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Gas leak or unburnt gas

I took my pickup ('87 Toyota gasoline carbureted 4-cylinder) for an emissions test today. The guy refused to test it because it smelt so strongly of gasoline. There was gasoline on the ground, and I could smell it too, and he’s been straight with me before, so I drove home instead.

The bottom of the gas tank is dry, as is the filter (which is near the tank, in front of a wheel well) and the lines underneath. The lines in the engine compartment are dry too, as is the outside of the carburetor. I put paper down, haven’t collected any gasoline yet.

There was gas on top of the air cleaner, on the outside, and on the bottom of the inside. I assume this is wrong, but I’ve never checked before. It seems to run okay. I started it for the first time since 2020 October 2. It started up immediately and ran okay.

Where was the gas, relative to the truck?

Gas does not belong in or around the aircleaner. Maybe a stuck or misadjusted carb float. Might give a better guess when you answer my question.

In front of the passenger’s side rear wheel, a little bit in, near the fuel filter. Of course it could have been from a previous vehicle. This guy is the cheapest in town and also runs a Vietnamese restaurant next door so he can be busy. I’ve been home for a few hours now, put paper under, haven’t found a single drip. I re-built the carburetor 4 years ago, have passed emissions tests twice since.

You assume correctly. Sounds like time for a carb rebuild, if all hoses and connections aren’t leaking.

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Grrrr… I re-built it 680 miles ago.

Sound to me like the float was stuck down from sitting. It probably unstuck itself on your way home.

If the float were stuck down to the point of fuel spilling out of the carb, the engine would have barely run.

Where is the fuel pump on this engine? Is it possible the diaphragm ruptured and the pump was leaking externally onto the engine?

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Mounted on the passenger side of the engine; it’s mechanical. I replaced it 11 years (2,500 miles) ago.

I don’t see how fuel that leaked out of it would have gotten on top of the air cleaner. Everywhere else was dry.

Could the moisture on and in the air cleaner been water? I was thinking gasoline.

I don’t see how gas could find its way from the inside of the carb to the outside top of the air cleaner.

Could it have been water? I dunno. Did it taste like water? :grinning: Is it particularly wet and rainy where you are?

No, you re-built it 4 years ago.


Both. Neither is long in the lifetime of a carburetor.

4 years is a long time for a carburetor sitting with gas in it.


4 years is a long time for a carburetor sitting with gas in it.

Agree I just had to redo the carb on my 82 Dodge after sitting a year.

Next time you find a puddle, smell the liquid. That should tell you quickly what it is. If the puddle is large enough, dump it into a glass of water. If it floats, it’s gas.

Should I see fuel in the sight glass when the engine is cold? I don’t.

I think the sight glass can be confusing. If the gas is above the glass, it can appear to be empty.

You are correct that if the float valve is not sealing well, it would be running rich.


I thought about that, but none of my manuals mention it.

Rich enough to backfire? 17 years ago my choke got disconnected; it’d backfire until it warmed up and started with more difficulty. Fortunately the arm had just popped out of the loop on the end of the bimetallic strip, probably on that -17° day I had to drive. It didn’t backfire yesterday and started more like it was too lean until it warmed up.

I was about to take the air cleaner off so I could inspect the float when I noticed that the gasket the PCV valve sits in is loose, no longer holds onto its hole; one of the clamps that holds down the top of the air cleaner butts into it so I often move it a bit. I’ll replace it, of course, as well as the valve. Could that have caused this problem?