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fuel smell! not driving fd for a bit

Old 12-29-18, 01:27 AM
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fuel smell! not driving fd for a bit

So recently my FD has developed a pretty heavy fuel smell. I'm suspicious that it may be the Fuel Pulsation Damper and will plan time to remove the UIM. While I'm under there, what else should I check?

For now, the car will be parked until I can get to it.
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Old 12-29-18, 08:47 AM
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mkiv,

The probability of your FPD (fuel pulsation damper) going bad is fairly high. Have you replaced it before? You are wise to park the FD until you could troubleshoot it further. No need to have an FD succumb to fire damage. Do you plan on replacing it or deleting it? Mine was replaced during an engine rebuild, whether it needed to be replaced or not. I chose to replace it because I wanted to retain near-factory performance. I can't comment on the difficulty level of the replacement because my engine builder did all the work outside of the car. I've been happy ever since and have not had any fuel related problems *knock on wood*.

Please let us know what you find and how you fixed it. Best of luck and wish you a happy new year!
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Old 12-29-18, 01:56 PM
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Originally Posted by mkiv98 View Post
.will plan time to remove the UIM. While I'm under there, what else should I check?...
Off hand....
*You can replace the check valves with DC's Viton versions. Not expensive or hard.
*Check the coil harness for crispyness. ~ $100 IIRC, but it'll never be easier to change if needed.
*Soft fuel lines.
*If you still have the original throttlebody coolant line, it's a good time to replace it since accessing the nipple on the rear iron will be ALOT easier. IIRC Summit Racing carries a high performance reinforced silicone line. Probably other sources too.



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Old 12-29-18, 08:48 PM
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I would definitely suspect the fpd. My own car and a guy I was working on car had them fail this year. Take the upper off, and jumper the fuel pump test connector to see for sure wher eits coming from
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Old 12-30-18, 02:12 AM
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Thanks guys, I do plan to get a whole new engine within the next 6 months so maybe I will just bypass the FPD for now. Is there anything else that could be leaking fuel (or other fire hazards) specifically?
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Old 12-30-18, 08:26 AM
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There's any number of things that could be leaking, good thing is they are all under the UIM and typically not hard to find when you jump the test connector and pressurize the system.

If you don't see leaks, it can also be the check valve in the brake booster vacuum line. Under boost air that is mixed with fuel can get pushed into the booster, resulting in fuel smell.

Dale
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Old 12-31-18, 05:28 AM
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Originally Posted by DaleClark View Post
There's any number of things that could be leaking, good thing is they are all under the UIM and typically not hard to find when you jump the test connector and pressurize the system.

If you don't see leaks, it can also be the check valve in the brake booster vacuum line. Under boost air that is mixed with fuel can get pushed into the booster, resulting in fuel smell.

Dale
Thanks! I'll look into that too...what's the recommended procedure to test check valves? And the solution is to just replace them with mazda oem parts?
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Old 12-31-18, 08:22 AM
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I think there's a procedure to test the check valve to the brake booster in the shop manual. It is built into the hose and not a separate part.

The FD originally had the check valve in the hose going from the UIM to the firewall pipe. Due to all the heat there, that valve would get cooked and you could lose power brakes. Mazda did a recall, it replaced that hose and the hose going from the firewall pipe to the brake booster. The kit moved the check valve over to the hose coming from the brake booster.

When I bought my car in '04 the recall hadn't been done. I would get a fuel smell under boost - no smell just sitting or idling. I had Mazda do the recall work, it's free and obviously took just a few minutes. You could also just buy the recall kit and do it yourself, but I don't know how hard those parts are to get at this point.

If you have the original hoses you can feel the check valve in whichever hose it's in.

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Old 12-31-18, 03:27 PM
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Originally Posted by Sgtblue View Post
Off hand....
*If you still have the original throttlebody coolant line, it's a good time to replace it since accessing the nipple on the rear iron will be ALOT easier. IIRC Summit Racing carries a high performance reinforced silicone line. Probably other sources too.
Might be a good idea to replace that nipple with an NPT fitting. That nipple can corrode and leak rather badly.

On my own FD I just plugged it with an NTP fitting and eliminated the coolant line as I didn't really need it.
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Old 01-02-19, 01:05 PM
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Get the fuel line recall kit rather than just using off the shelf SAE30R9 EFI hoses. Regular 30R9 fuel hose won't necessarily have the temperature rating required for this application. The Mazda recall kit probably uses nomex or equivalent reinforcement fibers rather than polyester.
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