Hard Starting - I've replace EVERYTHING!

[Suprabob]

I have a 1990 SUPRA COMP TS6M with 970 hours on it and I've owned this boat for 20 years. It's always been garaged and well taken care of her whole life. I have the power plus PCM 351 powerplant... she's never given me a lick of trouble. This year when I put her in the water, I had MAJOR hard starting issues. I had winterized with Stabil and my gas was only 2 months old when I first launched her. I would crank and crank the engine and it would finally fire and die. this process repeats several times and eventually I would get it started after raising my engine cover, taking the flame arrestor loose and inspecting the carb and linkage, choke position etc. I disconnect my throttle linkage and have my wife turn it over (I see fuel squirting into the carb throat) and finally it starts. All day long the same process happens... crank and crank, fire and dies and finally starts after a long period of trying. My choke is in the "open position" and operates like it should (about 1 minute before going to full open position). Soooo... I started replacing parts. My boat is like a part of our family and I was willing to do whatever it took to get old faithful (not any more) running again. Well here is the list of things I replaced in an attempt to get it to start quickly and reliably again: Coil (from an autopart store), plugs, wires, distributor cap, rotor button, condensor, and points (all purchased from skidim for the correct year and motor) all of these parts had NO AFFECT on my starting problem. Then I went to the fuel source: purchased from skidim new Holley 4160 marine carb, fuel line, fuel/water seperator, flame arrestor, and mechanical fuel pump. Installed all the above and I still have the EXACT problem starting my engine. All those parts and still have a problem starting the engine. I will throw this in there... it does SEEM to start a little easier cold than when I've been running around the river for a couple of hours pulling a skier or wakeboarder. When I lift up the engine box, the manifolds are very warm but my temp gauge is saying my circulating water temp is around 150-160 degrees and I put a brand new impellor in this spring after reading some threads on vapor lock.
I've tried everything and I just can't seem to land upon the root cause for the hard starting. It fires up and dies, fires up and dies. I pump the throttle several times and it fires and dies again... eventually like I said before it will eventually start but I feel like I'm going to wear my starter out and certainly I'm wearing my patience out!
Please help and I hope I have given you enough information for you to give me a good diagnosis. I feel like I have replace EVERYTHING that can possibly be replaced...
Does anyone know what might be causing my starting issue in light of all the parts I've already replaced?

[csuggs]

Is your coil wired through the ballast resistor? You have points, right?

See my recent thread: http://supraboats.com/bbs/showthread.php?t=9206

Long story short, I had some similar issues and it ended up being the coil that I had replaced over the winter - when I put my old coil back on the boat the problem is gone! If you still have your old coil, I would install it see if that helps.

[wotan2525]

It sounds like you've gone about this in sort of a backwards fashion. A good mechanic could have started troubleshooting what part of the system was failing rather than just throwing parts at it. Regardless, I'm sure the boat will be happy as a pig in mud once you get the problem resolved.

It does sound like you've eliminated a lot of what it CAN'T be, so let's start talking about what it CAN be. Does it start easy with a spray of starting fluid into the top of the carb? Could you have water in your gas or bad gas? Have you done a compression or leak-down test? What do the spark plugs look like when you pull them? Any oil contamination or other signs of trouble?

[Suprabob]

I don't really understand the "wiring the coil through the ballast" question... I just hooked up the positive and negative wires to the coil just like i removed them, and then hooked the lead to from the coil to the distributor cap... Unfortunately I have already thrown the original coil away. If it's any help, once the engine does start, it runs GREAT! No missing or backfiring, no hesitation at all.
I will try to put it in the river this week and get back to you guys on the suggested starting fluid tip. I did pull the plugs when I started this whole "parts swapping" adventure and the plugs were drenched with fuel. Also, black in color, which led me down the carborator rebuild/replacement trail. Like has been stated by wotan2525, once I figure all this out, my boat should be good for years to come! I've replaced just about everything that bolts onto the engine for goodness sake. I just wish I got more "bang for the buck".
On the bad gas thing, I have gone through several tanks since first skiing this spring, and have tried no ethanol and regular unleaded, without much difference. My fuel/water seperator is clean and doesn't have any water in it and has a new filter in it too (of course).
thanks for the help in advance, and when you respond, try to imagine yourself talking to a sixth grader... that would be me. I am an engineer, but smart about some things and inboards aren't one of them LOL.
Thanks guys.

[rludtke]

While cognizant that you replaced your carb with new, and it seems unlikely that both the old and new carb could be producing the same problem, I can't help but think that the carb may be flooding when you try to start.

A quick check would be to remove the arrestor, and observe the throttle bores while cranking to see if fuel is dripping or running out the discharge nozzles or vent j tubes. Also look to see if the dripping occurs with the engine at rest (not running).

Remove and inspect your spark plugs immediatley after operating the engine to see what they look like. Wet means flooding.

Will the engine start with the throttle set to wide open (be sure to retard quickly once started)?

[Suprabob]

Ok, I put it in the water this evening and I cranked and cranked again. It would fire, and I noticed that all my gauges lost power at the precise moment my engine fired and died... a few more cranks and it fired up and my gauges stayed "hot" and it kept running. Shortly after that while idling out out the no wake zone, my gauges again went out and my engine died. I was more patient this time and fiddled around with my ignition switch until it fired up again...
Somehow I am loosing my 12 volt source like my key is shutting off. Do you guys think my ignition switch is bad? Could it be anything else, like a bad ballast? Shoot, I've replaced everything else... What could it hurt?

[Suprabob]

Thanks for the help all. I really appreciate everyone's willingness to help. I'm not getting any fuel dripping after shutdown. The Ballest is still in place, and the terminals are a bit corroded, but I'm getting 11 volts on the left side of the Ballest, and 4.3 volts on the right side. Skidim tech support suggests running a wire to the positive side of the coil from the "I" terminal on the starter relay. It's apparently hot only during the period you're turning the key in the "start" position and then it goes dead once your key is returned to the run position. This I am told will send 12 volts to the coil for a strong start. I'm considering this too unless there's a good reason to not do this.

[rludtke]

Ok, I put it in the water this evening and I cranked and cranked again. It would fire, and I noticed that all my gauges lost power at the precise moment my engine fired and died... a few more cranks and it fired up and my gauges stayed "hot" and it kept running. Shortly after that while idling out out the no wake zone, my gauges again went out and my engine died. I was more patient this time and fiddled around with my ignition switch until it fired up again...
Somehow I am loosing my 12 volt source like my key is shutting off. Do you guys think my ignition switch is bad? Could it be anything else, like a bad ballast? Shoot, I've replaced everything else... What could it hurt?

Now wev'e got a smoking gun!

I think you have a bad key switch. I replaced mine when simular blinking/running problems occurred. The contacts inside corrode out. they aren't repairable. I think chances are good that this will fix it.

Old boats, what do you do with them...?