WOT and engine runs out of gas

Guys - twice this weekend I needed a tow because of the following sequence of events:
- Started and ran perfectly in the driveway. The battery needed a charge so I charged it up good.
- Started and ran perfectly in the lake at all speeds for about an hour.
- One hour or so in, I went WOT (not the first time doing that this day) and after a few seconds it died like it was running out of gas.
- I was able to restart it and started heading back to the dock and it did it again (not at WOT).
- That was the last of it... wouldn't start again and the battery died.

Brought it home, jumped the battery, put it on water, and it started instantly. Obviously I didn't go WOT in my driveway...

Back to the lake yesterday and the same exact thing happened after about 10 minutes.

Your thoughts? Could it be a bad fuel pump or clogged filter?

Thanks,
Jeff (1984 SN 2001)

Yesterday was the last run of the year. I'm going to be pulling the engine and doing the stringers this winter.
Not sure what you mean by clogged vent. You mean the gas vent on the transom?

I wouldn't rule out a carb problem but on the fuel pump, "T" a pressure gauge into the high pressure side to check it. The filter - just put a new one in.

Anti Siphon Valve clogged is my guess, which may be what Greg was also saying.

GottaSki wrote: Additionally, when the tank is out, remove and disassemble the dip tube, and check for a conical screen in the assembly, then throw it away.

Perhaps moot, since the boat is being torn down, and I am not the top mechanic on the site by any stretch, but I will relate my experience with similar symptoms.

Typical diagnosis for this is fuel, often antisiphon or carb. My amateur thinking tho, is that if it works for 10 to 30 or 60 minutes, then fails, then is good again after a break, its probably not one of those things. It probably wouldnt work at all, vs coming and going.

I fought with this a couple years ago. Ran for 30-ish minutes, died. Next time out, 30-ish minutes died. Sounded like time/heat related. People concur with that and generally suggest coil going bad with heat, then recovering. I tried that. Not it. Finally, replaced cap. Good to go. That was a couple years ago. Same symptoms this year. Didnt mess with it, got a new cap. Good to go. Now based on my reading, I have found that this is somewhat symptomatic of the Mallory flat (crab) caps, which I realize is a bit of an odd bird. Cause: warps/deforms with heat, contacts arent made, starts arcing. Cools off, works again. Has been my reason for said symptoms twice.

Just a thought.

EDIT: Anthony posted while I was typing. We're on the same page, or at least the same chapter.

Mine started like that. I cleaned the tank and anti-siphon valve. Also, I put a new gas pump. It got worst with time. I can idle fine but if I accelerate it will die after five minutes. Just check the spark when it dies. That will ruled out electrical problems due to the coil. I heard you can tap on the coil back of a screwdriver and the engine will die. Never did it. I replaced mine with MSD 8222. Is a solid coil so it can be mounted sideways on the engine.

Obviously every case is different Gary, so I certainly can't diagnose your situation. If you got a new cap in the spring, and if it is a cap wear issue (like the contacts wearing down) its hard to believe it would go bad half way thorugh the season. I got a couple years out of mine. Of course I got about 4 years out of the one before that? I did make a point of getting the "marine" version, which is not a clear distinction when you go shopping for them. The one I had for two years was tan like the one in your profile picture. Not sure what you have now, but the "marine" one is the maroon color. I think I got mine at Jegs, but unfortunatley I never write this stuff down and have to stqart allover next time. I am confused tho, in that Jegs doesnt seem to make the marine distinction, but Summit does 9-29416. In other discussions with vendors I have found that the 221B is the marine (i.e. not vent) Not sure difference between 29416 and 221B (except price 36 vs 53) One of these days I am going to pick up an extra to carry so if and when my engine does die, I can slap it on and 100% prove its the problem. I wish I could find the link to the story about the crab caps having this issue, but of course I didnt write that down either.

Jeff - You have a lot more patience than I do if you can leave this problem 'on the table' & start a major rebuild. I would want to solve this first, so if anything else goes wrong during reebuild, you are not fighting 2 problems at same time.

Just an update to this one. This is what prompted my "OK to put the gas from tbe boat in my truck" thread.
On Saturday I figured I'd spend 3-4 hours winterizing the boat. Well that turned into about 7 hours total over the weekend...
For the first time, it would NOT start in the driveway. Remember, after my first issue, I jump started it in the driveway about 90 minutes after it died on the lake and it started beautifully.
This weekend... nothing. It would crank on battery, and die but never attempt to start. Interestingly, it wasn't a strong crank, even when hooked up directly to my running truck, even when bypassing the battery and hooking up directly to the engine.
It definitely seems to not be getting spark.
Could it be the coil? I measured about 6.9v in and an even 6.0v out.