www.iFourWinns.com

2005 Funship 214. Volvo Penta Engine 5.0 GXi-E. SN 3869255 4012155538
I am looking for any successful fixes to the following idle surge problem.
With a cold engine after initial start, throttle at idle position, engine rpm surges from 700 to 2000 rpm.
After several surges the engine quits running. On restart the cycle repeats.
I am able to keep the engine running by adjusting the throttle up and down with the transmission in neutral.
After 3 to 5 minutes the engine stabilizes and idles normally.
No other anomalies with acceleration, deceleration or cruise power.
I have taken the boat to several mechanics and have had no success in fixing the idle surge problem. IAC replaced, tested for suction leaks, fuel system checked, throttle body gaskets checked and bolts torque checked.
No codes come up on the diagnostic.
I am marginally frustrated.

Sounds like classic Idle Air Controller symptoms, but you said your IAC was already changed, and manifold checked for leaks.

Any chance they could try another IAC?
Check all wiring and connections to the IAC.
Possible MAP sensor issue? (manifold absolute pressure sensor)
Possible TPS sensor issue? (throttle position sensor)

Here is a link to a Volvo Penta TBI manual:
http://boatinfo.no/lib/volvo/manuals/md_tbi.html#/0
(see page 75)

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I'll try another IAC and if that doesn't work I'll continue with the MAP and TPS.

I'll post back with the results.

Thanks rpengr

Feel your frustration, my Gi engine is giving me headaches, albeit slightly different to yours.
I cannot recommend getting a proper workshop manual enough for your engine - it will have diagnostics based on symptoms so you can check. Boatinfo is pretty good online for that type of thing.
As others have said, TPS/MAP and ICV are good places to start, in the manual the procedure for testing with a multimeter are covered in the manual.
Out of interest, have the codes been read?

Good luck.

Thanks Jsyphil. The site rpenger lists is a great site for the TBI manual. I hope to be able to trouble shoot the IAC this weekend.