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Post by jeff on Apr 16, 2023 14:58:40 GMT
Hi all.
Further to my recent post about the mystery cutting out, I've done about all I can in the engine bay. I haven't yet fully tested the car yet to try and replicate the fault.
Before I go scroffling about under the dash, looking for suspect wiring, I've decided to give the fuel pump the once over. I haven't yet, that's tomorrow's job.
Of course the car has been laid up nearly all winter and I just wondered if the dreaded E10/E5 fuel has caused some deterioration of the fuel system components, although what I pumped up from the carb inlet seems clean and the needle valve seems OK.
Maybe the diaphragm/valves within the pump are damaged??
Many moons ago, before my time with the car, the car was changed to negative earth. I just wondered if this could have an effect on the operation of the fuel pump. Coil? Points? Etc. Any ideas guys of what I could potentially find.
I believe the pump is original.
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Post by Penguin45 on Apr 16, 2023 17:46:13 GMT
The SU fuel pump fails because the points burn out. Latterly, they are fitted with a condenser (as per car ignition points) to try and prevent/reduce this. An SU pump without a condenser is not polarity sensitive. The armature simply moves back and forwards - reversing the wires will still cause it to move back and forwards. If the pump is failing, Burlen supply a repair kit to allow it to be fully refurbished - HERE. Alternatively, you can convert it to electronic points with a kit EPK12N. Expensive, and you don't get the diaphragm and gaskets etc. Then it becomes polarity sensitive. I've never had any bother with E10 over the years, despite all the bad press. If the car has been laid up for any length of time, I do usually add a gallon or two of fresh fuel at the earliest opportunity. Chris. |
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Post by jeff on Apr 16, 2023 18:20:00 GMT
Thanks Penguin, much appreciated.
I did put fresh fuel in last weekend but its probably worth checking the pump over.
I said in my post the pump was original. It isn't.
I note from the comprehensive history file that the pump was replaced in 1989, £28.
Replaced again, 1999, £35.
So now, some 24 years later, it's gonna be worth a look over.
I take the point of your comment, about the armature.
Thanks for the link to Burlen.
I'll let you know my findings.
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Post by andrewa on Apr 17, 2023 9:32:15 GMT
For what it's worth - just another point of view - but I never got on with SU fuel pump in the Landcrab and switched to a Facet - solid state. I used a regulator on mine but have now learnt you can buy different springs to tone down the fuel pressure.
Same issue with my Bristol - it had a double ender SU fuel pump and all the gaskets (cork I believe) would dry out if car left for a month or two then massive leak. So have also got facet fuel pump on that and no issues.
I do appreciate that many love their SU's and never have a problem - just not me!
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Post by dave1800 on Apr 17, 2023 12:29:24 GMT
It may be worth considering fitting an inertia fuel cut off switch to prevent the pump from continuing to pump petrol in the unfortunate event of an accident. Moss sell a kit for the MGB which is quite a lot more expensive than last time I looked. There may be other suitable options from breakers. MossDavid |
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Post by jeff on Apr 17, 2023 15:12:12 GMT
Thanks again guys for the input and ideas but....
I think I have found the culprit of the mystery cutting out.
As planned, I took off the fuel pump today.
The pump looks like it had been dropped, bending the battery terminal. Inside the cap, the plastic cradle looks bent, possibly cracked.
It ran rapidly for about 2 seconds and stopped.
I found by just touching the spring with the top half of the points it would run but sparked like a thunderstorm.
The points were badly worn with deep recesses in the bottom pair.
I managed to very carefully clean them up and the pump ran fine for as long as I wanted.
The filter and valves are fine.
So, now I'm debating whether it's worth rebuilding a 24 year old pump or replacing the whole thing.
If I could remember how to send a picture of my findings, I would.
Jeff
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Post by jeff on Apr 17, 2023 19:54:09 GMT
Well I finally decided that rebuilding the top end of my SU/ Burlen electric pump might well end up as good money chasing bad.
I've gone for a new one but not with SU.
Having had a conversation with the highly knowledgeable Tony Wood, from our owners club LOCI,
I opted for the German built Hardi pump AUF214Q electronic. The cost just under £75.
I read and hear its a very reliable pump at a decent price.
So here goes.
Thanks again for all the help.
Jeff.
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Post by Penguin45 on Apr 17, 2023 23:38:12 GMT
The blue top one? I've had one on the 18/85 for almost as long as I've owned her. No problems at all. The Austin has a Facet, also completely reliable. I did note in your earlier post that the SU had been replaced several times previously - not a great sign. Fitting an inertia switch as David suggests is a sensible safety precaution. Little bit of info on mine HERE (P73 if the link doesn't work properly). C. |
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Post by jeff on Apr 18, 2023 15:50:53 GMT
Yes Chris, it's a blue top. Unfortunately, it doesn't show pos and neg on the terminals. But, as its supposed to be dual polarity, (my car has been swapped to negative earth), so it shouldn't make any difference I hope.
Good idea to fit an inertia switch. And looking at your post, a handy place to fit one.
Cheers
Jeff.
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Post by dave1800 on Apr 19, 2023 1:21:26 GMT
Is it a straight swop for the SU? My friend in Bristol needs a new pump for his MGB and is looking for a reliable option to the SU.
David
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Post by foglaursen on Apr 19, 2023 9:22:05 GMT
I have a Hardi pump in my MGB, so yes, it is a straight swop. I should add, that the diameter of the Hardi pump is a little less than that of the SU pump.  |
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Post by jeff on Apr 19, 2023 14:49:08 GMT
The Hardi pump arrived today so I fitted it.
As said, it's diameter is a little smaller than the SU, and the bracket supplied doesn't really lend itself to fitting to the rear of the fuel tank lip, with a single bolt. The inlet and outlet tails needed orientation but that's easy by just slackening the two screws on the base of the pump.
The inlet should be at the bottom, and the outlet at the top, avoiding minimal bending or kinking of the rubber fuel lines.
I opted for using the existing bracket. I adapted it by wrapping a couple of tight turns of flat 30mm shrink tube around the pump body, and adding the supplied rubber packing inside the existing sponge packing so making a nice tight fit when tightened up.
I didn't fancy butchering the supplied new bracket, it might come in handy one day.
The terminals are marked + - in the moulded blue cap.
Also took the opportunity to redo the old electrical connectors and clean up the earth connections to help reliability.
Yes, it certainly ticks like the old SU, rapidly filling the carburettor then coming to a stop when filled.Then a good check for leaks while fully pressurised without the engine running.
I read on an MG forum it is advisable to fit a filter between tank and pump inlet.
I don't know if the Hardi pump has a filter inside the inlet like the SU. That's the next job.
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Post by andrewa on Apr 20, 2023 8:03:27 GMT
Good idea re filters but then again I tend to go a bit fuel filter mad - from memory I had one between tank and pump and another between pump and carbs!!
I put the inertia reset switch/fuel cut off thing top left in the engine bay from memory btw.
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Post by jeff on Apr 24, 2023 17:46:15 GMT
As we know, I've replaced the old SU pump with a Hardi.
I've decided to fit an inline filter, and replace the dodgy looking hose from the tank to pump.
The new hardi has 8mm tails and so has the inline filter.
Fitting new hose was a tight fit and now I'm a bit worried what size tail is the tank outlet. The old hose is currently plugged with a bolt.
Will 1/4 inch hose fit the outlet??
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Post by Penguin45 on Apr 24, 2023 19:32:46 GMT
6mm from memory. 1/4" should fit. Use proper petrol hose clips, not Jubilees.
Chris.
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