tarathatcher

I've been searching for answers to my problem since Feb. but I haven't been able to get anywhere on my own, so I thought I'd make a thread. I have a 99 Si stock engine with fresh tuneup (plugs, wires, cap/rotor, fuel filter, timing belt, water pump, belts). I've smelled gas off and on since I got the car. My check engine light is not illuminated. Some days I don't smell it at all, others I do. It seems to run fine.

When I remove the gas cap (also new) there is no pressure at the cap. I have a gauge on the filter that reads 40 when it's running. It will bleed off within 20 minutes of being parked. I can't find any physical evidence of a gas leak. I am getting ready to take a long cross country trip in the car, and thought I had better get a little input first. Any ideas at all? What gets me is that there is no check engine light. My fuel mileage varies. Car has 120,000 miles.

Former User

Where exactly do you smell the gas? Is it raw gasoline or a gas smell in the exhaust?

I think it may be normal for the fuel pressure to gradually bleed off.

beecee18

And you have no evap codes in the past so fuel tank pressure should pass, you might be looking into a fuel pump module in the future but some diagnosis will be needed. Might also be associated with a fuel pressure regulator. Do you have hard starts when engine is at operating temperature(takes a little longer then normal to start after engines warm?)

beecee18

Welcome to owning a Honda Motor vehicle, this has always been one of thier flaws.

Former User

To check whether the CEL works, turn the key from off to the ON(II) position. Does the CEL turn on and then off after 2 seconds?

Former User

One must also consider the possibility that the CEL is not on because there is no sensor-related problem.

tarathatcher

Yea, when I start the car it starts immediately. The check engine does come on for the 2 seconds and goes off. I also thought that the bulb was missing, but it's in there. No hard starts when hot, either. It's very bizarre. I hate to just start throwing more parts at it. It is definitely a raw gas smell, not fumes. Not overpowering, but I have a sensitive nose...LOL I know I smell it. Preventive maintenance wouldn't hurt to go ahead and replace the pump with a walbro. I'm hoping to make it to Texas in it from Ohio this weekend. I love the car, have had many Hondas over the years, and plan to keep it. This issue is just baffling.

beecee18

Do not just throw parts at it, we are against that, There should not necessarly be pressure when removing the gas cap, Im honestly at a loss of what it could be, although fuel pressure should not bleed off during sitting for that short of time. And that would be the first thing I would fix.
This can be caused by,
slight leak in fuel line/lines(check banjo fittings and make sure copper washers are present and in good shape on each side of the banjo)
fuel pump check valve(which requires replacement of fuel pump module)
fuel pressure regulator.
Have any of the conponments been thrown at the vehicle?
And how do you feel about your vehicles gas consumption opposed to how it was before the gas smell?

beecee18

I wouldnt get an aftermarket pump rated higher then the stock 130-140lph
walbro varients range from 190-255lph, and this could put more pressure then the ECU is calculated for at the rail, sometimes causing a slightly rich condition.
A stock replacement for 99-2000 civic si will suffice.

I would personally use factory troubleshooting guide for fuel pump module, and fuel pressure regulator found in the fuel section of the service manual. Ron is great at getting these exerpts to us. Im not so much lol.
And there is no need for replacing the car, when its figured out it will continue to serve as a great fun vehicle.

Former User

Bottom line -- To fix, you need to pinpoint where the gas fumes are coming from.

EJ8_Man

To throw out some ideas, as Ron said you need to inspect the fuel system and identify the leak. Luckily the fuel system on the 99 Si is not that complicated.

I'll walk through how I'd inspect it (follow your nose...):

I'd start in the engine bay and check for leaky fuel injectors, fuel rail, fuel regulator, fuel filter, fuel lines

Next I'd check the EVAP system. This will be difficult because the EVAP system purges fumes from the fuel tank and feeds them into the intake, so you wont see a leak, but you would smell one. One way to check the EVAP system is to unplug the gas tank purge line at the charcoal canister and pressurize it with an air compressor to see if the pressure bleeds off or holds. Be careful you don't over pressurize the system or you'll blow off your hoses at the tank.

It could be the pump seal at the gas tank (under the rear seat). However if that were the case you'd probably be throwing an EVAP code.

A maintenance manual will have more detail on how to better test specific systems. If you can't find anything it may just be the charcoal canister breathing off fumes.

beecee18

any leak/problem with evap will net the user a code.

I was going to throughout maybe OP is just hyper sensative of smells ??????

if you cant find a leak with your nose ect.
you will be looking into where your pressure is bleeding off to.

tony_2018

The evap canistor probably not hooked up right.

motegicivic

Do not get a Walbro pump, I have read many reports Honda's do not like them. Did you check the fuel pressure regulator? sometimes you can pull the vacuum hose when it is running and see if any fuel comes out. Also can be checked with a gauge.

Did you double check the fittings at the fuel filter to make sure it is super tight, mine took like super force to get it tight.

Also check you exhaust mani for leaks, sometimes exhaust leaks smell like raw gas, happened to me.