Issue on a European RX7 FD (gas leak)
 

Hello everyone,

I'm seeking your wisdom because I'm starting to run out of idea...
I bought this car a while back knowing fully that it was running but supposedly leaking a bit of gas from somewhere close to the fuel line according to the seller.
As of today, I have replaced most of the old air hoses and coolant hoses (because it was old and a bit leaky).
The car does starts; however the smoke is relatively white, and it seems like a mix of gas/oil is leaking at the entry of the exhaust.
I have checked ignition coils, swapped cables because they seemed to not produce a big spark, spark plugs are brand new and the correct bunch, however the front rotor spark plugs are almost shiny and not the classical black powder on them after running for a while.

As a recap on what has been done on the car:
Apexi Power Intake
Koyo radiator
HKS Dump valve
As for the rest it is mostly stock besides that

If any of you do have any idea on how to find and fix the issue, I'm open to anything at this point.
If this isn't the correct section, I'll repost it somewhere else.

Best regards,
Clément

If you have a fuel leak anywhere in the area of the turbos I would be very careful of fire. A common area of fuel leaks are under the upper intake manifold. A leaking injector, any number of ‘O’ rings and lines. There is also the fuel pulsation damper. It has a diaphragm that has some history of leaking with age, but both it and the pressure regulator have ‘O’ rings as well.

Download a copy of the factory service manual for guidance. But here’s a start....bon chance



https://cimg3.ibsrv.net/gimg/www.rx7...b227f212dd.png

Do not start your car if you think there is a gas leak. Try smelling for any gas and start looking at the fuel line in that area. Probably best would be to replace all your fuel hoses (with OEM) and the fuel pulsation damper which is just before the fuel rails. It is a known source of fuel leaks.

White smoke could be an indication of a bad coolant o-ring. Search the forum for that. Other indications are wet spark plugs, bubbles in your coolant, and/or an overflowing coolant expansion tank. You could also do a pressure test. If you lose pressure, that means you have a leak, which could be hose or an o-ring. A bad coolant o-ring means you need to rebuild your engine

@Sgtblue
After thinking a bit more with my father and a friend, we think that it might be an injector leaking since, when we were trying to find the gas leak the motor was flooded with gas, just like if one or more injector was stuck open.
Also I can confirm that the first thing I did was to get the FSM, they are lifesavers for basically anything on this car.

@TomU
I have ordered a compression tester to check the engine, I don't think it's the coolant o-ring given that the smoke doesn't smell like coolant as mentioned on fd3cs.net or other forum posts.

My main issue with this leak is that it doesn't appear to be external, such as a bad hoses or o-ring (like I had with the oil around my turbos) but is directly leaking into the downpipe, hence the idea of the injector(s) being stuck opened.

If it also helps, I have swapped the spark plugs, and the two of the front rotor are almost clean, while the two of the back rotor are black like the previous I pulled out of the engine.

A compression tester will not help with coolant leaks. You need something like this

www.skf.com/mityvac/products/cooling-system-service-equipment/mv4560

Plugs will tell you a lot. If they are wet, it could be fuel or coolant. Smelling them will help determine if it's fuel or coolant. If they are black, you are running rich which could be a leaky injector.

So, the clean plugs would be the working rotor, and the really black one would be the flooded rotor, which would confirm the leaky injector.

As for the pressure test I'm planning on doing it before doing anything. I'm hoping it's just a leaky injector given the flooded incident when we force activated the fuel pump using the diagnosis jumper.

Thanks a lot for your help.

If one of the injectors is found to be leaking I would go ahead and pull all four. I’m not sure about services in France, but here in the US most companies that clean and flow-test injectors will also replace all the ‘O’ rings and pintel caps as part of the service. It’s a good time to replace things like that FPD and the fuel hose while you are there.

OP,

what is meant by

”The car does starts; however the smoke is relatively white, and it seems like a mix of gas/oil is leaking at the entry of the exhaust.”

the last part specifically?

is this why you think there’s a leak or do you smell the leak around the exhaust area (rear)?

I had a similar issue but completely different problem.

AA

I "borrowed" something similar from the mechanics at my workplace and tested it last night. Found no stuff leaking out of the spark plugs holes, which means it is probably one or more leaky injectors.

I'm waiting on parts to test my injectors, try to repare them or use a spare set I got from another car.

I'll keep you all updated :-)

Happy new year to everyone and stay safe!

If you have a spare set of injectors, get them cleaned and flow tested. Then you'll have a set you know is good which you can swap with the current set

That's the plan, I'm just waiting on getting all the parts (including a new fuel damper)

Hey everyone, just giving you a small update on the car.

I just finished changing my fuel injectors and one of them had a completely destroyed oring letting gas go freely in the engine.
I also did a while back the pressure test to check if my engine was loosing coolant but it was all good.
After putting everything back together, I checked my engine compression and got a solid 7.9-8 which is a good news!

I''ve drained the gas from the engine and I'll be waiting tomorrow to finally start it again.

I'm attaching the pictures of the injector and the compression test
https://cimg6.ibsrv.net/gimg/www.rx7...0f7935e0f5.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...afcd11fead.jpg


Thanks a lot for your help :-)