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MG MGB Technical - Fuel pump not ticking
|OK, so I brought this on myself. My '66 GT has been slightly neglected of late - the last time she went out was probably 4 or 5 months ago since the last time I tried to go for a drive the battery had packed up. Then the usual weather/lack of time etc got in the way...|
This morning, brand new battery fitted and fully charged, I decided to take the B to work with me - only to find that for the first time in 13 years of ownership (including several periods of being laid up for months at a time) there was no click from the fuel pump. Wearing a suit and running late wasn't the best time to start rummaging underneath to give it a clout so I conceded defeat and took the modern.
So, I'm after the collective wisdom of the BBS:
- If a good thump gets the pump working again can I safely assume it will be reliable, or is it a sign that maybe new points or a new pump wouldn't be a bad idea?
- I've never had to fiddle with the fuel pump at all so don't know much about it - can the points be replaced/cleaned without removing the pump from the car?
- If I need (or choose) to replace the pump, is it just an unbolt job or do I need to do something to avoid spilling petrol all over the floor?
Many thanks in advance,
"If a good thump gets the pump working again can I safely assume it will be reliable" - NO. I had to give my ageing fuel pump an occasional thump, then one day whilst driving at 50mph the car just coasted to a standstill. Re-started and drove for a few yards then stopped again. Heavy traffic prevented me from getting under and whacking the pump, so gave it a good beating inside the boot. This got me home. Fitted a new pump and threw the old one away.
"If I need (or choose) to replace the pump, is it just an unbolt job or do I need to do something to avoid spilling petrol all over the floor?" - it would be wise to have something on the floor to soak up any fuel, or a tray/dish handy; I've replaced a couple of fuel pumps and just had a dribble of fuel (less than quarter pint).
"can the points be replaced/cleaned without removing the pump from the car?" - Not sure if it's possible to do this, but I bet it would be very fiddly and probably take longer than removing the pump and do the job on the bench.
Both my MGs suffer from lack of use and I would advise you always keep a good battery on your MG and switch on the ignition regularly (say every week/two weeks) to give the fuel pump some excercise - this helps keep the contacts clean. I also use an Accumate battery conditioner which ensures I always have fully charged batteries; keeping a lead-acid battery fully charged gives maximum battery life.
|As Brian says, thumping it can only be considered a temporary fix.|
Easiest to clean or replace points with the pump removed.
I have to do the same on my brother's GT as it cut out four or five times on the way to MG Live.
I also need to clean & test my own pump as it hasn't run for 12 years, although I did fit a new set of points to it once.
|I'd agree that clouting it is only a short term fix if it packs up "in service" (access is slightly easier through the battery cover if you have a long enough clouter, and a lot safer at the roadside) but I've had long-term success with it as a wake-up call after a long lay up, as in this case.|
|Tim - A good cleaning of the points may well be all that is needed to get your pump working properly. E-mail me at SUfuelpumps@donobi.net and I'll send you a procedure for getting the contacts cleaned very well. As the others have stated, removal of the pump will ultimately save you time and frustration. To remove the pump with minimal spillage of fuel, first loosen the fitting of the fuel line at the tank to break the siphon at the pump. The only fuel that will spill then is what is in the line from the tank to the pump. Cheers - Dave|
|Thanks all - and Dave, I'll drop you an email in a minute, thanks for the kind offer.|
I had a bit of time this evening to take a quick look - percussive maintenance didn't help. I have good voltage at the spade connector but I couldn't get to the earth easily to check that side. I had a go at cleaning the points in-situ - after a few colourful words and I managed to get the cover off the pump from inside the battery box and ran some emery paper between the points. Still didn't work and by that time my knees were giving way from kneeling in the boot so I gave up for the day!
My big problem is that the car is in a single garage, so there's very little room to get down and remove the pump. I can probably manage it if I jack the car up and remove the wheel but it will still be tough! With that in mind, any way I can fix it without removing the pump would be ideal!
|The ground wire, for the pump, runs from the license plate bracket hold down bolt. There are several wires that get their ground from this spot. It is notorious for becoming rusty and leaving you with an open circuit. Check this area for cleanliness before you start replacing parts. You can run a temporary wire, from a good known ground spot or the battery, to the body of the pump to test it for proper operation. RAY|
|I have smacked pumps once in a while for years on the same car, and when you get good at it, you can turn the key off/on/off/on while in motion, which usually brings it back to life. If that happens a few times, it is time to look at it. I like this because you do not walk home like with an electronic pump. Wiring fails more often than the pump.|
You can take the upper points off in the car and clean them pretty easily, which usually suffices for a while, and with difficulty clean the lower set. I have a 1/4" wide strip of 400 silicon carbide paper in my wallet at all times for the past 54 years - does any points you might meet.
Yesterday I started my Magnette for the first time in two years, and had to smack it. Last time it had sat for 28years and had to actually remove the points to clean.
|I did check the number plate lights worked to rule out the earth connection there but couldn't get to earth connection on the pump itself to check that.|
I'll have another go at cleaning the points using the useful guide sent by Dave (thanks for that!). In younger days I used to carry one of my girlfriend's nail files with me all the time before converting to electronic ignition. The distributor points are a bit easier to reach though!
|Perhaps I'm being a bit thick....Single garage: roll car out, jack up, remove wheel,use axle stand, remove pump, replace wheel, roll back in, repair pump on bench. As they say assembly is the reverse....??|
"I did check the number plate lights worked to rule out the earth connection there but couldn't get to earth connection on the pump itself to check that."
= NOT good enough. The lights might work, and even the fuel gauge, albeit not nearly as well as they should, but there may still be high resistance. The heavy current draw of the pump (compared to the other things - AND dded to them) will cause a significant voltage drop, maybe enough to stop the pump. More so if the other connections are iffy. It is very common that the power feed to the pump is delivering much less than full system voltage - I commonly get numbers around 10V at the engine end of the feed to the pump, by the firewall. If you attend to all these , you may find that the pump is alive or not, but you will know if it has a chance. Best part is, everything else in the car will work better too!
Get a voltmeter and learn to use it. If you want to know more than you dreamed of about voltage drops and system efficiency diagnosis and repair, email and ask for "Electrobabble".
Nail files are now far better, in the form of sapphire or diamond on flexible plastic base. You can even cut one to get several small narrow strips for a few pence per.
|Regarding the ground point at the number plate mounting - see the article, Electrical Connection Preparation in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave|
PS - Perhaps you should get together with Steve Church - he has a posting "Fuel pump ticking too much". Seems like the two of you could find a happy medium somewhere ;-)
|Michael - You're right, that would be easy except that there's quite a big slope and the drive is gravel. Have tried pushing a car on that before, it didn't work!|
FRM - Apologies, I was using sloppy language. I did check the voltage at the pump (12.3) but you are of course correct that the earth could be high resistance!
However, SUCCESS! Thanks to Dave's excellent procedure I managed to thoroughly clean the points without removing the pump and it seems to be working perfectly now. I owe Dave a beer should we ever meet in person.
Top tip to anyone trying this, though - don't do the job, put everything back together, forget to put new tape around the points cap and then have to take everything apart again to fix that!
|I would advise changing the earthing point to the lock latch securing bolts, it's less prone to corrosion, and switch cleaner on the points helps keep them clean and oxide free. Or, better still, replace with a pump without points!!!|
|Huh-slope, gravel-a mere detail!!!!!Well done!|
|For what it's worth - another method of jarring a pump back into life is to open and slam shut the driver's door - this can also be done whilst driving or in the pouring rain without getting wet.|
Electronic pointless pumps also suffer "sticking" but for different reasons - I too have used the ignition on / off trick to get the pump to deliver fuel one stroke at a time!
|Chris at Octarine Services|
|I can confirm that Chris' method does work.|
I had my first Midget when I was eighteen. One evening it refused to start. My rather haphazard fault finding method didn't seem to be getting me anywhere, so I gave up and slammed the door in frustration. I immediately heard the sound of the fuel pump ticking away and when I turned the key, it fired up.
For those of use driving on the right hand side of the road, dropping the right wheels off the pavement will usually jar the pump into action. As a young and usually broke Airman I covered 1000's of mile with brief excursions to the shoulder of the road.
|J. M. Haskins|
|I own a 1980 B and a few years ago the fuel pump stopped working on a trip home from the Drakensberg Mountains. A number of smacks on the pump = zero success. We jury rigged a live feed from the battery to the pump and by tapping the ends together managed to limp home. My wife is now sometimes known as "Tap Tap".|
The cause of the problem was rust flakes in the centre hole in the soft iron core of the magnet where the brass rod that connects the Armature to the points assembly resides and moves back and forth. These fouled the rod preventing free movement. Disassembly is quite simple but count the number of full turns on the armature to disengage the rod from the points assembly. I cleaned the hole and painted it with Self etch primer, refitted the rod with the same number of turns and refitted the whole pump. Has worked faultlessly for at least 6000/ 7000 kms. I did clean and check the setting of the points as well but they were fine.
|R. E Bester|
|Ray - Rust on the armature of the pump's coil is the result of moisture getting inside the pump, behind the diaphragm. There is a vent spigot at the base of the coil housing that should have an attached 1/8" ID tube routed into the trunk to insure that no water gets sucked into the pump when driving in the rain or through puddles. See the article, SU Fuel Pump Vents in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave|
|I finally got round to looking at my brother's pump last weekend.|
I cracked the inlet union at the pump and fuel started dripping. I then cracked the union at the tank end, but it carried on dripping away. The tank was fairly full, as the fuel gauge hadn't been working, but that's another story.
So, rather than remove the pump, I decided to try and clean the points in-situ. As access from underneath was extremely limited, I decided to remove the RH battery and work through the battery box... a bit like key-hole surgery.
Things didn't improve much, as I discovered that the pump was a 'Hardi' and not an SU, as I was expecting.
It seemed to be very similar to the SU pump except that the upper points arm was located by two screws, one at the end and one in the middle. It wasn't until I was re-assembling it that I discovered that the centre screw was actually for adjusting the tension.
Having cleaned the points and refitted the upper arm, I had to experiment with the adjustment until it felt right. This operation would be best carried out on the bench with a 12v supply, but as I was working through the battery box with the battery removed, I just had to hope for the best.
There was originally a blob of yellow paint on the screw to keep it in place. My brother's wife very kindly donated some of her nail varnish for this purpose.
All reassembled and working fine so far, although I would probably be happier replacing it with an SU pump at some point.
|Dave - "It seemed to be very similar to the SU pump except that the upper points arm was located by two screws, one at the end and one in the middle."|
Standard Hardi points arrangement. The Hardi pump is a great little pump, but it is impossible to get parts for them.
"I cracked the inlet union at the pump and fuel started dripping. I then cracked the union at the tank end, but it carried on dripping away."
Had you gone ahead and let the fuel drain from the line, it would have stopped very shortly. Cracking the union at the tank, breaks the vacuum in the line and the only fuel that drains is that fuel left in the line. Cheers - Dave
"Standard Hardi points arrangement."
That's what I assumed, but not what I expected, nor wanted, when having to work by feel rather than sight.
"Had you gone ahead and let the fuel drain from the line, it would have stopped very shortly."
Quite a lot of fuel came out...more than a pipeful, I think.
This thread was discussed between 01/08/2012 and 20/08/2012
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