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I drove my FD for over an hour in 90º+ heat yesterday and my garage (and house) reeked of gas when I shut off the car afterwards. This is the first time I've driven that far at once or in that heat since I had my engine rebuilt and did a lot of other work. I do not smell gas after normal shorter drives, but the strength of the gas smell yesterday has me worried.
I've done reading here and found the pulsation dampener can be a problem, but I jumped the F/P and ground diagnostics connectors and let the car sit with the ignition on for ~20 minutes and never saw a leak or smelled gas, at all, anywhere (behind the car, different spots under the UIM, etc). So, if I can't find the leak with the car sitting in the garage, and I can't smell anything after most drives, what should I do?
Relevant recent maintenance:
- engine rebuild, 800 miles ago
- new injector seals, 600 miles ago
- all new silicon vacuum hoses 800 miles ago
- new fuel filter, 1000 miles ago
- powerfc installed with base tune
Should I just preemptively replace the pulsation dampener now, and possibly any other parts? Is there a way I can check for a charcoal can that gets clogged with heat or something?
I'm not driving the car until I figure this out, but yes I also keep a fire extinguisher in the car, always, just in case.
On particularly hot days, I have often smelled gasoline fumes coming from the fuel tank cap. This has happened occasionally since the FD was new in 1992. When the fuel tank heats up the vapor pressure exceeds the pressure the cap can hold. The cap has passed emission pressure requirements repeatedly as recently as last year, so I don't think my circumstances are unique.
I've had and have seen problems with gas smell that are actually related to the brake booster. Mazda did a recall back in the day on the brake booster vacuum hoses, the check valve in the hose can fail and power brakes can go out. But, a side effect can be atomized gas and air getting into the brake booster and making a smell.
I THINK that recall kit is still available from Mazda new. I remember it's really cheap. Again, this is the BRAKE BOOSTER HOSE recall, not the fuel line recall kit. Though if you have a fuel leak that's a handy kit .
Ray can tell if it's available and how much.
Have you pulled the upper intake manifold and let the fuel system test run for a while? Many times that's the best way to determine if there's a fuel leak under the intake manifold.
Another thing to check is the vapor recovery system. As the picture shows start on page F-129 for the test procedures. While you're in there, for general maintenance, replace all the old hardened hoses.
I've had and have seen problems with gas smell that are actually related to the brake booster. Mazda did a recall back in the day on the brake booster vacuum hoses, the check valve in the hose can fail and power brakes can go out. But, a side effect can be atomized gas and air getting into the brake booster and making a smell.
I THINK that recall kit is still available from Mazda new. I remember it's really cheap. Again, this is the BRAKE BOOSTER HOSE recall, not the fuel line recall kit. Though if you have a fuel leak that's a handy kit .
Ray can tell if it's available and how much.
Have you pulled the upper intake manifold and let the fuel system test run for a while? Many times that's the best way to determine if there's a fuel leak under the intake manifold.
Dale
Thanks Dale, given the amount of fuel odor that cam out I find it hard to believe it's just a brake booster hose. I've never had brake issues either.
I haven't yet pulled the UIM. It's a bit of a pain, so is it worth ordering the pulsation dampener now and replacing it anyway while I have easier access, or is it a part that I should leave alone until it causes problems? And by 'fuel system test' you mean just jumping F/P and ground and letting it sit for ~30 minutes right? Or is there more to it?
If you get air/fuel mix into the brake booster it makes a big smell even though it's not a lot. Don't forget that booster is right in front of the driver as well.
Pulling the UIM is a rite of passage, you gotta get good at it . That's the only way you'll be able to look down in there and really see, smell, and feel if you have a fuel leak. Yeah, pull the UIM, jumper F/P and GND, and let the fuel pump run. It should only take a little bit of time to be obvious if you have a fuel leak.
Are you referring to fuel hoses? All vacuum hoses are new but I haven't touched the fuel lines
I'm referring to the vapor recovery system hoses. Since these carry mostly gas fumes a slightly hardened hose may not seal well and allow small amounts of vapor past the nipple or small cracks will let out vapors leaving little if any evidence of a leak. The reason I suggested the vapor recovery system is, if all the check valves are not working properly the system could pressurize itself when the gasoline warms and expands inside the tank. What is supposed to happen is the vapors above the gasoline are pushed into the charcoal canister keeping the system un-pressurized. Old hoses + pressurized vapor recovery lines = gas smell with no visible leak.
If it were me, while I had the UIM apart it would be a good time to replace the PD. Just as a bit of preventative maintenance.
Pulling the intake manifold is a super easy 5-10 minute job. Pulling the rat's nest out of the way enough to get to the pulsation dampener and replace it is a whole different thing. You're getting into crispy wiring, old vacuum lines, etc to go that deep. And it's held in with Phillips head screws that really really want to round out.
Of all the FD's I've worked on I don't think I've ever seen a leaking pulsation dampener. Not that it doesn't happen but it isn't an everyday occurrence.
Regardless it needs to be pressure tested to see where there's a leak or if there's a leak. Fuel is at a high enough pressure that even a tiny leak will show up quite well.
Pulling the intake manifold is a super easy 5-10 minute job.
I'm not sure about that, but the first time I did it it took 1.5 hours, and this time (third time) was only 27 minutes. Too many tight/stuck vacuum hoses in cramped places.
I removed the UIM, jumped F/P and ground, and let the car sit in the garage for an hour and a half. I did not find any trace of gas around the injector rails and fuel lines, and I did't smell any gas at all either. At this point I feel like it's safe to drive and keep an eye on. Could my gas pressure really have gotten too high and vented out the gas gap, or overwhelmed my charcoal can or something since I don't have a leak under normal circumstances?
Like Dale said removing the Upper intake is supper easy 15 minutes 20 max. Be very care when driving the car hard. Back in the day when I first bought my Rx7 I kept smelling fuel and took the car to the Mazda dealership twice and they never found the leak. The third time I let them keep the Fd for a week and still they didn’t find anything. So I drove the car hard about 4 days later and it caught on fire. Fuel from the pulsation damper/rails was leaking, hit the twins and up in flames it went. You can read some more here and also help you removing that death trap.
I'm not sure about that, but the first time I did it it took 1.5 hours, and this time (third time) was only 27 minutes. Too many tight/stuck vacuum hoses in cramped places.
I removed the UIM, jumped F/P and ground, and let the car sit in the garage for an hour and a half. I did not find any trace of gas around the injector rails and fuel lines, and I did't smell any gas at all either. At this point I feel like it's safe to drive and keep an eye on. Could my gas pressure really have gotten too high and vented out the gas gap, or overwhelmed my charcoal can or something since I don't have a leak under normal circumstances?
As I said earlier, yes the gas in the fuel tank could have built up enough pressure to vent. In my case, on a few occasions, the smell was very strong. If it's coming from the cap, you should be able to smell it most strongly there when you open the fuel access door if it is still venting, which happens immediately or very soon after shutting off, since that's when the tank would be heated the most from the exhaust, etc. and have the highest pressure.
IMO, that's more likely now since you haven't found another possible source.
As I said earlier, yes the gas in the fuel tank could have built up enough pressure to vent. In my case, on a few occasions, the smell was very strong. If it's coming from the cap, you should be able to smell it most strongly there when you open the fuel access door if it is still venting, which happens immediately or very soon after shutting off, since that's when the tank would be heated the most from the exhaust, etc. and have the highest pressure.
IMO, that's more likely now since you haven't found another possible source.
Thanks, I agree, I just didn't want to take chances in case I actually was leaking fuel on my engine. Next time I take it on a long drive I'll check the gas cap to confirm.
06-17-18, 06:19 PM
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