I took my 94 FD to a local rotary performance shop to ask about the gas smell when car is under heavy accelleration. The tech I spoke to was nice, he informed me that the car have a leaking lower intake manifold gasket. Under boost air fuel mixture get forced out into the atmosphere. This is dangerous and can burn down the car.

My question is would the car be idle and running like crap if I have a leaking gasket from the lower intake manifold?

I posted about this issue a while back...got many good advices but did not locate the cure.

I think the problem is in the fuel evaporating canister.

Thanks.

 

Yes, a bad LIM gasket can cause a gas odor problem.

If the odor is under boost (acceleration), then it's NOT the cannister. The cannister only handles the gas fumes at idle. While the engine is under load, the fumes are redirected back into the intake to be burned out through the exhaust. Thus, if your LIM gasket is bad, you can get a gas odor smell duing hard acceleration.

 

doubt its the canister as Mahjik said.

if you are getting fuel smell under boost, my first guess would be the fuel pulsation dampener.

 

Thanks all.

To get a second opinion, I spoke to Gotham Racing and they doubt the LIM was the culprit because the car would not performs well with a leaky LIM.

At this point the issue need to be identified and fixed...LIM replacement quoted at $1500.00...this is a good time to do the rest of the reliable mods.

 

Not to knock Gotham, but unless you phyically see fuel leaking, then it's either the PCV check valve or LIM. The problem is that if the LIM has been bad since you got the car, you would never know if the car "wasn't performing". The loss of performance for most people hasn't been that severe:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/finally-fixed-idle-problem-fuel-smell-58131/

I don't know about $1500 for a LIM replacement job. It is a pain but you might get a break down of parts and labor to see exactly what they are charging. They may just be throwing out a number to see if you'll pay it.

 

1500 in labor is alot, most shops charge that much to pull an engine.

 

yeah, 1,500 is a big wad of cash. I think you need to pull both intake manifolds and the turbos to get to the LIM gasket between the LIM and the motor, but it still sounds like too much for that work.

i only paid ~$500 to get my fuel pulsation dampener done.

there are quite a few threads about symptoms of a bad LIM gasket as well as FPD. Here is one for you that helped me out alot:
https://www.rx7club.com/showthread.p...ll+under+boost
https://www.rx7club.com/showthread.p...ght=fuel+smell

 

I did question the $1500.00 quoted but the tech told me the job required lot of work and about 12 bolts away from pulling the motor. IMO it is still on high side, last month I replaced head gaskets on my 94 cobra in 6-8 hrs, but I have been work on OHV motors since the 80s.

The estimate came from a very well known rotary shop here in Dallas, TX, and from I see going on in their facility their works must be top notch.

 

The LIM gasket is no easy job (while the engine is is the car).

I would call around as there are MANY good RX-7 shops in Texas and see what the typical price is for the job.

If you are going to have the LIM gasket replaced, you might go ahead and have the oil return lines for the turbos either replaced, or at least the washers replaced while they are doing the LIM. They tend to leak after a while and the shop will already be in that area so it really shouldn't be any additional labor.