Engines not producing power-320 w/ 350 mags

[jxm99]

Went out for a cruise yesterday, boat started up fine and idled out of the marina no problems. once i got out of the manatee zone and throttled up to get going neither engine was producing the necessary power to get on plane. both engines were maxing around 3300-3400 rpm. We usually cruise at around 38-3900.

Boat had 1/2 tanks of fuel and 50 gallons of water. I'm not sure what to think of this problem. If it was one engine i'd be less vexed as to what the problem may be. spark plugs etc... but since its both engines doing the same thing, im at a loss. Could it be electrical? Any help would be greatly appreciated

Jeff

 

[Ididntdoit]

Went out for a cruise yesterday, boat started up fine and idled out of the marina no problems. once i got out of the manatee zone and throttled up to get going neither engine was producing the necessary power to get on plane. both engines were maxing around 3300-3400 rpm. We usually cruise at around 38-3900.

Boat had 1/2 tanks of fuel and 50 gallons of water. I'm not sure what to think of this problem. If it was one engine i'd be less vexed as to what the problem may be. spark plugs etc... but since its both engines doing the same thing, im at a loss. Could it be electrical? Any help would be greatly appreciated

Jeff

when is the last time the bottom was cleaned?

 

[Dalma]

Had the same problem last season boat sat for 6 weeks and bottom (even though painted) was covered in crud! Pulled the boat power washed and was good to go! This should be your starting point!

Jay

 

[jxm99]

boat's been sitting for about a month. scrubbing the bottom is one at the top of my list but the diver comes pretty consistently. I'm waiting to hear back from him.

When you ran yours, was your engine getting overheated? I 'was pushing hard for a while but my temp remained at its usual op temp of between 155-160.

 

[spikeitaudi]

Also make sure you don't have growth on your props. That's a quick check. Had that problem last year.

 

[jg300da]

Sounds fuel related. Just had the same problem with my 2007 350Mag. Gen 3 cool fuel modules, either plugged filters or plugged fuel rails, or both, due to a known issue with paint flaking off and contaminating fuel system. Your boat year indicates that you have the problematic fuel modules. Easy check out, remove the fuel regulator from the top of the module, 3 bolts. You'll need an 8mm wrench. If the regulator is fouled with black paint you found your problem.

 

[Alex F]

The only time I had those symptoms on my 320 is when my scoop strainers and sea strainers would be blocked with eelgrass. Those engines are sensitive to poor water flow and I felt that the SC throws them in some kind of guardian mode. As soon as I clean the blockage they would run like a champ. So, if your running gear and bottom have been taken care of by the diver, then water intake would be on my list of items to inspect.

BTW, I don't know your boating experience, but in case if this is your first boat in the slip, I know that in your area people change the bottom service interval from monthly to by-weekly or even weekly during the hot months of the year. So, if end of May was your last bottom cleaning done you might want to discuss this with your diver.