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MG MGB Technical - Alternative Fuel Pump ?
|Having just had my 1972 GT removed to the nearest garage by the AA with a seized fuel pump, and having had this problem 3 times with my 1972 roadster. I would like to know if there is an alternative system that I could have fitted to avoid this constant irritation. The cars are not used daily all year round so I dont know if this adds to the problem, but it would be nice to think the car will actually start when I'd like it to. Any suggestions.|
1972 MGB GT 2.0
|a g dunlop|
I had lots of 'fun' with similar pumps on my wife's Morris Minor.
The usual problem on the Minor was that the pump's contact breaker points would burn out and stick.
The starting handle on a typical Minor was usually used more often for hitting the pump (which usually did the trick) than for starting the engine.
I understand that the standard B pump has a suppressor that usually solves this problem by reducing the arcing.
Are you quite sure that it really was the pump, not just a dodgy connection that was temporarily cured by moving it when changing the pump ?.
There is quite a lot of science in the subject of choice of contact material, and I suspect that some replacement parts are not quite all that they might be. Good quality contacts use 'exotic' metals, which are expensive.
Some people seem to have had less than satisfactory experiences when using the modern 'points less' pumps, including the previous owner of my car who went back to 'standard'.
Other people have used pumps from modern cars with good results.
Well, that should trigger some discussion....
I picked up a generic electronic fuel pump from Napa or Advanced four years ago when I bought my '73 B. The previous owner had burned up the wiring and the fuel pump somehow.
I was in a hurry to drive it and didn't do my research, but so far so good the pump has not let me down yet. My car is also not driven much (the B has been stored for up to 6 months at a time since I have owned it). I drove it about a month ago when I was home for nearly three weeks without problems.
|The SU pump is a good unit and stood the test of time. Don's point about the earth is very important but the earth goes to a point on the inside of the back panel in the boot and it notorious for trouble. Check this out very carefully. The other point is that if you dont connect the plastic vent pipes then moisture will get into the pump and it will have a short life.|
|As a result of 'cascading failures' (some of which are in previous threads) I'm in the midst of more or less a full rebuild for the fuel system - all the tubing, pump, flushing tank). |
With a little digging, I had 2 aftermarket pumps - a little square one near the tank and another cylindrical aftermarket in the engine bay. It loks like I got a tank of bad gas and it somehow gummed up the works, so that the flow and pressure vary wildly at the carbs.
My question, following up on Iain's comments, regards reinstalling an SU - I got a NOS from Ebay. I have a power line, the current pump is grounded to the body beside the pump, and no trace of the plastic tubes Iain mentioned. In a 72 roadster how is this supposed to be hooked up?
|1985 Honda fuel pump!!! Nuf said!!! Bob Thomspon|
part # Napa P70217.
|Steve, the tubes go up into the trunk space. You should find on grommet on the crossmember just behind the rear firewall this has holes in it for the tube to come through into the trunk space.|
Just as an aside Steve your comment reads as if you have two pumps in the fuel line at the same time. If this is the case I'm mnot surprised that your fuel and pressure vary wildly. Even if you disconnect one of them the other would almost ceretainly act as a pressure reducing valve.
|Yea, I'm not sure exactly why it was working or exactly why it stopped working. I checked the flow rate and pressure last summer and everything was right on where it was supposed to be. But I was assuming - problem there- that the pump I saw inthe engine bay was THE pump. I was looking for a leak that might be letting air in when I discovered the second pump still inline. |
In the last week I seem to have gotten a load of bad gas, which seems to have toppled the whole operation. So I see it as an excuse to put it back right, or at least close to right. So I'm replacing the 2 pumps with one NOS SU pump, flushing the hard lines and tank, and putting new soft lines in.
|Alan - Normally I suggest that the standard SU fuel pump, bought new will last as long as any other pump on the market, but with your statement to the affect that the cars are not driven regularly, I would suggest either the all electronic SU fuel pump or one of the aftermarket pumps like the little, square, run all the time, make a lot of noise Facet pumps. The problem with the points style pumps is that the points will film over after a period of time of disuse and this will cause a isolation of the contacts from each other. An all electronic pump without points does not have this problem. If you will send me you e-mail address, I'll send you a fuel delivery troubleshooting guide that can help you isolate your problem if it is not the pump.|
Steve - The NOS SU fuel pump is connected witht he wite wire to the power terminal on hte end cover and the ground wire to the screw (or spade lug) on the side of the coil housing. The clear plastic lines are vents for the pump and are routed into the trunk space where the atmosphere is (supposedly) dryer. They are not entirely necessary as I get many pumps where the lines were obviously not used and there is no detrimental effects on the pump. I have to dissagree with Ian regarding the dual pumps causing pressure fluctuation. All of the electric fuel pumps on the market (unless they are really exotic) have nothing more than check valves in them and will pump through each other with no effect on output pressure. I even advocate installing one of the little, square, run all the time, make a lot of noise, Facet pumps in line with the SU pumps and then have a switch to switch power from one to the other in case of problems (I even have one of these on our MGB). I would suggest, before installing the new SU pump, that you go through the fuel system from tank to carburetors, like you plan to insure that any and all crud is out of the system. The tanks are notorious for rusting and the residue can clog the system and cause the problem you are experiencing. Having crud in the system, if it clogs the inlet line to the pump, can burn out the internal swamping resistor in the SU pumps, greatly reducing the life of the points. I can send you pictures of the installation if you decide that this is what you want to do while under the car fussing with the fuel system anyway. Cheers - Dave
|Fuel pumps......AAaaarrrghh! Spent more time on my knees in wet weather coaxing Skinner's Union pumps than I care to relate.|
I have two Advance parts, (Napa would do too, but the plumbing's easier with the former).
They are mounted inside, warm & dry behind the right rear wheel well, just ahead of the tailight.
They are plumbed in parallel and I have a selector switch so that if one 'passes away' in the middle of Nevada......click!
They've been on the job for ten years without a hiccup.
|I have a Carter Silver series electric mounted high and dry in an enclosed version of the battery box behind the driver's seat (LH side.) Its a 6-8psi unit with a Holley regulator mounted just under the air cleaners for the twin HS4s, set at 3.2psi. Yes, even in the enclosed box it is quite loud at idle, but the noise fades away at speed.|
Regarding the Honda replacement pump...would you say that this was a very quiet or a very noisy pump? I would love to replace my present solid state unit because of the noise it makes at idle.
|Cliff - Are you using one of the little, square, run all the time, make a lot of noise, Facet pumps? If so, consider putting it on sound mounts. All the noise goes away whaen that is done. YOu can get a sound mount kit from Pegasus Racing. Go to http://www.pegasusautoracing.com/advcat.asp?CategoryID=AIRFUEL|
Click on Air and Fuel Accessories and scroll down to mounting kit. I used these mounts on the Facet that I mounted to the back of the battery box as a back up pump on our MGB and You can barely hear the pump with the ignition on but the engine not running. Cheers - Dave
|I use the SU contactless pump - direct replacement for the original.|
Obviously i can't say that it will last for ever but its done ok over the year or so its been in so far. I think i would prefer to use an SU than some of the other makes around - a lot seem to be of poor manufacturing quality so i can't see how their pumping abilities can be any good.
|Ah, my old nemesis the SU fuel pump! I think I hate (yes hate with a fiery passion) SU fuel pumps as much as I love MGB's.|
Yes, that embodiment of pure evil (SU) has landed me in many a difficult and dangerous situations and spoiled many a day. Its best effort was regularly stopping just prior to the top of the WESTGATE bridge here in Melbourne, a huge, busy and above all dangerous place to be. The hours I've spent lying in the grime hitting it (vigorously!) to get it to "kick over", ducking for cover while trucks threaten to annihilate me, rebuilding it, adjusting it, winding the wretched diaphram in and out, getting covered in petrol replacing various bits and pieces.
I replaced it with a pump from a second hand '85 Subaru that I happened to have. This is a low pressure pump and I believe is the same as the one in the Honda and in a variety of similar cars.
It makes the same noises as a SU fuel pump but is much more able to draw fuel. Unlike the SU which has to be at "bottom of the fuel tank level" the Japanese pump can be placed up in the engine compartment if you like. Infact I simply bypassed the SU with a bit of fuel line and placed the Japanese pump up in the engine compartment stashed (with a piece of blue foam camping mat wrapped around it) in that small cavity inside the guard at the back of the engine compartment. The tight location and fuel lines held it in place so it was a quick instal. This also meant that it was out of sight but readily accessible. I put a fuel filter before the pump to protect it. If you are nevous about pump future failure then carry a spare as the eazy access location and cheapness of the pump makes this a breeze.
It went perfectly up until I put in the V8 a year or two later.
|I installed a Facet pump (about $30) two years ago and have not had a problem with it at all. If it's installed with rubber isolators the noise is dampened and acceptable. Seems very dependable. My car is driven only about 1/3 of the year.|
Yes I am using small square Puralator pump and have it mounted behind battery box on large rubber isolator...the noise can still be a problem at low idle and at low speed in parking lots. I think it's when the floats close the needle valves and there is no flow permitted that it rattles away. Would love to swap in a completely noiseless (but functional) pump.
|Cliff, off to Advance Parts and get the cylindrical in one end/out the other pump $20 or so. They're about6" long and 1&5/8" dia. I've had one or the other in service for a decade. They're audible, but far from loud.|
They don't take time off like the S.U.
You will need a pressure regulator next in line as these puppies will overwhelm float needles with alacrity.
|Autozone carries an electronic fuel pump that operates at 3.5 PSI. You may have to repeat yourself a couple of times, but eventually they'll find it in stock. |
|Mark J Michalak|
|Advance part Auto #5773487 E8016S sounds like the pump Stewart describes. I have one I bought in May 2000, cost $30.49. I hear it when the ignition is turned on but not after the engine is running. BTW, LTD lifetime warranty.|
|Thanks for your advice. I have settled on an SU pump. It is an electronic one. Hopefully it will prove to be a bit more reliable.|
|a g dunlop|
This thread was discussed between 09/06/2005 and 13/06/2005
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