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Discussion Starter · #1 ·
Recently took my bike apart to clean the gunked up carbs and discovered a bad fuel pump along the way. Now because these are internal relayed pumps and not to mention discontinued I am a little stumped on what to use for a replacement. Can I use a universal 2 wire 2-4 psi 12v pump and just run it full time or do I need to add a relay somewhere? I know there is a trigger wire, how exactly does that work? I appreciate any help anyone can give me and apologize if this has been answered else where.

THANKS!
 

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I've got a long history of electric fuel pumps and motorcycles. The little plastic ones, one of which is labeled "Mr. Gasket"..Junk. I tried two of those little plastic ones over the period of about a year. Six months and they went to electron hell, leaving me stranded. Each of them lasting about six months.
I was on my way (Different bike) to Colorado going through Amarillo Tx. The factory pump failed. I pushed the bike into a parking lot. Lucky for me, there was an Autozone half a block away. I went in and told the guy I wanted an OEM replacement 2-6psi with 1/4" threaded fittings. He brought me one and I believe it was from a GM car. Brass hose barbs, a length of hose and clamps, some wire and electrical tape. Within the hour I was back on the road and the total was about $50. That was about five years ago. I no longer have that bike but my friend does, and that pump is still working. Stay away from cheap aftermarket and go for an OEM automotive replacement with the right pressure range. Hook it to the factory wire and give it a proper ground. The internal pressure switching is automatic and built into the pump. If your bike had an electric pump to begin with, the circuit can handle it as is. Good luck!
 

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There isn't actually a switch in the pump. When the pressure max's out the pump simply stalls out and restarts when the pressure drops.
 

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There isn't actually a switch in the pump. When the pressure max's out the pump simply stalls out and restarts when the pressure drops.
I don't know how they're doing the modern pumps. The bike I stalled out on in Amarillo was an 84 standard Wing. I kept the old pump and dissected it to see if it could be saved. It had a diaphragm and contacts. It was so old and corroded I didn't see any value in trying to salvage it. The new one was working fine so I tossed it. I do remember that the new one didn't shut off. I could hear it run even when the engine was off. I assume it had a pressure orifice and bypass similar to fuel injected ones.
 

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These are the two I have experience with. The first is the Mr. Gasket branded pump, two of which failed after about six months each...


This is a photo of the type I finally installed. This one continues to work to this day. Both seem to be priced near the same. Both have the same operating parameters and both worked well on my bikes, although the first didn't work long.


 

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Discussion Starter · #6 ·
Thanks for the replys. So am I understanding this correctly, if I use an oem auto 2 wire I just simply hook up the ground and power and its good to go? This in return makes it so that it is constantly running if the key is on right? So only drawback is god for bid I or someone else goes down the pump will continue to push fuel, or at least if it is spilling out and cant build pressure. Which leads to my final question, will the 2 wire pump shut off once the carbs are full?
 

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Whatever electric fuel pump you go with, it will pump so long as the float valve is open. When it reaches a threshold of resistance (float valve closed) fuel will stop flowing. If the pump senses the pressure buildup it will stop. Whether or not the pump stalls, is automatically switched off or bypasses, this function will remain the same. In other words, if fuel can flow, fuel will flow. If you rupture a fuel line or let's say the hose pops off, the pump will sense this condition as an open float valve and once again pump fuel. If your bike is equipped with an angle sensor which de-energizes the pump when the bike is dumped, then that function should operate.
Here is one typical of the one I am experienced with:
Amazon.com: Airtex E8011 Electric Fuel Pump: Automotive
Under normal conditions, whenever the key is switched on the pump is energized and the fuel inlet is pressurized.
 

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Discussion Starter · #8 ·
Very well put, I appreciate the time taken to describe the process with me. I ended up ordering an oem that I probably got lucky on finding but I now know if I am in a pinch I can use a normal 2 wire 2 to 4 psi pump.

Thanks again! Cant wait to get it on the road!
 

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Discussion Starter · #9 ·
Alright so I have some problems with the used fuel pump that I bought and now I am thinking it may be something else. Its an oem type pump with green, black and a blue and white wire. How would I go about testing this on the bench to see if it turns on at all. I do not hear it turn on when it is installed and the motor is cranked over but it may just be too quiet to hear. Now if this bench test comes out positive where else should I be looking for a problem? I did disconnect fuel lines and threw longer ones on to rig it up and see if it pumped anything out and it did not. I also have flow through my new filter I installed.

I appreciate any help given and will keep an eye out for new posts.
 

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In order to start the pump, you only need to toggle the run/stop switch back and forth. You don't have crank the engine. If the system is closed and you have pressure, the pump won't run. If you're unsure, open up a fuel line and put it in a container to test.
 

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Discussion Starter · #11 ·
I have tested with it out and pointing into a container with no luck, is there anything else besides the pump and internal relay that needs to be working? Obviously power from the ignition to the relay needs to be there but everything cranks over just fine. Is there a fuse somewhere maybe?

I am trying to locate a wiring diagram on my phone now.
 

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Discussion Starter · #13 ·
Ok pumps working now, and my carb bowls are full. I had to fill the tank up to let gravity help prime the system.

But now no fuel is getting past the carbs into the cylinders. I replaced the fuel filter, cleaned every jet and orifice in the carb and obviously have fresh gas. One of my biggest concerns is how the needles are actuated and if I put the rubber diaphragm together right or not. Are these lifted by vacuum some how? There are no cables, just a spring and the rubber boot. If I set it up right what else would not allow fuel to get to the cylinders granted all my jets and float needles and what not are 100% clean?
 

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Ok pumps working now, and my carb bowls are full. I had to fill the tank up to let gravity help prime the system.

But now no fuel is getting past the carbs into the cylinders. I replaced the fuel filter, cleaned every jet and orifice in the carb and obviously have fresh gas. One of my biggest concerns is how the needles are actuated and if I put the rubber diaphragm together right or not. Are these lifted by vacuum some how? There are no cables, just a spring and the rubber boot. If I set it up right what else would not allow fuel to get to the cylinders granted all my jets and float needles and what not are 100% clean?
Yes, the diaphragms are vacuum accuated. A/F screws out 2 1/2 turns? Choke applied? Definitely have spark?
 
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