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New Fuel Pump?

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Bobbee44

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1960 BT-7 seems to have a fuel problem. Starts well and is OK up to around 2500 rpm. Can drive at 50 mph, but when I accelerate, get a backfire through the auxiliary carb. Same holds true at slower speeds on acceleration. Changed gas filter, but no luck. Fuel pump ticks away, but seems a bit slower than normal, and it took an inordinate amount of time to fill up the filter bowl after filter change. So, what's the verdict?
Thanks,

Bob
 
FWIW, I've put over 120K on my BJ8 and had numerous fuel pump failures (I can change the pump on the side of the road in 20min). Every failure, whether original points, transistor-assisted, solid state kit or solid state new from SU has shown either outright failure or intermittent operation, increasing in frequency until outright failure. I've never experienced the symptoms you described. Not a lot of help, I know, but I think you still have some diagnosing to do. Or, buy a new pump and see what happens; if it's not the problem you now have a known-good spare (you'll need it sooner or later).
 
If one were to install a Facet pump instead, one would miss out on all the opportunities for development of expertise in speed-R&Ring of SU fuel pumps, as well as the opportunity to be serenaded by the gentle intermittent ticking, which is nicer than the sound of the Facet. :smile:
 
I would start by disconnecting the fuel lines at the carbs and fuel pump and blowing them out with a compressor. Check the fuel pump filters as well. If it is ticking, it probably not the pump.
TH
 
Have you looked at the screens on the fuel inlet to the carbs? Are they clear or full of junk? If full of junk, you may have tank or fuel line corrosion. If clear, you may have worn carburetor dampers. If they are worn, maybe a heavier dash pot oil will help.
 
You may also have some junk in the tank that is restricting the fuel pickup.

I once had a problem similar to what you describe and after going through the entire fuel system I finally zeroed in on the tank. I removed the fuel gauge sender and found a large leaf had inexplicably made its way into the tank--this on a 100 with its filler inside the boot! With the engine off the leaf would fall away from the pickup and everything would seem fine but under load suction would eventually pull the leaf against the tube and severely restrict fuel flow. After fishing the leaf out the problem was solved.
 
Hi Bob,

You have received good suggestions. Michael has a good point in that solid debris in the tank can randomly block the tank outlet or get into and partially clog the line. A long time back I must have over Siliconed when sealing the fuel sending unit and some had broken off when the unit was tightened. Over time, these pieces found their way into the pickup and lodged into the line going to the pump. Although some fuel would pass around the blockages, not enough to allow the car to make speed and not cause backfiring when leaning out on acceleration.

Since my first step happened to be to remove the pump for close inspection, I found some large silicon pieces poking out of the line and removed the blockage. Further, I disconnected the line from the tank and blew air through the line and the tank pickup to make sure any remnants were also cleared. Although my next step was to b e removal of the tank, further use of the car did not present any issues that caused this action to be necessary.

My discovery was opportunistic and the problem was resolved quickly. However, a leaf or piece of paper (that some have experienced) that randomly blocks the tank pickup may be a more difficult issue to resolve as clearing could take place on its own and reoccur again.

Something I would do as a last ditch if all else fails is to drain, remove, and clean the tank. I would disconnect and remove the fuel pump for inspection and disconnect the carburetors from the fuel lines. I would then blow out the lines before reinstallation and/or reconnection. Although there is always the chance that you may not find the culprit piece of debris in the tank (if it even exists), the chances of discovering and clearing your issue are better then any other approach I can think of.

Good luck,
Ray (64BJ8P1)
 
By all means check your fuel delivery but you could still have other issues like : ignition points or condenser, too light an oil in the dashpots , gummed up main jets, blah, blah , blah . Any accurate diagnosis based on what info you've given is a shot in the dark. Typically when I've had fuel delivery problems the engine acts like it ran out of gas as the float bowls empty : coughs , then dies completely. You've just got a backfire on acceleration it sounds like but the car still runs at speed so either your fuel delivery is being interrupted ( gummed up main jets, too light an oil in the dashpots ) or your fire is breaking down ( points or condenser). You could be a little on the lean side also. Good luck
 
Thanks for all the sage advice. I did change the fuel filter, and checked the vicosity of the dash pot oil (special order from Moss). When I accelerate, I get the same stumble and backfire through the carb that I would get if I were to accelerate when the engine is not up to operating temprature. I will check the points and condenser and the main jets. I, thankfully, have an appointment next month at Healey Surgeons, so if my handywork does not pan out, I do have an excellent fallback position.

Bob
 
Hi Bobbee44, I think you have a very easy problem to repair. I have had the same problem in the past. Set your carbs up with a richer mixture. I think you will be happy with the results. Good luck and contact me if need be . Bobby R
 
As a general rule you should never start to fiddle around with your carbs until you have checked that everything is in order with the ignition/spark/timing system. You cannot correctly set the carbs until that is done.
 
DerekJ said:
As a general rule you should never start to fiddle around with your carbs until you have checked that everything is in order with the ignition/spark/timing system. You cannot correctly set the carbs until that is done.
Click to expand...

Agree - it's been said that 90% of fuel problems are electrical. I've experienced the same symptoms described at the beginning of this thread - from a faulty ignition coil.
 
I have too - mine was (first time) coil lead eroding, and (second time) the low tensile wire in the distributor was broken under its woven fabric sheath. It wasn't will i pulled on it that it came apart altogether. It had still been making enough contact at low revs, but as the car revved up under some load (~2200 rpm+) it couldn't maintain the connection….
 
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