I've been trying to track down a strong smell of gas coming from the engine without much success so I had a look with a mechanic today and he found that the bottom half of the air filter is soaked with gas. He's going to start by checking the evap system on Monday. Has anyone else experienced anything like this? It's 3.4L 1999 4runner.

 

Had you been working on the fuel system at all??

Around The Evap System??

That you might have switched some lines around?/

I need to look closer but i would think if something has failed in the Evap system it is possible to draw liquid out of the tank like what your issue is.

 

The only thing I've done is replace the air filter and reset the EFI relay. The old air filter wasn't soaked in gas. So something changed after I put the new one in.

 

We had my wife's '96 at some fairly steep downward angles once on a trail, and the evap 'moo box' system was going crazy, and there was a smell of gas wafting around the front of the car. But the cause and effect there was pretty clear.

 

Did the mechanic figure anything out?

 

He said it was the fuel pressure regulator.

 

So it was overloading the injectors and flowing upstream through the manifold all the way to the airbox? Wow, I didn't know that could happen

 

The FPR regulates fuel pressure vs. the manifold air pressure, by using a diaphragm with the fuel on one side, and the air on the other (plus a spring). If the diaphragm develops a leak, fuel will go through the FPR and into the intake via the hose.

Generally, when this is happening, there's so much gas in the intake that the engine won't run, and it can even hydrolock. This must have been a fairly small leak?

 

Thanks. That makes sense now.

 

Yes, this is what he said. It must have been a small leak because it ran fine except for hard starts after it had been running awhile. Started fine first thing in the morning after all the fuel had evaporated from the air filter.

 

I should also add that replacing the FPR cured the problem of the engine bogging when flooring the accelerator.