Volvo 8.1 Missing/Surging

[Viper]

No Oberg filter on a Volvo, not from factory anyway.

[km1125]

Can you describe more the part about "missing on the tach" in the comment "I noticed a surging or missing on the tach for the starboard motor." ??

If you're seeing a quick fluctuation in the tach, that indicates it's not a secondary ignition or a fuel starvation issue, but surging could definitely be fuel starvation (and usually is). If you mean the tach is slowly moving up and down with engine RPMs it's a "following" symptom but if there is quick movement it's a "causation" symptom, meaning whatever is causing the quick movement is likely causing the engine RPMs to fluctuate and that it's related to the primary side of the ignition or what's triggering the primary side (things like a crank sensor or ECM).

[Cooler]

As Viper said, definitely check the tank vent. Could be clogged up with anything. Very common cause for surge at that RPM. er

[Cliffm]

Source of the post I will look when performing my engine room yoga Friday, I didn't see one when I looked last week.

on our 2006 -Volvo 8.1 TBI, the fuel filters are located on the motor, above the bell-housing area.

[tjh408]

Hello again,
Marina tech finally arrived on Thursday (13 days) he found no code issues, and fuel pressures to be in normal ranges. Sorry I don't have the values he found. I did pull the fuel line and remove the check valve from the tank, it was clear and clean. So now I am waiting for a call back from the next Marina tech at an adjacent yard to see when they can look at it. Short season in New England!

[bud37]

Quick question....when he tested the fuel pressure etc was the boat out and under load or just at the dock ?

[tjh408]

Just at the dock.

[Cooler]

Need to get under load to simulate pressure increase. One more thing to check. Any possibility the oil is over filled. Had a friend who put too much oil in one of his 8.1's. Had some surge, but more engine shut off experience. Removed a quart from that side one that solved that. er

[tjh408]

Problem solved! A very simple, but expensive one. The first tech from our home yard spent 2 hours looking at it, checking fuel pressure, engine codes etc. only to tell me "I don't know I'll have to call somebody". My next step was to move the boat to the next marina a where he was going to call. So now we have wasted 3 weeks! They started with a compression check and found several bad plugs, some were loose. So with a fresh set of plugs and re-testing the engine codes and fuel pressure the sea trial was a success! The motor turned 4,200, so I had the plugs changed in the other engine as well. They were tight, but needed to be changed. Disappointed as they were supposed to have been changed last fall right after we bought the boat when we changed the risers. So now I have paid 3 different yards for this, but it runs good now!

[bud37]

Thanks for posting....loose plugs heh, geez what's next.