I've searched many times for a thread that deals with a very sporadic, but alarming issue I've had 3 times in the last 4 months.

Possibly TL/DR, but I want to go into detail since I haven't read about this specific issue before.

Most of my driving is interstate commuting, short errands, and occasional recreational twisty road excursions.

The first time it happened I attributed it to a temporarily installed cheap cat that was on my 8 for a couple of weeks to pass emissions inspection;

Leaving a car wash on a hot July day after having sat in line for a while, my car suddenly started sputtering, stalling, and dying repeatedly, to the point where I was stuck on the street with flashers on trying to get it to run long enough to move it.
I could feather the throttle enough to keep it running, but every time I put it in gear, it would sputter and die.
It seemed like misfiring, but with no CEL.
It seemed to be heating the cat up to the point of smoking.
After about a long 5 or 10 minutes, it started to stay running long enough where I was able to drive home a mile away at about 20-30 mph with it sputtering when I would try to accelerate.
By the time I got home, it seemed to be getting better.
I took the cat off, and it ran normally for a couple of months.

The last 2 instances occurred in nearly identical circumstances about a month apart;

Warm, but not hot days, driving through rolling city streets at 30-40 mph for about 20 minutes with frequent red light stops going to the same chicken joint drivethru after work.
Both times, when leaving the drive thru and entering traffic, the same sputtering and dying issues occurred almost identically, where I could barely get it off the street and feather the throttle for about 10 minutes or so with it dying a couple of times.
Both times, after going through it about the same amount of time, it would suddenly start running normally again as if nothing ever happened.

Took it out this morning onto the interstate for some 80 mph cruising for about 10 miles, getting off exits into city stop and go traffic, then back onto the highway with fast, high RPM gear shifting with no issues, just like before.

Read the OBD with the Torque app, no codes at all.

I suspect it could be the aftermarket Chinese fuel pump I installed a couple of years ago acting squirrelly, but I really don't know.

I will attempt to troubleshoot it, but in my experience, sporadic issues like these are nearly impossible to pinpoint unless the problem is occurring at the time.

I'm thinking about buying a quality, RX8 Club recommended fuel pump just to see if it helps.
I'm a good nuts & bolts guy, but electrical troubleshooting is still a mystery.

Any input is appreciated.

 

I would think fuel pump....they usually act up when the fuel level is low and they have been running long enough to get hot

How many miles on the original basket/filter?

If the regulator sticks open then the fuel pressure can drop out as well till it moves properly again.

 

I would bet fuel pump as well. Injector failures are very rare so the pump seems to be the likely culprit. Did you just replace the pump itself last time or the whole assembly?

 

Fuel filter.

There are TWO on the `8, the mesh one on the fuel pump intake, and the huge one that surrounds the pump.

I thought my problem was the pump - went the same route; cheapo chinese replacement, then BigNameBrand re-replacement, also in vain. Finally went for the Series 2 complete unit upgrade, which worked.

However, when I cut the old Series 1 filter apart (as you do) I found it absolutely full of fine powdery/gritty black ****. There is really no way to replace that filter, other than a whole new assembly.

This particular set of symptoms also leaves NO codes or traces for techs to follow up on.

Took a tech from the dealership onto the highway for about five miles - he had his Official Mazda Laptop plugged in to the ECU and was watching it intently....car starts to chug and miss, I say "Are you seeing anything?"
'Nope'
Car is now slowing seriously, throttle to the floor....
"Anything showing?"......
'Nope'

Car finally chugs it's last, and stops in the slow lane.
"No, computer says the car is fine."

"Well maybe you could put down the laptop and give me a push onto the shoulder........"

 

Sorry for the delay, was running errands.
I replaced the whole fuel pump assembly about 20k miles ago.
Aftermarket Advanced Auto.
IIrc, the only filter is on the pump?

 

Yeah, whole thing.
What's your recommendation for a replacement?

 

I know the feeling.

Weird thing is when the factory pump failed, it was barely working for many miles, cutting out on me multiple times and barely functioning, took me about an hour for a 20 minute trip, and got progressively worse.
This is a 10 minutes episode then nothing.

 

Also, 1/2 tank this last time, and I have never let it get much below 1/4 tank since I replaced it.

 

Is the regulator part of the pump, or a separate component?

 

The regulator is built into the assembly. I have always used the Airtex brand, no issues, we just replaced Grungepups on Thursday. Not sure what brand you used, could be that but I dunno.

Being able to monitor fuel pressure (high and low alarms on mine) is great for stuff like this. Datalogging would also be great but your problem is so intermittent that would not help.

 

Thanks.
I think I might still have the box.
I'll try to find it.

 

Ok, more issues today, but this time multiple instances that started at highway speed, so that was different.
Luckily I was on my way to pick up a new pump.

More details later, but for now,
GOD BLESS BHR!
My new BHR fuel pump ring tool made taking the ring off easy peasy.

My old pump was an Airtex, has a Japan sticker on it.
My new one from Advance is also an Airtex, but was sold under the Carquest brand.
Made in U.S.A., same part number.
Much different design.

 

much different design - was this specific to only the RX8?

 

Yeah, same manufacturer, same part number.

 

It's fixed.

I didn't realize how bad it was getting, it runs better than it has in quite a while.

 

Yeah that is the new design that follows the S2 unit. Same as the one we installed in Shadycrew31's car that I posted in the fuel pump thread. Did you have to shave off some of that lower nipple? It was easy to do but we had to on his car. Glad you got it sorted man.

 

I had more trouble getting the old one out.
After I got it in and connected the top fitting, I started thinking that the lower one did seem long and I was wondering if it was actually connected right.

I didn't want to take it back apart unless it didn't work right.
The clip seemed like it had degraded some and didn't clip right, so I put a little zip tie around it.
If I have to do it again, I'm buying new clips, and would suggest anyone else do it.

 

My BHR Fuel pump tool gets used an abused. Lot's of dying fuel pumps round these parts lately. Other than it getting scratched up, it works like a champ.

 

PM sent.
I'll post a bit more here about it later when I have more time.

 

The last time I changed the pump, I used a universal rental tool.
The length of the legs and the fact the legs were not part of the frame allowed them to flex, and chewed up a bunch of the tabs on the ring.



Another thing that I really liked about it was that I didn't have to crouch down the whole time.

I have a surgically repaired back and an arthritic thumb that makes doing things like that challenging.
I positioned the BHR tool on a tab on one side, lined up the other side, and tapped it down easily with a deadblow.
I tried a rubber mallet at first, but it had too much bounce.
Once I had it on, it stayed on and didn't slip.
As a bonus, I have a 1/2" drive 24" extension that allowed me to do it standing up where I could get more leverage on it comfortably.
I really liked that.
It's worth every penny to me.

 

the tools make the job easy

 

Ok, I'm going to go into more detail with the symptoms as a last follow up.

As I stated in the 1st post, the first serious incident was in July.
It didn't happen again for a couple of months, BUT, I had noticed some periodic hesitation or stumbling at high RPM that I thought could be ignition related or due to the fact that I forgot to clean the ESS the last time I did maintenance on it.

It was running decent, but I'm pretty sure now it was not 100% as I've noticed a substantial difference in performance since I replaced the pump.

I did notice before the actual failure that the stumbling at high RPM was getting more noticeable.
It's why I finally ordered the new pump.
I had been waiting to see if any codes or indication of another problem would manifest itself.

I was on my way to pick up the new pump when it started dying in the typical fashion of a failing fuel pump, this time at highway speed, with multiple stalls and struggling to stay running, and I barely made it home.

There has been discussion that my heavy premix of 1 oz./gallon of Lucas 2 stroke may have contributed to the premature failure of the last pump, which didn't last 2 years.

I think I will continue however, because other than this episode, my 8 has been very dependable, and still running strong.
I feel the benefits of premixing the S1 Renesis outweighs the negative of possibly replacing the pump every couple of years.

That's all I can think of for now, hopefully this thread will be beneficial to anyone else who may experience it.