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Lycoming O-235 will not run above 1500RPM

PerryB said:
Its almost certainly fuel starvation. Check the gascolator screen. If its full of debris you're going to have to pull the finger screens out of the tanks too. Disconnect the fuel line from the carb. How fast does the gas run out ?
Click to expand...

Gascolator screen was clean, fuel pours out of the fuel line from the carb when its disconnected.
 
Well crap, another beautiful theory killed by an ugly gang of facts I guess. I'm doing a little thinking out loud here, ...... a leaking primer will have the biggest impact at high vacuum/low manifold pressure and very little effect at full throttle, so if its getting worse with increasing application of throttle then I seriously doubt that's your problem. Switching mags doesn't change anything so its not ignition related. It has to be fuel related. Cracked venturi booster maybe ? That would cause starvation.
If its rich it'll blubber and stumble (and grey smoke out the exhaust). If it's lean it'll pop and backfire.
Also, when you had the float out, did you blow back through the seat orfice? I'm still leaning towards starvation. Either that or an internally collapsed muffler.

P.S. 5 years is an old muffler. -- After re-reading and seeing the comment about carb heat having no noticeable effect, I'd remove/inspect the muffler.
 
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Go full throttle and then shot of primer slowly.If rpm goes up-fuel starvation.I am leaning toward exhaust restriction as Mike suggested.

Bill
 
Steve's the man. Try the different carb. I would still suspect an exhaust obstction. New or not.
 
First of all thank all of you for the help and suggestions.
Well I just now got time to work on the plane and this is what I did.
1. Checked muffler and exhaust, no restrictions
2. Rechecked fuel strainer for blockage/trash, was clean
3. Hooked up the carb heat so I could turn it on and test if it helped when it was on, just had wired off to test run before
4. Tested the ethonal free fuel for with the water separation trick and it tested good, ethonal free
5. Drained the entire fuel system from the plug on the carb fuel bowl till 100LL came out.
6. Test ran and it ran great, making full power, nice and smooth. I think Cubdriver2 has the explication off draining all the ethonal free fuel out and running the 100LL. Maybe the ethonal free fuel sitting in the carb for a few days gathered water, even though it's not supposed to. So now I will order a few gaskets and put it all back together before I test fly it.
 
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If you had ethanol gas in it and it phased out with moisture then the test doesn't work, it won't absorb any more water. I'd drain it and add new efree

Glenn
 
After you get it all sorted out go back to the gas station and get a fresh sample of the fuel they say is EFree and test it from the pump. They may have had a bad batch of fuel or are selling something that's not EFree; would be good to know.
Marty
 
MCS Mike schooled me a couple of years ago about how a teaspoon of water in the float bowl will mess up engine performance and have you chasing everything but the problem. If it happens again, drain the float bowl first. Run some isopropyl in your fuel to get any other water out.
 
Its' possible to get an air lock in the top of the gascolator. I had to crack open the feed line at the top of the sump and let fuel flow out, otherwise it would quit on take off every time. Sounds like lousy gas. Glad it's better.
 
One more time for cub driver. After fuel flow, check the valves and springs. JMO of course.
 
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Besides alcohol, there are other weird gas additives that could possibly show up in fuel batches. Once my son and I re-fueled my PA-12 at the gas station near the Talkeetna turn-off. I went inside to pay and when I came out I noticed my son starring at the sight glass tubes. The little floating balls were fizzing like Alka-Seltzers. The next day the carb started to leak fuel, A lot... So I ended up having to rebuild it.
I am not sure what the heck was in that gas. But it wasn't pure gas...

There have been two or three incidents of bad fuel around my area in the past 3 years.
 
You can't always be sure what you're getting from the pump, even at the airport. I remember some years ago a WV truckstop got cleaning fluid delivered instead of #2 diesel. The oil company paid for a bunch of engines over that screw up. Was it AD95-21-15 that a bunch of aircraft were improperly fueled? jrh

That action was prompted by reports of aviation gasoline (avgas) being contaminated by Jet A fuel. After investigation, the source of the contamination has been determined to be the refiner of the avgas. Through its distribution system, the refiner inadvertently caused Jet A fuel to be loaded into distribution tanks intended for avgas. Contaminated avgas from these distribution tanks was then shipped to local fuel distributors.
 
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