3.7 488r mercruiser
 

I have a 3.7 488r I/O mercruiser. The last time I had the boat out I was just trying to see how fast it really was and had it full pin and was just trimming up the outdrive. Every time I would hit the up the motor would stumble and recover right away. My RMP was about 4600. Later on that day I was cruising and had been for about 2 hours. I was at 10 mph and throttled up to plane and when I did the motor stumbled, recovered and when up on plane. Just before I was going to bring the boat back to dock I hit a huge wave and the motor stalled and I have been unable to start it.
I was going to check for water in the gas, spark plugs and coil wire. I am thinking coil due to the trim problem. I have charged the battery and will try fixing tomorrow, any suggestions will be appreciated.

is the battery good and charged? Check the battery cables, make sure the ground cable is in good shape. Next check the points, better yet, replace them with a pertronix conversion kit. After you get it running, check the charging system to make sure its charging

OK, I have the day off and will check what you ask. I was thinking maybe a trimming chain or maybe I should just not think and do... Thanks for the info.TO answer your questions, I have a smart charger and it tells me the battery is good, I did check the connections and they are good. I was going to check the gas and the pump as well..

those smart chargers suck, get an old school one with the needle on it. Will the engine turn over fast when the starter is engaged?

OK so I was able to look at the motor. The distributer cap was loose, really loose. I broke one of the spark plugs when I was checking them so I am going to get new ones, but I think I broke it and it was not broken before I started.

Next question, should I be looking at a new distributor and cap?

X2 !!! Old school is the way to go. I DO NOT trust those "smart" chargers.

Countless good batteries are thrown away every year because the owners "smart" charger said it was bad. (And the battery makers don't say anything since it's good for business). In reality, they were just so discharged that the battery charger couldn't get a reading and so it said it was bad. This is especially so with gel and AGM type batteries.

By the way, you can fool a "smart" charger and (usually) save your battery by using a simple trick. :head:

Hook up your charger to a good battery, and then, using a set of jumper cables, hook up your "bad" battery to your good one. (Positive to positive, negative to negative) Your "smart" charger will think it's just charging the good battery that it can get a reading from, and at the same time it will be charging your "bad" battery. Once you have some juice in your bad battery just charge it like you normally would to top it off. :beer:

All good advice, my charger reports the battery is good and the motor cranks good. When I try and start it, it sounds like it's going to start but just chugs and dies. I think what I am going to do is replace the sparks as they are done. I was going to replace the cap and was thinking of the distributer but don't know what is involved or if it's over my head.

By the way, I did join thehulltruth and you guys rock. I no longer own a Wellcraft but you people here are the best,,, just saying,, LOL:part:

once again, search for pertronix, you can thank me later

This place DOES rock... hull truth is ok but iboats is better if you aren't a big spender king of the ocean.

I have an account for ibosts but it does not seem to work and the administrator is taking for every to fix or send me a new activation.