crankcase filling up with methanol

spincycle

spincycle

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obtained a used ltd mod animal recently, haven't had a chance to run it yet, the motor has a history of the crankcase accumulating an excessive amount of methanol, especially when allowed to sit at idle, even for a relatively short time, the motor has 3 differnet vents that dump into a overflow can. its got a dominator series HL 304wxa carb on it, question is, is this an area of concern, and if so, what are some things to look at to try to correct this problem? I have a 2nd ltd mod animal with another of the same carb on it, can run it all night with just a little bit of fuel in the crankcase and overflow tank.

my first thought was pop off pressure, if the pressure is too low, the inlet needle maybe isn't closing all the way allowing the motor to flood itself, conversely, if the pop off pressure is too high, the inlet needle isn't opening enough (or fast enough) to allow sufficient fuel flow, do I have this right?

Thx for anyones help!
 
In addition to the pop off pressure you might want to compare the orifice sizes from the carb that works ok and the one that doesn't. That means removing the welsh plug to access the holes underneath it also.
Someone may have made one or more of them too big.
 
Jimbo said:
In addition to the pop off pressure you might want to compare the orifice sizes from the carb that works ok and the one that doesn't. That means removing the welsh plug to access the holes underneath it also.
Someone may have made one or more of them too big.
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Thanks, definitely something to look at. Theres a reason for it happening in there somewhere....hopefully..... :)
 
Change the fuel pump. I've seen the diaphragm leak and push fuel into the engine through the pulse line more than once.
 
When I ran limiteds and open briggs I never let them idle very long as this has always been a problem. You can lean the carb down to help when you are wanting to let it idle but why. If the engine runs good leave it alone and dont let it idle.
 
Can't idle a tillotson. Very common problem. Tillotson doesn't have an accelerator pump so in order to have the carb accelerate the low side is rich. This is why its dumping fuel. Close the butterfly and problem will more than likely go away. Pop-off Pressure should be set at 10lbs and fulcrum arm height .065" Set the low side needle at 2-1/2 turns out and 1 turn on the high. Since you didn't buy the carb directly from us its hard to say the carb hasn't been further modified but if you still have problems call us. Worse case you can send us the carb and we can check the print and rebuild the carb to get it back into proper working condition. I can also email you our tuning instruction and maintaince sheet for the carb I just need your email.
 
Mark @ EC said:
Can't idle a tillotson. Very common problem. Tillotson doesn't have an accelerator pump so in order to have the carb accelerate the low side is rich. This is why its dumping fuel. Close the butterfly and problem will more than likely go away. Pop-off Pressure should be set at 10lbs and fulcrum arm height .065" Set the low side needle at 2-1/2 turns out and 1 turn on the high. Since you didn't buy the carb directly from us its hard to say the carb hasn't been further modified but if you still have problems call us. Worse case you can send us the carb and we can check the print and rebuild the carb to get it back into proper working condition. I can also email you our tuning instruction and maintaince sheet for the carb I just need your email.
Click to expand...

Thanks Mark.... It's resin300s@aol.com
 
I pulled both of my HL 304wxa carbs apart today, and put them side by side trying to compare to see if anything is different between the two, the dominator model that has the problem of filling up the crankcase with raw fuel, there is a small hole drilled inside the bore of the intake manifold that goes through the flange where the manifold bolts to the carb, that hole also goes into the carb itself, that hole is somewhat larger than that same hole on the 2nd carb that runs just fine. I don't have the tools to give exact measurements, but visually, all other drill holes in the carbs appear to be the same, the hole in carb #1 that begins in the intake manifold and goes into the carb appears to be the only difference. Could this hole being bigger than the hole in carb #2 possibly have anything to do with the excess fuel issue? I bought total rebuild kits for both, and have specific instructions on how to set fulcrum height, pop off pressure..etc, i'm hoping to see some improvement with carb #1 after the rebuild (unless the hole I was explaining is too big?)
 
oh and also forgot to mention, I measured the bore of the end of intake manifold from carb #1 and the bore of the carb, the bore of the intake is 1.015 and bore of the carb opening is .990-----could this be causing an air flow problem adding to the overly rich condition?
 
The pulse hole that you're talking about should not be an issue. Usually if there is an issue with the pulse hole it causes erratic tuning and mostly a lean condition. The mismatched bore is not enough to cause any issue with the fuel signal. Many guys will port match the intake and carb. A rich fuel problem usually starts with idling the carb or the inlet needle and seat. The idling is pulling fuel from the carb, the pop-off pressure is too low or the needle and/or seat are leaking. If you're still having issues you can send it to us to check.
 
Mark @ EC said:
The pulse hole that you're talking about should not be an issue. Usually if there is an issue with the pulse hole it causes erratic tuning and mostly a lean condition. The mismatched bore is not enough to cause any issue with the fuel signal. Many guys will port match the intake and carb. A rich fuel problem usually starts with idling the carb or the inlet needle and seat. The idling is pulling fuel from the carb, the pop-off pressure is too low or the needle and/or seat are leaking. If you're still having issues you can send it to us to check.
Click to expand...

Thanks the motor will get ran again on new year's weekend I'll let you know how it performs
 
curiousity killed the cat, I couldn't wait, fired this motor up today, idles so much smoother and the exhaust seems to be way cleaner, revved it few times and let it idle for about 60 sec or so, very little, if any fuel in the oil, thanks to EC/Mark for a great rebuild kit and the technical assistance, I think its ready to rock and roll!
 
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