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FROM http://www.miata.net/garage/maint.html

\"There are two fuel filters on the Miata. There is a high-flow, low-efficiency pre-filter mounted in the fuel tank that should not need to be replaced under normal conditions.\"

Ive recently replaced my main fuel filter which had a murky brown colour fuel and thought I had the problem solved but have since had minor versions of what Im sure is fuel flow issues re-occur.

Has anyone ever had to replace the pre-filter mentioned on miata.net? I never knew it existed but would like advice before going to Mazda for such a part. Also - has anyone just removed the pre-filter?

Peter

Hi Peter, the \"filter\" attached to the in-tank pump is really just a screen (ie. not a filter that actually holds the contaminants). It may be worthwhile draining the tank next time your due for a refill and getting any sediment and residual fuel out of the tank. Then put a brand new EFI filter on as your relatively new one may have been working overtime and had it's effective filtering life substantially reduced.

Cheers,
Danny

yer basically ya need to clean out ya tank before you put another filter in

Someone had a problem with surging or pressure drop or something within the last month or so. Who was it?

They took the pre-filter and in-tank pump out and it was a light-brown colour instead of dark-creamy colour.

apparently ethanol E10 does well at loosening fuel tank debris that get caught in the fuel filter

In-tank pump and pre-filter/screen



the screen that ORX626 mentioned is the thing at the very right. Looks like a pantyhose.

anyone want to give some step by step instructions on how to do this on an NB?

Rip out the parcel shelf carpet, remove screws holding tank inspection plate cover on, remove fule lines (and plug with something so they don't leak fuel everywhere, I used drill bits)

Remove screws holding fuel pump assembly in, replace, rinse & repeat

Is it possible to a. check the operation of the pump whilst its out
b. disassemble it and clean it thoroughly?

Thanks for the advice all - I bet that inspection / access point is right under my BD Roll bar base - yes?

I'll have to search for a fuel tank diagram and where a drain plug is but assume it accessible from under the vehicle?

For Brisbanites Im confident enough to say I got this problem after purchasing fuel on two sep occasions from the last fuel place on your left just before Willowbank. I may be wrong as its always been premium fuel and may be related to it just being a low km 17 yo vehicle but I wont be purchasing there again regardless.

Thx again all
Peter

OK, this is a problem close to my heart as I have a low kms 1990 roadster (import) in the shop right now with fuel tank contamination problems. I suggest you might want to take a close look at your tank.

Some months back, the fuel pump failed from contamination, and was replaced. My mechanic advised me there was significant tank contamination - some brown gunge coating the internals. He tells me this can happen with polymer tanks that are stored empty for extended periods, such as, oh, a container ship from Japan. He wanted to check it again at the next service.

It didn't make it. About before 2 months later the new pump failed. This was just before Christmas, and I've just had the vehicle back to him this week to sort it out.

The obvious option of replacing the tank was a no go - the vehicle is apparently assembled around the fuel tank. Mazda gave him a labour quote of $1600 just in labour to get the tank out.

So, he's spent today in the tank with a high pressure water hose blasting away at it till its run clear. What he couldn't get at that way he's managed to wipe out - its a convoluted moulding.

It seems to be dealt with. I should get the car back tomorrow, and I'll give you an update if there's more info. But I'd strongly urge you to look a bit further than just the pump & filter.

If you find yourself stranded, like I did, cranking the engine and no fuel, a tip: pull off one of the hoses to the inlet manifold and spray some petrol in to start it. If the pumps just on its way out, it should start and you'll be able to drive it to wherever. A bit more suction from the engine and a bit more juice from the alternator does the trick.

Let us know what you find when you check it out.

cheers,
john

adherent wrote:Mazda gave him a labour quote of $1600 just in labour to get the tank out.

I'm sorry to say John, whichever Mazda dealer your mechanic got the quote from just simply didn't want the job and quoted accordingly . Even if their hourly rate was $160 it still doesn't take 10 hours to remove the fuel tank from an NA.

Best of luck with the fix and I hope your mechanic gets all the water out of the tank..water and fuel generally aren't a good mix.

Cheers,
Danny

Anyone use fuel additive on a regular basis?
I've been using Lucas for years on both my cars.
What are your opinion on it's claims of water dispersal, cleansing, and lubrication of upper cylinders?

I never touch the stuff. There are generally warnings in the owner's manual about using fuel additives - like don't. I have never had any of the problems that they are supposed to fix either.

... whichever Mazda dealer your mechanic got the quote from just simply didn't want the job and quoted accordingly

I think the full remark was \"$1600 and we don't want the job\"

Whether its a fair price, I think the point is still its bloody expensive. Looking through my workshop manual it looks like you need to drop the rear subframe, which looks like a pretty substantial job. Is there any other way you know of?

Anyway, I retrieved the car today and all is well. He wants to check a couple of times over the coming month to make sure he's cleaned it all out (no charge).

The main thing is, CapitalF, have a good look at the condition of your tank, and maybe save yourself a fuel pump and breakdown.