Merc 6.2 Runs a few minutes, then dies and won't restart

[Pacfanweb]

2000 Ebbtide Mystique. 6.2 Merc, EFI. 600-ish hours. Hasn't been in the water for close to 3 years now. Was winterized and running fine previously.

Didn't have time for it in 2021. Tried to get it going last summer, decided to put an impeller in it since I bought it used in 2019 and had no idea when/if the last one was done. That wasn't fun.

New battery, tried to start it on muffs. Ran about 5 minutes, then started surging up and down, cut off. Wouldn't restart. It fires briefly and cuts right back off.

Also didn't notice any water flow out the exhaust at all. So maybe my new impeller isn't working, but don't think that's making it stall. But maybe I'm wrong.

So I said the heck with it, covered it back up and left it until yesterday. Put plugs in it. New battery. Fired up on muffs. Ran fine for long enough to get warm. Revved up nicely. It actually got warmer than I'd like, about 200 degrees. I cut it off and let sit a few. Started back up when the temp dropped. Ran another couple minutes, then did the same thing as last year: Surged, then stalled and won't restart. Fires briefly and cuts off.

I'm aware of the vapor lock issue these have, and this one has it. But I don't think that's the issue after only running 5 minutes. When it did that at the lake, it was only when you'd run it a good while, and let it hot soak. I got around that by idling for a few minutes after a run, and opening the hood letting it cool. Never happened again once I started doing that.

Any thoughts? It has, since I got it in 19, cap/rotor, wires, plugs (twice), fuel filter, coil.

 

[Scott Danforth]

after 3 years your fuel is no longer fuel. your fuel system needs a full flush and clean. that also means your injectors will need to be pulled and sent out for cleaning

your raw water pump needs replacing. that is your overheat. if you are missing parts of the impeller, find them.

it isnt vapor lock. your fuel system needs attention.

after you drain the stuff formerly known as fuel out of the tank and completely clean the tank, pumps, lines, injectors, etc.

check your fuel pressure. if you dont have 43# or more. clean it again.

 

[Pacfanweb]

If it was bad fuel, then it should never run correctly should it? It runs perfectly fine takes the gas and everything until it warms up. And the fuel wasn't 3 years old a year and a half ago. It did the same thing then.

I won't rule that out but I don't think that's the problem.

Will definitely check the fuel pressure. Would have done that yesterday if I hadn't been so disgusted with it, lol

 

[Pacfanweb]

Just thought I'd follow up on this:
It was the fuel pump. The rest of the system was fine, the gas is old but still fine. Pump and filter, runs like a top. Went ahead and had some other maintenance done, but the running issue was the pump.