Possible Fuel Pump Contamination

I fear that my probably original '56 cj5 4 cylinder vacuum fuel pump, sucked up some fuel tank 'junk'.
I figure I should test it somehow, but I'm not sure of a simple process. (I'm not a real mechanic)
But, it appears learned folks here are saying don't take it apart without being ready to rebuild it, with new parts. (I actually drove it around some as soon as I took delivery, then motor stopped working and I realized it had no fuel filter! So, big mistake! and carb also leaked!.) The carburetor was obviously a problem, so I had a shop rebuild it, but, I worry that the newly done carb could suck up nasty junk from a possibly contaminated fuel pump. (I did blow out some nasty gunk from the pre-pump fuel line.) So, next I'll do the little gas can gravity feed directly to the newly rebuilt carb, to bypass the fuel pump, and see how she runs. For now I'll assume I'm gonna have a decent purring engine. I do know I should be certain of fuel pump status, put in a fuel filter, and probably remove fuel tank to inspect, clean or replace. I have done some successful mechanical things, I just don't want to make any dumb mistakes, but I'd kinda like to use the old vacuum fuel pump since it seemed to work fine for a short time, before possible contamination. So, ... Can I simply use the little gravity feed attempt for the carb, switch it over to the fuel pump with disconnected lines, and battery crank the engine a bit to run the gas thru to maybe clean out the fuel pump, and see how well the flow comes out?? If plenty of fuel shoots out the fuel line with no leaks, does that mean it'll prolly be OK?
Any advice appreciated, Thanks.

 

I would disconnect the file line to the filter and let it drain through a coffee filter into a gas can. Then add a clear housing fuel filter near the carburetor and another metal housing filter before the fuel pump (you don't want a plastic filter melting) then go ahead and gently open the cover on the fuel pump (screw in the center of the dome) then clean the gunk out with carb cleaner. There should be a seal on the cover and button it back up. Reconnect everything and give it a go. (You might need to prime the carburetor with gasoline)

 

It's a common enough thing to periodically clean out the fuel pump and gas tank. Simple enough procedure to take the top half off by removing the 6 screws and cleaning out the internals and poppet valves with some compressed air, carb cleaner, and a few q-tips. No need to take the bottom half off the engine block. While the top half is removed, Also inspect the diaphragm in the bottom half for tears/cracks.

While the pump is disconnected, blow some air again back down the fuel line and into the tank to clear any debrit from the line. Then drain your tank. This will clear out a majority of stuff thats settled at the bottom. should take about an hour total to do all of this and all you need it a couple wrenches and a screw driver. I also recommend going ahead and pulling the tank and dumping the remainder of fuel from the filler neck as more crud can flow out that hole than the little one at the bottom.

Recently, the cork float on my original style fuel sending unit started deteriorating and was clogging everything so I had to replace the sending unit with a newer plastic float version.

It's highly recommended to install a fuel filter but make sure to use hard lines and not rubber when possible. Here's an example of one way it can be done. I doesn't help keep crumbs out of the pump but stops em before they reach the carb.


As for the testing of the pump, Disconnect the line from the carb and crank the engine for a couple seconds while you run the line into a catch can or small jar. You'll be able to tell pretty quick if the pump is pumping.

 

Universal(?) carburetor. Upstream is a pressure regulator. Further upstream is a pump that is known for unreliability. By removing the plug at the 'T' fitting at the carburetor and placing a barbed fitting there you can measure the fuel pressure with an old-fashioned Vacuum/Fuel Pressure gauge. I suspect the regulator may not be properly calibrated and you are getting fuel pressure that is too high.

 

First,
I like a filter prior to the pump. Fuel pumps are "pushers" not "suckers" so it is much easier to shut down the fuel system with a bad filter, which means you need to check it much more often. The upside, especially with older rigs and vehicles seeing sporadic use, is it filters debris such as rust prior to the pump. This keeps the check valves working properly.

As suggested, gently disassemble the pump and clean the valves. If there is debris in the pump, you ca clean out the inlet, outlet and anything sitting on the diaphragm.

 

I suspect you might have confused my pics with the OP’s post. I had just posted those as an example of one way to run a fuel filter set up. You are correct though…. The T fitting is where I check my fuel pressure and it’s set currently to 2psi which is where the Solex carb seems happiest.

 

Also, @gromit….. if you’re interesting on learning the inner workings of your carb and how to rebuild it yourself in the future, Scoutpilot has a TON of write ups and great information over at oldjeepcarbs.com .

I actually, just yesterday, used his tutorial on timing my engine and tuning a carb using a vacuum gauge. Super helpful resource!

 

So rebuild it? It's atonement for sloppy maintenance

 

Mike,

I think you sorta missed the point. The carburetor has already been rebuilt, he took it to a shop for the rebuild. I think what was suggested was to learn about how to do it himself. The key word
was "future".

"Atonement for sloppy maintenance" doesn't make much sense when someone is trying to rehab a 68 year old vehicle, unless they are old enough to have bought it new, which would probably mean they were nearly 90 years old, and even then things usually need to be rebuilt after a lot of use, no matter how well it was maintained.

 

My bad.

 

Thank you all so much! Great advice as always!