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MG MGB Technical - Fuel pump not working, sat for 7 years

I just recently moved my MGB from it's portable garage into an area so I can work on it and possibly get it ready for the summer.

I've owned the car now for about 11 years but I haven't registered it in nearly 7 years now.

To get it ready to start, I changed the battery, oil, oil filter, plugs, and wires today.

I turned the ignition to "ON" but noticed the fuel pump did not make any noise. I recall it was giving me trouble years ago which is why I parked it and never touched it again.

My troubleshooting so far has been to confirm the ground wire (under vehicle black wire) does indeed contact ground (confirmed with continuity test against negative battery terminal). Next, I confirmed that the positive side of the electric pump (inside trunk white wire side of pump) does in fact have 12V going to it.

Have I missed anything?

Suggestions on a pump to order for a suitable replacement?
Jeff

Jeff,
I put a Facet pump on my B and it works fine. It's not original, and makes a little noise which is not that not loud when the car is running, and they are cheap. Mine was a little over $30. Moss sells them for double that. Easy to install. Not original, but my car runs well.
Randy
1977 mgb roadster
randy olson

Probably your points are filmed over. There are threads in the archives about this being a problem on stored MG's. I think you can clean them or maybe will have to replace them later on.

I wouldn't leave the ignition on for very long without the pump clicking. Apparently if the diaphragm isn't in the park position you can burn the swamping resistor out.

Make sure fuel is getting from the tank to the inlet.

I'm sure you'll get lots of good input shortly from the site.
Robert McCoy

I'm the thread starter, couldn't figure out how to get to the forum from the logged in screen.

Randy, you mentioned that Moss sells the pump for double the cost, does that mean you got yours locally?.. or was it just from another vendor?

I'm not familiar with carb vehicles at all!

The amount of gas present in the tank is unknown, but I'm positive I drove it to where it sat, so I know it has some fuel in it... either way, I'd hear the pump ticking even if it were empty.
JG Grant

Jeff,
The Facet "cube" pumps are readily available at the corner auto parts store. They come in a high pressure version too, but you want the low pressure variety. A transmission mount make a pretty good way of mounting one of these to reduce the noise. This will give you the leisure to fix the pump properly as well as serving as a good spare to carry with you after you get the SU back in.
David "keep on pumpin" Lieb
David Lieb

I went to the local parts store after my last post to see if they had any "generic" carb pumps. They had one for $40 so I picked it up.

It's rated for 2-3.5psi and up to 28 gallons per hour.

The other research I saw today between this board and other sites were to have anywhere from 3-3.5psi so it sounds like this pump will do just fine.

It's about 2/3 the size of a can of soda.

I picked up 6 feet of 3/8" hose too, I know, I probably only needed 2-3 feet, but figured more is better if it saves me a trip to the parts store. Plus a few hose clamps to clamp them all down.

Does this setup sound like it will work?

David, if I were to mount the pump to the transmission, wouldn't it not work as well as stock because it would be higher? Isn't the pump supposed to be feeding from the lowest (or as close as possible) point in the system?

Side question, can someone confirm that if I have the ignition placed in the ON position that I should get 12V on the trunk lead for the pump. I just want to make sure it doesn't turn off after "priming" the system by default.

Thanks!
JG Grant

Jeff. The fuel line is not 3/8th inch, but 5/16th inch. A fellow by the name of David DuBois, who, after retirement, started up a somewhat full time business of rebuilding SU fuel pumps, was kind enough to write up several fuel system technical articles and allow me to post them on my website, www.custompistols.com/ under the MG section. Dave's articles are listed under his name and at least one of them has his e-mail address as a part of the article. He is quite good about helping people out and has helped me out on several occasions. His tech articles may form a basis for discussion, both here, and you with him.

The concept that there was "gas in it when I parked it" is an interesting one. I once spent several hours helping a friend, one Walt Billings, try to get his pick up truck started in the dead of winter in Cheyenne, Wyoming. The first question I asked was, "Does it have gas in it?" to which he answered, "Yes". After checking the ignition system, the valves, the ignition timing, all being correct and with no engine response, I had him attach a rag to a straightened coat hanger and dip it into the gas tank. It came out dry.

"Darn", he said, "I put in a dollar's worth of gasoline a couple of weeks ago!". A few gallons, with several miles driven, in a 25 gallon tank had allowed most of the remaining gasoline to evaporate over the period since it was "fueled" and the time when it next needed to be driven.

When gasoline is left sitting in a gas tank, in a vehicle which does not receive regular use and frequent "top ups", the fuel present tends to evaporate. This leaves a residue which seems to be similar to shellac or varnish. When fresh fuel is introduced to the system, the shellac is somewhat disolved by the new fuel and is carried forwards into the fuel pump, the fuel lines, and the carburetors. The shellac comes in contact with these surfaces and begins to coat them, causing problems through out the system.

My experience, with several vehicles, is the best thing to do is to drain the fuel tank, remove it from the vehicle, and have it flushed to remove the contaminants. If this is not done, i.e. removing the primary source of the contamination, the system will continue to provide interesting problems. I, once, had to do three carburetor rebuilds in a three month period before realizing that old gas in the tank was the source of the problem and having the tank flushed out. By attacking the root cause of the problem, I corrected it.

Thus, in my view, you have two problems. The one you have noticed is a non-functional fuel pump. This is, as has been noted, probably because the points have developed a layer of oxidation, making the system unreliable. The second is the old fuel in the system which can cause problems beyond the fuel pump and, if not corrected by cleaning out the tank, can cause you to have to clean and rebuild the carbs.

Please read what Dave has to say. Contact him and ask him to respond to your thread (he posts here, regularly) and let us see what he has to say.

Les
Les Bengtson

Jeff - What the others have told you is correct, a points style SU fuel pump left sitting for 7 years will probably not run due to the film build up on the points. You can clean them off by removing the upper set of contacts and lapping them on some 400 grit sand paper. The lower set of contacts are harder to clean. You need to remove the pedestal mounting screws and carefully rotate the pedestal back to expose the contacts on the lower toggle. You can then use the sand paper on a small strip of metal or a sharpening stone to clean the lower contacts. Follow up on both sets of contacts with some solvent. This will get the pump running unless the diaphragm has become stiff.

The after market pump that you got should work fine on the MGB and anywhere under the car is a good place for the pump. From your description of it, the pump is a Carter pump, which is a rotary pump that doesn't make the racket that a Facet pump makes so you can mount it anywhere that is convenient without worrying about noise being telegraphed into the passenger compartment.

Finally, Les' comments about stale gas in the tank or gas that has evaporated, leaving a varnish in the tank are something to consider. Since there was gas in the tank, the fuel lines, the pump and the carburetors, you now have that varnish through out the fuel system. The varnish that resides in the fuel lines and the carburetors will flush out without much of a problem, but the gas in the tank and the pump are a different situation. The gas in the pump, if it has not caused the diaphragm to become stiff, will also flush out without much problem. It is the situation in the tank that can cause the most problem unless it is flushed out can continue to flush through the system, causing problems. I would suggest that as a minimum, you fill the tank, let it sit for a day or so, then drain it out and use it in your lawn mower or whatever and put clean gas in the tank. I would not fill the tank more than about half way, that should get all the heavy contamination in the tank without breaking the bank.
Cheers - Dave
David DuBois

Thanks for your responses Les and Dave.

Les, I had read about the points, and though I am fairly mechanically inclined with automobiles at this point, I just figured it was time to not fiddle with it and just replace it. Remember, it is 28 years old now!

Also, thank you for letting me know the fuel lines are 5/16" and not 3/8". I thought I had read they were 3/8", but perhaps that was for an EFI upgraded motor application.

Dave, it sounds like I will be using the $40 pump I purchased last night.

To both of you, and anyone else reading, there are a couple of issues with dropping the tank for flushing.

1. What if the bolts holding it in place break during removal, now what.
2. Assuming the tank holds 10 or more gallons, how do I go about storing this gas until I have time to use it in another application to save the MGB engine from it? Would it be safe to use in my more modern EFI vehicle?

Are there any additives I could place in the new fuel which could help disolve some of the varnish to help avoid much of this hastle?
JG Grant

Brand-new SU pumps come with a slip of paper saying to clean the points before returning the unit as faulty as even new ones develop an oxide film on the shelf. Just drag some fine wet and dry through and you should be fine. I got one working just by bridging the points with a screwdriver and using the screwdriver as the contact surface that made and broke as the diaphrgam went up and down. After a few seconds it worked on its own, and has continued to do so since.
Paul Hunt 2

Jeff,
I was not suggesting that you mount the pump to the transmission, I was suggesting that you purchase a spare MGB transmission mount. These serve very nicely as a mounting device for the Facet pump and help isolate some of the noise of the pump.
David
David Lieb

Like Paul said, clean the points. SU pumps are great fuel pumps that will give long service.
Carl Floyd

I picked up some 5/16" line today along with a new set of plug wires (one broke when changing the plugs).

I also grabbed a cheap $4 fuel filter to place before the pump when I change the lines. What do you think about this new filter catching a good portion of the gunk coming out of the fuel tank? I'd be willing to change it even a couple of times rather than trying to get rid of the contaminated gas.

I'm becoming tempted to see if I can fix the points like you all have mentioned. I thought I bookmarked it, but I can't seem to find the pictorial I was looking at yesterday about doing this.

But it's so much simpler to use the brand new (and likely much quieter) $40 pump I bought last night. At least for the short term it'd be much simpler to just make sure the car still runs.

I'm trying to avoid putting a huge amount of money and time into this. If it doesn't run properly, I know I won't sell it as I've had it so long, but the project might get shelved for another unknown period of time.
JG Grant

Ditto all of what Paul sez.

However, before getting surgical, you might try
getting a wooden dowel and hammer - and give
the pump a few sharp wonks (w/ pump switched
on) - and see if that'll wake it up.

Do not hit the plastic cap!
Daniel Wong

Jeff,
The problem is not merely contamination, it also involves a chemical change in the nature of the gasoline. It will not burn well and will coat the fuel system. Perhaps you might want to compromise? I might suggest that you connect as fuel filter to the tank output, then attach the new pump and your whole chunk of new tubing and pump the tank out into some appropriate containers. This way you get most of the old gas out, you don't risk breaking any bolts, and you have filtered gas that can be burned a little at a time in your lawnmower or other non-fussy engine. Dilute it well with new gas and you should be ok.
David
David Lieb

David, I'm very interested in compromises!

I know, you probably run across stubborn new people like myself and probably when you first saw the thread you thought to yourself "why bother answering, he'll probably never fix it right anyway".

TRUST ME, I understand this completely. For my EFI car, I'm quite the expert on it's message boards and run across the same types of threads. I try to respond with helpful information regardless to how likely they are to do the job with the detail I've provided.

Anyway, back to topic..

I'll pump the tank as it sits right now till empty. Then I'll put a couple of gallons (2) of fresh 93 octane gas in, let it sit for a couple of hours (possibly a day pending time to work on it), and pump it out again till empty. Then I'll get another couple gallons of fresh gas to put in for it's first startup attempt.

How does that sound for a compromise?
JG Grant

I tapped the pump with the handle of a screw driver, no luck. Confirmed power and ground AGAIN and they are correct.
JG Grant

Jeff,
That is pretty much the scenario I was trying to broadcast without going into that much detail. How perceptive of you! You are right, I could have gone for the simple approach (trade it in on a proper Spridget), but I do try to feel helpful (and somebody has to take care of all those MGBs out there). I have the dreaded malady known as "compulsive fixer" for which there is no cure (but a significant collection of Spridgets can help keep it under control by providing a socially acceptable outlet). I am, nonetheless, a pragmatic person who feels that it is more important for the car to get back on the road (especially after resting for seven years), than that it be imperative that the SU pump be repaired as the first order of business. They are good pumps (although in seven Spridgets, I have not yet acquired a functional or even repairable SU pump), and I would continue to suggest that you retain the option of repairing the pump properly and put it back in place (the other one is smaller and lighter, thus making a better spare), but Spring is almost here and you shouldn't make the pump repair the priority. Stop reading parenthetical remarks (like this one) and get that car running!
David "parenthetically inclined today" Lieb
David Lieb

Side note, I pulled off the filler pipe inside the trunk, on the tank side. There is visible gas in the tank, but not a lot. As it sits with the front driver's tire flat, gas is visible about 2-3" toward the front of the car from the filler port.

If the new pump runs but doesn't pump any gas, I'll just add a couple of gallons because that would mean it must be below the outlet point.
JG Grant

hah! Thanks David. I must say, with this car sitting on grass for 7 years mostly covered (portable garage when the top wasn't torn), it is in remarkably good condition underneith! The leaf springs are very rusted, but otherwise I am quite pleased.

Back 7 years ago, I did not know much about cars at all. Now, I don't know nearly anything about the B as compared to other cars I am an enthusiast of, but I am definitely looking at it through new eyes and I'm not quite as intimidated.

First "crank attempt" even though the pump didn't work, it didn't even try to start. I checked the wiring from the starter, confirmed it had the 12V constant, which it did. Followed the trigger wire up to be amazed it goes to a relay instead of the ignition (like more modern cars do). Checked for power and trigger ground, they were there. Checked for trigger positive having someone else turning the ignition to START (signal from ignition) and when I was checking that, it cranked! I guess the relay was just a little tired and needed another try.

I cranked it that time for about 10 seconds without even an attempt to sputter. Then I was positive it was the lack of fuel as the pump still hadn't kicked on. I wasn't sure from the years if it had been audible for a prime or not in the past, now I'm sure the SU pump does.

Anyway, I won't throw out this pump once removed. It's going to sting to drill the couple of necessary holes to mount the new pump, but pulling that back out and putting the stocker SU back in will make me fairly happy as it will be one more piece that's "original" if I can get it to work in the future, or even send it out to be inspected as prices of some seemed reasonable.
JG Grant

Jeff - Broken bolts for the fuel tank is more of an inconvenience than a real problem - new mounting kits are available with all the necessary hardware to replace the broken bolts. That said, I favor the "pump the old gas out, put some fresh gas in and let it sit over night, pump it out and then fill the tank. I would definitely recommend AGAINST putting the old gas, or even the gas used to soak and clean the tank in a car with fuel injection unless you want some gunked up injectors.

"It's going to sting to drill the couple of necessary holes to mount the new pump..."
I mounted a Facet pump as a backup on the rear of the passenger side battery box. That is easy to drill and doesn't detract by havine a couple of extra holes in it.

"I also grabbed a cheap $4 fuel filter to place before the pump when I change the lines."
A filter between the tank and the pump is fine to use with the after market pump, but if you ever reinstall the SU fuel pump, be sure to get the filter out of there. If the inlet side of a SU fuel pump (or any of its clones) becomes clogged to the point that no fuel can be pulled through, the pump will stall in a current on condition and will result in damage to the pump. To see an article about this situation and and array of other articles (some of which are on Les' web site, go to my new web site at: http://homepages.donobi.net/sufuelpumps/ and click on SU fuel pump articles.

David L. - If any of those 7 midgets came with a SU fuel pump installed, I am betting that I can make them work for you, although not until after October first. I am presently in the process of moving my 86 year old mother up here to a retirement home and then the rest of the spring and summer will be spent working on home projects and going on cruises. Cheers - Dave


David DuBois

Thanks for the link David D. I think I saw at least one of those articles on another page earlier today or yesterday.

I'll post back once I have more information. My first priority is to assemble a grill I bought last fall during season closeouts because the wife wants to have a BBQ this coming weekend. Hopefully I can get that done and tested tomorrow evening and get back to this project on Wednesday.

Not to get too off topic, but if anyone has a good link to a pictorial about installing a manual choke conversion kit, it'd be appreciated. I searched on here but nothing promising came up. That automatic choke in the single SU was always a problem for my idle both cold and warm.
JG Grant

I used a hand pump I purchased to put oil in the differential and transmission to flush the fuel lines. I hooked the pump to the fuel filter in the engine compartment and pulled gas from the tank through the lines to make sure there were no blockages and to flush the lines. I then hit the fuel pump with a large crescent wrench. My car had been sitting for three years. The pump has been working fine now for a month.
Kimberly

I don't want to damage the pump beyond repair, but maybe I'll give it a bigger whack before completely giving up on it!

If I were to use a siphon pump as you're describing Kimberly, could that pull fuel through the pump as well or do I need to remove the pump and connect the tank to the metal line under the car directly?
JG Grant

Fuel can be pulled right straight through the pump since there are only check valves in the pump to prevent the fuel from reversing direction through the pump. If tapping the pump gently doesn't get it going, beating the living daylights won't get it going either. Cheers - Dave
David DuBois

The only line I disconnected was the one from the fuel filter to the carb. I only disconnected the one end that went to the filter. I hooked my hand pump to the barb on the filter. I pulled approximately eight ounces from the tank, through the pump and lines just to make sure the fuel lines, pick-up tube, and fuel filter weren't obstructed.
Kimberly

Okay, so let me explain from where I left off. Here's what I've done.

Yesterday evening I put 4 gallons of fresh 93 octane fuel in the tank.

Fast forward to today...

I decided to take David D's advice and not bludgeon the pump and just replace it, even for the short term.

I left the OE pump in place, hooked up my new pump to a line up at the front of the car (put a hose on the hard line coming up to just before the fuel pump) and turned the pump on. Apparently the new pump doesn't work as well as a puller as it was likely designed to be a pusher.

So I pulled the OE pump out of it's mount point to get all the old lines removed. I planned on replacing every rubber line I had to touch anyway. Good no, fuel came out to spill on the ground from any of those rear rubber lines. Or at least I thought it was good so far.

Next, I decided to mount the new pump to the bottom side of the rear deck in the trunk. Couple reasons for this. 1) I just wanted to see if the car would run, so I didn't want to take the time to fab up a nifty bracket. 2) I didn't have any metal to do the job and since I've got the flu, I didn't feel like driving to go get some.

Mounted up the pump, that went smoothly. Ran the incoming line from the tank to the pump, ran the outgoing line from the pump to the hard line going to the front of the car.

Whoops, forgot to put that spare filter I bought in!.. I looked at it again but there's no straight line before the filter to install it, so I just left it out for now. I *might* place it on the outgoing pump to hard line hose just for the extra filtering, but that wasn't necessary just yet.

Hooked up a hose to the hard line below the OE filter and put it in the 5 gallon jug I'd emptied into the tank the night before. Turned the car to ON and it began pumping fuel out into the gas can! Took out about 4.5 gallons, so apparently between evaporation and it just being low to begin with, it had hardly anything in it when I started this little project.

Next, I hit the local parts store again to buy a new OE filter as I'd never changed it in the 11 years I've owned it (3-4 of which it was driven a total of maybe 8k miles, the rest it sat). Bought another couple feet of 5/16" hose too. Installed all that as well as replaced the short ~4 inch coolant hose that was just above the incoming fuel line on the single SU carb.

Turned the car to ON to check for leaks up front this time. It was leaking from this "pivot" point which I had hooked up between the filter and the carb. I'm not 100% if it was the line or the pivot item.

I hooked a line direct up between the carb and fuel filter outlet to bypass that pivot point for now.

Crank crank crank.... VROOM!! She started up! . . . then stalled right out. I'm not surprised, the automatic choke was always a problem for me at least. My mechanic I used to use said they were essentially garbage and that if I wanted it to idle correctly, I'm probably going to have to have it readjusted yearly.

Cranked again, full thorttle'd a couple times... started up again! I kept it running with my foot for about 3 minutes around 1200rpm. Tach and oil pressure gauge came to life after about 30 seconds, that's good news.

So right now, I have two questions..

1. What is the function of that fuel line pivot piece that I bypassed?
2. How accurate is the oil pressure gauge?

Thanks everyone for your help! I took some pictures with my digital camera, I'll see about posting them up if I can find my CF card reader.
JG Grant

Not sure what the "pivot" item is that you refer to, unless it is the inertial cutoff valve that is supposed to shut the fuel flow off in the case of a collision. Cheers - Dave
David DuBois

Can you post a picture of the "pivot"?
Kimberly

It's the only item attached to the line between the fuel filter and carb.

It's mounted to the "shelf" about 3" away from the fuel filter.

I say "pivot" because it rotates in whatever it is mounted to.

There were no wires coming from it... unless they're attached below the the shelf to the car interior.

The top can depress by hand.

I'll see about posting a picture if I can find my camera card reader.
JG Grant

Sounds like it is the mechanical fuel inertia cut-off valve. Remove it since they are prone to leak. Just get a new length of fuel line from the filter to the carb.
Kimberly

Thanks Kimberly. That's exactly what I've already done. I just need to zip tie it so it doesn't get chaffed by the hood hinge.
Jeff Grant

I filled up the tires and took it out for a drive around my culdesac yesterday a couple of times. The B shifted smoothly and the brakes seemed to do their job as well which is great considering the rust on them.

I didn't get to test the brakes much as the car wasn't idling very well at all. It did run strong though when I got over about 1500rpm, I never passed 2500rpm though yet. See my manual choke conversion thread for info on my idle and to provide any feedback/help.

Time for me to see about getting some new tires to get rid of these dry rotted ones!
Jeff Grant

This thread was discussed between 29/03/2008 and 03/04/2008

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