MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Fuel filters.

This was discussed recently I think, but I can't find it.

In 45 plus years I've never had a fuel filter on my Sprite. Never needed one. But now crud coming from my tank, getting to fuel bowl, bad seating fuel valve(s) - (both near new, sprung viton), flooding carb(s). Already flushed tank, but some remains.

I need a fuel filter.

And I assume the best place for it is, pipe from tank before su pump.

What's the best type of filter? Or are they all much of a muchness?
anamnesis

I just used a plastic (WK31/2 or equivalent) before the carbs as that way I could see the petrol had at least made it that far and it's easy to get at.





Nigel Atkins

Cheers Nigel. On ebay for less than 4 quid.

https://www.ebay.co.uk/itm/403325959100
anamnesis

By coincidence I bought two from that suppler just very recently. Turn the the brand name out of sight as you don't want to show (too many) German part(s) on an old British car. 😁

I think the cheap filters are about £1.50-£2 at a show and Mann about £2(?) for one in a shop but those Hengst do look better quality than Mann and the cheap ones.

The QH (Hardi) pump I had fitted for 15 years was supposed to have a filter fitted before it but I never bothered, the fuel tank was replaced 11 years after the pump.

I did wonder about fitting a metal filter before the pump but then I've had a metal filter leak on another car. I thought about risking another plastic there and changing it regularly but I couldn't be ar*ed with more hassle and mess under the car.

If you've got a flaky tank you might want to consider a filter there but what's the point if your pump is filtered, one filter clogging up is as bad as another if you've got to crawl under the car to sort it.
Nigel Atkins

Interesting Anam as I was thinking of posting a similar thread as I've had a second bout of misfiring.

When the float chamber was opened up, the depressions either side of the exit pipe were black. Closer examination showed they were full of crud.

Cleaned it out and this is what it looks like when dried. Magnified it looks like boulders.

An inline filter, like Nigel's, is sited about 6" away from the front carb. It maybe that the previous filter was full and so petrol and crud by passed it.
I didn't notice this earlier.






Jeremy MkIII

I thought that I’d heard that it was a bad idea to fit a filter before the pump, and here it is, from Paul Hunt’s MGB-stuff website:-

“ Do NOT fit a filter on the tank side of the pump. As Dave Dubois says the existing filters in the tank and the pump are designed to stop rocks and small birds and will pass fine rust particles which have no effect on SU pumps or SU (particularly HS) carbs. But in a fine filter they can clog it, stall the pump and burn it out.”
Dave O'Neill 2

Well there's a happy coincidence then Nigel. On order.

I could've taken that picture and written that text Jeremy; except no misfires, only flooding.

Dave, thanks for reminding me about that from Dave DuBois. I had a half thought I'd read something like that from somewhere too, but wasn't sure I hadn't imagined it. So I wrote "assume", hoping someone would know something. I guess it never registered with me, because I've never used a filter before on my Sprite. Cheers. Before the carbs it is then.



anamnesis

I've never used a fuel filter either. UK fuel is clean enough as it is. I can understand a filter might originally have been needed on export cars for some parts of the world. And over time a decaying tank might require a fuel filter as a work around.But so far, to me its just another unnecessary addition and Ive not needed one.
GuyW

Given that I've alredy flushed the tank, and it's rust causing my problem, what I really need is a new tank, not a filter.

But as a quick fix, a filter'll do me for now.

anamnesis

Sorry anam I forgot you have an SU pump.
Nigel Atkins

Jeremy,
that's loads of crud, could some of it have been there before you fitted a filter?

I had one very thin flake about the size of the collection in the red circle (photo below) in a fuel bowl when I removed my carbs to clean them a couple of years ago at HGF.



Nigel Atkins

Hi Nigel, agreed that was a lot of debris and it surprised me. However since the car was put back on the road in 2007 it's had a filter fitted so that seems unlikely.
The only significant change is using petrol with ethanol as Esso has stopped supplying un-ethanol fuel in this area.
Like you I use E5 super unleaded with the Millers additive you've previously suggested. It may be the result of fuel (and ethanol) being left in the tank over winter when the car is not used as much.
Or it maybe rust but the tank is 'relatively new' at 15 years old, I think an inspection with the endoscope is in order. Let's see if that's ethanol proof.
Jeremy MkIII

That's a good question Jeremy. Are endoscopes oil and petrol proof?
anamnesis

Sorry Jeremy only just seen your post.

If the petrol is left in the tank over winter and the car not used a lot then perhaps the ethanol water combination goes through the filter and sits in the carb bowls causing some sort of corrosion there(?) or even the fuel is ok until it sits in the fuel bowls and separates out(?).

The Millers additive needs to be stored in a cool place, not a boot subject to great amounts of solar gain where I originally kept my bottle, and it's supposed to be used within 2 years of date on the bottle. How much overheating it in storage and how critical the use-before is I don't know.

Could the crud have formed before you started using the additive - assuming the crud is anything to do with water corrosion.

To save your endoscope why not just syphon out say half a pint of petrol and put it in a clear plastic or glass jar or bottle and leave it to see if it settles out to petrol and other. You could also perhaps compare the smell of the petrol taken out with the smell of fresh petrol.

If you can syphon out from the very bottom of your tank you may get your answer quicker.

Or if you don't mind crawling under the car you could take the inlet pipe off the fuel pump (unless that upsets these SU pumps of course) and gravity feed a sample from the bottom of the tank. Some sort of grips to seal off the hose might save a little mess. Do you have to seal off the outlet too with these SUs I don't know or can't remember. I can't remember much hassle with the QH (Hardi) pumps when I had to mess with the previous tank a couple of times and when fitting the replacement tank but I might just have forgotten.

Petrol might be the end of the endoscope - especially fully immersed.

You are certain that's not some sort of dreadful earwax on the tissue, if so seek medical attention.

I was dismayed to discover the 11 year old tank I took out was the same make as it's replacement.
Nigel Atkins

Don't know if this is relevant or not, but here a couple of years ago there was a real issue with a new mixture of avgas and the problem was exactly like your pic with black flakey stuff and a cruddy black gooey film with it-, My mate who looks after his plane himself didn't have a problem with his.but others did.
Heaps of planes were grounded while it got sorted, and it turned out to be Nigel's favourite, crap rubber--
The new fuel was attacking the hoses on the filler nozles at the refuelling stations, the fuel would sit in the hose and when the trigger was pulled it was a case of -take that, I've been melting this hose just for you-
So maybe, just maybe your favourite servo has been injecting it's old bowser hose into your car each time you fill up

willy
William Revit

Willy,
Jeremy's crud isn't black, I'm no good at describing colours but I think I'm safe in saying it's not black. I'd say it looks more wet-sand or mortar type of colour but then they are many types of sand and mortar so not very precise. 😄

I'm sure now I've no longer got the midget that piss-poor rubber is a thing totally of the past (other than planes out your way which is surprising as I've never had a plane).
Nigel Atkins

Thanks Nigel,

that's a good idea; may draw some fuel from behind the filter and let it settle to see if there's anything still lurking in the tank.

The experiment with the endoscope wasn't a success. The endoscope survived so we know it's petrol and ethanol resistant but as the cable is semi-rigid I couldn't get it to where I wanted (the outlet pipe) by putting in through the fuel filler. I may need to remove the filler tube and try from that angle.

Does anyone use a Malpassi filter king? I had one on an Alfa Sud and it worked well. IIRC it's also a pressure regulator.
Jeremy MkIII

I suggest one of the plastic filters between the tank and the fuel pump and another one under the bonnet before the carbs. The S.U pump has a tiny strainer incorporated but this is insufficient to avoid rust infiltration.

If rust accumulation in the filter(s) is a problem, "slosh coating" the tank should solve it. I had an Morris 1300 that had been sitting for many years and once the rust started flowing, it clogged filters in short order. The marine slosh coat fixed the problem.
Glenn Mallory

Thanks Glenn. I did wonder about the filter itself becoming clogged with crud from the tank. My tank's getting on a bit, so I'll see how the filter gets on, with perhaps a view to a new one at some point.

Clint Eastwood Jeremy. 😁


anamnesis

In the UK we don't get some of the products they're allowed in America, no idea about slosh-cleaners.

When I tried to get a carbon cleaner (bloody VW TSI) from a USA manufacturer they put they'd love to but it's not allowed (to fly into?, I forget) the UK, one of the ingredients I guess.

I surprise Willy when I tell him that a product, tool or service e takes for granted in Taz isn't readily available to the general public here, unless you know someone who knows someone in motorsport, motor trade or engineering.
Nigel Atkins

This thread was discussed between 10/09/2022 and 12/09/2022

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.