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MG MGB Technical - Fuel Pumpm Problems - Help Needed

Yesterday my fuel pump seems to have decided to stop pumping. Probably my fault it stopped. Any thoughts or suggestions there?

What I have observed did.

I was replacing the battery cables and adding a ground side cutoff switch on my car. During the same install / electrical work I was adding both a voltage meter and a vacuum gauge.
When I pulled the battery, the ground wire that goes to the fuel pump was caught on the battery base and broke. I could not see where the ground cable went from the top of the battery compartment.
I could only see a spade connector and a silver or chrome piece what I thought was the end of a bullet connector.
Without doing anymore investigation, I pulled that connector out (not easy) and soldered the ground wire to it. With an ohm meter, it did show it was grounded. I then hooked up the wires and reinserted the battery / battery cables.
The new cables and the cutoff switch worked perfectly. The car fired up and ran.
When I turned the key, the voltage meter did not register. I had tapped into the same line as the voltage for my radio which also did not work.
I ran the car several times and for several minutes trying to trouble shoot the problem and it shut down – lack of fuel.
I then decided to tap into the white wires under the dash for the volt meter source. Thus without knowing it, I compounded my potential problem solving.
There were three white wires coming into a double bullet connector from the dash side and one white wire coming from the switch bundle I believe. Since I wanted to add one more wire I pulled the double connector and replaced it with a triple connector. I made up a white wire with bullet connector for the voltage meter. I then inserted all the wires into the tripe connector. When I turned the key, the volt meter read correctly but I did not hear the fuel pump “click”. Radio worked fine but it appeared I had no power to the fuel pump.
I pulled the battery as I could not get the fuel pump connectors with it installed so I could do a resistance check on the wires. I was not getting a check to the positive side of the connection. I took the volt meter out of the system and replaced the triple with the double connector just to set things up as original. Still no luck.
Next I went to the fuse box to see if I was getting power there. Here some weird things popped out that I did not expect. I pulled each of the white wires at the fuse box and expected one to be the right wire for the fuel pump. None checked out but when all were disconnected and I hit the connecting spade bundle, I did get a good resistance check which makes no sense to me. I took out the fuse (original Lucas fuse that said 35 amps on one side and 17 amps continuous on the other side) and got the same and then realized it was probably coming from the brown wire above.
I then got under the car and saw that I may have hooked up the ground wire to the wrong connector as there was another wire down there that went to a spade connector and an added ground. This wire had a crimp splice in it which appears to be where the wire broke at. So I removed the wrong ground I had created and put the wires back together.
Everything looked fine so I again reinstalled the battery and cables.
I turned the switch and heard the fuel pump click.
I then tried to start the engine.
Still no fuel and the pump stop clicking
At that point I was fried and stopped to reread the info I had on fuel pumps. I think I have an original pump given its condition but it is hard for me to tell. The positive lead points into the battery box area and the negative or ground spade is pointed to the ground at the bottom of the pump. (I can send photos if that would help.)
The connector I took off and solder the ground wire to was the breather pipe. I cleaned the solder out of it and reinserted it in the black elbow it was in but it does not want to stay in place.

I’m tempted to directly run power to the pump from the battery to see if I have a switch or some other wiring problem or if the pump is dead. Rumor has it to hit it with a hammer to get it going but that concerns me but will do if you recommend. I can or will run a new white wire to the fuse box if you recommend that.

I really want to get this fixed today so I can drive the car to Buttonwillow and run it on the track this weekend. Moss sponsored event.
Any direction or thoughts would be most appreciated. I posted this in two places hoping to get a reply from someone. Thanks in advance.


Steve Vandal
Steven O. Vandal

Try to jumper it. If the pump then is operational and the car runs, you could add a separate line with an inertia switch in it and bypass the harness, just to get to the races.
But I would try to identify the fault if time allows.

Do not race without the inertia switch. The last thing any track needs is a banged up hot car pumping fuel into the engine compartment and on to the track.
.

The click - then no click, sounds like a dirty connection somewhere.

BTW, I don't think i have ever seen such a widespread post.
.

Check my response on the MGB general list. It is better not to multiple post questions.
George B.

All:

All:

Sorry about posting this in multiple spots. I was trying to post this on the MGB Technical site and MGC site but in my hurry and frustration, it ended up in the MGB General and the MGF sites. When I went back to look to see the responce, I did not see it and put this in the wrong spot. I noticed right away I had it on the MGF site but not the MGB general site.

Quickly, I think it is the points inside the fuel pump. I ran a line from the fuse box hot side to the pump and it started to work and filled the fuel filter. I then ran ran a new line from the switch to the fuel pump and it did not work even though it read 12.35 volts. I then repeated the power to the hot post on the fuse block and no clicking. Tested it several other ways so I am now convinced that it is the fuel pump. Short term I will get a replacement pump from a local shop and send out the SU pump for rebuild.

Again, sorry for the multiposts.

Steven O. Vandal

Steve,
I'm not sure that you understand the S.U. pumps are not constant duty. When they have pressurized the system to about 2 pounds/sq. in., they will stop until the pressure drops. I don't know the pressure delta.
George B.

George:

When I started this adventure I had no real knowledge of the fuel pump and I am still lacking. As a youth in my dads new TD, I learned to turn the key, listen for the clicking and when it stopped I hit the starter (TD or A) or turned the key the rest of the way on the B and C. I had read that it was an "on demand" system so I did not expect it to pump - click all the time. Dave DuBois sent me an article on trouble shooting and understanding so now I am probably more dangerous.

I have a visible fuel filter and when the fuel pump is working, it is always full or near full. It is nearly empty right now. So being able to see that helped me determine my fuel pump was not working when it should.

Short term I have bought a universal low pressure fuel pump from Pep Boys for $32 and will send my SU pump out for rebuild and conversion to solid state by Dave in WA.

Again, thanks for the information. I'm learning.

Steve
Steven O. Vandal

This thread was discussed between 02/05/2002 and 03/05/2002

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