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Replacing Fuel Pump

3.6K views 17 replies 6 participants last post by  Gregory Tubbs  
#1 ·
My fuel pump has died. The flow rate and PSI have dropped to where I can barely keep the engine running. The first indication was a slight hesitation when accelerating. It felt like my clutch was beginning to slip, but it got worse quick.
Of course Honda only sells the entire fuel pump assembly for $435+ so I took out the pump and found out it's made by Mitsubishi and is used in many other bikes and some cars. So I've ordered just a pump for 1/10th the cost of the whole unit. I'll let you know how it works out.
The pump I have is a Mitsubishi UC-T33. Just do a search and there's a lot of choices, but I hope I haven't picked a generic brand that won't last.


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#3 · (Edited)
Got my paws on the new pump today. It's a match to the original, no modifications or adapters needed.
The fuel filter fitting was different but would fit fine with the original adapter removed from the pump inlet.
After turning on the ignition three times for the two second pump run the lil blue dragon fired right up. It seems to be slightly more perky but not much. My pump must have been failing for some time.
There wasn't much wear showing but it must have been enough.
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The new filter is a plastic screen, but I'll save that for another time.
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I'd have to remove the white plastic adapter from the pump to use the new filter.

If you ever need to change your pump, just remove this from the bottom and gently pry out the pump. It just plugs into a rubber grommet.
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#10 ·
An update on my fuel pump replacement.

If you have seen Scotty Kilmer on YouTube, he's a pretty good mechanic. He says if you hear your submersible pump making noise it's going bad. So I did have a failing pump, and this new one is almost silent.
But I've had intermittent problems with fuel delivery. The bike runs fine under "normal" conditions. But when I try to get a little spirited with the throttle, the engine is obviously starving for fuel at high RPMs.
I checked the pressure relief valve and it doesn't open until pressure exceeds 50 psi, perfect. The fuel line should have 50 psi of pressure.
But I didn't have a fully unrestricted flow through the pump assembly. I sprayed carburetor cleaner into the outlet and used an air hose to back flush it. A dark colored sediment came out of the white plastic chamber of the pump assembly. What this chamber is, I'm not sure. But after back flushing several times the flow restriction was gone. I hope none of that sediment exited the pump and on to the injectors but I never saw anything come out in the outlet pipe. It was always in the backwards flow.
Went for a test ride and I was hitting the rev limiter pretty quickly. The acceleration was much better. I hadn't done that for awhile. And the instant mileage meter was showing a much higher mpg than it has been.
Hopefully my mpg average will increase a little.
 
#7 ·
Ive read the hardest thing on a submerged pump is running low on fuel so it sucks air.
Looses cooling and lubrication, might not ever feel it loosing pressure.

Did you let it hit low fuel warning regularly? If not then must have got a bad one. Guess not a crazy idea that if honda is paying $20 a pump one goes out occasionally.
Only pump Ive lost was a car that was stored along time, I thought probably sucked up some ethanol goo.
 
#11 · (Edited)
Update on this fuel assembly chamber.

I've been looking through YouTube videos trying to get a description of this.
This chamber is the fuel filter but not all submersible pumps have the filter in the tank.
The filter on the pump inlet is basically a pickup screen and not the primary filter element.
It's no wonder Honda wants you to buy the entire assembly, which I refuse to do. I don't replace an entire unit of anything when it isn't necessary.
(Edit) Thinking about what that dark sediment could be, since my tank is clean and my pickup filter is in good shape. I believe it may have come from my old fuel pump. I'd taken the pump apart and found the brushes and contact surfaces were worn rough. The motor didn't have a copper commutator like most motors, but looked more like graphite. This was probably what was in the main filter.
 
#13 ·
Got my paws on the new pump today. It's a match to the original, no modifications or adapters needed.
The fuel filter fitting was different but would fit fine with the original adapter removed from the pump inlet.
After turning on the ignition three times for the two second pump run the lil blue dragon fired right up. It seems to be slightly more perky but not much. My pump must have been failing for some time.
There wasn't much wear showing but it must have been enough.

Second post
But I didn't have a fully unrestricted flow through the pump assembly. I sprayed carburetor cleaner into the outlet and used an air hose to back flush it. A dark colored sediment came out of the white plastic chamber of the pump assembly. What this chamber is, I'm not sure. But after back flushing several times the flow restriction was gone. I hope none of that sediment exited the pump and on to the injectors but I never saw anything come out in the outlet pipe. It was always in the backwards flow.

Third post
Update on this fuel assembly chamber.

I've been looking through YouTube videos trying to get a description of this.
This chamber is the fuel filter but not all submersible pumps have the filter in the tank.
The filter on the pump inlet is basically a pickup screen and not the primary filter element.
It's no wonder Honda wants you to buy the entire assembly, which I refuse to do. I don't replace an entire unit of anything when it isn't necessary.
(Edit) Thinking about what that dark sediment could be, since my tank is clean and my pickup filter is in good shape. I believe it may have come from my old fuel pump. I'd taken the pump apart and found the brushes and contact surfaces were worn rough. The motor didn't have a copper commutator like most motors, but looked more like graphite. This was probably what was in the main filter.
Greg,
Thanks for the extensive write-up. My pump is also squealing, and you convince me to replace it myself [along with an experienced biker friend for moral support]. This will be a first for me to work on anything but bolt on, wired accessories, or plastic.

I bought the same pump you recommended. But I don't understand some details in your three posts above.
1 I haven't opened up the tank yet, so don't know what the assembly is. Looking at a parts diagram, I see what looks like a mounting rack attached to the round plate you remove from the tank. Yeah?
2 Where is the primary filter element? Is this where you cleaned out the dark colored sediment? Is that the filter under the chamber, or elsewhere?
3 Did you replace the mounting plate gasket? My pump didn't come with one, and I doubt I can buy it separately.

Thanks much for your help.

Bruce
 
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#16 ·
This was the most serious work I've performed. Next up, replace the pistons! :ROFLMAO:
This was the most serious work I've performed. Next up, replace the pistons! :ROFLMAO:
Oh lord.....
I was on a Facebook group for the 900 Vulcan. Some if the questions about what to do made me want to say; For you and others safety, please put down the wrench and slowly back away. 😂
One that stands out in my memory is a photo of a cotter pin in the axle castle nut. They wanted to know how to remove it. That may have been in this forum actually. But honestly, one shouldn't be messing with a wheel if you're that mechanically clueless.
 
#15 ·
Following these instructions above and my tech manual, I replaced my fuel pump a few weeks ago. Not that difficult, particularly when you have an experienced friend next to you [doing a lot of the work (y)].

My additional observations
  1. Drain the tank as much as you can. Then remove the mounting plate while the machine is level, and make sure you have drained enough to lean it onto the kickstand if you plan to do so.
  2. Take pictures as you go along, to remind you what goes where. I did so and you can see them here if you like >> Flickr album of pump replacment . Helped when I was uncertain about reinstalling the outer filter.
  3. Hardest part was removing the pump from the bracket. It wouldn't slide down until we disconnected the wires and manhandled it. Again the pics came in handy.

I'm not sure that the new pump sounds any different from the old one. For $40, it was an easy decision to play it safe on a pump with 71k miles. I have about 500 miles on it now, and it works flawlessly.

This was the most serious work I've performed. Next up, replace the pistons! :ROFLMAO: