Strong Smell of Gasoline

I just returned home from a few days out of town and noticed that my garage has a very stong smell of gasoline. I have the front end of my speedster on ramps so it is several inchs higher than the rear. Is it possible that gas could be flowing from the tank, through the carbs and into the engine? I don't see any evidence of fuel leaking anywhere, but the smell is very strong. Any ideas?
Troy

Troy,
Before you spend time looking for some small leak just check to see that the gas cap is very tight. The cap in mine twists tight ... and then twists a bit looser! That caused me to have the gas smell in the garage for a week until I discovered it.

I hope this is an easy fix for you

Dusty

Thanks Dusty, but its more serious than that. Upon closer inspection, I see that there is a leak on the right side of my engine and my crankcase is full of gas! Obviously, before I start the thing, I'll have to drain everything out of the crankcase, but does anyone know if there is anything else I should do? Shouldn't the floats in the carbs prevent this from happening?
Troy

I believe the float stuck and with the forward end of the car higher it siphoned into the carb and motor. ~Alan

As I think about it a little more, I suppose this means that the cylinders on the right may also be full of gas. I guess that means there will be more involved than just draining and refilling the crankcase. I welcome suggestions.
Troy

you *could* remove the plug wires (and rotor / cap), plull the plug wires and spin it over once you have fresh oil in it.

My buddy crashed his car into a lake ala dukes of hazard and that's how he emptied his engine.

or pull the heads

Don't pull the heads -- this is easy.
My guess is there's enough gas between the two banks of cylinders to fill a soda bottle. Take the plugs out, put a wrench on the crank pulley and turn it manually. The gas will geyser up out of the plug holes (so loosely cover all four) and you'll want to have a shop towel on standby to mop up with. I'd suggest a pair of safety glasses and a cotton towel you don't care about for this operation.
I'd suggest something absorbent under the car, too. Kitty litter works fine; it cleans up easily with a little broom and a dustpan. Drop the refuse off at the local oil-changing joint or gas station, 'cuz it's HAZMAT and your garbage man won't appreciate it very much.
There's a good chance your floats are stuck because the walls of the float chamber are gooped up with gummy old gas, especially common in cars that don't get fed detergent gasolines. That's also an easy fix if you know your way around your carbs. If not, maybe it's worth a trip to the old mechanic's shop for a winter cleaning.
You can check the plugs while they're out.

This happened to me last year, and the good folks here had similar suggestions. Worked like a champ.

Do you have a mechanical VW fuel pump on the engine? When the diaphrom goes on it - it can fill the crank case. I couldn't see a picture of your engine to confirm. An electric pump shouldn't leak regardless of tilt angle but the a faulty mechanical would surely would. What type carbs?

maybe a large syringe with a piece of tubing to siphon any possible gas in cylinders. after draining oil i'd let the inside of engine air out real well before refilling.

The way I go about this....
Check for possible fuel pump / excess gas issues as described above.
Disconnect the coil wire AT the coil ............TO AVOID SPARK.
Pull plugs, drap shop rags over the plug holes.
Crank over motor with the starter for 5 seconds to clear cylinders
Repeat if necessary.
Clean plugs, check gap, or better yet replace new plugs.

Ah-HA! The turkey baster and some rubber hose! Why didn't I think of that? Nice, Bob!
Alan, it's cheating to disconnect the coil! (Oops! BOOM!)

FIRE EXTINGUISHER! FIRE EXTINGUISHER! And don't do it your garage! A car on fire will fill the garage with black smoke and you can pass out within a very short time. Also, a car fire in the garage will blacken the walls inside the house and really piss off your wife! Been there, done that!

Here are some more details.
This is a brand new Vintage Speedster, with less than 400 miles on it, so there is no issue with worn out parts or gummed up carbs due to old gas. It has dual Kadron carbs and an electric fuel pump and a pressure regulator. There is a small riser between the manifold and the carb and there is a gasket between the manifold and the riser and between the carb and the riser. Last night, before I took the ramps out from the front end, both of those gaskets appeared wet. I could wipe them off and they just appeared wet again in a few minutes. This morning they appear dry. Only the carb on the right side appeared to be affected. It just seems to me that it must be a float issue on that right carb, but how would the gas be getting outside of the carb to make that gasket wet?
Troy

I was wondering about this. It is a new car...mabe a call to Kirk would be in order. You shouldn't have to screw with this.

~WB

Yes. I'll be calling Kirk, but he has been closed since the 22nd and doesn't open up again until after the new year.
Troy

I drained about 2 gallons of gas and Synthoil from my crankcase and I ran a couple of quarts of 30 weight through it and then drained that before refilling with Synthoil. I also cranked it by hand and made sure there was no gas in the cylinders before I started it. Everything seems ok now that the front end is not up on ramps, but I still need to fix the float issue.
Troy

Troy - I had EXACTLY the same issue you did. I also park in the garage on an inclined ramp (a Kwik Lift - I love it). I do think this may contribute to your problem. A full gas tank is actually higher than the carb inlet when parked like this, and nature likes to siphon. I actually filled up #4 cylinder with gas, right up to the plug. Luckily I caught it before I turned the engine over. After cleanup and an oil change, all ended well, engine runs fine.

My solution was to add a manual fuel shut-off valve in the engine compartment. I swear, if I park on level ground, I do not have this problem, but I always park on the ramp at night. It's also a secondary security device. It may work for you.

Hi David.
I spoke to the expert "Mr. Kadron" at Low Budget.com and here is the skinny on what actually happened to you and I and apparently a lot of others too; its pretty basic physics and not really a "siphon" problem. That would be the case if the fuel tank was lower than the engine and the fuel traveled up the fuel line and then down to the carbs. Our problem was pretty simple and comes down to two facts.

1. Electric fuel pumps have a piston that is either in the up or down position. If it's up, fuel can't flow past it, but if its down, the fuel will flow straight to the carbs.

2. The float/needle valve assembly in a carb. is only rated to hold about 2 lbs of pressure and with the fuel tank elevated by having the front end up on ramps, the pressure at the spring loaded needle valve is much higher than 2 lbs.

So, if your electric fuel pump piston is down and you have dual carbs, the carb. with the weakest spring will leak and fuel will flow straight through and into the cylinder with an open intake valve. It then flows past the rings and into the crankcase. Additionally, it will soak the gaskets between the carb. and the manifold and leak out onto the engine and floor.

This is a potentially VERY dangerous problem that everyone should be aware of. Obviously, the biggest concern is the risk of fire, which is extremely high, but even if you didn't have a fire, the risk of damage to your engine is also very high. Liquid does not compress, so if you attempt to start your engine with a cylinder full of fuel, you risk blowing head gaskets, cracking heads, bending rods and breaking cranks in addition to starting a fire.

Here is what you can do to avoid this problem.

1. Install a mechanical fuel shut off valve at the tank.
2. Carefully pinch the fuel line near the tank with vise grips while the front end
is up on ramps.
3. Never attempt to start your engine if there is a strong smell of gas.
4. Roll your car out of the garage if there is a strong smell of gas and then look closely for the source.

Stay safe.
Troy

Not so certain I agree with everything he told you. He may very well be the worlds best and foremost expert on the carbs, but even a full fuel tank will not exert enough pressure on a 2 pound rated valve to open it if it is working properly. Please note that is 2 PSI and the contact area of the needle valve in square inches is figured by pi r squared. I think you will discover that if the contact surface is 1/16" then the area is is what .0032 square inches? (.032 (r)x.032 (r)x 3.14 (pi)) That means it would take quite a few pounds of fuel at nearly the same level to push by the 2 psi control valve... even if it is 1/8" it would take a lot of gas in the tank to push by the float needle valve. Could be the valve just plain sticks open?

I have had the problem with a stock fuel pump that had a defective diaphram....a crankcase full of fuel...not a head full of fuel. I replace the mechanical pump with an electric and had no more problems with the Kadrons... If your fuel is actually flowing from the carbs into the heads, and it sounds like you are sure that is the problem, I would think the more likely culprit are in the needle /float valves in the carbs.... one of them is sticking OPEN is the only conclusion I can see that fits your symptoms.??????

Yeah, what Jim said! pi r :) = all gone...or sumpthin!
I can hardly believe a properly set float with a good valve couldn't hold back the fuel. In most of our cases that means TWO properly set floats.
I've heard more than once from a few of the builders that new carbs from the box aren't necessarily set properly and are slapped right on cars.
This may be the case here. I know one would assume a new carb from the box would be perfect, but that just doesn't happen all the time and this isn't a good area to "assume" anything.

~WB

Thanks Jim. I did wonder a little about some of what he said, because people in San Francisco and other locations, park on hills all the time without any problems. I'll check that float adjustment. Whatever the cause, it's still a very dangerous situation.
I'm curious, how did the fuel from your bad mechanical fuel pump get into your crankcase without going through the heads?
Troy

May I suggest......
http://www.cbperformance.com/catalog.asp?ProductID=577
None of the "pulse" action of those ol' fuel pumps I ran on my hot rod chebbys and no need for a pressure regulator.

Troy,

With a hole or crack in the diaphram the gas will run from the gas line at the pump down through the crack/hole in the diaphram down the pushrod right into the crankcase....and it WILL syphon under those circumstances. My crank case was completely full of gas.......running out the dipstick tube onto the floor of my garage....had I not seen the puddle and smelled it before I cranked it I could have killed myself and burnt down my house too......

Jim

Troy:

If a stock, mechanical fuel pump develops a hole (usually a tear) in the diaphragm, then the fuel seeps through (sometimes it can become a torrent) and drips down directly into the crankcase because the fuel pump mounts on the top of the crankcase in this big hole made for it.

As far as the CB performance rotary pump, it's a GREAT pump; good flow, right pressure for our carbs AND it's very quiet, especially compared to one of those Facet, clickity-klack, block-style pumps.

Just be aware that the CB rotary pump is a pusher, not a puller. They work far better if mounted up in the front, right under the fuel tank, so they receive gravity feed from the tank and then push the fuel to the engine in back.

Will it still work if you mount it in the rear? Yes, but you may suffer from fuel delivery problems from time to time and wonder what the heck is going on.

While you're installing the pump, get a fuel shutoff from a lawn mower parts place and put it in the fuel line just before the pump so you can positively shut the flow off if you wish. Nice feature to have...

gn

While we are on the fuel problems subject, as I've mentioned many times during the past years, it's a good idea to check that the fuel line rubber grommet is intact in the front engine tin. They dry out from the heat and wear away creating a chafing condition of the fuel line. A leak here drops right on the #3 cyl. exhaust pipe....=kaboom.
just a reminder.

As Troy is finding out, there will be issues that arise even with a "new" car that will need sorting out. Assume nothing! Case in point, Kelly's new JPS right off the truck had a steering wheel that was all but ready to fall off!? It's a good idea to check every fuel line clamp and connection and such. It only takes one guy that has a brainfart (as we all do now and then) to ruin your day.

Keep an eye out in the engine bay and on the floor for any drips, be it engine oil, fuel or brake fluid from a leaking hose etc.

~WB

For sure Gordon...
Put the pump under the tank! Away from the motor, I might add!
One of my upgrades (this winter) is to add an under dash hidden toggle to shut off the pump. Since the pump emits a slight hum, I'll easily know if I've mistakenly left the switch open.

Ernie:

Even better than that would be to install a roll-over or impact switch in series with the pump +12V. That way, if you get hit and don't have the presence of mind to turn off the ignition, that switch will stop fuel delivery.

Happy New Year All Y'all Speedstah Guys and Gals!!

gn

Just to clear up one little thing. To do so, I will remind everyone that atmospheric pressure is commonly taken as 14.7 psi and the weather guys talk about this as 30 in.: "The barrometer is at about 29.8 in. today and rising." -- they sometimes say. Huh? pressure measured in inches?? -- say what?? -- What they mean is this pressure will support a column of about 30.0 in. of mercury where there would be a vacuum at the top end of that column. Mercury is about 13.6 times as dense as water, so that same 14.7 psi will support 30 x 13.6 = 407 in. of water. Gas is about 80% as dense as water so that is 508 in. of gas. Or 34.6 in. of gas per psi. You will need about 70 in. of elevation difference between float valve and gas in tank to achieve 2 psi differential. This all has nothing to do w/ pi R squared and the size of the needle valve seat. If you want to know how much force is applied to the needle to hold back 2 psi, then you will need to know the area upon which the pressure acts. Since that area is really rather tiny, the force to open/close the valve is rather small. Didn't we all go over this once before? Class dismissed.

So it seems that the electric pump allowed gas to flow with little resistance and that the float valve was open, and so the gas did indeed flow. And, like some other substances, it will run down hill with very little extra encouragement. Float valve could be open because float has a hole in it, and so sunk into the float chamber, or got stuck open somehow -- dirt?? -- or was assembled wrong. When you get to the root cause here, pls let us all know.

...and being that my brain is 80% less dense than Kelly's, my trying to follow and comprehend the above post has resulted in blood exiting my earholes at 14.6 psi across my 23.35' living room. :(

~WB

Kelly you had better go back to school and pay attention in fluid dynamics....

Troy -

Hope you've been able to resolve your gasoline/fuel smell issues. Keep us posted (or have I missed your response post?).

Hi Jim.
The fuel leak stopped as soon as I took the car down from the ramps, but I've still got to take the carb apart and look at it. I'll try to do that this weekend.
Troy

I finally had time to take apart my right side carb and discovered that contrary to what "Mr. Kadron" told me, there is no spring (at least that I can see) in the float and needle valve portion of the carb.. I also do not see any way of adjusting the height of the float. I did, however, notice what may have been a problem, but I am not sure. The float hinges on a pin at the back of the bowl and the flanges that curve over that pin appeared to be very close to the wall of the bowl, which could possibly have caused the float to bind and not be able to completely close the needle valve. I bent them slightly so there is no chance of binding and the float can travel freely. I'll probably never know if that was the cause of my problem, because I don't intend to leave the front end of the car up on ramps for an extended period of time ever again.