To be fair I said a lot of stupid stuff over the years too

I'd qualify that now with "as long as it's not one of those gauges that beeps and makes all kinds of noise every time the ignition key is tirned on ...". Yeah, getting old now

 

I don't think there is anything wrong with the pump(s).

Especially since the problem persisted, unabated, through a pump change.

I would put money on Team's diagnosis of the fine filter, reference posts #70 & #72, a problem my '8 had for quite a while.

Interesting fact - a plugged filter and the havoc it plays with the engine, sets zero CEL codes - the car can grind to a halt, with the ECU happily bleeping "nothing wrong here!"
I complained at the dealership so frequently that they sent a technician out on a test drive with me, with his Mazda laptop plugged in to OBD port.
Soon enough, the car started to hesitate, then chug, and finally ground to a halt on the highway.
Laptop boy just focuses on his screen, saying "no, nothing here, no codes, nothing wrong..."
After some more of that I asked if he would mind giving the car a push onto the shoulder.....

 

Any idea why that wouldn't cause a lean code to be thrown? I'm sure I'm overlooking something but it doesn't make much sense that it wouldn't.

 

^^^ I know I was wondering that too.

I just took it for a quick spin to try and empty out some fuel (3/4 full) and the symptoms got WAY worse. To the point I won't drive it at all anymore. I couldn't even come close to giving it any throttle this time without it going lean and hesitating. It actually died once. But here's the kicker, after it died l, I started it right back up and it worked like nothing was wrong for the next 1 mile left to get home.

Also over last night, this morning my pressure gauge read 0.

 

It didn't happen at all when the S2 pump was first put in. The original was replaced due to known failure and I wanted the reassurance

 

No code because it's been an intermitent issue. WOT is pushing it open loop (not always initially, but eventually) and the lean code is for fuel trim level, which the low flow/pressure is sufficient for all but the limited WOT runs he's made.

 

Personally I would vote for the pump before the filter in a new pump body. The filter can hold a ton of crap. .... and fuel pumps are getting crappier all the time. If he had just replaced the pump and not the enclosure the filter would be more suspect.

There could also be something floating around in the filter body that occluded the pump sometimes....like a piece of plastic or something that shouldn't be there....that would be the most likely

 

If everything goes to plan I will find out tomorrow afternoon!!!

 

It's about time.

 

Well maybe if you would have helped!! Jk hah

Yeah I know and if it ends up being the fuel pump (for whatever reason) I'll be kicking myself in the ***

 

Makes perfect sense, thanks.

 

He changed to a new S2 pump before the problem started and it was only a month or two old. That's why we didn't suspect it being the fuel pump despite someone telling us to check it because he had the same issue and a new pump fixed it.

 

So what pump did you end up buying? Hope you didn't buy the oem s1... after having this issue I purchased a walbro and premixed with no issues up until I swapped the renesis for the 20b. good luck man!

 

OEM S2 and thanks man

 

 

Well I put in a new S2 pump (the pump itself) and IT WORKS!!! The pump that I pulled out appeared to have a dark sludge looking substance all around where the sock attaches to the bottom of the pump. Aside from that, everything appeared fine.

The new pump puts out 58ish psi and only dropped to 54-55 during WOT. I was not able to check afr during the test run, I'll do that tomorrow. The old one would drop all the way to 0 psi overnight so I'll see what this one does tomorrow morning.

Thanks everyone for the help, and especially TeamRX8 for coming through in a pinch. I appreciate it man

 

Edit: I spoke too soon. When I put the new pump in and drove for maybe 5 miles, doing like 7-8 WOT pulls in 2nd and 3rd, it worked just fine. I was too excited and happy so I just took it back out to check afr's and it started doing it AGAIN!! The first 5-10 minutes were fine, 14.x when cruising and when I let it eat it would go to 11-12, perfect right? Well after about 15 min of driving I saw this kid in a 350, so naturally I got next to him. Went to take off and it spiked up to 19-20 and started sputtering. It kept doing it the rest of the way home. I'm getting pissed. It happened if the car was 174* and at 202*, so it's not limping....

 

Well ...... if the old sock filter had sludge on it , the new one probably has it now as well .

Which is why I thought you should check the sock before blaming the pump.

 

What was I supposed to do, cut the sock in half? It appeared fine

 

 

Clean it maybe ?


Just re-read what you wrote , I thought the sludge was on the prefilter so I read that wrong.... Have you had a look at the internal filter ?

 

If by cleaning you mean spray it with brake cleaner and blow it out, yes I did that

 

I have it all back apart right now. The sock on the bottom is clean. Are you talking about the one that surrounds the pump itself? If by internal you mean the "fine" filter that team says is IN the pump itself, I thought there was nothing that could be done about that

 

This is with flash on, it does look a lot darker than teams post in this thread, but then again his was BRAND NEW.

https://www.rx8club.com/series-ii-af...thread-261755/

 

To get to the bottom of it you will need to remove the new pump and inspect that as well . Could be that there was sludge in the tank that is now blocking the new prefilter or the internal filter . Or it's possible that something got through to the fuel supply line in the process of swapping the pumps. To check for that you could go out again with the fuel press. gauge hooked up and see if the pressure drops when afrs go lean . If pressure doesn't drop but afrs do, the gunk will have got through to your injectors....