Rpm's slow to rise

[post42]

I have 892's 735h.p engines. I was out last night and when I was bringing the rpm's up on both engines the starboard was very slow to catch up to the port. The starboard did get up to the same rpm I brought the port to(1900) but it was definately taking longer to get there. I seem to remember someone here mentioning that a faulty turbo could cause this. Any info would be greatly appreciated. Thanks, Chris.
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[Top Shelf]

Simple things first right? Was this on the synchro or idividual throttles. I realize this was at night but were you able to determine if there was any unusal smoke on that motor?

Next thing would be is bottom and running gear clean? I've got a situation that where I dock my boat and the way the sun hits it, I can get twice as much build up on the stb gear than on the port side. Similar issues on RPM when I let it get too bad. But there's always plenty of black smoke along with it and that's the tip off. Check the easy stuff first. Thx.

 

[post42]

This was on individual controls, not the synchro. As far as any unusual smoke I did not see any. The ride over was day light the ride back was dark. The bottom should be pretty clean as the boat is used regularly. I apprciate the input. Thanks, Chris.

 

[Genesis]

If you're not getting smoke you may have a turbo problem and/or a bad throttle delay, or the throttle delay could be set wrong.

The throttle delay is a diaphram device located under the rocker cover that prevents the rack from advancing beyond a certain point until there is boost available from the turbo. Its entire purpose is to make the EPA happy by reducing smoke on hard acceleration. Its only on one side; you can trace the hose going from the airhorn to the cylinder head to figure out which side yours is on (they're USUALLY on the left bank of the engine when one is facing the bow of the boat)

The adjustment is a bit tricky and if its off, sticking, or just plain not working right you can get the sort of symptom you're seeing.

I'd put some gauges on the airhorn and airbox and see what your boost looks like once you're on plane and the engine has caught up. If its ok then I'd check the throttle delay. The only reason to do it this way is that putting gauges on the airhorn is a 10 minute deal where monkeying with the throttle delay requires removing the valve covers and is a bit more work.

The easiest way to see if that's what's causing it is to back it off so it doesn't delay the throttle and go for a run; bring it up slowly (don't slam the throttles with it backed off or all you'll get is a LOT of smoke and burbling for good long time!) and see if it picks up ok. If it does, then the delay was either set wrong, its leaking, or sticking.

They're expensive - I know a few people who have just disconnected them and backed off the cam instead of replacing them when they've had this problem. In extreme cases they can prevent the engine from getting out of the hole at all!

 

[post42]

Karl thanks for the info.I'll look into that and let you know. Thanks so much for your response, very much appreciated. Chris.
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[Nonchalant1]

Like Top Shelf said: simple things first..... change both the RACOR and the final engine fuel filters. When those start to clog, the first symptom is slow to rise. Then won't go above 1800, then stops dead when clogged. Those little final filters will fake you out if you have RACOR vacuum gauges because they're after that gauge. The little final fuel filters can get clogged when you change RACORs even if they're almost new. Remember to fill them with really clean diesel fuel or diesel engine treatment (see other threads) before you screw them back on. They're cheap, so just replace both and go out and try it again. Think how happy you'll be if it was something simple like this.

Doug Shuman