When warm will not start

My 1989 supra comp left me stranded again in the middle of the lake. I have put new starter, points, condenser, rotor, cap, battery, coil. I have started it out of the water and let it warm up. Shut it off and it cracks right off every time. I put it in the water and it won't start. The more it runs, the worse it gets. It was even cutting out a few times today. I also have it timed too. What am I missing. Tired of throwing money at it. And not sure I want to buy a new carb. Any help would be greatly appreciated.

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Originally Posted by khyland

My 1989 supra comp left me stranded again in the middle of the lake. I have put new starter, points, condenser, rotor, cap, battery, coil. I have started it out of the water and let it warm up. Shut it off and it cracks right off every time. I put it in the water and it won't start. The more it runs, the worse it gets. It was even cutting out a few times today. I also have it timed too. What am I missing. Tired of throwing money at it. And not sure I want to buy a new carb. Any help would be greatly appreciated.

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I would look at your ballast resistor as well as could be a bad condenser. I had a similar problem and to me sounds like an electrical problem not a fuel one but still not a bad idea to rebuild the carb. I replaced all those same parts to find out my brand new condenser was the issue... Go back through and recheck electrical with multimeter or replace old parts to make sure that u didn't just get unlucky and get a bad one.


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Float level too high , bad power valve. If your carb is more than a few years old it probably needs a rebuild.

Remove spark arrestor immediately after turning off the engine when fully up to temp. Look for dripping from boosters on primary and secondary side. Dripping is too high float level, bad needle and seat or dirty, or carb too hot (get a phenolic spacer).

Check for spark when it won't start. Bring a spare plug, pull a wire, hold ground strap againt metal on engine and have someone crank while looking for a nice white/blue hot spark. No spark or a weak yellow/orange spark is indicative of an ignition problem.

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Originally Posted by SuperSam

I would look at your ballast resistor as well as could be a bad condenser. I had a similar problem and to me sounds like an electrical problem not a fuel one but still not a bad idea to rebuild the carb. I replaced all those same parts to find out my brand new condenser was the issue... Go back through and recheck electrical with multimeter or replace old parts to make sure that u didn't just get unlucky and get a bad one.


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I think it's spark too. I did fix my floats so it doesn't drip. I also had the resister jumped. I think it must have something to do with the temp under the dog house. Thanks for all the input

Verify the new coil is compatible with the resistor.

I've had some coils overheat with or without a resistor after switching to an electronic pickup, and later an entire new electronic distributor. After 20-30 mins spark got weak and boat would misfire, stall, or not start. Verified checking spark when symptoms occurred and touching coil (ouch!), then immediately swapping the coil to my spare that also would overheat. Same sympton with a Mallory coil and with the old coil that was on it, got a coil from NAPA while on vacation that has been working fine for several years.

I had a similar problem with my old ski boat (with a 1993 Indmar engine) and tried for a few years to figure out what it was. Took it to the dealer numerous times and they always found things to replace and charge me big $ and low and behold I would get out on the water and the same thing would happen again. Hard to replicate the conditions that caused the problem in the garage. Wouldn't start when it was hot.

After a bunch of research and trial and error I did 2 things that fixed it:

1. Thought it was a vapor lock issue with the fuel and I added a supplemental electric fuel pump back by the fuel tank. This would pump cool fuel through the vaporized fuel that the mechanical fuel pump on the motor could not do.
2. Replaced the coil and the coil ballast at the same time.

Not sure which one was causing it, maybe both were, but we never had a problem with warm/hot starts ever again and the boat fired right up even after long storage times every time we took it out which is something it rarely did before. It took a lot of cranking to get it to fire up when it had been sitting for a few weeks. Getting fuel to pull through the lines with a mechanical pump took a long time and the electric booster pump really fixed it.

Both were pretty simple and inexpensive to do - I have very basic mechanical knowledge/experience.

I did that about 6 years ago and never had another problem with it.

My guess is that one or both are causing your problems too.

Good luck
Craig

You can add a wire from the empty small stud on your solenoid to the power input side of your coil to bypass the resistor when cranking. With will give your points a full 12vlt when cranking then go back to r the resisted circuit when not. But if your coil is getting excessively hot then you have a resistive mismatch between the coil and resistor.

+1 on the bypass when cranking, most solenoids have a separate set of contacts just for this. Did it to mine and it made a huge difference.