mysql

I had my OEM fuel pump for over 2 years without any issue. I had been premixing and all was well. When I went FI, I decided to upgrade the fuel pump, as I wanted to avoid possible issues such as pushing the OEM pump too hard.

Thus I bought a well known vendor's aftermarket fuel pump upgrade for $599. With install fee and tax, the total price of this upgrade was approx $1,000.

One month after the install of the fuel pump, this same vendor dyno tuned my turbocharged RX-8. I was using this vendor's fuel management system as well. The first 3 runs were decent, and I gained 20 whp. However after that the car started to go lean. He kept adding fuel but the car was running lean and nothing fixed it. We called it quits to avoid damaging the vehicle. The car had 1/4 tank of gas.

A short time after, I brought the vehicle to his shop to have the pump checked out. The vendor said the fuel pump was clogged. This was with just one month's usage on the new pump.

The vendor blamed premixing. I didn't premix after that in order to prevent the fuel starvation issues, because the last thing I want is for the pump to be unable to push fuel to the engine under boost.

Fast forward a few months later, and my car started to jerk around at 60 mph. A few minutes later I am unable to sustain 50 mph without it jerking around. Then 40 mph. The AFRs were going lean if there was any load on the engine. The car still had 1/4th tank of gas remaining. The car then stops running and I coast to the side of the road. I called a friend, got some gas, put in 2 gallons and then the car ran fine. So I chalked it up to the fuel gauge being inaccurate.

A few months later, I had a similar situation. Same symptoms, but the car had a half tank of gas. My initial reaction was that something was wrong with the vehicle since I clearly had enough fuel. But because of the previous problem, I filled it up with gas, and sure enough the car ran properly again. Once again, I just dismissed it because the car ran fine and it quit happening.... trying to get a mechanic to fix a problem that you cannot replicate is not exactly an easy task. It's only happened three times in a period of a year.


Yesterday I drove from Tampa to Orlando. The car ran fine till about 150 miles out, it started having these symptoms till I was traveling at 30 mph on interstate 4. I was low on gas, so I really thought this is what happens when the vehicle is low on fuel. I fill up and the car is fine. On the drive back to Tampa, the symptoms reappear. Only the car has a full tank of gas. I pull over, grab a bite to eat, and 30 minutes later the car runs OK again. Remember it still has a full tank of gas and nothing changed besides letting it sit for 30 minutes.... So I get on the road and I'm driving. 50 miles later, the car starts going lean and I'm unable to sustain 60 mph. I pull over, and wait 20 minutes. The car now runs again. During the times when the vehicle is unable to accelerate, I can't even rev the engine at idle without it faltering at 4-6k rpm range. At idle the engine also dies, so I need to rev it a little bit to keep it over 1,000 rpm.


I'm pissed off at this situation. I've talked to several people who've also reported needing filter changes with this "upgraded" fuel pump. I wasn't even premixing after the first filter change and during the first few incidents that I apparently had fuel starvation issues, so ... uhhh...

I just thought I'd post about it here. Does it sound like the filter is getting clogged or something else? Right now I'm planning on pulling it out and going back to the OEM pump unless someone has ideas on what else might be causing this.




EDIT: Pulled the fuel pump and took pictures of the filter.

5 pics of the filter below, and details in this post:

https://www.rx8club.com/showpost.php...&postcount=138


EDIT: Some people are bashing me for coming forward with this situation. If you feel I'm being unreasonable by speaking up about my problems, please read this post and let me know what you would have done differently:

https://www.rx8club.com/showpost.php...&postcount=302

Vasichko

iTrader: (1)

Sorry to hear that.

Any possiblity it could be an injector issue?

mysql

i've had the injectors pulled out and installed twice (once when i upgraded the fuel injectors along with the 3071R, and a second time when the engine was rebuilt). So I don't think so...

Also if an injector is broken, don't they just stay open?

MazdaManiac

iTrader: (3)

The pump is overheating.

mysql

So I paid $1000 to have the exact problem I wanted to avoid?

Any way to fix, or is the pump crap?

chrism

hmmmmm.....

maxxdamigz

iTrader: (1)

When I got my pump installed, it didn't maintain fuel pressure properly. The guy I had install it swapped the FPR for an Aeromotive unit mostly because the Aeromotive has a port to tap into for fuel pressure. The car ran fine with the aeromotive. Went back to the other FPR and the car would lean out. So, shipped the FPR back to the vendor and the vendor shipped a new FPR out. I'm not sure if they inspected to FPR to see why it was defective or if they just tossed it. My car still runs on the aeromotive. The shop is a 100 mile drive so I'll stick with the aeromotive until I'm ready to get tuned. I don't want to change my fuel pressure right now as the car is running well. I can't tell you what the symptoms would be like on the road as I never drove on the bad FPR. It was persistently unable to maintain pressure rather than what you are seeing which seems to be a gradually failing system.

mysql

I don't know if I would say it's gradually failing. It doesn't seem any worse now than it was brand new. I've only driven my car out of Tampa three times, including this weekend. So the car is almost never used for more than 40 minutes at a time.

rotary.enthusiast

I don't know much about the particular pump you had installed, but I'd have to agree with MM that it sounds like the pump is getting hot and failing. It's the only thing I can think of that would explain why letting it sit for 20-30 minutes fixes it (until it's driven for a long enough period of time again).

Maybe you just got a bad apple... is there any kind of warranty that comes with it? I would take it to the vendor and demand a replacement or a refund personally.

chrism

seems like you have had a few rough run ins lately...sorry to hear

mysql

I checked, the pump has been in my car for approx 1.5 years now. I don't know if there is a warranty. Especially if the vendor insists it's a filter clog, and is telling others the same thing.

MazdaManiac

iTrader: (3)

Pre-mix does not clog your filter.

mysql

yeah... I tend to agree with that since I went 2 years without any hint of a problem while premixing, before this pump upgrade.

rotary.enthusiast

Did the pump come with some type of disclaimer or instructions stating not to run your gas tank below a certain amount? Maybe with enough gas in the tank to cool the pump this isn't a problem... you said it only happened at first when you got down to 1/4 tank? Or maybe that was just a coincidence?

At any rate, I'd be upset with an "upgrade" that cut my range per fill-up by 25%, but if that information was disclosed I wouldn't hold the vendor at fault.

chickenwafer

iTrader: (9)

I've been premixing for over 1 1/2 years and not clogged my filter. I've also seen fuel pumps pulled out of RX-8's running premix for long periods of time and the filter looks fine.

It does sound like the pump is overheating. That would explain why you let it sit for a period of time and then it works again.

Just go back to the OEM pump, it supports plenty of horsepower, and a brand new one from Mazda is only like $150 bucks.

mysql

This was actually the reason why I quit going into boost when my gas tank was down to 1/4. However as my first post states, it clearly can happen even with a full tank of gas.

maxxdamigz

iTrader: (1)

I've boosted my car with the fuel light on and have regularly put 200+ miles on a tank of gas with fill ups around 12ish gallons so I think this being a parameter of the pump system as designed should be ruled out. I don't know a ton about how the pump is built. At the meet yesterday, some of the FD guys were discussing how frequently they changed their fuel filters but they attributed it to newer fuel additives. You can tee into the line that goes to the FPR and run a fuel pressure sensor to get an idea of what is happening. That starts getting into doing work to fix a problem you shouldn't be having. Hmmm.

Brettus

iTrader: (2)

does not sound like you have actually inspected the filter .
I've had this kind of thing happen in other cars I've owned and it turned out to be the filter .
Perhaps a partially blocked filter is causing overheating of the puimp as MM suggested

Jedi54

iTrader: (7)

wow, talk about a shitty upgrade. You paid good money to get exactly what you were trying to avoid.

have you spoken to the vendor lately?

MazsportScott

Sounds like the sock is clogged with something again Jason, as we had discussed before when you were contemplating premixing again, bring me the car to inspect whats going on and I will take care of it at no cost to you. Last time it was an oily gunk of premix and since it's on the premix again, it may be the same thing. We have been taking photo's of the socks for awhile now to compile a bad premix list and this (if it's bad) will be more data collected. BTW, if we do the work and the pump is bad, I warranty it for you even though it's been over a year.

Let me know, I will be happy to help, Scott

tajabaho1

I too have this upgraded pump run along with the turbo

I think the fuel pressure regulator is out of whack though, since my fuel pressure gauge is telling me that in boost, the pressure drops instead of increasing, I don't really understand why my pump is very very new too, so I don't understand what the problem might be

I might have to change the FPR as maddawg suggests also I guess

maxxdamigz

iTrader: (1)

Well, the FPR that was in my car was from last summer.

tajabaho1

mine i think is from 4-5 months ago? I thought the pressure would rise whwen you're in boost, not go lower no?

05rex8

iTrader: (7)

wow, good man right there