Car starts & drives fine, runs normal temps etc. But at full throttle there is a loud sound from the rear that sounds pretty unhealthy and the car de-accelerates. I'm assuming my fuel pump is dying?

 

Does the noise happen if you rev the car in neutral or does the car have to be moving for the sound to happen?

 

I does'nt in neutral no. Any ideas? I've ordered up a bnr33 280l pump, as the pump will need to be uprated soon anyway. But if you have any other ideas regarding the problem then they will be much appreciated

 

the way to check is with a fuel pressure gague and a test drive.... if you swap the pump be sure to do the filter. are you still sequential? what is the boost level when this happens?

 

Yeah I don't have a fuel pressure gauge yet. I am running sequentials (until I go single in a few months ) & it happens throughout the whole range, even as low as 2k rpm. I cant go over 70-80mph without triggering it.

 

Fuel pumps generally work properly, or don't work at all. It's unlikely that the pump is your problem. If you have not changed the fuel filter in a long time, definitely change it.

 

It doesn't happen until you get to 70-80 mph? If so, I would wager the noise is coming from something other than you fuel pump.

 

If I accelerate very carfully & slowly to 70 then I get a problem. If I accelerate hard at any time I get the problem too. The noise comes from the back left.

 

You might try jumpering the fuel pump and see if the noise is there. You connect pins GND and FP in the diagnostic box, then turn the key to ACC.

 

Okay, the situation has changed slightly. Now its accelerating fine up to 3krpm. Then with anything over a tiny ammount pressure on the gas, it constant backfires and has close to no power. I then dropped down to second and went all the way to 7.5k rpm with a tiny bit of throttle, it stuttered occasionally on the way through the range (not at anyspecific point) after this the car drove as normal for about 15 seconds. Then a missfire and large backfire and back to the beginning again. I'll get the plugs out tonight and see what state they are in/how its running. Oh well.....I needed a new fuel pump anyway lol.

 

So this looks like plugs/wires/coil? Maybe I'll have to drive down to dragon performance tomorrow if I cant find anything....

 

I would wager that your car does not have a Engine Check Light on the dash. I would suggesting checking the engine codes using the following link:

https://www.rx7club.com/3rd-gen-archives-73/there-any-chance-read-ecu-codes-without-ecl-238994/

 

Plugged Cats can cause this.

 

Hmm, I would start with the cheaper maintenance issue's first like plugs and wires if there old....fuel filter and re drive. Clogged cat can do that yes but the vehicle would feel sluggish or lack of power throughout the whole range, do a temp if you can with a hand held temperature gun. If I was to diagnose from the symptoms you have stated I would stay fuel filter or coil. Best of luck!

 

boost pressure?

 

I've done nothing and it is running a lot better. It still gets that no power thing just over 3krpm, but only occasionally now. Also it missfires every now and again too, guess its an electrical problem. I've filled up with a new tank of fuel, ran the last one right down (although I don't think fuel would cause this?). Guess I'll order up a coil - Any recommendations of where/what to get? Could'nt see one on rhdjapan.com.

 

Ceylon,

You need to try and pull ECU codes. The car being in limp mode can have the same effect.

 

Thanks for the advice . I have a powerFC - I'm guessing the procedure is differant. I'm going to take it down to Dragon Performance in Devon. They look pretty awsome beinga rex only garage, anyone used them before & recommend them? (www.dragonperformance.co.uk)

Cheers.