When i turn off the car it smells a little like gas. 91 honda accord theres no leaks have checked everywhere

I had a 91 that smelled of gas because the vent line to the file hole rusted out. It got to where it would leak out on the ground if I opened the nozzle all the way up when filling.

First advice: do not park the car in the garage until you've found the cause of the smell and fixed the leak. It takes very little gasoline vapour in a confined space to form an explosive mixture which could be detonated by a small static spark.

Could be two different problems.
If the check engine light is not on, I would look at the vapor canister for the gas tank. Its usually mounted in the engine compartment.
If you have a small oil leak, the fumes will be sucked into the passenger compartment thru the cowl vents.

Make sure battery has a full charge. If it cranks good but won't start, check the basics. Have a helper crank it while you visually check for spark at the spark plugs, if spark everywhere, use a gage and check proper fuel pressure. I looked at info for the 3.8L engine, 35--40 psi. Also, after you build fuel pressure, turn off the key, see if fuel pressure holds for a bit? If the pressure drops like a rock, check for fuel pressure leak. Check the vac line for fuel pressure regulator, if it has gas in it, the regulator is faulty, or a leaking fuel injector. The pressure could also drain back through fuel pump.
Also, check fuel injector pulse, engine cranking. Any applicable trouble codes?
Smell of the crankcase oil dipstick, if it smells like gas, either you don't change oil and filter very often or the engine is running very rich for some reason.

You shouldn't have any gas smells, maybe a little if the engine were cranking over without starting. But your car is not even cranking, right? Or will it crank and not start? In that case you might smell a little gas, so next step would be to check for spark.

The leak on front passenger side: if that is where the front of the engine is, check carefully your water pump for leaking (then it is bad) and also check all hose connections there for leaks.

Sudden no-start conditions are usually loss of either spark or gas to the cylinders. These are the first things to check when it won't start.

When the heater is turned on, it is drawing in air from the cowl at the bottom of the windshield outside the car. If your smelling gas when you turn it on, it would suggest to me that there may be a fuel leak under the hood. A lot of Honda's have the fuel filter under the hood against the firewall. Open the hood, and see if the gas smell is any stronger, or any gas smell at all for that matter. I would strongly recommend getting the car checked as soon as possible, if you can find the source of the smell yourself.

Try to give it a little time because you just did some work, it may need to burn out... but black smoke is an oil burning problem. even though the car will still run you dont want this problem because if oil is burning in your engine, it means oil is getting where it does not need to be witch HOPEFULLY, is just a gasket but you are not just burning fuel so it may be affecting your gas mileage!. it sounds like old gaskets!? maybe? gaskets are a **** to replace especially in a civic, and they are everywhere! i know i just took the whole engine apart and put it back together again in a 95.

As far as the heavy exhaust smell... may be a leak or crack in the manifold!

And as far as your sensors and dash lights go, save your money and dont replace any more! especially if you smell a problem and are getting only 20 miles to a gallon (especially in a honda) because the sensors are probably right!

Tim

2 things come to mind.. Fuel pressure regulator.. and Leaking injectors..

I've got a '99 Oddy with the same symptom of gas odor inside and outside of the vehicle. Gas cap was secure and the level of fuel made no difference, so by process of elimination, I checked and followed the fuel lines and made sure there were no cracks that I physically could put an eye and hand on and eventually ended up at the fuel injectors and fuel rail. From there, all you need to do is remove the plastic cover plate from the intake plenum and the injectors will be exposed as well as the fuel rail. Turn the car on and wrap some paper towel over your hand like a mitten and run it over the suspected areas. You'll either find your leak there or the fuel filter located under the rear sliding doors.

You just replace the O rings and check if its leaking ,before doing replacement check for blocked injectors which is causing this problem:

Please click on this link:

http://www.autozone.com/addVehicleId,1954802/initialAction,repairGuide/shopping/repairGuide.htm?pageId=0900c1528003bbf3

Good luck..