2000 volvo penta 502 gsi
just bought the boat and went through the motor and replaced heads exhaust and what not. Fired it up and had ruff ideal and backfireing and popping. I replaced the tps and map sensors and the problem has got alot better.But Now it seems to be adding and retarding timming all over the place at ideal timming jumps all over, I pulled the knock sesor conection and still no change. I set the timing with my timming light at 10 degrees adv with jumper wire in and motor at 1k rpm. Pulled jumper wire restart engine and let warm to operating temp shut down, removed dist cap marked #1 cyl on distributor and manualy rolled motor over untill rotor was facing cyl #1 mark. my timing marks on my balancer were advanced 40degrees. I then set timing at tdc manualy and restarted engine and it runns like it is 40 degrees retarted. I have checked dist gear, cam gear, flushed tank of old fuel,checked for spun balancer, and timming chain. I am thinking the reluctor wheel on the distubutor shaft has spun slightly.
PLEASE HELP ME
DAN

The reluctor may have moved, but the timing marks on the damper can also be wrong. Check the timing mark to make sure it is actually TDC.

the chances of the timing marks being wrong are near zero. before you go an inch further confirm what is true. pull number one spark and roll the motor to TDC CONFIRMED on the piston... no other way. check where the distributor is pointing... if its 180 out roll it until its correct... and the piston at tdc.

NOW check the balancer/dist position etc etc. that procedure at least gives you a solid foundation to start.

the suggestion above about the dist itself may be falling apart or a bad pickup is good and a good place to start but the first question i would have to ask is if this all started after you did the work ...
if so then what makes you think that all those sensors went bad all at once and what do you figure caused them to fail in unison like that ?

the answer is most likely that there wasn't anything wrong with them at all and that this issue is going to turn out to be something you did or didn't do when you where reassembling...

think about what you did in the order you did it and the answer is going to end up being obvious.

when I rolled the motor over i pulled cyl 1 plug and stuck a staw in to make sure it was at tdc. And I ran the boat for about 10 mins of ownership before I found all thes probs so Im thinking it was not right when I boaught it. I ordered a new dist and cap and rotor for it yesterday and when it came in today I noticed that the rotor and cap that were on the boat were way wrong, not even gm parts. I am going to start with the cheep stuff first and see if it fixs

A bad plug wire will cause the timing to jump all over the place at idle. As far as the other stuff...you have a lot going on all at once.

Good choice to do the cheap stuff first.

balancer was spun 12 degrees i feel like a retard, I have read many of post about gm balacers spining but wanted to make it hard on my self i guess
thanks for your info guys

I was going to say it is possible for the balancer to spin. Its just rubber in there and can be off once they deteriorate

i would have thought the distributor would have been out a tooth or two to make it search like that im guessing the balancer spun a good amount. i always check my timing marker when i remove the balancer and timing marker.