Stumped: Fuel Pump

[62BT7]

Howdy: I have a problem that has gotten progressively worse, to the point that as of this afternoon the car won't start. I'm 99% convinced it's a fuel pump issue.
<span style="text-decoration: underline">Hardware:</span> '62 BT-7 Tri-Carb. Relatively new sealed aluminum gas tank w/ race-style flip-up gas cap. Metal fuel lines except under the rear seat/fuel pump area where the prior owner connected the metal lines to 1/4" rubber fuel lines (in which I have inserted a universal fuel filter). I have an SU solid state fuel pump, about 3 years old.
<span style="text-decoration: underline">History:</span> The car has been running really well at all speeds as recently as the day before yesterday. But over the last month I've noticed progressively more fuel pump ticking. It's always ticked a bit, but it seems like since the engine rebuild (3 months ago) it's gotten faster. It's now ticking constant and fast. Almost like a rattlesnake rattle??
<span style="text-decoration: underline">Repairs:</span> I assumed an air leak, so I replaced all the rubber lines and the fuel filter (in which there was minor but noticeable foreign material) and snugged the clamps tight. No improvement. I then inspected the fuel pump body and noticed no cracks in the housing. Also tightened the ground wire; it wasn't loose but it wasn't tight either. I then tightened the brass in/out pump fittings, and pulled one off and replaced the teflon tape. No improvement, and fwiw that's when the car would no longer start. I know the next drill: detach the fuel pump>carb line and see if it's pumping out gas, but any ideas what could be causing the cavitation/ticking? Sorry for the length of this, but it seems faster to be complete than respond to queries about things I've already done. Ideas?
Many thanks,
-Tom

 

[BOBBYR]

Hi Tom,
If the carburators are not flooding, I wouldn't think your problem is on the pressure side of the pump. Maybe the suction side of the pump is not getting fuel. You might want to look for a clogged fuel line between the tank and the pump.Just a thought. Let me know what you come up with.
Bobby R

 

[Michael Oritt]

Tom--

Sometimes the most expeditious solution is the least elegant: Why not get a cheap universal Facet type pump and plumb it into the fuel system and see what happens. Since you might be dealing with an air leak somewhere in the existing plumbing you will have to eliminate any possibility of that while plumbing in the new pump. Eliminate the inline filter when making this temporary connection as it is simply one more possible source of a leak.

BTW this approach to problem-solving is why I have a sizeable collection of unneeded new parts....

 

[roscoe]

You might clean out the check valve. If the pump runs, but you are getting no fuel you can check for air leaks by putting a tube on the end of the fuel line before it goes into the carburettor fitting, and submerging the end in a container of fuel . Run the pump and if there is an air leak you'll get bubbles out the line. It doesn't sound like an air leak based on what you've done, so that leaves either a check valve with some debris in it or a bad diaphram. A 3 year old pump is not likely to have a bad diaphragm. Is your filter before or after the pump. One would normally put it before the pump, butprevious owners can do some strange things.

 

[andrea]

Hi TOM
Put one FACET in series, before your <span style="font-weight: bold">SU pump</span> and switch it off-

On the photo at left:
this is my sub frame with a FACET and a large Ford fuel filter -to avoid debris from fuel tank

https://picasaweb.google.com/lh/photo/Bd_0oxdG5AiDfaEHjoSViQ?feat=directlink

Life can be easy and sweet

Before pls controll the Fuel filler cap -
it must be vented

 

[Michael Oritt]

And we haven't discussed a crack in the fuel pickup--something that is allowing air as opposed to fuel into the fuel between the tank and the pump.

I spent many years living aboard a single-engine diesel boat with a 3306-T Caterpillar engine. The boat had two 500 gallon fuel tanks. The fuel pickups were about 4' long and all fuel tank fittings were of the suction type--that is, all came off the tops of the tanks.

There were selector valves that allowed me select which tank was supplying fuel and others that selected which tank fuel would be returned to. In short there were a LOT of potential sources for fuel suction leaks and diesel engines do NOT like air in the fuel. Some of the newer designs will self-purge air but not the CAT, and it would simply die when air got into the injector pump.

I bring all this up because I ultimately found that the best ways to find fuel suction leaks was by the use of clear plastic hose and a Mity-Vac type pump--air bubbles are easy to spot as they pass through the line. If you can't get it to run with a FACET pump plumbed as directly as possible between the tank and the engine then I would be looking for something that is allowing air into the pump. The copper pickup in the tank may very well have work-hardened and there might be some hairline crack that is causing the problem. Chase it down.

 

[62BT7]

Thanks all for the responses. I spent the day breaking apart part of the system and plan to do a thorough assault tomorrow. I'll reseal all the brass fittings, etc. and I have about 9' of spare fuel line. Instead of buying another pump I'll just run the line from the gas tank via the fuel filler tube directly to the pump. If it works OK then I've at least isolated a small area where there's a leak. If it still doesn't work properly my suspicion will then shift to the pump itself. Many thanks again for the tips, I'll let you know what I find.
-Tom

PS: And yes, to answer one query the filter is in the line before the pump, so I think the pump has been protected from contamination. Thx.

 

[Patrick67BJ8]

Thanks all for the responses. I spent the day breaking apart part of the system and plan to do a thorough assault tomorrow. I'll reseal all the brass fittings, etc. and I have about 9' of spare fuel line. Instead of buying another pump I'll just run the line from the gas tank via the fuel filler tube directly to the pump. If it works OK then I've at least isolated a small area where there's a leak. If it still doesn't work properly my suspicion will then shift to the pump itself. Many thanks again for the tips, I'll let you know what I find.
-Tom

PS: And yes, to answer one query the filter is in the line before the pump, so I think the pump has been protected from contamination. Thx.

Tom, You may have a filter between the tank and pump but if you didn't blow out your fuel lines you could still have dirt making its way to your carbs and pump. I don't think you have a dirt problem but as long as it's all apart you might consider making it "clean". I had a partially clogged fuel line several years ago and spent a very long time in trouble-shooting it. The clog was the result of a "tank sealer" coming loose and the clog ended up at the high point of the fuel line from the tank to the pump. And then I only found its location after inserting a 1/8" drain cleaner and carefully measure the point where it was clogged and cutting out that section of the fuel line. Same for dirt in the sump of my fuel tank...bought a new fuel pump and the problem was dirt in the pick-up tube area.
Patrick