Fuel Pump Blues

I went to the barn, put on some R. L. Burnside, and installed the new fuel pump. The ‘57 CJ5 has been sitting for a couple of years and wasn't getting fuel to the carb, so I replaced it. The fuel tank is out of the vehicle, so I attached a rubber line to the fuel line at the inlet and put it in a gas can. I made sure the line was clear, in addition to disconnecting the line to the carb and making sure that line was clear. I reattached the fuel pump and put a cup at the carb end. I cranked and cranked the motor, for up to 30 seconds, and never got fuel.

Suggestions? I’m wondering if the old pump was even bad.

 

There are others here FAR more qualified than I am, but two thoughts come to mind. First: the tank and the pump are nearly the same level so I imagine it is much easier for the pump to draw fuel horizontally than to lift it from a can on the ground. Was your gas can level or lower than the pump? Secondly: would priming the pump help? Moving fluids would seem to have different characteristics than moving air. I don't recall all the laws of physics from my days hanging out with Isaak Newton. Several times I had to place my palm over the mouth of the carb while cranking to use the vacuum of the engine to help draw fuel into the pump. Once flow started, it was easy for the pump to maintain.

Note to "others" mentioned above: if these ideas are wrong, please set me straight.

 

I would suck on the output line until the pump is full of fuel, then try. If sucking doesn't prime it, you may have an air leak somewhere on the suction side.

I doubt the height from the ground is a major factor - a decent vacuum should lift 20 to 30 feet.

Alternatively, when you say you "never got fuel" how are you judging this? It is possible the carb float valve could be stuck shut.

 

I’ll try sucking. There are a few things I suck at, so I might be good at sucking fuel.

The metallic fuel line was cut off forward of the firewall and a rubber one was used to run to the tank. Who knows how long ago that was done, so maybe it’s porous. I’ll replace that.

The only way I know I “never” get fuel (since I’ve tried to revive her) is that the only way she fires is via fuel or starter fluid poured into the carb. When I disconnected the fuel line at the carb I get no gas from the fuel pump when cranking.

 

"The metallic fuel line was cut off forward of the firewall and a rubber one was used to run to the tank. Who knows how long ago that was done, so maybe it’s porous. I’ll replace that."

The fastest and easiest way to an air leak in your fuel system is to square-cut a metal tube and install a rubber line with only one clamp. The clamp will cause the rubber to "bunch up" and leave an air gap that won't leak gas out but will suck air in. The standard spiral clamp, while very common, is not recommended. A solid strap clamp, available at NAPA, is my preference. As well, old rubber tube deteriorates to the point when cracks will develop which will also allow air infiltration and subsequent pressure loss.
Ideally, the line from the tank to the rubber cross-over tube should be unbroken and have mechanical connections at both ends. Additionally, all connecting fittings MUST BE TIGHT.

 

Agree with everything "Scoutpilot" said, and that supply line should be replaced. Ideally the only flex line in the system should be from the hard line on the frame to the pump and that should be a proper line with mechanical fittings. I avoid any rubber hose with clamps.

However, your test setup bypasses that patched supply line, and is similar to what I do when getting a vehicle to run after sitting long enough to cause concern about the fuel system, except I use a small 3 gal boat gas tank with a priming bulb and I sit the tank higher than the pump. I have a number of boats so have several of these tanks. I just modified output end to smaller fuel line with a short piece of flared line with a fitting so I can attach the rig either to the carburetor or fuel pump to test each.

Been a while since I bought a boat tank and line, so don't know what they cost nowadays. A similar test system could be made using a small garden sprayer. I bought a 1 gal version at Lowes to make a pressure brake bleeder out of last Summer for less than $10, just don't go crazy with the pump, you don't want enough pressure to override the float valve.

 

Doubles as a flame-thrower and Molotov?

 

I should have the stuff hanging around to rig one of those test rigs together.

X2 on restoring the fuel line.

Thanks for the excellent suggestions folks! I’ll execute the plan and report back.

 

It could indeed double as a flame thrower or a Molotov if one is not careful.

 

I know that is how the factory did it and had the glass bowl pump which has a strainer built into it. When I got Willie, the PO had cut the steel line down by the tank and inserted a filter with rubber connections. I replaced that with the Walcks original style steel lines. Do you recommend an in line filter? If so, where?

 

Stock is between the pump and the carb.
I like one between the tank and the pump. The down side of this location is most mechanical pumps are pushers not pullers. This means it can starve the engine with a lot less crud in it. The up side is that the crud isn't in your pump.

 

So far, this is working for me. (I have only been able to run the engine as the wheels are not on the ground yet.) I was inspired by several in another post about fuel line material. I purchased a 51 inch nicopp tube with fittings, a standard flex tube from one of the major vendors, a filter off an online auction site, fittings at a local hardware store, and obtained free inspiration from Oldpappy and others (inspiration on what kind of filter and where to install) on this forum. It took a little patience. The fuel line followed the path I removed the old copper tube from. The bowl of the filter gets plenty of wind from the fan and is slightly more distant to the exhaust pipe compared to fuel pump bowl, so I am not worried about heat. The black tube in the photo on the right is a heater hose and will ultimately be somewhere else. There are paper elements available for the filter still (Oldpappy likes the stone filters, if I recall) and I recommend replacing it as my first attempt at this exposed a dry and leaky bowl gasket. New element and gasket fixed that and is fairly easy to reach. I hope that if any of the more experienced mechanics on here see any problems with this set up, they will chime in. I did have a concern about the vulnerability of the glass bowl to rocks hitting it, but it is fairly well tucked in behind some heavy steel parts. I will carry a back-up bowl.

 

First. A couple of definitions. "Strainer", as in brass mesh screen. This device stops the BIG pieces of trash. "Filter", as in ceramic or paper, blocks the small pieces with the paper element being the cheapest and least effective of the two. Remember, a piece of detritus no larger than the tip of a sewing needle can block the carburetor needle and seat.
The best before-the-pump filter location should be where it can be easily reached for replacement. The initial install can be a PITA. But, cutting the metal tube, placing, and flaring for, a brass or steel female fitting that will accept a barbed brass male nipple will allow for a good seal for the rubber and especially so with a solid strap clamp.

 

The barbed end will give you a good sealing surface, but IMO it is sufficient to make a bubble end on the bare tube for your hose to fit over. If you have a flaring tool, you can make a bubble end by omitting the second step in making a double flare that bends the end of the tubing over. Also use the best quality rubber hose you can buy. EFI hose is generally good but expensive. The standard Gates hose is good, but they also sell a premium hose that you may find at big truck or marine parts stores: https://www.gates.com/us/en/fluid-power/engine-hose/fuel-line-hose.p.4219-000000-000001.html

 

Look here https://autopartsobsolete.com/47-65-Willys-Kaiser-Frazer-double-action-fuel-pump-9616-4318.html

 

Still no love from the fuel pump. I tried two ways. I was able siphon into the fuel pump and also gravity feed. I was able to suck fuel via the carb connection up to the carb, so I know fuel is getting to the pump. Started the Jeep via starting fluid and gas dumped in carb, and no fuel comes up to the carb. A couple of notes:

1. The fuel pump that I replaced had a steel spacer, roughly 3/16”, between the block and FP. I re-installed it with the new FP. Could this be pushing it out enough to limit the contact with the cam and hinder function?

2. This is the FP. It’s just like the one I removed. Should I try a different one?

 

Your pump may have jammed/stuck valve(s).

 

You should be able to blow through pump in the direction of fuel flow and not able to blow through it backwards from output to inlet. If you can then internal valves stuck open.

 

I’ll pull the new one tonight and test it.