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2010 XP 800 won't run when cold, flooded?

5423 Views 7 Replies 4 Participants Last post by  Beanfarmer
Overhauled the engine month or so back. Runs well,,no issues, except.

when cool or cold, when it cranks and starts, if you try to move or accelerate, it will die. It will start after cranking for 15 seconds or so and smells flooded.

If you start it, let it idle for 30 seconds, then it is fine for a few hours.

whats going on here?
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When it dies out and doesn't want to re-start do you start trying to re-start it right away? if you do, does it crank over and sound like it has no compression?

I'm suspecting you've got a stuck oil pressure relief valve, just from judging that after letting the oil warm up for 30 seconds you're able to drive it.

put an oil pressure gauge on it to verify.

Why was the engine overhauled previous to this?
Yep, I's suspect your oil pressure relief valve is stuck closed. When that happens, it maxes out the oil pump causing oil pressures over 150 psi. in some situations it'll rupture the oil filter and you'll lose all your oil without even knowing it.

When the oil is that high, and is higher with cold oil, it causes the hyd. lifters in the engine to "pump up" which holds the valves open and causes a "no compression" situation until the lifters have had time to push out the extra oil, or until the engine runs long enough to warm the oil up a bit, thin it out, and reduce the oil pressure some.

Best thing to do is remove the plug directly under the exhaust manifold, followed by the spring, and then the piston. if the piston refuses to come, start the engine for a second, to see if the oil pressure will fire it out. don't run it much longer than that. it's best to have a rag or magnetic tray handy and an extra helper so you can avoid loosing the piston if it comes out of there. .

Once out you can polish the plug with emery paper, a scotch brite pad, or both. I lightly chucked mine in my drill, buffed half, then flipped it over and did the other half. then when I was done I used a scotch brite pad and buffed it by hand and re-installed. you can also try a new one, they're only about $5

I have a video going over a bit of this process, but it's not deeply involved on how to get to the plug, give it a watch, hopefully it helps.


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