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Friday
06-04-2008, 01:22 AM
Hey guys I have a 83 S&S with a 351W that is newly rebuilt last season. When its cold starts like a champ every time. When we have warmed it up or skied behind it starts hard. We converted to electronic ignition with the rebuild. When you turn the key it will just crank and crank, but right when you let off the key it will fire up. Almost like there is a short in the system. Using a volt meter we checked the amps at the battery its 12-13v. At the coil its around 11 and when its cranking it drops to about 8v. Is this normal? This issue is driving me crazy, I've had to be towed back to the dock twice because I couldn't get it started. What am I missing or should I check first? Trying to rule everything out. Any help is much appreciated.:confused:

Skipper
06-26-2008, 11:23 AM
Used to have a 351W with a Holley Carb. Diagnosis usually starts with isolating whether it is a fuel or spark issue. Pull the flame arrestor and look to see if fuel is getting into the carb. If not, look at the carb, fuel filter/water separator, and fuel pump. If you have fuel then check spark. I use a tool that clamps to the spark plug and measures the spark. If you are not getting spark, then use an ohm meter to check the coil and start working back.

The wild card is that it starts cold but not warm. I had to know just how many times to pump the throttle and where the put the throttle when I started the boat when it was warm (if it did not start right away). Not sure I ever figured it out.

Gamble
06-29-2008, 05:06 PM
I have the same setup here. I had the same problem a few years ago. It ended up being the carb out of adjustment. As soon as you took your hand off the key it'd run. Check your mixture screws on your carb and I'll bet you'll find one or both of them out of adjustment. Hope this helps. PM me if I can help further.

JimN
06-29-2008, 05:23 PM
Make sure the bypass wire is intact. Normally, if a motor has points, there's a ballast resistor before the coil because the points can't handle 12+V, so the resistor drops the voltage to about 8-9VDC. When you crank, the starter draws so much current that the voltage drops to the level you stated but at rest, you should be seeing battery voltage, not 11V. When you look at the coil, there should be two wires on the positive post- one for 'run' and one for 'crank' and the resistor will be there only if you have points.

Look at the safety switch for this. Do your gauges act weird? Press on the safety switch next time and see if it starts properly. If if starts when you open the throttle, your carb needs adjustment or the flame arrestor is dirty.

cbryan70
06-29-2008, 06:46 PM
this has been happening to me as well. But not all the time when it is hot. If you ever can not get the thing started try taking off the flame arrester and push the flapper all the way down and i bet it will fire right up. That has been the case with mine which doenst make sense as i beleive that is the choke......? Also i have found that when cranking the motor pull the throttle back and leave it for more air and that will start it as it only gives one pump of gas then just more air. Its weird that either restricting the airflow or giving it more will do the trick when its warm. When its cold it fires right up just like you stated.

TMCNo1
06-29-2008, 09:02 PM
You may want to try installing a 12V coil, from here, http://www.skidim.com/prodinfo.asp?number=R117004. Did you bypass the ballast resistor and check the resistance?

brookview
07-19-2008, 02:59 PM
What did you find I am having that exact same thing with my 83!!

Friday
07-19-2008, 07:04 PM
I did find the problem. Several of issues: First I had a short, turns out on the oil pressure gauge on of the vanes for the light came loose and shorted on the power pole. Second, the ground to the engine was bad. Third, Distributor had to much end play. Forth, coil was fried primary resistance was almost 5 ohms was supossed to be 1.4.

Fixed everything and replaced distributor and coil with a new YLU and Promaster. I have 12V at the ballast resistor and 10v at the coil. Starts up on the first turn now. One added bonus I gained about 150rpm on the top end. Pushing about 5200rpm now. She's purring.

In order to find the solution I literally had to go through the entire electrical system. I would start with the starting circuit, then move to the charging circuit, etc.. Hope that helps. If you let me know what your voltage is at several different locations both with the key on and then running I can try to help you. First, start at the battery, then move to the key, then to the coil or ballast resistor.

brookview
07-19-2008, 07:15 PM
I still have points and just picked up the conversion so i will start with that !