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MG Midget and Sprite Technical - Fuel pump?

Driving home last night and about 200 metres from home, the engine starts to splutter and cuts out, wont re-start. The float bowls both have fuel, although only half full. I disconnected the fuel line at the first carby and cranked the engine and no fuel was being pushed through the hose. I assume this means that I need a new fuel pump?
From a quick search and read, the general consensus seems to be that its better to replace the original mechanical pump with an electric/electronic pump?
Thoughts? Recommendations? Location of electric pump? Leave mechanical in place or get blanking plate?
1979 MG midget 1500 (UK spec.)
S Travis

Im Not to up on 1500s

But if the pump stopped working suddenly just a few feet from home, then id look at the pump for a catastrophic failure, like a ripped diaphragm... if nothing is there, then id lay odds on a damaged camshaft, if thats the case, then hopefully just a electric pump replacemnt will be okay

I just dont know how reliable 1500 camshafts are

If is just a blown out fuel pump, id probably stay with the replacement mechanical type...

if it aint broke, why fix it

What is strange and concerning about your situation is it takes several thousand miles for a mechanical pump to die of natural causes. Yours died with in a few feet.

Prop and the Blackhole Midget

Could it be a clogged tank filter ?

Use an air compressor with about 30psi and blow it thur the fuel line back into the fuel tank... fuel cap removed of course
Prop and the Blackhole Midget

There's fuel in the filter near the pump (before), so I assume that the line to the filter is okay?
S Travis

True... but the tank has its own filter thats not very accessable... and you did mention that your carb floats are only filling half way

I didnt mention the filters close to the carbs because I assumed that would be your 1st observation

Prop and the Blackhole Midget

Btw... if you do opt for a electric faucet pump in place of the mechanical pump there are several things to remember

1. There are 2 kinds of fuel pumps, pushers and suckers... in the 1275 thepump is in the rear wheel arch, those or pushers, the factory 1500 is considard a sucker because it sucks the fuel out of the tank

2. If you are still using the Duel SU HS4 carbs then you want a LOW pressure fuel pump nothing more then 3 psi or you can go more psi with a fuel pressure regulator to reduce the pressure back to below 3psi

Some pumps have to be placed below the lowest point of the fuel level to operate properly... if the pump is placed so that its mid level of the fuel tank the pump will stop pumping fuel at the half way point of the fuel tank... if it on top of the engine, it wont pump any fuel

4. Faucet pumps are noisy and run full time... they make rubber washers for them to mount to, but I found by pure accident that stiff galvinasied strapping material (2 inches wide and a hole every 1/4 inch ) strap one end to the car with a single bolt and the other end holds the pump so the pump is not connected directly to the car... that makes them very quite

Prop and the Blackhole Midget


You can rebuild SU fuel pumps, putting in new mechanical points (like in a distributor) and can get other bits in a rebuild/service kit, Burlen Fuel Systems sell rebuild kits as well as new pumps:

Rimmer Brothers in the UK is also useful for MG Midget 1500 parts.

You could also try Colin Dodds of Sprite Parts in Australia:

M Wood
M Wood


It hot in Australia now, did you drive slow for the last part of your trip? Could it be vapour lock?

Flip Brühl

Thanks for the info all.
How would I diagnose (and fix) vapour lock? Yesterday wasn't hot (low 20's)and I've never had an issue before (not that that means anything) and drive this car daily, right through the hot summers we have here. And, its very rare that I drive 'slow' anywhere!
I read somewhere that the replacement mechanical pumps don't always match up (slightly different design) and given the poor availability of parts here, I generally buy internationally, which makes return difficult. Hence, considering the 'upgrade' to electric. Rimmer list 2 types of mechanical pump, one cranked and one straight however they both look the same in the pictures (Mike's link above). I've also emailed Colin, to see what he has.
Would this be suitable: or too much pressure? What are the issues of running without a regulator? Could the flow rate be reduced by simply mounting the pump higher?
S Travis

Hmmm... "super cheap auto" as the company name would send me running with my hair on fire just by that name alone ... haha

Yeah thats to high a pressure for the SU CARBS you might be able to put an inline pressure regulater and be okay

Im not sure about mikes post for rebuilding the pump, agian I dont know much about 1500s but I think mike may be thinking your car is a 1275 which that fuel pump can be completely rebuilt... but I dont (THINK ???) The 1500 can be, im welcome to be proven wrong with no resistance on my part :-)

Prop and the Blackhole Midget

This has a good chance of working its rated 2.5 to 4.5 psi

Ideally a 1.5 to 3.0 psi is what your looking for that has NO pressure regulator

Id recommend amazon, summit racing, jegs, and ebay for online international automotive parts companys

Prop and the Blackhole Midget

I decided to just replace the mechanical pump (too lazy to make a blanking plate, run new wiring, mounting points, etc and avoid additional cost of regulator, originality) and ordered one from Rimmer Bros. Hopefully, they are sending the correct one! I ordered TKC3417 and they just send a shipping confirmation advising the following:
GHF201 STEEL NUT 5/16"UNF x2
TE605105 STUD 1.25" LONG x2
Confused, because RKC1624 is the pump for the earlier Midgets, with shorter straight lever yet the correct TKC3417 is mentioned at the end of the listing. I have sent them a query.
Further, whilst researching, I discovered an article on Moss Motors US which advised rotating the pump top to reposition the inlet/outlet however I can not see a benefit to this?
Lastly, is it necessary to replace the current stud bolts? Do they stretch or something?
S Travis

So, Rimmer Bros got back to me. It seems that they don't actually sell the pump with the longer, curved lever - they send you the earlier model pump and new, shorter bolts, so that you can remove the spacer (and remove the potential benefits to minimise the risk of vapour lock). I feel misled and not happy - their website does not make this clear and actually contradicts this on the Spitfire parts list.
S Travis

Sounds like a good plan to me.

Sorry to hear about the experiance... shade tree mechanics can certianly be a least your closer to have this fixed then at the beginning.

Prop and the Blackhole Midget

Steve I can remember rebuilding these pumps in the past. A quick google search suggests you can still get the rebuild kit. Even Rimmer Bros list them as In Stock. My memory is that you get a diaphragm, a pair of poppet valves with springs and a collection of assorted seals. I don't remember it being hard to do, in fact I recall it being a pushover.

I think the usual culprit is the diaphragm. Worn poppets and weak springs certainly reduce the pump's effectiveness, but a torn/detached diaphragm will stop the car in its tracks, as you described.

If your actuating lever is in good shape you still have the option of repairing your existing pump.

It was not good service from Rimmers. I see what you mean about the listing. Photos of the correct pump and all. I'd be PO'd too.

Are they AC delco?

Coincidently, I just rebuilt my Consul Capri mechanical fuel pump. Hole in the diaphragm, plus broken spring in one of the non-return valves. This allowed fuel to drain out of the pump, into the lower body, and escape via thje brether hole. It also prevented the pump making an effective vacuum to suck fuel from the tank properly.

VERY easy to fix.

If you can get an AC delco parts catalogue, you can find the kit you need. For mine it was a BD6.

Have a look on Ebay, there's probably someone selling a kit for a Triumph 1500/Spitfire, I asume that will be the same thing.

In fact, if you can't find the kit number, give me a day or so, and I might be able to find it for you. The bloke I bought my kit from, has an AC listing of the kit numbers.

Lawrence Slater

I just looked up ebay uk for triumph 1500 fuel pump rebuild kit

There is a complete kit with everything for 15.95 + 3.00 uk money

Or you can buy a brand new pump for 18.95 uk money

Mmmm ... decisions decisions

To be fair, ebay did have kits that appeared to have fewer parts for around 11.00 to 15.00 plus shipping cost

Hey 3 dollars saved will almost buy you a 1/8th liter of fuel ... haha

Prop and the Blackhole Midget

New pump

Ac delco rebuild kit
Prop and the Blackhole Midget

Sorted then Prop.

The chap i've just asked came back with the same advice.
Lawrence Slater

Yes, Lawrence - AC pump it is.

However - what I didn't know until about 10 minutes ago is that there is a version that is not dismantleable. I think the body halves are swaged together. The way to tell is that the repairable type (Type Y) has 5 screws holding the two halves together. This is the pump I remember rebuilding for a Spitfire about 15 years ago, I think. It was super-easy as you say. I've done others for straight 6 Triumphs too, besides other cars. My wife successfully rebuilt a very similar pump for her sister's Lada!

Sod's Law says that Steve's car will have the swaged body type :-( However, I just ambled out to The Shed for look at mine and it's the screwed-together rebuildable type and my car is a '78 so only a year older than Steve's.

Also I had a look at Haynes which gives a pretty good rundown on fixing the pump.

Search Rimmers online catalogue for part number 506423 and I'm 99% sure that's the kit for my pump. The shape of the diaphragm gives it away, plus the fact the kit has gaskets for the spacer block. It's £11.50 including the dreaded VAT.

I dont know lawerance.

I posted that because of the humor of it, but in all seriousness, id probably buy the AC delco kit and rebuild my current pump, its only going to twke an hour but in the end you will have a top of the line pump that will last for years with no problems, AC delco is a trusted name

I just would fear a new pump made in china, as im sure this is a good example of you get what you pay might last a day or maybe a year, but the risk is to high

This is just my personal thought


Prop and the Blackhole Midget

x2 Prop. All else being equal (ie - the actuating lever being in good shape &c) I'd definitely rebuild an original rather that chance a cheap repro.

I agree, I would have been happy to rebuild the current one, I should have searched harder. I thought it was only the electric pumps that had repair kits. Anyway, the replacement earlier model mechanical pump is already in transit, so I'll just trial that. Hopefully, I don't start experiencing vapour lock.
S Travis

The saga continues.
I fitted the new fuel pump this morning, fairly easy job, however the engine wouldn't start. It was cranking over but wouldn't fire up. I feel I may have flooded it, fuel was flowing from the overflow on the front carb (shouldn't the needle and seat valve prevent this?).
I left it to sit for a while then tried again but still wouldn't fire up. Then it stopped cranking, just a click. I assume this means that the starter motor has gone? I could hear it whirring but not cranking.
S Travis

The carb shouldn't be overflowing like that. As you suspect, this will be that the needle valve in the carb lid is sticking. They tend to do that if they have been left dried out for a while. Whilst it is overflowing like that the engine will flood and refuse to start.

So fix that sticking valve first. Its usually just a matter of removing the carb lid, cleaning any residues and putting it back together. Be careful though - there are small parts that can easily get lost or misaligned. The valve needle (usually a little white nylon thing) can just drop out. Check that the pointy end goes uppermost when you replace it and also check that it is clean and has no wear ridges on it. Also try not to damage the thin gasket under the lid - they are fragile and easily tear.

The starter will be fine. It is behaving as you describe simply because you have drained the battery. Recharge the battery ready for the next attempt. If everything is ok, a well serviced car should fire up almost instantly, - certainly within 3 or 4 revolutions of the engine. If you need to go on longer than that,then stop and check as something else is wrong.
Guy W

At least the carb overflow tells you your new pump works. Which is good :-)

1500 Midget mechanical fuel pump. My original pump fitted to my 1976 1500 Midget was not repairable (if my memory serves me correctly). However, it had a small bowl on top of the pump's body. The bowl (secured by single screw) housed a simple circular replaceable gauze filter. I remember the pump's body being swaged/sealed, access to the diaphragm being impossible without wrecking the pump. I had to replace the entire pump because the swaged joint (that held the two halves of the pump together) had started to weep petrol. I hope my memory isn't playing tricks with me!

I bought a new replacement mechanical pump from Moss in Sunbury UK, probably 15 years ago.

Andy Hock

You're right Andy. There were at least two types used, both on Midgets and Spitfires, and they are interchangeable. Three types if you count the one that does away with the spacer block.

My '78 car has the Type Y pump that can be opened up and repaired, but I have no idea if it's the original pump.

IIRC Vauxhall in the '70s and '80s commonly used the swaged-together type of pump, and there are many small diesels that use them as LP lift pumps to this day.

Thanks for your confirming post, 'greybeard'. I was beginning to doubt myself after I posted my thoughts!
Andy Hock

This thread was discussed between 20/10/2015 and 13/11/2015

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