mx5cartalk.com

Hey guys,

The fuel pump died in my NB8A (returning fuel system like the NA), so we replaced it with a DeatschWerks DW300 we had sitting around. The car runs again now but it seems to be running incredibly rich any time it isn't in closed loop. If you give it a WOT squirt or blip the throttle, it will result in black smoke that is visible from the rear view mirror!! Although I haven't confirmed it, maybe the regulator is being overwhelmed?

I was looking at putting in another OE pump, but the prices are extortion!

The yanks seem to use the Walbro 190LPH on their NAs without overwhelming the regulator, but it often gets reports of being noisy. I'd rather pay a bit more to have a quiet pump.

It looks like Bosch make a whole swag of universal fit pumps:
http://www.bosch.com.au/content/languag ... lpumps.pdf

Anyone running one of these? Any other success stories?

Cheers

saboteur wrote:http://www.bosch.com.au/content/language1/downloads/fuelpumps.pdf
Anyone running one of these? Any other success stories?

Can't comment on the Bosch fuel pumps, but in terms of other success stories, get a Walbro & run it with one of three thickness of sound deading sleeves that are available from:
http://apeusa.com/html/kits.html

Walbro:
http://www.ebay.com.au/itm/WALBRO-GSS34 ... 564b2324de

You have linked to a 255LPH pump, but this thread suggests the 190LPH is a better bet for a returning system:
http://forum.miata.net/vb/showthread.php?t=315164

So many people on that forum read stuff and then repeat it without first hand knowledge so it's really hard to know what really works!!

We hooked a fuel pressure gauge up and it was reading 50psi at atmospheric pressure and not much less with vac applied to the FPR, so something is definitely not right. The next steps are to measure fuel pressures with a different stock pump, then try an alternative pump with a faster flow than stock.

saboteur wrote:You have linked to a 255LPH pump, but this thread suggests the 190LPH is a better bet for a returning system:
http://forum.miata.net/vb/showthread.php?t=315164

So many people on that forum read stuff and then repeat it without first hand knowledge so it's really hard to know what really works!!

Tim, linked to the 255LPH Walbro as that well priced supplier didn't have the 190LPH advertised when I looked. Couple of things: only from memory but I thought the NB8 had a returnless system, but may be it came in with the NB8B as opposed to the NB8A. IIRC, concensus, if we can call it that on Miata.net, was that stock or lightly modified MX5s were better off using the 190LPH as it seemed that the 255LPH was causing some issues. Of course, different story for moderate & more highly modded MX5s.

Thanks mate.

It's a bit confusing when reading US stuff, as the yanks had returnless on their NB8A, but not on ours or the Jap ones. NB8B was returnless across the board.

I'm going to experiment with an RX-8 pump but failing that the fallback position will be the Walbro 190LPH.

Cheers

saboteur wrote:It's a bit confusing when reading US stuff, as the yanks had returnless on their NB8A, but not on ours or the Jap ones. NB8B was returnless across the board.

Ah, that explains it, I was looking at a NB8A fuel rail I got off a Canadian delivered car. Good luck!

I have a new Walbro in my SP. A little noisy when you turn the ignition on but when the motor starts you can't hear it.
I still have the original one at the tuners its only done 22,000 km. It was fine up to 150rwkw but I needed a little fuel so it was replaced.
The Walbro was $260 from my tuner and $200 for the installation. Cant see me ever using the old one so here is another option.

Richard.

Thanks Richard for the offer but I think I'll go with a beefier pump too. Is yours a GSS250?

Cheers,
Tim

saboteur wrote:Thanks Richard for the offer but I think I'll go with a beefier pump too. Is yours a GSS250?

Cheers,
Tim

Hey Tim,

Mine is a GSS342 - 255L/H, 550HP,

Richard