Sisco360

What's up all, blast from the past from Sisco360. Still have the 8 and she's mint, however, have a new issue and need some advice.

Background: 04 RX-8 120k Manual, all service done, new plugs, coils and wires recently. Cat is 100% & compression is very good (mind you, original motor - that's a success story in itself )

Issue: Car drives completely normal, no issues when keeping the RPM's down under 6k or so. When I do some spirited driving in excess of 6k and really get on it for a little bit she starts to bog. She will still rev up but there is noticeably lower power and the exhaust note changes. It feels like the pump is just giving up.

SSV / VFAD you might think? No. They are fine and gunk free. Actuator for the SSV / VFAD? No, they work fine too. I think it might be the fuel pump. Mind you I'm on the original and have 120k on it (don't flame - I know I should have replaced it by now but it was working real good). Anyways, I noticed my seat cushion is a little warm above the fuel pump and I suppose that's an indication of overheating. The tank is 1/2 full.

She will start completely fine even a moment after experiencing the bogging issue. One would assume all indications point to the pump. Thoughts? Honestly don't have time to get it pressure tested etc. so before I dump 100 + bucks on the new one. I would like to know if there is anything else I should look for / test etc.?

9krpmrx8

iTrader: (46)

It could be a few things, it would need to be properly diagnosed rather than just guess at figuring out the problem. Try searching.

Or follow the troubleshooting guide in the FSM

Engine--> Symptom Troubleshooting

M A Z D A

Sisco360

Thanks for the reply. Already chased everything in the manual. Going to replace the pump regardless and see where it goes. Cheap enough and it needs it anyways. Anyone try the cigar smoke method for vacuum leaks here? I did a visible inspection and everything seemed fine but a vac leak would throw a code regardless.

Williard

iTrader: (18)

I have used the Cigar trick. If doing it by mouth....get a friend.... If you actually can rig up the right way to use a cigar then yes it will work perfectly. Before hand, remove the stock airbox and seal off the front of the intake accordian.

From what i've read, it does in fact sound like the fuel pump is going.

Sisco360

Yeah it seems like the only logical thing. Coupled with the fact my seat was warm right after a couple hard runs makes me think that too.

Grace_Excel

iTrader: (5)

I, however, experienced it differently. With the weather outside above 90 and if the car have been driven for more than 30 minutes. The symptoms for my weak fuel pump were bogging, RPM drops even at full throttle, and car goes into limp mode before it will completely stall.

This only happened when it is very hot outside and if the car have been driven nonstop for at least more than 30 minutes and didn't matter if the tank is full or less than half, one thing I didn't think of checking when it happened in the past is the warmth of the rear seat cushion... Anyway, hope it resolves your issue.

Sisco360

Yeah it was definitly hot a **** outside here too when it happened.

04Green

iTrader: (1)

Sounds like the pump as well.

Run it down to 1/4 tank, find a parking lot, go in left hand circles. A weak pump will not be able to maintain pressure. This simulates the track failure mode.

Or, you got 130K out of the thing, it is done.

gwilliams6

It is likely the fuel pump overheating and shutting down. I had the same issue with my 2008 40th Anniversary edition at 54,000 miles. Long trips (three hours straight highway speed driving) on 90+ degree days would cause the oem pump to overheat and shut down at just above 1/4 tank (where the pump is getting uncovered inside the fuel tank). Sitting and letting the oem pump cool down or filling the tank up with more fuel also cooled the pump down and temporarily solved the problem. I bought a DW200 pump from BHR and had it installed by Jim of JPR (a well-known east coast rotary wrench). did the pop-off cap modification and all. Runs great now. many have gone to the Series 2 pump setup which requires some modification, but is a much better pump than the Series 1.