SOLVED: Buddy 170 fuel delivery problems

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mukaiboston
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SOLVED: Buddy 170 fuel delivery problems

Post by mukaiboston »

Note: the Buddy 170 is fuel-injected so there is no carburator.

A few weeks ago, I noticed my scooter was having a rough time cold starting. I would have to hit the ignition twice which seems unusual in summer weather when it should start right up. On Sunday, I was out and noticed the idle seemed unusually high and it also seemed like the engine was hesitating a bit.

A few days later, I started it up and the engine really started surging two or three times before going to a high idle, misfiring and the engine light was on.

Since these are symptoms of many things, I started eliminating possible causes:

-Battery is new as of two months ago and fully charged
-Valves got checked a couple days ago and are good with a .08mm gap
-Spark plug replaced today just to be sure and did a spark plug test to make sure there was a spark
-Belt and sliders replaced a few weeks ago
-Reset ECU obviously, but it didn't do any good
-Checked air filter and pipes - no dirt, no liquid spills, no blockages
-Checked gas cap - properly sealed for fuel pressure

Now we are getting into things like the fuel injectors, the fuel pump, fuel lines, maybe a sensor is broken. I want to make the most educated guesses possible now because replacing these parts is rather expensive. I just found out that if the EFI is defective for example, that part costs $600.

The engine has not stalled yet, but with all the misfiring, it sounds like it could.

The engine light comes on right after the key is turned to the on position and before the engine is even started. This leads me to believe that the problem is detected as the scooter preps for the ignition - like maybe the fuel injectors are not pressurizing right. Any ideas?

And I apologize if this is dumb question, but is there a fuel filter on the buddy 170 that I am supposed to check? I don't see anyone ever mention a fuel filter and it is not in the Buddy 170 service manual nor is it in the Scooterworks catalogue.
Last edited by mukaiboston on Thu Jul 23, 2020 9:51 pm, edited 1 time in total.
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tenders
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Post by tenders »

I don’t have any FI experience but agree that your symptoms could be related to fuel problems since they seem to be detected so early in the startup process.

But another thing that might be detected so soon is an electrical issue. I would check every electrical connection you can, starting with the battery, paying particular attention to the ground connections. Is it possible that something got left off when replacing the battery, putting the transmission cover back on after the belt change, etc.? It is easy to overlook an innocuous little ground wire when you’re focused on chasing down the dozen or so fasteners holding on the transmission cover.
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Post by personality »

I would probably try some fuel injector cleaner additive in the gas first. Then removing, inspecting and cleaning the throttle body if the problem stuck around.
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Post by mukaiboston »

I’ve run fuel injector before and I use sea foam regularly. I heard those can also push the dirt further in if it doesn’t come out.

What I might do is just replace the fuel injector as a gamble and then have it towed to the shop if that doesn’t work. Without the diagnosis cable, I’m going to spend more money replacing fuel parts and potential computer parts and get nowhere.

The documentation doesn’t show the 170 has a filter. I’m wondering if that contributes to the fuel injector getting clogged
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Post by DeeDee »

How hot has it been when this first started? I did a quick search for 170i, and this is what I found: https://www.ebay.com/itm/Quantum-Fuel-P ... 2958452176 I didn't look any further, I have never been into the 170i fuel pump. If this is the correct pump, your filter is attached at the bottom of the pump. These things are fine mesh, made out of solvent proof nylon. They last forever. Any sediment or crud will slide off of the filter sock and rest in the bottom of your tank. Unlikely you have a filter problem. This pump looks an awful lot like the notorious Yamaha 30mm pump that has caused massive problems in all of their fuel injected scooters going back to 2007 and before. Same pump is used in a number of large frame Modern Vespas which have also had problems with permature failure. I have first hand experience of these things failing in Yamahas. I have replaced over a dozen in the last 9 years in everything from 50cc Zumas and C3s up to a T-Max. Same pump, same problems. Heat is the enemy of this pump. Most of the time, the problem shows up on a hot day leaving you stranded. You Uber home and return later that evening with a friend and a pickup truck to fetch your scooter. You decide the turn the key for grins, and the scooter fires up and you ride it home. Lather, risne & repeat.
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Post by mukaiboston »

It hasn't been that hot lately until this week and the problems started before then. The problem with the hard starts started on cooler days so I thought it was just the drop in temperature.

That pump doesn't look like mine at all and I don't think it is OEM. My pump is white and is available for $350 which is why I don't want to replace it if I'm not sure it is broken.

Here's a photo of what I see when I look in the tank. Is that circular thing the filter?
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Post by mukaiboston »

This is the Buddy 170 pump. https://www.scooterdynasty.com/fuelpump ... buddy.aspx

As you can see from the photo I posted above. The bottom of my mesh doesn't look white like this. It looks like it is covered in black and silver sand. Any way to clean these things or replace just that part without buying a $350 pump?
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Post by mukaiboston »

I'm watching motorcycle maintenance videos online and from what I can see from similar bikes is that the fuel filter is built into the pump and not replaceable.
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Post by DeeDee »

The pump from scooter dynasty is the whole assembly. You don't need the whole assembly. You need the 30mm pump that fits inside the assembly. It's mostly nylon made to hold the pump and mate it to the tank. Most fuel injected vehicles have this type of set up. You buy the pump only, and remove the old one from your nylon housing. I blew up the picture from scooter dynasty. See the shiny silver cylinder in the center there? That is your pump. That's the part that wears out. Not the nylon holding it.
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Post by Stanza »

Buddy 170 is very sensitive to weak batteries. I know you say the battery is fully charged....but is it? A green light on the charger is only half the battle. You also should check to see how far the battery voltage drops when you are actually cranking the bike. A strong one should dip into the 11's, or MAYBE high 10s if it's cold out. But if it's dropping into single digits while cranking, your new battery is a dead duck, and you should get it replaced (hopefully under warranty).
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Post by mukaiboston »

Thanks DeeDee, I'll look into getting a fuel pump and see if that fixes the issue. I'll report back on what I see if I can get the old pump out of the tank. Hopefully, the eBay link you posted is good. I don't see any many places to get only the pump.

I poked the filter with a straw while it was still in the tank and it looks like the sediments are in the mesh, not sliding off of it.

--
Also, no problems with the battery. I does not drop into the single digits under load and I also checked all the fuses as well and spark.
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Post by mukaiboston »

One more thing for anyone who knows how to remove a fuel pump. I was researching this for cars and want to make sure I have this down:

1. Depressurize fuel lines by removing the fuel pump fuse from the fuse box under the front panel.

2. Start the ignition and run the scooter a few seconds. Instructions seem to say run the car or scooter until the engine dies, but I don't want to burn out the fuel injectors so I'm hoping a few seconds will reduce the fuel pressure enough.

3. Unplug the negative lead from the battery so any fuel leaks don't cause a fire.

4. Unplug old pump from assembly and plug new one in.

Is that it? Do I need to manually put fuel anywhere or repressurize the system or will it repressurize all the way after the battery is connected and the key is turned on? I don't know what happens if air in the pump goes to the injector.
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Post by DeeDee »

You don't need to depressurize this system. A thimble full of gas will come out. I've searched this forum for info about replacing the pump. Came up with nothing. It looks as though the stock original fuel pumps in these are fairly robust.
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Post by mukaiboston »

Yup, that's why I haven't looked into this at all. I searched for fuel filter on here for years and nothing has ever come up. I had no clue it was part of the pump.
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Post by mukaiboston »

Searching for help about the Buddy fuel pump is maddening. It seems almost no one (except DeeDee here) knows anything about the pump or replacing it.

I've called Scooter Lounge, left a message on Scooter works, called the mechanic near me and they have no idea how to replace or remove the pump and even Quantum Fuel Systems, where I bought the replacement, says they aren't sure about installation and are just going off of what is listed in their own catalogue. But the tech said as long as I have the assembly out, removing the pump shouldn't even be that hard. I just want to make sure the connectors and everything match up but they have no idea.

Scooter Lounge told me the pumps are so robust, they don't even stock them and have never heard of them failing.

Seems crazy to me that the fuel pump filter (also called a strainer) has never gotten clogged or needed replacement for anyone else.

It makes me wonder if I'm even chasing down the right issue, but I pulled the pump out and looked at the filter and it is completely black all the way through...the dirt is inside the mesh.

(photo attached)

Worst case scenario if the replacement doesn't fit -- can I clean the existing one? Is there an aftermarket pump assembly. Looks like suppliers aren't importing OEM replacements at this time.
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Post by DeeDee »

Use this as a guide for putting it back together. You want even firm (not too tight) pressure on the gasket mating to the tank. You should be able to open up the nylon holder and remove the pump from the holder. Are you sure the black stuff is dirt?
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Post by mukaiboston »

Dirt was maybe the wrong word. It's either deposits or sludge. I don't know. I've squeezed the filter with my fingers and whatever it is, it appears to be inside the mesh. It looks like a pocket of soft mesh that is heat sealed on all sides.

It should be white though so the fact that it's black all the way through is a sign to me that it's finished.
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Post by mukaiboston »

Successfully replaced the pump!

However...that was not the problem! Scooter runs like crap just as before with the engine light coming on.

I'm thinking the fuel injector has a problem then. The engine light is coming on before I touch the ignition. So the computer is detecting something is wrong without anything running which should mean the fuel pressure is not right because something is clogged or because something is not setting it right. That's my best guess.

Anyway, if your fuel pump ever goes out and you have a Genuine Buddy 170i, be advised that the Quantum Fuel Pump HFP-397-U fits perfectly. Be advised that it comes with no instructions though so you really have to know what you are doing.
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SOLVED

Post by mukaiboston »

The scooter is now fixed. The temperature sensor was to blame.

I was able to obtain a diagnostic tool to pull the fault codes off the engine and it flashed the code for "engine temperature sensor".

I had checked that sensor with a multimeter and it had resistance that was within specs but obviously something wasn't right with it. I stuck at 2.5K ohm resistor in the sensor plug as an experiment and the engine started right up with no hesitation.

Genuine and the dealers will give you hell trying to replace this part saying it is special and custom-made for that type of scooter. A shop even told me, "Genuine? One of those cheap Chinese bikes? We don't stock parts for Chinese bikes."

I won't bore you with all my detective work, but the part you want for the engine temperature sensor is a "21176-0009 Water Temperature Sensor for a 2008-2014 Kawasaki 450R" The Kawasaki 450R's service manual has a resistance table that looks like Genuine copied as all the values match perfectly and it's perfect fit in the Buddy 170i.

$20 fix on Amazon Prime. Engine runs smooth and finally the engine light stays off!
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Post by tenders »

Wow. Impressive diagnostic and detective work! The Force is strong with this one.
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Post by DeeDee »

Good for you, and thanks for updating this thread to close the loop. I just followed something similar with a Yamaha C3. Owner replaced: ECU, Injector, and throttle body. Sold the bike out of frustration. New owner started to trouble shoot why it wouldn't run, long story short, ended up being a $10 fuel pressure regulator.
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