Throttling Issue / Sensor, Please I need Help!!

[davids94]

i've got a volvo penta 5.8 FSi. it runs great up till about 3500 rpm at which point it throttles down then back up - over and over. I assume this is a problem with a specific sensor but i have no clue as to which one it could be

I blew my 302 around 2 years ago and just took the boat out for its first lake test and had this issue, it's kind of disappointing really especially considering I built the engine. I'm on a students budget so if i can avoid taking it to a shop and having to pay to have them run it connected to a computer I would like to.

Thanks for your help
~Dave
Go Gators!!

[mats]

Is it surging under load? I would guess fuel pressure. Could be anything in the supply of fuel. Fuel pick-up, fuel- filter, fuelpump, etc. This can be checked by measuring fuel-pressure while under load.

[Ted G]

Check the neutral safety switch. On later model Mercs they will do what you say if the computer thinks it's in neutral. On the Merc it will run o.k. if you disconnect the sensor. Sorry, I really don't know much about Volvos.

[Dave_N]

If it is a 1996 or earlier, you may be going into "Power Reduction Mode" which is triggered by low oil pressure or high engine coolant temp. Check the oil pressure and engine temp sensors and wiring.

Are you able to check for trouble codes?

Dave

[davids94]

Its a 1996 model, I'll see what I can figure out from the info you guys offered, thanks I really appreciate it