Help - 502 Loss of Power!!
 

OK here's the deal... 92 Baja 240 Islander, stock 502 Mag (carb). Recently installed new distributor cap and rotor (7/5). Boat ran fine. Yesterday, I installed new spark plugs and wires; went with Rapid Fire #1's gapped to .040 and Napa Performance Marine 8mm wires. Previous plugs were Champions and wires were stock Merc. Also, trying new prop, Bravo 1, 22P.

Go to the lake and can't hardly even get on plane. Drop the throttle and it just runs about 3000 rpm for over 30 seconds before planing, half tank of fuel, gear and 4 people. Can't be overpropped, I've turned a 21P Mirage at 5200, a 23P Mirage + at 4400 and a Hydro Q4 24P at 4400. I never got a chance to make a WOT run (too many people on board). All the previous props planed fine. Boat started OK, it did die a couple of times, but always started back up with a little throttle.

Come back home and pull the new plugs, quite a bit of carbon deposits. A couple were somewhat wet with fuel.

Is the timing off somehow? Are the plugs the wrong temp?
Where do I start? Any help is appreciated.

Thanks,
Travis

PS: Not only was this a problem, (first time at this lake) but just before coming in, I got hung up in some mud and broke off the bottom of the skeg!!! Argh!

Low RPMs and wet plugs, sounds like you may have a couple of plugs that are not fireing. Maybe a bad connection on distributer or plug end?

That crossed my mind too. I made sure that all plug caps were pushed on all the way and checked the distributor also. At the plugs, they did not seem to fully "snap" into place, a little bit of play. Can you somehow crimp the connection closed a little to remedy this?

I would remove all plug wires and start again. 18436572.

BT :cool:

BT - Thanks for the obvious! Even though I removed and re-installed each plug/wire one at a time, I will reconfirm.

Any thoughts that the temp rating of the plug is wrong or the timing could somehow be off? Distributor cap was not removed or turned during this recent install.

Thanks and keep the ideas coming.

Start with the bacics.....Check firing order {I know.I know}
go back to old prop {I know.I know} If you didnt mess with the timing it will be fine. Its always the dumbest things that foul me up....Good luck ....let us know!

I think you need a rpm reading at WOT after the basics check out. Three heavy set people can reap havoc with getting on plane. :D

BT :cool:

If you still have the old parts compare them closely. Are they exactly the same? any chance the rotor isn't quite on properly.
other thought is that you have bad wires. Get some good spiral core wires. I use TAYLOR wires. NEVER a problem.
This sounds like a weak spark issue.

Here's the latest... Last night I checked the firing order and made sure the right wires were to the right plugs. Check.
I went ahead and slightly crimped the connector at the plugs. They seem to have a much better connection and now "snap" into place with no play at the spark plug tip. Now, it's just time to get out again and see if there is any improvement.

Tinker - rotor should be fine, boat did run fine for a period (about 3 weeks) before changing the plugs and wires. I've also inspected the previous plugs (Champion RV15YC) to make sure they're the same depth and gap as the new Rapid Fire's. Check.
I used 8mm spiral core wires, per the Napa guy, not sure of the manufacturer. Seriously, he was very helpful, knew plenty about marine performance engines. Wires good, check.

BT - it was my in-laws that were with me. I'm glad to see you didn't include me as one of the "heavy-set people"!!:D

Thanks guys for all the help! Any other ideas are much appreciated.

Continuing Loss of Power Dilema
 

The "new" latest...
Checked all wires and caps, tried a set of NGK's just for grins, and still have extreme loss of power. Seems to be running "rich". Came back from the lake last night and start looking for additional signs. Low and behold the stock coil is leaking its oil out the top. Determine that that can't be good.

So the question is... will this hopefully cure the problem and if so stock Merc or MSD coil replacement, (been reading all the threads about Merc vs. MSD). Who's got the part numbers and best prices.

It's not idling the best either, but I think re-adjusting the carb should take care of that.

Thanks, T