.  I do get the ocassional out of wack tachs, but a couple light taps usually corrects that problem.  However, when I  throttle up the boat to get onto planning speed, pushing both the throttles to wide open, the engines go out of sync.  The Starboard engine is running at around 4500 rpms, while the starboard engine is around 3500.  The sync gauge also indicates that the port side engine is running slower then the starbaord side.  Then once the boat is up on plane, the port side engine then catches up to the starboard side and they both run at about 5000 rpm at wide open throttle.  

I have a code scanner that I use for my automobiles, but I dont seem to see anywhere on the engine to plug it into.

 

212rowboat

Merc has a special slave for the scan tool... unfortunately, the OBDII is non-existent on it...

do you have any beeps at key-on?

serpico1

I have Volvo Engines.

Yes, I get the normal audible alarms from both engines as I turn the keys on.

Dream_Inn

More than likely you are not getting enough fuel.  Been there done that, with exact same symptoms.  My regulator was getting clogged with paint.  I've heard it's not just a Merc issue, but also a problem with volvo as well.

 

212rowboat

there is my reading comprehension deficiency kicking in again... :-)

the volvo has its own socket, though.. still you can't use the OBDII... :-(

fuel, fire, air in/air out... and then then the ignition timing and trim game the computer plays with air to fuel ratio..

-are your air filters clean?
-is your fuel pressure uniform? fuel filter on that engine fresh?
-is your ignition system in good order on the ailing engine? (wires, connectivity, ect)  Have you replaced the dizzy cap fairly recently?

I would reckon vp has beeping codes, too... similar to merc, i would further wager..

serpico1

@ Dream_Inn. - thats sounds like a possibility.  I had the port side fuel pump replaced because of the ethenol making the paint inside flake off and clogged the screens on the pump.  I also recently read that Volvo has issued a service bulletin on the regulators make prior to 2008 ( i believe) the old regulators have a screen on them, where as the newer regualtors have whats known as an e-clip. 

As for the rest of the engine. all new plugs, filters, dist cap, rotor where installed this past April.

Dream_Inn

well, if you already had issues, then it may be that the paint got thru to the fuel injectors.  I'd actually bet on it.  At this point, they will need to be removed and cleaned by a professional (or replaced).

212rowboat

contaminated injectors will hang open most often... if there is flakes of paint, hopefully they are above 10 microns in size, and the filter caught them... but it could be, all the same..

is it difficult to start that engine? does it smoke gray-to-black (as in rich) at low RPM?

you may want to get a pressure gauge on the rails of that engine, and get pressure readings throughout the RPM range.. if it is low, this is tattling on either the filter, the pump, or the regulator.. you're lucky in that you have a duplicate engine along side, and can swap the regulator to see if it follows..

serpico1

Aside from the issue at hand. the port engine runs smooth.  starts right up, idles smooth, no smoke at all.

I will pick up a fuel pressure gauge and check the pressure this weekend.  Will also try, swapping the regulators to see if the problems then goes to the starboard engine.

Capt_Steve

@serpico1 ... since most of us have the forum setup to see all new posts, you only have to ask your question in one category for it to get a response. I'll delete the others. 

serpico1

Thanks ofr the info. that saves time