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601 hand carburetor primer

Wesley Mutch

Wesley Mutch

New member
I'm interested in replacing the hand fuel primer for my 63 Thiokol 601. It can sit for weeks between use, and the fuel in the carb drys or drains out. I originally just cranked on it and pumped the gas pedal to get it started but that was very hard on the battery especially in sub zero temperature. I have been keeping a container of gas and pouring a little right down the throat of the carb. This works much better. It usually fires right up. The problem is, it's hard to open the engine cover hold it up with my elbow while trying to carefully pour without spilling. The original owner kindly removed the original primer. Does anyone have an original they could show me. I've been looking at pumps for weasels and othere military vehicles but I don't want to go that direction without seeing what the correct one looks like.
 
While not OEM, I have the same problem (only more so) with my SnowTrac. I got an electric fuel pump that allows free flow when not powered (most do) . Its installed at the fuel tank and I have a switch on the dash that is "ON"spring return off, OFF, ON . I can hear the change in the pump when the carb gets full and the float shuts it off. The full on is in case the fuel pump on the engine dies, I can still run. The combination of both over comes the float and it floods.
 
Sorry - no primer to show you. Getting or replicating OEM primer parts may be tough so going with an electric pump and some sort of primer switch may be easier to source. Plus, if you have vapor lock issues, the e-pump will resolve it.

If you opt for an e-pump, put a see-through filter near the carb for trouble shooting and avoid putting the pump at the lowest "elevation" in the fuel line. Even with an upstream water separator, water can accumulate in the pump corroding the internals or even freezing it.
 
all my snow planes come with primer pumps on the engines, keep in mind that, the primer system is used on these engines with carbs under the engine itself with very long intake runners, so on a automotive setup, if used, you might flood the engine very easily
 
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^^ Exactly what I was going to post. I have a combo of everything above. I put a fuel shut-off valve right at the tank (to prevent a potential stuck float from draining the tank) and then a squeeze bulb pump right behind the seat. I prime the inline system until the bulb is firm, then turn on the electric pump for a couple seconds to make sure the bowl is full. It fires right up without the hassle of dumping fuel in the carb.
 
Cidertom said:
While not OEM, I have the same problem (only more so) with my SnowTrac. I got an electric fuel pump that allows free flow when not powered (most do) . Its installed at the fuel tank and I have a switch on the dash that is "ON"spring return off, OFF, ON . I can hear the change in the pump when the carb gets full and the float shuts it off. The full on is in case the fuel pump on the engine dies, I can still run. The combination of both over comes the float and it floods.
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I like this idea. Gives you a redundant system in case the mechanical pump dies and provides a means to prime the carb. Best of both worlds in my feeble mind.

I may look into doing this since I currently have my tank removed in prep for painting my Imp.

Did a little Googling and came up with an article and a YouTube on just this topic. Now to search for a pump.
 
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zspryte said:
Sorry - no primer to show you. Getting or replicating OEM primer parts may be tough so going with an electric pump and some sort of primer switch may be easier to source. Plus, if you have vapor lock issues, the e-pump will resolve it.

If you opt for an e-pump, put a see-through filter near the carb for trouble shooting and avoid putting the pump at the lowest "elevation" in the fuel line. Even with an upstream water separator, water can accumulate in the pump corroding the internals or even freezing it.
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So...can electric fuel pumps pump uphill, as in mounting it up near the carburetor vs down at the bottom of the tank?
 
There are pumps that will pump from a tank lower than they are, look for "self priming". I will try to get out to the cat tonight to see what I put in. It is self priming to a point anyway. Pumps that really have high lift self priming may not allow freeflow as the high lift requires a really good seal.

On mine, the pump is even with the bottom of the tank (about 1 ft high) and has to pull fuel from the tank, fill the filter bowl and then get to the pump. It has worked nearly dry in the tank, so it will do at least a 1 ft suction lift.
 
Cidertom said:
There are pumps that will pump from a tank lower than they are, look for "self priming". I will try to get out to the cat tonight to see what I put in. It is self priming to a point anyway. Pumps that really have high lift self priming may not allow freeflow as the high lift requires a really good seal.

On mine, the pump is even with the bottom of the tank (about 1 ft high) and has to pull fuel from the tank, fill the filter bowl and then get to the pump. It has worked nearly dry in the tank, so it will do at least a 1 ft suction lift.
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I just bought a Carter P74021 (ex Airtex E8251) that should arrive tomorrow. Free flowing, I suspect it will self prime to a point but will see. I would prefer to have it top-side in the engine compartment, which would mean probably a foot above the bottom of the tank. Just for ease of access.
My tank is vertical...probably 30" tall, so the gravitational pressure alone would keep the fuel level pretty much even with the carb until the tank is 3/4 empty.
 
Should have said slightly above the lowest elevation point in the fuel line so when the engine has not been run in a while, water in the fuel line will settle in it instead of the pump. Many e-pumps have their inlet and outlet on the pump's top and the rotor vertically below when mounted per instructions. (All mine do.) This makes the rotor area the logical place to collect water.

Backstory - On fifth electric fuel pump now. All mounted at lowest elevation point in fuel line. Water collected around the rotor in pumps one to three, and when I tried to start them in the season's first cold weather, the ice around the rotors kept them from spinning and the pump motors fried. Was only using gas stabilizer then. As I would wait until the day warmed up before I investigated things, it took three years before I discovered ice in the pump. Last two E-pumps are/were Mallory marine ones; quiet compared to the Napa ones. With pump four I installed a marine fuel filter with a water separator by the tank and switched to SeaFrom - stabilizer and antifreeze. Pump four lasted eight years until corrosion in the by-pass canal caused the plunger to stick. The canal, at the pump's bottom, likely collected water and caused the corrosion even with the prophylactic measures. While the Sierra mountains get lots of snow, they aren't that cold and have lots of sunny days. Perfect weather for gas tank condensation.
 
zspryte said:
Should have said slightly above the lowest elevation point in the fuel line so when the engine has not been run in a while, water in the fuel line will settle in it instead of the pump. Many e-pumps have their inlet and outlet on the pump's top and the rotor vertically below when mounted per instructions. (All mine do.) This makes the rotor area the logical place to collect water.

Backstory - On fifth electric fuel pump now. All mounted at lowest elevation point in fuel line. Water collected around the rotor in pumps one to three, and when I tried to start them in the season's first cold weather, the ice around the rotors kept them from spinning and the pump motors fried. Was only using gas stabilizer then. As I would wait until the day warmed up before I investigated things, it took three years before I discovered ice in the pump. Last two E-pumps are/were Mallory marine ones; quiet compared to the Napa ones. With pump four I installed a marine fuel filter with a water separator by the tank and switched to SeaFrom - stabilizer and antifreeze. Pump four lasted eight years until corrosion in the by-pass canal caused the plunger to stick. The canal, at the pump's bottom, likely collected water and caused the corrosion even with the prophylactic measures. While the Sierra mountains get lots of snow, they aren't that cold and have lots of sunny days. Perfect weather for gas tank condensation.
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Gotcha. Especially with ethanol blends which are hygroscopic and will eventually pull water from the atmosphere, creating a layer in the bottom of the tank.

As I mentioned, I would like to mount the pump within the engine compartment slightly below the carb and obviously well above the bottom of the tank by probably a foot or so. As long as the fuel level in the tank stays equal with or above the position of the pump, then there should always be fuel present for it to prime itself. If not, it would have to be able to self-prime dry and pull enough vacuum to raise the fuel up to it. I'll find out with some trial and error.

The marine fuel filter/water separator is a good idea. I use one for my used oil burning stove at my cabin since some of the used oil I get my hands on can have small amounts of water in it, creating a poor burn.

Thanks for your thoughts. My main intention is just to have an electric pump with momentary switch to prime the carb, then just run off the standard mechanical pump. If it should fail, the the electric would be there for backup.
Mark
 
Well guys I decided to add an electric pump in-line with the mechanical, primarily to aid starting after sitting for too long and a dry float bowl. My Imp has been sitting in full hot summer sun for about 4 months since last started. Turned the pump on, let it run for 5-10 seconds then shut it off, gave the pedal a couple pumps to squirt some gas, and she lit right up with about 1 second of cranking the starter.
Have it wired to a spring-loaded (in one position) momentary switch (or locked-on in the other position). For kicks once the engine was running I turned on the fuel pump expecting it to over pressurize the carb and flood her out. Not so, continued to run fine. This pump puts out I think 3-5 psi, probably what the mechanical pump puts out.
Anyway, happy to have some redundancy. Carter e- pump P74021
 

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With the electric pump, It pushes fuel past the mechanical pump?
Did you opt out of the water separator?
Curious is all.
ra
 
I installed it directly in line before the mechanical pump, so it pushes through the mechanical if/when energized, or the mechanical pump pulls through the electrical in standard operation. Both the mechanical and the e-pump are diaphram pumps with spring loaded check valves inside. No water separator, that may or may not be an issue since the pump is probably a couple inches above the bottom of the tank. As long as the pump is at or slightly below the level of fuel in the tank, it will always have fuel just through force of gravity.
Probably the proper way to install this would be as a bypass, parallel to the mechanical, with an on/off valve directly before the mechanical. That way, if the mechanical dies (via a diaphram rupture and puking gas all over the place) you could valve off any flow through the mechanical and run with the electric via the parallel bypass. Would just take extra hardware. In my current setup, worse case is if the e-pump check valves freeze or corrode closed, preventing fuel from flowing to the mechanical.
 
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