Slow petrol filling

alice · Post by **alice** » Thu May 17, 2007 5:48 pm

In the last few weeks my 1998 NB has become very slow to fill.
At best, all I can do is trickle petrol in, so the operation takes several minutes. No question of being able to use the lock on the filler nozzle - it kicks out immediately. Any suggestions from out there?
mike

SLYDIT · Post by **SLYDIT** » Thu May 17, 2007 7:35 pm

AH ha! this is my specialty....i work in the fuel industry fixing fuel pumps and heres why your nozzle keeps clicking off....
its nothing to do with your car...
First you need to understand how the auto shutoff in the nozzle works...basically it has a venturi in the nozzle which creates a vaccum and air is drawn in via a small hole in the tip of the nozzle....when the fuel in the tank gets to the tip of the nozzle it blocks the hole causing the vaccum in the nozzle head increase which "pulls the pin" on the main valve diaphram stopping the flow.....

Basically what happens is that over years of use, the aluminium nozzle tip becomes Burred over causing fuel flowing out the nozzle to get sucked back in the little hole causing it to trip.....(have a look at the nozzle tip and youll see what i mean...)

GO AND COMPLAIN LOUDLY TO THE STAFF THAT THEIR NOZZLES KEEP TRIPPING OFF AND THEY NEED DE-BURRING!

Grant · Post by **Grant** » Thu May 17, 2007 7:58 pm

Thanks for the info.
I always wondered how they worked.

Grant.

alice · Post by **alice** » Thu May 17, 2007 10:03 pm

Thanks Slydit, but I have the problem at every gas station, not just my regular one. I've tried holding the nozzle just inside the filler tube and the same thing happens. I get kick back at anything more than a trickle. Are there baffles in the tank and can they move/collapse?
mike

skams · Post by **skams** » Mon May 21, 2007 5:42 pm

Heres something to take a look at; my 98 Nissan Sentra has a spring loaded flap a few inches down the filler pipe, if I don't put the pump nozzle all the way in, the flap remains closed and I have the same problem or worse still I get a momentary blow back resulting in fuel on the feet. Maybe you are not inserting the pump nozzle far enough to open the flap or it has become dislodged and is causing a restriction, asuming if course that your NB has one fitted.

cheers Simon.

KSCRIM · Post by **KSCRIM** » Mon May 21, 2007 10:58 pm

There was a problem in the filling for the USA '98s and there is a Mazda USA recall issued for it See this thread in the Miata.net forum
http://forum.miata.net/vb/showthread.ph ... g+problems
Apparantly there is a check valve at the bottom of the filler pipe that sticks, causing back pressure and early shutoff of the pump.
Mazda NZ should be aware of it, but will probably claim ignorance.
The Americans have been getting warranty repairs done to their '99s (our '98s) up to last year at least.

alice · Post by **alice** » Wed May 23, 2007 10:13 am

I think KSCRIM may have hit it -- I'll follow up with the local Mazda people. Many thanks.
Thanks skam, but I don't think ther'e a flap in the pipe like the Sentra, and I've tried putting the filler nozzle in all the way, part way and hardly in at all, all with the same result.

alice · Post by **alice** » Mon Jul 30, 2007 5:44 pm

Finally got the problem fixed.

KSCRIM was exactly right, local agents had never heard of the problem but did agree that the non-return valve was the cause. Had to get it from Oz, fitted it today. It's a $10 part. Filled up on the way home - oh joy! Took about 1 min instead of the 6 it took last week.
Thanks to all who responded to the original post.
Go well!
mike

KSCRIM · Post by **KSCRIM** » Mon Jul 30, 2007 7:26 pm

Glad to be of assistance. Any problems with changing it it??

agent99 · Post by **agent99** » Mon Jul 30, 2007 7:36 pm

Hi Mike,
Did they also check the lower connecting pipe between the tank and the filler pipes? Found out last night it also should be replaced on that year model. not sure of the chassis no's that it covers will try to find it again and forward the info. Cheers, Doug

Euen · Post by **Euen** » Tue Jul 31, 2007 9:33 am

Kevin, on the 96 that I sourced my tank from, the filler neck had a plastic ball about the size of a ping-pong ball inside a metal cage fitted into the end that connects to the "flexible" coupling. I presume that one purpose is anti-siphoning. The cage was quite easy to prise out with a screw driver once the flexible hose was removed.

Cheers
Euen

alice · Post by **alice** » Tue Jul 31, 2007 3:08 pm

Kevin, no, no problems, just 90 min of workshop time.
Doug, no, nothing said about the lower pipe. There's never been any petrol smell, so I hope you're wrong on that one!
Cheers
mike