Hey guys, recently I've noticed a strong fuel smell when I really get on it. I've spent the past 20 minutes reading old posts. It appears that the pulsation damper is the most common cause of a fuel smell. Is the fact that I only notice it under hard acceleration indicative of something else?

I would like more conclusive proof that this is the problem before throwing money/time at it. I'm really not anxious to remove the rats nest again, so if someone can think of a cause that is less labor intensive to repair please let me know

-Chris Carlisi

 

I don't think there is a definite answer. A majority of the time it's the pulsation damper, however it could be your injectors, a fuel line, fuel pump, or anything that has to do with fuel delivery...

People generally start checking with the pulsation damper though...

 

Do you think the fact that it only seems to occur under WOT(particularly when I take it to redline) is significant? Does this indicate that it could be something related to the secondary injectors? My knowledge of the fuel system is extremely limited, so bear with me.

 

Nope, I don't think that it only happens under WOT is really that significant. To me, that just means there's not enough fuel flowing through the car to make the leak happen which could still be in a few places.

I'm no mechanic. My car is doing the exact same thing right now. It's going to the shop this Friday (as soon as I get the interior put back together. Repainting panels).

In the manual there are a few areas they suggest to check for this problem, but you'll just have to start checking them one by one. But certainly it could be the injectors.

 

I wouldn't drive the car anymore til you fix the problem.

I would start checking the fuel lines. This is much easier to do. If it's not visible, take a fire extinguisher and start the car and rev it to see if any leak.

If not, you'll have to look into Fuel Pulsation Damper, injectors. That's no fun. However, they are both in the same place so it's not more work if you are cking both of them out. The injector o ring can be the problem causing the leak. Get them cleaned while they are out. Even if only the inject is bad, you should probably just replace the fuel pulsation damper anyway since they are known to go bad. You don't want to take it all apart again a couple of years down the road.

Good luck dude!

 

Oh, is the fuel line recall done on your car? Call Mazda's 800 number to find out. They will change your fuel line for free if it's not done yet.

 

I had a gas smell in my car only under heavy boost. I figured I would fix it when I did my vacuum hose job, so I replaced the injector o-rings, fuel distributor seals, and fuel pulsation dampener. I still had the smell. I just recently got done replacing the lower intake manifold gasket (it was severly blown), and now the problem is fixed.

Hopefully thats not your problem, since replacing the LIM gasket is a major bitch. The turbos have to come off.

 

Thanks for the replys guys.

Paw140: That's interesting, I'll have to do some more testing to see if it is effected only by boost, or rpm and boost. Again I may be misguided here but I would assume if I had the problem only at high rpms it would be connected to the secondary injectors.

I also want to note that I have a 94. I believe they were not subject to the fuel line recall. If this is incorrect please let me know.

 

My 94 had the fuel line recall done. I think earlier 94s are still affected. Call Mazda to find out. Get this fixed, don't wait.

 

I have some new information to add. On my way home tonight I gunned it and didn't smell anything the first three wot runs(car was warm for all of them). The forth run I turned on the heat and bingo the smell returned.
I don't know if this makes a difference but thought it was worth mentioning.

I didn't notice any fuel puddles under the car or wetspots on the engine/tranny after my drive, but it was a 15 minute drive and the lighting was poor. Tomorrow I'm going to investigate further.

djantlive, I'll call mazda tomorrow to find out about the recall.

Paw140: a friend of mine also belives it's the lower intake gasket. He said the secondary injectors feed fuel in about 5 inches upstream of the gasket. Under high rpm boost the fuel coming out of the injectors could flow out the gap. It seems reasonable. Unfortunantly it is even more labor intensive to replace than the pulsation damper.

 

Dude, don't drive it or you'll have a BBQ underhood! Many FDs have suffered, don't be another victim. Stop dicking around and get it fixed. Don't say we didn't warn you.

 

Or in the least, just make sure you have a fire extinguisher in your car.

Whether or not you are smelling gas from the engine bay or not, it's still a good idea to have one in the car.

 

Do you have any other problems with the car (like idle problems?) I replaced my lower intake gasket because I had a crazy high idle (1.5K to 2.2K), and I couldn't adjust it down at all. My car had such a bad leak, that I could remove the hose going from the plastic throttle body elbow, and with the car running, cover the intake with my hand, the idle would not change. I was pretty much choking off all the air that my engine was supposed to get, and it still ran. When I got it apart, I found I had about two 1 inch sections of gasket gone.

It took me probably 10 to 12 hours of labor to do the job. It kinda sucks. But now my car runs great.

Paul

 

Check the fuel vapor recovery check valve - it should only allow air to pass towards the UIM. It is brushed aluminum located near the oil filler neck. It is common for the check valve to fail and allow boost pressure back into the fuel vapor recovery system causing a raw fuel smell under boost.

Otherwise, park the car until you check the fuel pulsation dampner.

 

I experience a very similar thing. I have no fuel leaks. In fact, it is only in the cabin that I smell the smell.
I have heard that sometimes the one-way valve on the brake booster can fail and allow boost into the well, the booster! But I checked mine and it only flows one way so it must be good.
That fuel vapor recovery check valve sounds like the culprit in both our cases.....
I guess I ought to check mine out.....

 

I recently got my 7. No service manual yet, where can the fuel pulsation dampener be located?

 

I wish i could give you the exact procedure, but yoiu can "jump" the circuit to the fuel pump while the car is off, then pinch the fuel line.... if its your FPD it'll likely smell like fuel or even spray fuel from under the UIM.... email dave @ KD rotory for specific procedure... he helped me.... FYI mine prob was the brake-booster valve. Its imbedded in the black rubber hose from the fire-wall to the booster and you can't see it. I had i advertently replaced it.

Could also be the 1-way valve mentioned above (the only metal one on the car) or the charcoal canister under the elbo could be full.

 

My car did this too last year. It turned out that I still had the paper LIM gasket and it was blown at the secondary port. Same symptoms, high idle (1200 to 1500) and fuel smell at WOT. At WOT the manifold is under boost (high pressure) and is more likely to make fuel blow by the gasket and atomize, creating the fuel smell. My experience anyway.

Frank

 

Listen to DaveMc!

This is the easiest thing to check for this problem, and probably the most common cause. If it were the FPD you would smell it all the time. The fact that you only smell it after pressurizing the UIM points to a check valve problem, and this is the check valve that'll do it.

I've said this before, and I've had this problem before. The key is Fuel smell _AFTER WOT_...

 

By the way...you can download the manuals here...

http://iluvmyrx7.com/

 

Here's sort of the follow-up to my problem which I talked about in this thread months ago:

https://www.rx7club.com/forum/showth...threadid=88176