sweetpotato Posted November 3, 2015 Share Posted November 3, 2015 I drove the 53 straight 8 about 50 miles yesterday. Toward the end of the drive I began to smell fuel fumes. When I shut it down at home I removed the air cleaner and fuel was being spit up out of the barrel at about 5 second intervals with the engine shut down. Some fuel was also coming out of the throttle shaft and dripping on the manifold. This is a recently rebuilt Carter 2bbl. The carb was very warm to the touch but I don't think it was unusually hot. During the drive temps were normal. I can only get ethanol blended fuel here and I understand that it is more volotile. I know liquids have a lower boiling point at altitude also and I live at 8000 feet above sea level. Does anyone have any other thoughts on this ? Link to comment Share on other sites More sharing options...
NTX5467 Posted November 3, 2015 Share Posted November 3, 2015 The carb's temperature should mimic underhood temeratres, also influenced by ambient air temps and driving environments. What you might be describing is "percolation", where fuel temps in the carb result in "boiling over" of the gasoline in the float bowl during "hot soak" conditions. In prior times, "winter gas" on a warm spring day might result in similar situations. But now that all gas is more volatile than the most "easily-evaporated" winter gas of old, not terribly surprising. Still, not something we like to have happening! There's a LOT of cast iron under that hood that is "hot". The level of "hot" is cooled by the engine fan and coolant in the cooling system. When that heat ceases to be cooled (i.e., stopping the engine and related engine cooling fan), "heat rises" and the carb is the direct line of that heat radiation. Not much can be done short of opening the hood and letting the heat escape, or rigging an electric cooling fan to run after the engine stops. Seems like in prior times, the diagnostics would include making sure the heat riser valve was operating and not stuck closed? On an inline motor, that would help keep the carb cooler, possibly. NTX5467 Link to comment Share on other sites More sharing options...
SpecialEducation Posted November 3, 2015 Share Posted November 3, 2015 I would also make sure that your fuel lines have no metal-on-metal contact. While the fuel is flowing it may keep the hotter spots cool enough to prevent vaporization, but once the flow stops, the opportunity for the heat to vaporize the fuel is greatly increased. System pressure caused by vaporization is going to normalize somehow. I'm not familiar with this specific setup, but generally any vapor pressure before the pump is going to head toward the tank, where pressure after the pump is likely to head toward the carb. It may not be vaporizing in the carb, but vapors before the carb are forcing fuel out of the bowl. That's one of the reasons we like tank mounted pumps and fuel return lines in modern vehicles. The excess flow acts to keep the system cool and purges vapors if/when they occur. It's not a cheap option ($4-$6/gallon), but if you want to try a less volatile fuel, find a small local airport and get some 100LL AVGAS. Airplane gas is low on VOCs because airplanes obviously have to operate at high altitudes. Your valves will probably like the lead, too! AVGAS is cheaper at smaller airports, as the slower fixed based operators are hungrier for the business. This means they are also more likely to be helpful in regards to getting your car to the pump, or letting you on the field with a 5 gallon can to get your fix of the blue stuff. 1 Link to comment Share on other sites More sharing options...
sweetpotato Posted November 3, 2015 Author Share Posted November 3, 2015 Those are all good thoughts. I don't know if the tank on this car is vented or not but it does have an after-market cap which may be allowing pressure to build up. The idea of trying 100LL to see if it is a volatility issue had occurred to me. I never had a vapor lock in 40 years of burning 100LL in my 182 but after getting an STC to allow burning car gas I did have one on the climb-out from Phoenix once. Not sure if the new FBO at my airport will sell me 100LL but it is worth a try. Link to comment Share on other sites More sharing options...
old-tank Posted November 3, 2015 Share Posted November 3, 2015 The more volatile winter blend fuel started Sept 15 and is virtually everywhere in the country now, even in South Texas where it is still hot. I filled one of mine up a few days ago and only got a mile before fuel starvation. Flipped on the electric pump to correct. Then when parked it had the same slobbering carb from percolation. Link to comment Share on other sites More sharing options...
SpecialEducation Posted November 3, 2015 Share Posted November 3, 2015 Those are all good thoughts. I don't know if the tank on this car is vented or not but it does have an after-market cap which may be allowing pressure to build up. The idea of trying 100LL to see if it is a volatility issue had occurred to me. I never had a vapor lock in 40 years of burning 100LL in my 182 but after getting an STC to allow burning car gas I did have one on the climb-out from Phoenix once. Not sure if the new FBO at my airport will sell me 100LL but it is worth a try. Now that I know you are a pilot, I'll cut straight to the A&P speak in the future! Link to comment Share on other sites More sharing options...
sweetpotato Posted November 4, 2015 Author Share Posted November 4, 2015 The more volatile winter blend fuel started Sept 15 and is virtually everywhere in the country now, even in South Texas where it is still hot. I filled one of mine up a few days ago and only got a mile before fuel starvation. Flipped on the electric pump to correct. Then when parked it had the same slobbering carb from percolation. Makes me feel some better to know I'm not the only one with this problem. It is a little nerve-wracking to think of fuel dripping on a hot manifold. I will be carrying a fire extinguisher (which is never a bad idea) from now on. During the restore I did add an electric fuel pump and a manual switch. Link to comment Share on other sites More sharing options...
carbking Posted November 4, 2015 Share Posted November 4, 2015 Unfortunately, sufficiently common for me to put a blog on the issue on our troubleshooting page: http://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak The fuel fumes while running are probably coming from a different place. This should be addressed. Jon. 1 Link to comment Share on other sites More sharing options...
NTX5467 Posted November 5, 2015 Share Posted November 5, 2015 Be SURE to also check for any "cavity plugs" in the carb body which are on the outside of the carb itself. Usually, they look like a small ball bearing at the end of a passage, "peened" into place with some sealing solder. Many of the passages sealed like that head direct to the float bowl! The ethanol'd gas will deteriorate the original solder, allowing the ball bearing-seal to "leave" . . . which empties the float bowl on top of the intake manifold . . . with flaming results many times. One of our late chapter members caught the problem BEFORE it happened, as he'd seen that happen on a '56 Cadillac as it drove into a weekend cruise event. One possible issue with Avgas is the lack of "road tax" being collected when it's sold for "road use". You might check the various websites for "ethanol-free" gas in your area, too. Enjoy!NTX5467 Link to comment Share on other sites More sharing options...
60FlatTop Posted November 5, 2015 Share Posted November 5, 2015 Now that I know you are a pilot, I'll cut straight to the A&P speak in the future! Although I am not a pilot my Brother In Law, who retired as an Air Force Major, was standing behind my Impala SS at a family function and gave me a funny look when he asked about the license plate frame; NCC 1701.High altitude.Bernie Link to comment Share on other sites More sharing options...
sweetpotato Posted November 5, 2015 Author Share Posted November 5, 2015 Unfortunately, sufficiently common for me to put a blog on the issue on our troubleshooting page: http://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak The fuel fumes while running are probably coming from a different place. This should be addressed. Jon. Great blog Jon. That just about covers everything. Link to comment Share on other sites More sharing options...
sweetpotato Posted November 5, 2015 Author Share Posted November 5, 2015 Although I am not a pilot my Brother In Law, who retired as an Air Force Major, was standing behind my Impala SS at a family function and gave me a funny look when he asked about the license plate frame; NCC 1701.High altitude.Bernie It took awhile but it finally clicked.... Starship Enterprise Link to comment Share on other sites More sharing options...
SpecialEducation Posted November 5, 2015 Share Posted November 5, 2015 One possible issue with Avgas is the lack of "road tax" being collected when it's sold for "road use". You might check the various websites for "ethanol-free" gas in your area, too. I figure if he's running mogas in his airplane and avgas in his car, the FAA and the highway department are still getting their share. Link to comment Share on other sites More sharing options...
old-tank Posted November 5, 2015 Share Posted November 5, 2015 Toward the end of the drive I began to smell fuel fumes. The fuel fumes while running are probably coming from a different place. This should be addressed. Jon.The fumes were probably from the same place and for the same reason. If driving slow the fuel consumption is not keeping up with the additional pushed into the carb. This happened to me today after getting stuck in traffic after high speed driving: smelled gas and the engine was stumbling and loading up...it all cleared when speed increased again. Gas mileage went from 16 to 14 mpg. Seems they use butane to increase the volatility (like ethanol, another low energy component) Willie Link to comment Share on other sites More sharing options...
Airy Cat Posted November 5, 2015 Share Posted November 5, 2015 I run a 40% mixture of 100LL Av Gas and 60% 91 octane in all of my Buicks. I have been doing this for the last 30 years and have had no problems or issues with my cars. 1 Link to comment Share on other sites More sharing options...
sweetpotato Posted November 7, 2015 Author Share Posted November 7, 2015 Filled up with avgas today. It had about 1/4 tank of mogas. Drove about 60 miles, no gas smell and when I parked it, no boiling. I'm sure the valves liked it too. I have a big halon fire extinguisher in the back seat now so all is good. 1 Link to comment Share on other sites More sharing options...
old-tank Posted November 8, 2015 Share Posted November 8, 2015 We have all seen the signs on the the pump: "contains up to 10% ethanol". All major brands have a 'Top tier gasoline' designation, and by definition must have 10% ethanol. I wonder if the independents have less ethanol? (probably not, since ethanol is a cheap octane booster and is subsidized ) No avgas or marina gas available here . Link to comment Share on other sites More sharing options...
NTX5467 Posted November 8, 2015 Share Posted November 8, 2015 Texas has a fuel pump labeling law so pumps which dispense ethanol-blend fuel must be labelled as such, BUT all states don't have such regulations. There are still several websites which have lists of places which allegedly sell non-ethanol fuel, state by state. Some of the listings are "2015" as others are "prior". Some are brand-name fuels as others are "generic". Some are also for "racing gas" with Research Octane Numbers rather than "Pump Octane" numbers. NTX5467 Link to comment Share on other sites More sharing options...
SpecialEducation Posted November 9, 2015 Share Posted November 9, 2015 (edited) A few years back, Kansas had a governor who thought we'd sell more ethanol if the pumps didn't say there was ethanol in the gas, so she pushed legislation that would allow up to 10% with no labeling whatsoever. Two governors later, the law still stands.That said, if there's NO ethanol in the gas, THAT fact is hevily advertised. Edited November 9, 2015 by SpecialEducation (see edit history) Link to comment Share on other sites More sharing options...
buick man Posted November 12, 2015 Share Posted November 12, 2015 … and these growers, producers and distributors are most likely one and same no doubt that complain at every opportunity especially during election cycle years, about welfare recipients, queens and general welfare subsidies in general, unless of course it is to subsides their palms and their interest groups ( corporate welfare ) i.e.. subsidized farming and planting for ethanol. Which by the way takes a hell of a lot of water to just make one gallon of this alcohol based fuel. This ethanol in turn then delivers inferior MPG fuel economy than compared to real gas which it replaced resulting in having to burn even more of it thereby also defeating the so-called per gallon emitted pollutants that ethanol was suppose to decrease in the first place from that of real gas. Yes a complete cluster - cluster for sure Regarding attempting to obtain aviation and then mixing it which is the real cure to all of these carb/fuel ills, many small independent or county run airports out here will not fuel up an automobile. 30 years ago they would. Now, one has to come in with 5 gallon cans and they frown on that as well. You can tell them your rebuilding your Cessna engine or ultra light just so many times. One could I suppose, mount a proper 50 to 100 gallon tank on the back of your truck bed complete with proper safety valves and such or on a dedicated small fuel tank trailer. Browsing on-line sources for sales of contractor truck mounted or trailer mounted fuel tanks, i.e. like the ones used to refuel field and job site equipment all seem to be rated for diesel fuel only. Link to comment Share on other sites More sharing options...
NTX5467 Posted November 15, 2015 Share Posted November 15, 2015 And now, the United States Department of Agriculture is going to subsidize/"help" retailers upgrade to ethanol blender pumps so "not so prosperous" retailers can enjoy "the riches" of selling ethanol-blends of gasoline. Our tax dollars at work! I'd better stop there . . . NTX5467 2 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now