This has been driving me nuts for over a year. Hopefully someone can point me in the right direction here.

Problem:

Windows up or down, vents open or closed, full or low gas tank...doesn't matter. When accelerating in positive boost, I get a very strong smell of gasoline in the cabin - even before letting off the throttle.

Possible causes that have been ruled out:

First I thought it was my injectors: when I installed the 1600cc secondary injectors, they forgot to send me the aluminum sleeves, so I installed the injectors without them. Then I thought it was the banjo bolt on the secondary fuel rail. Then I thought it was the connection to the hard lines in the engine bay (attached to fire wall, that run to back of car).

Well I've since replaced almost my whole under-hood fuel system with all new lines and fittings, and there are definitely no leaks from any of them. I've checked, many times. I've also checked my fuel tank bulkhead cover - no leaks. Meanwhile, my tune isn't too rich - I actually leaned it out recently for high way cruising.



At this point, I can only guess that maybe there is an issue with the rear charcoal canister...? However, I'm not sure how such a strong smell in the cabin could come from back there....

Thoughts? Suggestions?

Thanks in advance.

 

I had this problem when I first got my FD (which was near stock at that point). Common problem is the brake booster check valve that's built-in to the vacuum hose to the brake booster. If it goes bad, you get pressurized air/fuel mixture to the brake booster.

You can swap those hoses out with a buddy's car to check (Rich: why do my power brakes suddenly not work? Dan: Hmm, that's weird) or just get the hoses new. Mazda has a brake hose recall kit, the original hoses had the check valve on the passenger side of the car, the heat would cook the check valve and kill it. The new hoses have the check valve on the driver's side. I think the kit is like $18 or something, it's pretty reasonable.

Dale

 

Sweet Jesus, Dale, I hope you're right. I knew you would have some good tips. Going to check tonight.

 

Do you still have the evaporative control system on the car (i.e. plumbing back to the UIM with the aluminum check valve)?

 

The line that goes from the UIM to the aluminum check valve, to the solenoid...right?

If so, then yes I still have that. I'll check that check valve also...

 

usually i find it's the primary injector seals to the block, they never seal very well and blow by under boost.

 

plus one.. ive had this fail on me on three fds.. the other two was due to a blown LIM gasket..

 

Ouch Gio, mentioning the LIM gasket like that... might as well kick his dog while you're at it...

 

Had the LIM off recently when I put on a low-mileage set of twins - LIM gasket was just fine.

Primary injectors were removed at the same time when I tapped the primary rail for NPT-to-AN fittings. Checked the diffuser pieces that the injectors sit on and they looked fine too.

Too late to check now...but I'm going to check the stuff Dale & Mahjik suggested, tomorrow.

 

I had this problem for 4 years: only under boost do I smell gas. Turns out the Mazda mechanic didn't put the flat rubber washer between the fuel rail and the manifold caused this problem.

 

You mean the plastic phenolic spacer between the block and primary fuel rail?

Dale

 

Yeah, I assume he is talking about that capsule-shaped flat plastic shim that has two holes in it, one for each injector.

I definitely have that installed.

 

If it is a strong smell in the cabin, I would check your charcoal canister. There are a lot of connections near the fuel tank and I would check those...

 

light a match and search, you'll know when you've found the source.

 

^ reminds me of the time i lost my eyebrows lol

 

Nope. assume that you have assembled the injector into the secondary fuel rail then as you get ready to insert the two business ends into the manifold boss, there needs to be a rubber spacer for each of the business ends.

 

You mean the diffusers?


Photo credit to Damian.

Yeah I definitely have these installed.

 

I think he's referring to the "injector insulators". They are the soft rubber rings with a rectangular cross section.

 

yup those tend to go out all the time, specially in the FD

 

I don't know much about why the smell exists but it could be coming through the shifter hole; I've seen that in other cars I've owned.

Maybe you have an exhaust leak of some kind?

 

There are two grommets that fit around outside of the primary fual rail, these seal the rail to the block. Sounds like you do not have them installed.

 

Negative. Had a small exhaust leak before but fixed it when I put on a set of low-mileage franken-turbos recently. ha

I'm pretty sure I have the primary rail in nice and tight with all the fixins'

But would you mind providing a photo of these grommets that you're talking about?

Here are photos of my primary fuel rail, draw some arrows on here to show where they go if you want.

 

Have you had this problem since the build or is this a recent development?


John

 

See attached.

The grommets from Mazda look just like these things:
http://injector-rehab.com/shop/Gromm...rs-Other-Parts

David

 

PN# N3A1-13-257 sits outside of the rail, on the machined flat at the top of the taper.