Hard Starting after Anchoring 30min+

[Renken2000Classic]

1986/88 Cobra, 4.3L w/2bbl. Points.

Boat fires right up when cold, or if it only sits for 15 or 20min at a time. Otherwise runs great too.

I had this prob when I first took it out this year, and attributed it to the battery (3 or 4 years old) not being fully charged. I don't really think that's the issue though, as it was fully charged this morning, and seemed to be cranking fast enough on the lake after we'd sat for 45min, but it wasn't even trying to start.

I tried partial throttle to begin with, then pumping it, then wide open, starter fluid 2 or 3 times, and finally it started. TOTALLY unacceptable.

I may revisit the battery thing and have it checked, as I could be wrong about it cranking fast enough, if I haven't heard that from it in a while, heh. Seems like it wouldn't fire right off to begin with though, if that was the case.

Thanks for input.

 

[itsathepete]

What temp does your engine run? Cooling system working well? Thermostat correct temperature? If the engine is hot and the engine bay is fully heat soaked, you could be having vapor lock

 

[Renken2000Classic]

Between 120 and 180 on the lake; settles in just a little over halfway between them. I've never had the t-stat out. There's even a few inches of gap at the rear of the engine cover due to a long padded piece not being in place (like for heat to escape).

What about the ignition coil? I've got a new one of those I never put in, but don't really like to just change parts w/o knowing why.

I mean electrical stuff can be weird. I had a '93 Chevy that started just dying for no apparent reason after I did a tuneup on it. Codes mentioned the ignition control module or circuit. Mine tested good at Autozone, but I went ahead and got another since it was so hard to get to. Haven't had that issue since...

But yeah, vapor lock, that came up in some research I was doing. I don't think I have a heat issue though.

 

[itsathepete]

If you still have spark it's not the coil

 

[kenny nunez]

Do you have to only get Ethanol added fuel? It could be boiling out. Next time after doing the same run and stop remove the flame arrestor then have someone pump the throttle with the ignition off, look down the air horn and watch if there is any fuel squirting from the accelerator jet nozzles. If there is fuel squirting and it does not want to start the problem could be the ignition by pass circuit that provides 12volts in cranking mode only. For some reason I have found that problem happens on a warm engine more than a cold one.

 

[Renken2000Classic]

No, I put 100% gas in it (if the pump labels are to be believed). I thought about trying to prime it w/a little pure gas next time it doesn't fire right off under those conditions, but I'll visually check that instead, first, thanks.

I ran it on the hose several times after the first run of the season where the problem popped up - 15min or so On, 15-20min Off, to try to see what worked best as far as throttle position for restart (like in case I was flooding it, or not giving it enough), and it seemed fine with the normal part-throttle position, but maybe I wasn't letting it set long enough, or it's different on the water.

 

[Renken2000Classic]

Kenny: Question re the wiring thing: if it was that, wouldn't that manifest immediately upon trying to restart hot?

It fires right up if it doesn't sit too long, like after dunking the trailer and getting the boat at the dock for retrieval, etc.

I got the issue to repeat today, but I was alone, so no one to look at the carb for me. Man, it banged right off when I got to the lake on the first start in a week (2 full pumps 1st), I warmed it up on running around the lake and then anchored for 45min. No start after that with about 1/2 throttle or a little less (didn't try for long).

I pulled the flame arrestor and poured just a little gas down the carb - it was pretty warm there, and there was some vapor coming out of the carb if I'm not mistaken. No go. I got it started after not too much more trouble though, with a little starting fluid and full throttle.

I ran around the lake for a while after that (it's running and driving great otherwise), and then anchored for about 10min. Bam, fired right off with no throttle at all.

I'm still not 100% satisfied with the cranking speed though; it seemed like on 2nd or 3rd try after the 45min anchoring, it was slower than it should have been, esp initially. Batt was fully charged this morning before I left.

Q: What about the starter heating up and acting weak after that? That theory doesn't match with the firing off easily hot if it doesn't sit too long, though.

I'm thinking it's carb or fuel related, but I don't know. I was reading old posts on Nasty Z28 about needing full throttle to restart for very similar situation, and a lot of the talk centered around ethanol. If it's only 10% though, and that all evaporates, there's still a lot of gas there... just thinking out loud here...

Another thing I need to do is clean the batt cable connections at the starter, and wherever the neg goes...