Rough Idle at Startup then fine

[kkirt1]

I have a 2005 Volvo Penta 5.7 GI-E Occasionally over the last two summers when I start it the whole boat shakes horribly. As soon as I just bump the throttle it idles fine. Other than that the motor performs flawlessly. This spring i replaced the plugs, wires rotor and cap with no change in frequency of intermittent rough idle. Any ideas?

 

[kkirt1]

The boat only has 340 hours. My guess is fuel problem or air. Does anyone know what the fuel pressure should be? What about Idle Air Control Valve? Is there a way to tell if it is functioning properly? I pretty much ruled out vacume leak as as soon as you hit the throttle it idles fine. Any help or ideas would be helpful.

 

[dypcdiver]

Here you go .

 

[Fun Times]

Hi there, without looking up the fuel specs, typically the fuel pressure is in the 50 - 55 psi range with these engines.
http://www.volvopentastore.com/Marin...view_id.765158

Also typically when you first start a fuel injected engine, the engine RPM should go up somewhere around 1000 to 1500 RPM to excite the alternator to get the charging, oil, fuel and cooling system activated. So make sure the RPM goes up on it's own at first start up or it cold idle rough.

If the RPM's don't go up then you'll want to try cleaning the throttle body, IAC and inspecting the throttle linkage. Also check the condition of the fuel filter for water and debris then install a new fuel filter making sure the old filter O-rings are removed from the filter assembly to avoid sucking air. Make sure the filter is on "tight" and sealed properly or it could run that way as well.

How did the spark plugs look?

Hope it's easy to find, let us know, good luck.

Edit, dypcdiver and I were posting at the same time....Nice chart dypcdiver, did Don post that someplace or one of yours? By the way, keep an eye on your private message.. I'll be sending something soon.

 

[kkirt1]

Thanks for the info. I checked the fuel pressure 55 psi key on 68 psi idle. According to the chart the idle number is high. Pressure regulator or not a problem? I changed the fuel filter but haven't had it back on the lake. Any other ideas? This intermittent problem is driving my kids crazy - it feels like the motor is going to jump out of the boat

 

[kkirt1]

I changed the fuel filter and ran $50 worth of fuel injector cleaner through 60 gallons of fuel. No problems now. Thanks for the help.

 

[Lawnpro979]

what kind of cleaner did you use ? courious for my 4.3 carbed volvo

 

[kkirt1]

Sorry, I can't remember what it was. Mid-priced at O'riely treats 20 gallons. I used three to treat a whole tank.

 

[thedinz]

Mine isn't fuel injected but isn't this normal? mine does the same thing until the electric choke opens up. Only for the first minute on the first start of the day.