SU Fuel Pump or Hardi replacement?

[rocco]

Hi Gang

I have a new Hardi 13312 fuel pump that came with the car and having looked it up on eBay, it states a compatible use with a number of Austin and MG engines but not for the 948cc Minor.
Ordinarily I would dismiss the part as incompatible but I do wonder that if it works for the 997cc Mini Cooper, surely it would do for my car, wouldn't it?

https://www.ebay.de/itm/353786923402?mk ... media=COPY

I also have what looks like the original SU pump (part No. 4080) and wonder whether it makes more sense to simply clean up and recondition this one for originality? Or are they generally considered unreliable?

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The closest looking model I can find on the SU website is AUA66 but I don't see the small (what looks like) a vacuum nipple on it in their photo (which are all rubbish and don't show a complete unit at all). The EPK700 repair kit seems to be for all AUA66 models so if that is what I have, I'll get one.

At the risk of ridicule, why is a dual polarity pump cheaper than positive or negative unit? If you can use it for both polarities, why would anyone buy a positive or negative only pump?

[geoberni]

Let's clear up some of the mythology and 'fake news' around SU Fuel Pumps.

There used top be lots of different models, simply because of the foibles of different car manufacturers and SU jumping through hoops to meet their requirements.

Have a read of this: https://www.mg-cars.org.uk/imgytr/sufuelpump.shtml
The introduction is one of the truest things I've ever read about have a classic car...

S.U. electric fuel pumps are amongst the most reliable fuel pumps found on older cars providing they are properly serviced and maintained. When supplied new with MGs they could be expected to easily outlive the engine without adjustment. Our cars and all their components are now well past their design life, yet many of us are still using original fuel pumps. They will still operate, albeit unreliably, with eroded and incorrectly set contacts, poorly adjusted diaphragms and partially blocked filters. Often a sharp tap will restore a stalled pump to life for another month. This ability to just about keep working with no maintenance, has unfairly given the product a reputation for poor reliability.

Hardi pumps are not repairable, or overhaul-able, unless you send them back to Hardi, and I'm not sure they even offer that service these days. They have a habit of failing 'hot' rather than just 'playing up' like an SU will.

That 4080 part number is for that bottom body part only and is common to many different pumps.
That little 'nipple' is an air vent that vented the space above the diaphragm, it was not on most pumps and doesn't feature on their current range.T
The High Top dates from when they tried fitting a capacitor/condenser as a arc suppressor to improve the lifespan of the contacts.
You might find if you remove the cover that it still has one in there.
When it comes to overhauling the pump, the only difference is whether it's a pre or post 1985 as there's a slight difference in content.
Although to be honest, I brought a Diaphragm from ESM and didn't realise it was a pre 85 one, it's just a slight difference and I fitted it no problem to my post 85 pump.
See here: https://sucarb.co.uk/su-fuel-pumps-spar ... s.html?p=2

I've overhauled 2 pumps recently, without any problem.

I would strip that old SU down and see what condition it is inside.

Take the top off that SU and post a photo of the insides.

There's several videos on youtube, including this one: https://www.youtube.com/watch?v=oU5uLjuOQdM

I must admit the instructions that come with the SU Kit are not brilliant, but their website has all the info you need, as does that MG link I posted above. The video is pretty good.

[King Kenny]

A lot of questions, I can only help by telling you about my situation. The Original fuel pump on my 53 year old Traveller is still giving me good service. I did replace the points and diaphragm somewhen in the late 1980's.You have to be careful when replacing the whole pump as I believe there are two types. One (the Minor pump) sucks the fuel out of the tank whilst the other type (Mini) pushes the fuel to the engine.
I remember that getting the throw on the point correct took a little patience, but once set up it should give you years of trouble free pumping.

[svenedin]

ESM sell Hardi fuel pumps as a budget option instead of an SU. I have no experience of Hardi pumps as they are not an original fitment. They appear to be an SU "clone".

Your SU pump is an LP (low pressure) pump and may well be an old AUA66. The nipple is for a plastic pipe. It is a vent to prevent pressure building up behind the diaphragm but it is certainly not used on current AUA66 pumps or any older ones I have seen either. It is possible that your pump has the body from an HP pump and the rest from a LP pump, I don't really know.

The polarity conscious pumps that SU now sells have an electronic module instead of contact breakers ("points") and are more expensive.

I ran the standard, points, SU AUA66 for over 30 years but started to have issues with the car in Winter which were points related (even though I had rebuilt the pump) and converted it to electronic. No trouble since.

SU fuel pumps are very reliable if given a little bit of maintenance from time to time. People expect them to go on for ever with no attention at all and then call them unreliable which is complete nonsense.

Stephen

[geoberni]

A lot of questions, I can only help by telling you about my situation. The Original fuel pump on my 53 year old Traveller is still giving me good service. I did replace the points and diaphragm somewhen in the late 1980's.You have to be careful when replacing the whole pump as I believe there are two types. One (the Minor pump) sucks the fuel out of the tank whilst the other type (Mini) pushes the fuel to the engine.
I remember that getting the throw on the point correct took a little patience, but once set up it should give you years of trouble free pumping.

Yes, there's LP and HP pumps.
LP suck up to the engine bay and then just a little push to the Carb.
HP basically use higher pressure to push all the way from close to the tank.....

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I'm really unimpressed with the new SU website; the old one looked a bit dated but was very easy to navigate with excellent information. The new site seems to have the same info, but scattered all over the place.

[myoldjalopy]

Another thumbs up for the SU pump. I put new points in 23 years ago and have had no issues at all since - and I do use the car regularly, its the only one I have.

[Peted7202]

The Hardi pump for the Minor is 1112-5 not 13312. The difference is the end plate and connections.

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[geoberni]

The EPK700 repair kit seems to be for all AUA66 models so if that is what I have, I'll get one.

At the risk of ridicule, why is a dual polarity pump cheaper than positive or negative unit? If you can use it for both polarities, why would anyone buy a positive or negative only pump?

Check the age of the pump by reference to the Earth Screw to get the right Kit.

Part Number: EPK 700 - Pre 1985 - identifiable by 2BA earth Screw in coil Housing (Same size head as the case screws)
Part Number: EPK 705 - Post 1985 - identifiable by 4BA earth Screw in coil Housing


All their conventional Points type are now Dual Polarity.
Only the Electronic ones are polarity sensitive due to the electronics being different.
Although the selling point it the Electronic ones don't depend on the Points so are 'more reliable' if they fail, then they have failed, your stuck with no pump. A Points one can be maintained or just banged to get it going a little longer if it does fail,unlike the electronic.

Older points pumps were polarity sensitive because of the 'devices' they used to try and reducing points arcing.
The new 'device' works either polarity.
See my recent post here: viewtopic.php?t=76655

[rocco]

Thank you Geoberni and others for the great helpi! I couldn't ask for more.

I'll get an SU repair kit next month (pre 85) and give it a go using the video you linked to. I must admit that I do prefer the SU pump option.

I found another sticker on the SU pump >> AZX1302, superceded to AZX1308 which is a HP pump. It's a bit more confusing now after finding this >>> https://www.triple-mregister.org/upload ... 0Chart.pdf

This makes the rebuild kit EPK300 negative earth. Why can't things just be clear and simple?

[svenedin]

Thank you Geobern and others for the great helpi! I couldn't ask for more.

I'll get an SU repair kit next month (pre 85) and give it a go using the video you linked to. I must admit that I do prefer the SU pump option.

I found another sticker on the SU pump >> AZX1302, superceded to AZX1308 which is a HP pump. It's a bit more confusing now after finding this >>> https://www.triple-mregister.org/upload ... 0Chart.pdf

This makes the rebuild kit EPK300 negative earth. Why can't things just be clear and simple?

I think you have a Frankenstein's monster pump (made of different parts) or a "marriage" (as they say in the world of clocks and watches). As I said earlier, I think the body of your pump, with the nipple which is not on LP pumps, is from an HP pump but the base is from a LP pump.

Stephen

[geoberni]

Thank you Geoberni and others for the great helpi! I couldn't ask for more.

I'll get an SU repair kit next month (pre 85) and give it a go using the video you linked to. I must admit that I do prefer the SU pump option.

I found another sticker on the SU pump >> AZX1302, superceded to AZX1308 which is a HP pump. It's a bit more confusing now after finding this >>> https://www.triple-mregister.org/upload ... 0Chart.pdf

This makes the rebuild kit EPK300 negative earth. Why can't things just be clear and simple?

Woah... take a breadth...
From the photo of your pump, it can't be the EPK300.
Look at the kit contents, it has larger bits (washers etc) that couldn't possibly fit the pump you have.

SU website has some very strange details... For example, Why does the HP 'Positive Kit' not have a replacement spring?

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Why do they even supply Positive and Negative kits?
The little Arc suppression device is not polarity conscious, so any overhaul makes it suitable for either...

Their own 'blurb' on the kit page (EKP600) says "Suitable for negative earth pump model AZX 1331"... yet if you look at that number it says the pump is Dual polarity.
They really need to get their act together in this regard.

This is why I said to take it apart and see what's inside.
I mentioned earlier that I had recently overhauled 2 pumps. One was that from my car, the other a pump I brought from ebay, sold for having a small leak. That ebay purchase had a vent connection.
The insides were standard LP pump, post '85 with the smaller earth screw.
It had the 11 separate brass discs as the 'guides' as see in the kit used by the guy on the video. My pump meanwhile had the 'plastic clip' as he refitted on the video....

Even the SU website various write-ups aren't clear which pump had a vent and which didn't, generally it was cars with HP pumps, but there's no definitive info on that.

Take your pump apart and see what's inside it, then you can decide which kit to get, the 700 or the 705.

[rocco]

OK, I've just opened it up but I have to confess, I didn't watch the video yet. I will do so later tonight because I don't yet know how to remove the last pivot pin unless I tap it through. It doesn't want to go as easily as the longer one did and it has no excess protruding to be able to get a grip on it.

As the clear expert of fuel pumps, do these photos offer any clues as to whether I have a frankenstein pump please, Geoberni?

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I am looking forward to get the thing cleaned up in the ultrasonic bath and putting it back together with the right repair kit.

[geoberni]

I wouldn't say 'clear expert' ....but I have done 2 recently and such things as these were part of my trade in the RAF as an aircraft electrical fitter, later 'technician' as the terminology moved up to date.

Bottom line

There is always the chance that this is an HP pump, it's one of the problems with SU fitting silly little tags under a bolt head to indicate how it's been built. There doesn't appear to be any difference in the HP and LP diaphragm.

What you could do, since you're presumably not in a rush to overhaul this pump, is ask SU for a definitive way to identify what you have. Is the HP diaphragm a different thickness rubber from the LP for example.?Or is there a different Resistance (Ohms) value for the respective Coils?

But some more of my ramblings and observations...

I'm not sure what you mean by "I don't yet know how to remove the last pivot pin"?

In the bottom photo, you seem to have the 2 Pedestal Screws and the Rocker Pivot Pin out, I suspect the Diaphragm is still screwed into the Rocker Mechanism. That'll be holding the top on still.
See the exploded view I posted on this other question earlier this afternoon: viewtopic.php?p=692003#p692003

Best see the video before you accidentally break something.

To me that looks exactly like a LP pump fitted with a Condenser as an Arc Suppressor. They fitted Condensers in the mid 1950s; some people say it was only on the HP pumps, but that isn't consistently reported in articles and it wouldn't make sense to only do it on HP pumps.
If it was their attempt at prolonging Points life, it would make sense to do it to all their range.
On the SU website, this page about reassembly https://sucarb.co.uk/technical/technica ... reassembly
It does say under the sub-heading 'All Types' at section 8:

Where a diode resistor is fitted it is in parallel with the coil connections. This component is polarity conscious and therefore all connections must be correctly made. A condenser, where fitted, is not polarity conscious.

Going back to your earlier comment about finding a sticker AZX1302, that makes no sense as the AZX1300 series were the 2 connection side by side, like this : https://sucarb.co.uk/su-fuel-pumps-spar ... ity-1.html

That's another thing that SU get themselves muddled up over. If you look at the website descriptions of their replacement Diaphragms...

LP Pumps Pre 1985 - Fuel pump diaphragm spindle length 2 3/8" .This diaphragm has no steel stiffening plate & a flat armature plate
LP Pumps Post 1985 - Fuel Pump Diaphragm Spindle Length 2 3/8" . Armature plate only (No steel stiffening plate) Suitable for all modern fuels.
HP Pumps (all) - Fuel pump diaphragm spindle length 2 3/8" . This diaphragm has a armature plate & steel stiffening plate

Yet when you look at the LP Diaphragms post '85, they do have a stiffener plate in them.
This is one of the Diaphragms I replaced; it's a Post 85, as it has the ring around the top (pink Arrow) but it also has the Stiffener (Red Arrow).
.

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.
When I inadvertently purchased the replacement Diaphragm which turned out to be pre 85, since it had no ring around the top, it also had no stiffener. Personally, I made an engineering decision and fitted it anyway.
The ring around the top can only be to help keep the spring central and if they managed 40 years without either the stiffener or the ring, it's not going to make that much difference.

Fell free to ask more questions.

[rocco]

Thanks again mate, appreciate you taking the time to make such detailed responses.

I'm starting to wonder whether I'll be better off just buying a new pump or a used pump that hasn't been bastardised. 50 quid is a fair chunk of change to waste on a repair kit that may not be compatible and I have to get it shipped over here so an EU rip-off tax will be applied too (unless Moss sell it).

I do have one more question that is bothering me, what is the screw on the following photo for?

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And the pivot pin I thought I had to remove, I don't. The video you shared was very good and it transpires that the diaphragm is removed by turning/twisting it out - so you were right. I would never have worked that by myself.

Here is the sticker on the points/pedestal cover.

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[svenedin]

The screw is for an earth connection. The original connection is via a ring terminal on the earth lead from the car that is clamped by that screw (and a washer). Some cars have a Lucar type spade terminal on the earth wire so the screw can secure a blade terminal. There are 2x earth connections to the pump. 1 on the body and the other on the base.

[geoberni]

That's the Earth Screw they mention that denotes whether the pump is pre or post 1985. That's the same size head as the 6 main screws, so it's the pre-85, 2BA size.

I think I've looked at Moss before and for some reason they only had the HP repair kits, at that time. You might find a seller on ebay??

As that label is on the top, I suspect it may have been refurbished at some time decades ago and they fitted a different top.

[mogbob]

I endorse the " replacement " end cap theory. The material it's made of , doesn't lend itself to being dropped.( If your's get broken you pinch
another from the pile of spares hanging around your garage to keep the car running.Isn't that right ? )
I've worked on numerous SU petrol pumps. LP and HP and a double ended ( on a beautiful Alvis , the petrol dripping profusely signalled
" all was not well " .Never mind the fuel consumption what about the fire risk , eh !! ).
Plenty of pictures , notes sketches , diagrams , etc.whilst dismantaling. Be gentle some of the parts can be quite delicate.
Note what you say about cost but how does that compare with getting a garage to do it for you ?
Good luck with your decision. Bob

[rocco]

Back to my own thread to avoid hijacking someone elses.

I got a reply from Burlen today who confirmed that my pump is a high pressure unit designed to be fitted at the rear of the car and I suspect that is the main body. The in and outlet flange, I assume, is from an original low pressure unit.

I don't want to mess about with funky modifications that I don't understand so I will now search for a "proper" replacement. It'd be handy if I could find one in the next few weeks. I'm travelling over to the UK next month and will scrape together as many parts as I can to bring back.

Is there anyone on here that wants to swap a good pair of 1000 rear wings for the short ones I currently have on mine?

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[geoberni]

I got a reply from Burlen today who confirmed that my pump is a high pressure unit designed to be fitted at the rear of the car and I suspect that is the main body. The in and outlet flange, I assume, is from an original low pressure unit.

I'm curious as to how Burlen identified it as a HP pump?

They may be going by that vent pipe connection??

From your photos, it looks to have the 'standard' body' with 2 ⅜ inch coil housing.
Earlier HP pumps did have a taller 3" Coil, but since 1985, the only difference, AFAIK, is the strength of the Return spring.
Originally, LP pumps used a 2BA earth screw and HP pumps used a 4BA screw. The earth screw provided a reliable earth connection and for a while also provided a useful means of differentiating between the pump types.
Today, both ‘post 1985’ LP and all HP pumps feature a 4BA earth screw in the side of the coil housing, so external ID features have gone (aside from that old vent pipe connection)...
I think the definitive thing is now the Pump Return Spring... because it could be a former HP coil, which has an LP spring fitted to it....

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[rocco]

I really don't know mate and I've lost any motivation to find out any more. I'll be getting another pump whatever else happens.