fuel filter

Technical Guides primarily to do with the NB series

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wato
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Joined: Mon May 02, 2016 12:20 pm
Vehicle: NB8B

fuel filter

Postby wato » Tue Apr 30, 2019 12:41 pm

Hello all, Ive read a dozen write-ups on how to change the fuel filter but for the life of me cant find the fuel pump relay.Yes im looking under the dash and haven't had any luck and almost got stuck under there. Question is whats the difference in pulling the fuel pump relay to de pressurise the system and just pulling the fuel pump fuse to depressurise it? Thanks!

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hks_kansei
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Re: fuel filter

Postby hks_kansei » Tue Apr 30, 2019 12:47 pm

The fuse should be fine.
The idea is really to just have the engine run shortly to suck the fuel from the lines.


Personally when i've done the fuel filter I've not bothered to do either, i've just opened the fuel cap and then pulled off a fuel line and drained it into a container.
Either at the engine bay, or at the filter. Whichever I could be bothered with really.

The pressure isn't that high back near the tank unless the engine is running.
1999 Mazda MX5 - 1989 Honda CT110 (for sale) - 1994 Mazda 626 wagon (GF's)

wato
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Re: fuel filter

Postby wato » Tue Apr 30, 2019 3:32 pm

Sounds good to me! i'll give that a go tomorrow. Many thanks!

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hks_kansei
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Re: fuel filter

Postby hks_kansei » Tue Apr 30, 2019 4:40 pm

just follow the usual safety stuff.

-Let the car sit overnight after it's last start to bleed off excess pressure, if any.
-Don't have your face right next to the line when removing
-Wear good goggles just in case
-Have water handy to rinse the inevitable spilled fuel off you/the car
-Don't do it with a lit ciggie
-once done let everything sit for a while so any fuel can evaporate (dont start the car right away, fire risk etc)
-Do it outside, or at the very least have the garage door open the whole time

Also don't wear antiperspirant deodorant while doing it.
Petrol seems to react with it weirdly and makes your armpits burn like hell if it runs down you arm.
1999 Mazda MX5 - 1989 Honda CT110 (for sale) - 1994 Mazda 626 wagon (GF's)

wato
Learner Driver
Posts: 24
Joined: Mon May 02, 2016 12:20 pm
Vehicle: NB8B

Re: fuel filter

Postby wato » Tue Apr 30, 2019 4:46 pm

Ok good advice, it also appears the nb doesn't have a fuel pump fuse. Ill give it a lash tomorrow , thanks again

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hks_kansei
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Re: fuel filter

Postby hks_kansei » Tue Apr 30, 2019 4:52 pm

It does.

Looking at the factory manual it's the "EGI INJ" (30amp) or the "ENGINE" (10amp) fuse

Both are listed as feeding the fuel pump relay


ENGINE is probably the better one to pull, if you're doing it.
It will most likely be in the fusebox under the bonnet, in the corner near the brake booster.
1999 Mazda MX5 - 1989 Honda CT110 (for sale) - 1994 Mazda 626 wagon (GF's)

wato
Learner Driver
Posts: 24
Joined: Mon May 02, 2016 12:20 pm
Vehicle: NB8B

Re: fuel filter

Postby wato » Wed May 01, 2019 4:07 pm

Ahhhh ok , i didn't know they fed the fuel pump. Even better then, thanks ill do it that way

wato
Learner Driver
Posts: 24
Joined: Mon May 02, 2016 12:20 pm
Vehicle: NB8B

Re: fuel filter

Postby wato » Wed May 01, 2019 4:28 pm

so the 15amp engine fuse is in the cluster under the dash so ill pull that with the engine running and see how i go


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