Volvo 8.1 Gi hunting for idle - where to start.

[Silverbullet555]

Have a 2002 VP 8.1Gi that likes to hunt for idle after running at WOT. The motor has about 325 hours on it, regular maintenance, new filters, good gas. I boat in fresh water and the batteries are fully charged.

When hunting for idle, the RPM range will move between 750-1000 rpm. It never stumbles or tries to die out. It just hunts for idle.

Where should I start looking?

 

[Don S]

Re: Volvo 8.1 Gi hunting for idle - where to start.

The first thing you do is start with the basics, check the ignition system ( how long since last tuneup ?) check the fuel filter/water separator for water and contamination. Do a compression test Here's a link on how to do one properly. http://www.boatfix.com/merc/Bullet/97/97_25.pdf
It's from Mercruiser, but it's almost word for word what Volvo had around the same time. it came from GM.

What's the full model number of your engine 8.1Gi-??

 

[Silverbullet555]

Re: Volvo 8.1 Gi hunting for idle - where to start.

It's an 8.1 GI-B

Been about 50 running hours since tune up and the tune up was completed in 2007. Most of our time on the boat is spent at anchor.

Compression checked at same time, but I will do it again.

Thanks for the starting points. It will be a couple weeks before I get to those, but I am preparing myself so I have a game plan.

 

[Don S]

Re: Volvo 8.1 Gi hunting for idle - where to start.

and the tune up was completed in 2007
Compression checked at same time, but I will do it again

4 years is a lot of sitting, which causes more problems to engines than actually using them.

 

[Silverbullet555]

Re: Volvo 8.1 Gi hunting for idle - where to start.

4 years is a lot of sitting, which causes more problems to engines than actually using them.[/QUOTE

It is a long time. I should provide clarity, the boat did not sit for 4 years. We use it all summer long each year. Our lake is pretty small so we can cover it pretty quickly. We normally go out in the afternoons, cruise a bit, find a place to anchor and then swim/relax for the afternoon, then go home. A day on the lake may only be 45 minutes of run time for the motor.

That being said, I have a place to start and have printed the document you posted above. Thank you for the procedure. I have the VP service manuals and I am sure it's in there as well. I'll need to pick up a pressure gauge and then will get to work. One question on it, it says nothing about fuel supply. Should it be disconnected for this so fuel is not injected into the cylinders or does it not matter.