496HO Not Spinning up...
 

Took mine for a quick lap last weekend, and I found my starboard engine not wanting to do it's fair share getting up onplan or running. Pushing wide open the stbd only spun up to approx. 3500 rpm while the other was doing all the work and working hard at 4500. Starts/idles fine and no alarms not does it act like the guardian kicking in.

Any thoughts?

I'm gonna check the fuel pressure first, pull the fuel separators and check the fuel condition (had a bad gas problem last summer thanks to Ethanol) then pull a couple of plugs to see what shape they're in (215 hours).

I'd start by connecting it to a scan tool.

Make sure you didn't have any plug wires come off.

I went thru a fuel/ethanol problem last year and had to replace both boost pumps, and numerous separators before it started running fine. Also had it scanned and it read out fine. Now it sat over the winter and now this.

I'm hoping after doing the stupid-simple stuff mentioned above it'll be fine. If not, then I'll have another go-around on the scanner.

if its left over winter fuel you are running change the filters and add some fresh fuel to it

Have experienced issues with the injectors, there is a very fine screen at the top of the injector, they clog. This paticular boat was an older one repowered with a 496. The ethanol loosened up sediment in the tank it went through all filters and to the injectors. No codes found & had perfect fuel pressure, removed injectors, blew the screens out and it ran fine.

Just had a similar prob. on a 496. Make sure all cyl. are firing! Simple test if you can get to the bottom of your exhaust manifolds, Touch each one before it is warmed up and you might find one of them colder than the rest.I scanned the injectors,everyone passed...ohmed every injector,all passed...Cut each cyl. one by one and #4 was it....swapped #2 and #4 injector and then #2 was not firing! But every scan tool test said it was working fine..:rolleyes:

Well I'm basically hoping this ios my issue. Early january I fired it up to flush again, circulate the oil, and charge batteries while on my lift. I had took the practically empoty approach to winterization. I went thru roughly 10-12 separators last season to clean out my tank in my 2005 boat. The last spearator change showed good clean fuel when poured into a jar.

Anyway, while running it the one motor died and I'm assunming it ran out of gas. I rpomptlt went and got a five gallon can of fuel, mixed all the potions avaialble off the shelf, and put it in. I then fired it back up. I noticed it started idling crappy and decided to check it again later. Now it's later. I'm hoping when it ran dry, it in fact clogged up the separator maybe with some remianing bottom garbage from last season since it was well settled by then from lack of movement.

In the meantime I will use your tips for checking the injectors once all else fails.

Speedreeder once you found your issue, what was you fix? New injector harness? If so how much?

Given the fuel issues that you have had, checking/replacing the injector screens is an excellent idea.

Dave

Sounds good to me to check regardless. So what's the basic 101 backyard mech approach to accessing the screens and blowing them out?