Help My AQ131A is eating spark plugs

I have an 18.5' bayliner w

I have an 18.5' bayliner with cuddy. I lost rpms and couldn't get on plane. I pulled the spark plugs to find that the #1 plug electrode and all had been apparently melted off. I at first thought that it was a defective plug. I replaced them and the boat would run for 5min at wot and then I would lose rpms to fouling plugs. I suspected a carb problem at first but now I think I have an ignition issue. I read an older posting with the exact same problem posted about a year ago but wasn't able to draw a conclusion from it.

"if its melting the electrodes

"if its melting the electrodes, it's getting real, I mean REAL hot.....
Are you using fuel additives? What type of fuel are you using? Is there an intake leak?
How does the boat run? High idle? Need details....."

"also check your timing, point

"also check your timing, points settings. I also agree with Eric sounds like that cylinder is running very lean I.E. Very hot.."

"I've been running premium

"I've been running premium in it since about the middle of last year. The guy I bought it from used regular. I saw the octane requirement on the air cleaner of 88 and immediately started running premium. It eliminated spark ping and I noticed more power until recently this year. I started noticing power loss again. It was taking longer to plane even with just two people. The previous owner claimed he put new plugs and wires on not too long ago. I decided to put new plugs in figuring maybe the low octane had taken a toll on them. I put in E3's a new performance plug that was a cross reference for the Bosch W6DC on the air cleaner. It started right up in the driveway. I put it in the water and idled out for about 5 min and then went wot. It was hell to get on plane with only three people. I didn't make it far and had to idle back to shore. I checked the plugs there and noticed the electrode on the #1 plug was gone! I thought I got ripped on the plugs. I got more (densos) and went right back out. It didn't plane as quick as it should have but it was as good as before. I rode around the lake for the next couple of hours no change. I figured my suspicion was right. I took the boat back out the next week, put in some stp carb and fuel system cleanerand topped it off. Went about 5 miles at wot and started losing rpms quick. I was able to idle back. (long ride). Pulled the plugs, #1 appeared ok but flooded and #4 wasn't much better. The next morning I put brand new autolites in and a new fuel filter, rode for 5 min at wot, same thing. Plugs fouled but not damaged. I thought needle and seat, now I'm not so sure. Seems like a lot of guys do what I was going to do which was run out and get a new carb but I've read a lot of similar complaints and this didn't solve their problem. This boat just ran so well before this. I read about this same problem (disappearing electrode on the #1) on an older forum and would love to know how that guy made out."

"Dude!!!!!!! Don't mess wi

"Dude!!!!!!! Don't mess with the manufacturer's rec's on these engines. I know it sounds great to put the high test stuff in, but DON'T!!!!!
Run the regular plugs, and the rated octane gas!!!! You are burning up your engine!!!!! Making it run too lean, and HOT!!!!!!!
Try what is reccomended. 88 octane, regular plugs, and up to 4800 rpm. You will see.. Don' t mess with the recommended ratings. You are borrowing trouble!!!!!!!
No need for additives til winter. TRUST ME!!!!!"

"If it is "pinging" ,

"If it is "pinging" , the timing is off. Do what i told ya, or buy a new engine.......You will be sorry if you don't."

"well put Eric..

Robert I

"well put Eric..

Robert I think you need to start over with this whole problem, do what Eric has recommended and then do a complete check over of the motor. 1. check compression. 2. check points and condenser 3.Timing 4.air/fuel mixture once all is complete then address the problem at hand, go out for a test run and see if there is any improvement if all is good then problem solved now all you need to do is get rid of the point system and install a electronic Pertronix system.. if it is still having the problem start looking a little closer at the individual cyclinders and what the plugs are telling you.."

Stop the use of additives!!! t

Stop the use of additives!!! thats the source of the problem. You are making a "HOT" spark!!!! BAD!!!!!!

"Thanks for the support, BOB!!

"Thanks for the support, BOB!!!!"

"Hi Robert. What engine do you

"Hi Robert. What engine do you have in your boat? What spark plug and make does the manufacturer recommend? What plugs and make are now installed (all the numbers please)? Where is your timing set? What rpm do you get at wot? What temperature do you see on the engine gauge, at idle and at wot? This info is very necessary if anyone is to assist you else we are all just guessing.

Tom"

WOT for 5 minutes?? Holly Cow!

WOT for 5 minutes?? Holly Cow!!! Cruizing speed is 20% off of WOT. I would look into the TOTAL timing on this engine and see if the stops are worn out and letting the dist. build to much timing. I've come across that before on these little bosch dist.

Higher octane gasoline will ru

Higher octane gasoline will run cooler but that would not account for your problem. The heat range of a spark plug refers to it's abitiy to dissapate heat but has no effect on the running temperature of the engine or the spark. You should be running a cold plug.

I think Tom is on the right track.

"Thanks guys, the premium fuel

"Thanks guys, the premium fuel has seemed to solve too many problems to be a bad thing. It eliminated the pinging, gave the boat the proper power and even helped it run a little cooler. Besides the air cleaner reads "Min 88 octane" which is a higher rating than regular at 87. I most recently add some carb/fuel system cleaner but no octane boost. I don't think the fuel quality or octane is a factor. I know I'm running the proper plugs Bosch W6DC equivilents its right on the air cover. Besides I have tried all the brands denso/autolite/e3's. The carb has been perfect and I've read about a lot of guys chasing carb problems with similar engines when they should have been looking for ignition problems. Its like I'm getting weak spark that eventually gets overpowered by fuel. I have noticed a very slight miss just very periodically. The cap and rotor look great. When its running before losing rpms its about perfect. I don't have alot of exp with points but it seems like a lot of guys are going with the electronic Pertronix systems."

"Sorry, the engine is a volvo

"Sorry, the engine is a volvo 2.3 liter AQ131A OHC, 130 HP I think. 4200-4400 max rpms depending on prop. Redline at 4500. The problems started before the carb/fuel system cleaner."

"Robert

start from the ba

"Robert

start from the basics and start eliminating things from the equation, start with compression and work your way through everything.

Check compression on all cylinders if all OK
then check spark, points look ok
check the gap on them / good gap OK
check the coil / OHMS out ok and has good input and out put
Check and OHM out the plug wires / Check OK
then check timing / checks out ok
then fuel make sure fuel pump is working properly / correct PSI OK
ACC.. pump / working properly OK
Mixture screw setting / setting OK

if everything checks out then your problem is intermittent or caused by heat
So now you have to bring the engine to temp and start your testing all over again..

Hope this helps and can understand the point I am trying to make..

Good Luck and don't worry with all the great people on this site you will figure it out.."

Is the miss at high rpms and m

Is the miss at high rpms and more noticable after it warms up?

I've noticed it at all rpm

I've noticed it at all rpms. No ryme or reason. It might only do it three times within an hour of riding around.

"I would guess You have a lear

"I would guess You have a learn burning problem on cyl one. Haveing melted down the plug - running with an alu head, there is only one recommendation: Off with the head and have Your valves and seats checked. With the temp that has been in that combustion chamber there is a great risk that Your valve seat has come loose and the valve is dammaged as well. You might do a compression check, but it might even not show up on that.
Keep on testing, and my guess will be that You end up with a dropped valve and crushed piston, bent rod..................."

"Compression checks out, point

"Compression checks out, points look good, coil new last year. Took the boat out again. It still seems to be slowly flooding itself and is not running at full power. Tough to get on plane. Had a couple of backfires. Seems to be loading up. I noticed that there is not much gas in the fuel filter. Should I suspect a fuel pump? But that contradicts the flooding. Mixture screw?"

"You better listen to Morten o

"You better listen to Morten on this one. Except for the compression check, you are looking in the wrong places."

"What about the float valve in

"What about the float valve in the carb? I have had an ongoing issue with mine, but only when I jump a large wake. The float valve wants to hang, and I starve for fuel, or flood the engine. And the engine backfires as well."

"There are 2 posibble items to

"There are 2 posibble items to check without pulling the cylinder head. Most important is the ignition timing. If it is too far advanced that could account for the pinging and the hot condition in the cylinder. I am also a little dubious that you got the right spark plug equivielent. After you set back the ignition timing, change out your worst spark plug with the Bosch W6DC plug. You might double check with a good auto parts person that you had the correct replacement plug. YOU SHOULD BE RUNNING A COLD PLUG! A hot plug WILL NOT make the temperature rise but will not survive hot temperatures well. The combination of far advanced ignition and a hot plug could account for the electrode being burnt off."

Volvo Penta AQ131 - Very slugg

Volvo Penta AQ131 - Very sluggish throttle response and wandering RPM. Starts hard and idles very weak. Adding throttle either kills the engine or when the RPM does climb it feels like it's being starved of fuel. Just had it checked out and the shop last week and they said they found the timing off was off by 30 degrees. They fixed the timing and added a new fuel filter/water separator. Boat seems to run worse now. After its warm it will mostly holds full RPM but still feels like its not getting required amount of fuel. Really seems like it's running too lean. Any ideas?
Fuel pump? - Air leak in the manifold? or maybe the accelerator pump in the carb?

I just took my boat in as well

I just took my boat in as well and found the timing to be off almost 30 degrees. It should be advanced 6 degrees. This seems to have solve my problem for the most part. The carb was somehow missing a gasket as well which may have been contributing to a lean condition. I had 1 backfire when I juiced it to take off after trolling for a while but this may be a result of some carb adjustments they made at the shop. My power is back!