Engine idles but dies when given throttle

Chesapeake

Not the way I wanted to start my Independence Day vacation... I have a 2005 FV 342 with twin Volvo Penta 5.7s with fuel injection. My starboard engine runs fine but my port engine is giving me fits.

It starts and idles fine, but as soon as throttle is applied, is sputters, pops, and dies. It seems to be going lean. I replaced the fuel pump and filter, the injectors, and the spark plugs. I cleaned the distributer cap, and even swapped the computer with the starboard engine. Nothing worked, but it does seem to idle better. I even thought about water in the fuel but the starboard engine and generator run fine.

I'm at a loss about what it could be. Any ideas?

LaRea

If there's water in the fuel filter, that would do it.  I'm not familiar with the VP ... do you have a spin-on fuel filter, similar to an oil filter?  Remove it and dump out the fuel into a clear container.  

Could be there's enough water in the port filter to cause fuel starvation, but a bit less in the starboard filter.  

Dream_Inn

I agree, start with fuel water separator.  

Chesapeake

I replaced the entire fuel pump and filter. The starboard engine and generator run fine so I know it's not water in the fuel.

212rowboat

two things i'd look at: 

knock sensors- will allow the engine to idle when there is a compelling pre detonation, but limits engine to 10% load. 

air lock on the fuel line- enough fuel to run when the engine isn't demanding a lot of fuel, but can't keep up- which will also cause a knock, as well as/because of lean.  go over those fuel lines again- get a towel and open the valve on the fuel rail either while it's idling, right after key on and it pressurizes, or right after killing it.  get a fuel pressure gauge from the parts store- get a reading after key on (after it pressurizes), at idle, and watch it after key off to see how quickly pressure is lost.... hint: if it drops quickly, there is a leak somewhere allowing air in OR it has air trapped.   you should have equal fuel pressure no matter the load or RPM- the engine's PCM demands that in order to trim fuel properly.  My guess is, you'll likely just need to depress the valve stem on the rail until fuel flows. akin to this, and wondering what prompted you to install new pumps/filters- is it possible the rail is fouled with debris? 

and a bonus/other suspect: fuel pressure regulator. 

Chesapeake

Those are great ideas. I will check them out. I am in a holding pattern for now. We had a boat explode in our club today and I am a little gun shy about working on my fuel system.

aero3113

WoW @Chesapeake , is everyone ok?

Chesapeake

Three people were onboard the Searay 240. The captain was fine. His wife was standing on the engine hatches and has a sprained ankle from the upward blast force and his guest has 1st and 2nd degree burns on his lower legs. He is still in the burn unit but will be ok. They were able to get the fire out and the boat back in the slip. They haven't determined a cause yet. 

aero3113

WoW

rinker270nb

It was the IAC when I had those symptoms. Pretty easy fix.  

Chesapeake

I finally got it sorted out. The problem seemed to be the connector to the high pressure pump. Apparently, the Volvo fuel pumps are known to have connection problems after a while of vibrations. I was able to bend the connections in the plug enough to make it secure and it is running great now. Sometimes, it's the simple things.

aero3113

Nice fix!

Dream_Inn

It's crazy sometimes how it is just the simple things.  Glad you found the issue!  Just in time for a nice hot weekend to enjoy!