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Vaporlock revisited
- Thread starter Phils
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Phils
Platinum Member
Ok, tweaking the Supertrap out didn't work either. I worked the machine pretty hard last weekend. It never vaporlocked, but it was pretty cool outside. However, when I turned it off to refill the fuel tank, I could see bubbles coming up from the fuel tank elbow. It got worse after I shut the engine off too. Kept going for awhile... confirms that it wasn't junk in the elbow or in the carb bowl. Simply too much heat too close to the fuel hose.
I'm going to try tracdoc's suggestion (although not exactly) and wrap the fuel line with a few layers of the fiberglass/foil insulating stuff that I got. I have plenty so I'll put a layer inside the tub too, on the exhaust side.
Should've just ordered the stuff tracdoc recommended in the first place. Same price as the fuel pump and maybe it'd be fixed by now.
Sure wish he or another PT'er would find someone to make custom headers for these, at maybe $49.95 plus $10 shipping (as long as I'm dreaming I might as well make it good!!).
Phil
I'm going to try tracdoc's suggestion (although not exactly) and wrap the fuel line with a few layers of the fiberglass/foil insulating stuff that I got. I have plenty so I'll put a layer inside the tub too, on the exhaust side.
Should've just ordered the stuff tracdoc recommended in the first place. Same price as the fuel pump and maybe it'd be fixed by now.
Sure wish he or another PT'er would find someone to make custom headers for these, at maybe $49.95 plus $10 shipping (as long as I'm dreaming I might as well make it good!!).
Phil
tracdoc
Platinum Member
</font><font color="blue" class="small">( Sure wish he or another PT'er would find someone to make custom headers for these, at maybe $49.95 plus $10 shipping (as long as I'm dreaming I might as well make it good!!). )</font>
Oh, you are a mind reader, Phil. I was thinking of popping off my header, and taking it over to my friends at A&E Racecars in South Boston, VA to see what they could do in terms of a custom header. Your post pushed me over the edge, so I called them today. It will have to wait since they are up to their a**es in alligators trying to get stuff finished for this racing season. I'll have to check back in a few weeks to see if they have the time for this. Remember, I am just going to get a price quote, only a quote, nothing else, just a quote /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Oh, you are a mind reader, Phil. I was thinking of popping off my header, and taking it over to my friends at A&E Racecars in South Boston, VA to see what they could do in terms of a custom header. Your post pushed me over the edge, so I called them today. It will have to wait since they are up to their a**es in alligators trying to get stuff finished for this racing season. I'll have to check back in a few weeks to see if they have the time for this. Remember, I am just going to get a price quote, only a quote, nothing else, just a quote /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Gravy
Platinum Member
I've checked into the Robin side mount exhaust system. (See pages 42 and 43 of the parts manual at: http://www.robinamerica.com/engines/manuals/parts/EH63_EH64_EH65_EH72_prt.pdf ). My local dealers will sell the whole system P/N 92630004 for about $120+S&H. I'm guessing that it will fit with the addition of a spacer between the manifold and the muffler. I've got several other projects that come first, so it will probably be a while before I get around to ordering one.
Gravy
Gravy
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Phils
Platinum Member
I got a lot of work done this weekend. The PT never once died from VL. However a couple of times when I stopped it for a break I noticed bubbles coming up into the fuel tank. The little bit of insulation I installed between the fuel hose and the exhaust-side of the tub helped and indicates the problem indeed lies there.
I discovered something else too: the run-on and/or backfire when shutting down was greatly reduced if not entirely eliminated. I'm guessing that the boiling fuel was making the engine run hotter because of the lean condition.
My next tentative plan is to reverse the exhaust manifold/muffler. That is, take it off and reinstall it so that it exhausts out the right side of the PT. I haven't tried it, but it seems like it'd bolt right up that way, with a cutout in the engine cover on the right side to match the one on the left. Fortunately I'll be able to completely try it before cutting anything.
That would move the hot exhaust to the side opposite the gas lines. Seems to make more sense than trying to insulate gas hoses from nearby exhaust heat. The SuperTrap would be pointing up which would make it less vulnerable to bumping into brush.
Am I overlooking anything here?
Phil
I discovered something else too: the run-on and/or backfire when shutting down was greatly reduced if not entirely eliminated. I'm guessing that the boiling fuel was making the engine run hotter because of the lean condition.
My next tentative plan is to reverse the exhaust manifold/muffler. That is, take it off and reinstall it so that it exhausts out the right side of the PT. I haven't tried it, but it seems like it'd bolt right up that way, with a cutout in the engine cover on the right side to match the one on the left. Fortunately I'll be able to completely try it before cutting anything.
That would move the hot exhaust to the side opposite the gas lines. Seems to make more sense than trying to insulate gas hoses from nearby exhaust heat. The SuperTrap would be pointing up which would make it less vulnerable to bumping into brush.
Am I overlooking anything here?
Phil
tracdoc
Platinum Member
</font><font color="blue" class="small">( My next tentative plan is to reverse the exhaust manifold/muffler. That is, take it off and reinstall it so that it exhausts out the right side of the PT. )</font>
Hmmm.....now, why didn't I thunk of dat?
It certainly sounds like a reasonable choice. I'm sure you'll find out toute suite if the spacing between the exhaust ports is symmetrical once you remove the header and try to flip it around the other direction. If that works, I would consider that arrangement for any future custom work, too.
BTW, I did note that the gap between the forward edge of the header pipe and the steel firewall protecting the battery is pretty narrow. This might become an issue in fitting standard rounded exhaust pipes.
Gravy, I'm having trouble with that link....seems dead, and I can't access it directly either right now. Maybe Robin's website is the problem...I'll try later.
Hmmm.....now, why didn't I thunk of dat?
It certainly sounds like a reasonable choice. I'm sure you'll find out toute suite if the spacing between the exhaust ports is symmetrical once you remove the header and try to flip it around the other direction. If that works, I would consider that arrangement for any future custom work, too.
BTW, I did note that the gap between the forward edge of the header pipe and the steel firewall protecting the battery is pretty narrow. This might become an issue in fitting standard rounded exhaust pipes.
Gravy, I'm having trouble with that link....seems dead, and I can't access it directly either right now. Maybe Robin's website is the problem...I'll try later.
BillCroasmun
Gold Member
Phil,
On the 180 the short exhaust pipe connected to the manifold is longer off one cylinder than the other so reversing on the 180 would require some modification. Hopefully yours is different though. /forums/images/graemlins/smile.gif
On the 180 the short exhaust pipe connected to the manifold is longer off one cylinder than the other so reversing on the 180 would require some modification. Hopefully yours is different though. /forums/images/graemlins/smile.gif
OP
Phils
Platinum Member
Thanks, Bill.
I'll be checking it this weekend. Originally I was considering slicing the stock "muffler" and welding it back together 180 degrees different -- with the outlet pointing up instead of down. Then it occurred to me that maybe I could just reverse the entire assembly, as I mentioned.
That manifold comes off so easily that it'll be quick to check. If it won't fit, as apparently the 18hp won't, I'll rethink it all. If it's as you say on yours, it may still be easier to cut/reweld one of those small pipes rather than the muffler but alignment would be critical.
S'posed to rain into Saturday morning. Perfect time to work on the PT as I won't be able to use it until later in the weekend.
Phil
I'll be checking it this weekend. Originally I was considering slicing the stock "muffler" and welding it back together 180 degrees different -- with the outlet pointing up instead of down. Then it occurred to me that maybe I could just reverse the entire assembly, as I mentioned.
That manifold comes off so easily that it'll be quick to check. If it won't fit, as apparently the 18hp won't, I'll rethink it all. If it's as you say on yours, it may still be easier to cut/reweld one of those small pipes rather than the muffler but alignment would be critical.
S'posed to rain into Saturday morning. Perfect time to work on the PT as I won't be able to use it until later in the weekend.
Phil
OP
Phils
Platinum Member
Dang it, Bill.
Mine's offset too.
That means I'd have to chop off the pipes and reweld in the opposite positions.
Not as easy as I'd hoped. But not too difficult either.
Knowing me, I'll put it on the back burner until I vaporlock again.
Phil
Mine's offset too.
That means I'd have to chop off the pipes and reweld in the opposite positions.
Not as easy as I'd hoped. But not too difficult either.
Knowing me, I'll put it on the back burner until I vaporlock again.
Phil
Gravy
Platinum Member
Phil,
FWIW,
After installing the second electric fuel pump (the first one was from my junk box and died after an hour), I worked full throttle at heavy digging for 5 or 6 hours with no vapor lock or fuel starvation problems. Since an electric pump didn't solve your problem, it appears that our problems may have different root causes.
Life has gotten interesting for the last week or so, so I haven't gotten around to actually ordering , much less installing the factory exhaust system. It looks like I won't get to do that until at least next weekend. However, rather than rearranging your exhaust system, you may want to try relocating your fuel pump and hoses. The fuel pump and bracket can be unbolted from the engine and moved to wherever you like, and the hoses can be run around the other side of the engine compartment.
Also, if you haven't tried it, run a hose straight from the electric fuel pump to the carburetor. The mechanical pump could possibly be restricting the flow from the electric pump.
Good luck!
Gravy
FWIW,
After installing the second electric fuel pump (the first one was from my junk box and died after an hour), I worked full throttle at heavy digging for 5 or 6 hours with no vapor lock or fuel starvation problems. Since an electric pump didn't solve your problem, it appears that our problems may have different root causes.
Life has gotten interesting for the last week or so, so I haven't gotten around to actually ordering , much less installing the factory exhaust system. It looks like I won't get to do that until at least next weekend. However, rather than rearranging your exhaust system, you may want to try relocating your fuel pump and hoses. The fuel pump and bracket can be unbolted from the engine and moved to wherever you like, and the hoses can be run around the other side of the engine compartment.
Also, if you haven't tried it, run a hose straight from the electric fuel pump to the carburetor. The mechanical pump could possibly be restricting the flow from the electric pump.
Good luck!
Gravy
