Rotary Engine build Blog

Building the Rotary Engine is all in the right tools, experience and knowhow. Get it right

fuel injectors

8 Min Read

Mazda Rx8 series 1 fuel injector issues | Get it right.

The series 1 Rx8 has been a solid performer since its launch back in the early 2000's

Mazda Rx8 engine rebuildBy now, many of these cars have had a lot of miles put on them, with that comes the need for another engine.
I have seen them come into the shop with over 180,000 miles, with the body still in good shape, interior showing its age and yet needs another engine rebuild.
This particular car came in, in really good shape, got a rebuild, a few upgrades and back to the customer....and within a week started leaking fuel out of the injectors. This is how we got it right...
We brought the car back to the shop, removed the intake, accessed the injectors and found the injector seals had rolled and pinched creating the leak. Problem solved.
Not so fast, the car did it again after a week, leaking fuel out of the injectors....back to the shop.
This stumped us, all new parts (injectors and seals from the rebuild). Why was it leaking? It didn't leak after a few road tests, but after a few hard heat cycles, it started leaking again.
Mazda Rx8 fuel injector leakingThe key issue here is properly diagnosing the problem and coming up with a solid solution. The secondary fuel rail was the only original component and it looked right. What did we do?
We surmised that the issue was the that metal fuel rail was bending when the 4 (OEM new) injectors were called for under hard acceleration, lifting the injectors up, rolling the seals enough to cause it to push fuel past the sealing surface. Remember, the fuel system is pumping out fuel at 53 psi up to 58 psi on demand. Multiply that by 4 fuel injectors and that is a lot of force.
Since Mazda didn't have or make a factory replacement, we took it upon ourselves to come up with an improved fuel rail for the secondary injectors. I machined up two brackets to go on top of the fuel rail mounting tabs thus adding strength to the fuel rail so it would not bend under increased fuel pressure demands. Here is one of our test pictures for improving the fuel rail.
Mazda Rx8 fuel injector leaking repairThis worked very well. Don't forget that when we tested the OEM fuel rail, it was noticed that the metal was easily manipulated (we tested by adding a bit more angle into the fuel rail mount, it bended easily).
The reality is that not all information is available through the internet or paid for automotive repair subscriptions (for us, Mitchell / Snap-on) to get it right. Diagnostic prowess isn't automatic these days, oftentimes it takes more than just looking it up and replacing parts. Details matter and knowing when to slow down and think the process through makes all the difference in getting it right.
This Rx8, got a lightweight flywheel, street porting, improved cooling system and is a solid driver now, the customer is happy and we learned something about older Rx8's.
Now, all Rx8 series 1 cars will get this simple modification with every rebuild. It makes sense to improve performance / reliability.
Ready to start a conversation?

Topics:   fuel injectors

google-site-verification: google66f53be324ef579e.html