Author Topic: Stranded (Fuel Pump shutoff from overheating?)  (Read 2444 times)

Offline RetroTexan

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Stranded (Fuel Pump shutoff from overheating?)
« on: August 06, 2023, 05:12:46 PM »
Decided to push it a little too far this morning (but it’s just so much fun to ride!)

Acewell 4553 connected to BEP 3.0

Tach-ok
Speedo-ok
Batt-ok
Temp-only shows -L-•F (instructions say it should read a temp after it has warmed up but no-go)

Fan never kicked on. Then as I was pulling out after grabbing a water, the fuel pump stopped whining and the bike died. Every time I tried the starter, the pump did not kick on like it normally does. Left it to cool down, still no fuel pump. Checked the connections and fuses. Everything else powers on and wants to work, injectors still clicking, starter is ok, etc.

It has sat for over 8 years with no fluids. Could the temp sensors be to blame? Do they ‘go bad’ if they’re left dry for too long? I’m stumped on next steps to take for diagnostics.

It has 2 temp sensors but I only hooked up the one from the standpipe. The one underneath on the pump is left disconnected. I tried switching them but still no-go.

Any help would be greatly appreciated, I’m already addicted to it and need my next fix 🤣
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline frankenduck

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #1 on: August 06, 2023, 05:52:32 PM »
Fuel tank connector or ignition switch are common for causing this type of problem
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #2 on: August 07, 2023, 10:57:26 PM »
Well, I did like you said and replaced the fuel tank connection. As I was going through the ignition switch connector I realized I didn’t have another 4 pin connector to replace it but everything has strong continuity. Tried to start it again and again strong starter, lights, horn, turn signals, etc but now instead of no noise from the fuel pump I heard a click.  I went ahead and applied voltage to the brown and green/white leads at the fuel tank connector and heard the same click but the pump did not hum.

I took the fuel pump out and applied current directly to the leads, just the same click. Did a bit of percussive maintenance with a rubber mallet but still doesn’t want to budge. Everything in the tank is new but when I look at the pump strainer I see a hole in it.

My guess at this point is that little flap of filter material from the strainer got sucked into the pump and gunked it up real good. I DO NOT want to pay another $180 for another new pump. Anyone know if there’s a good resource on fuel pump disassembly before I go about it blindly on my own?
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline Martin

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #3 on: August 08, 2023, 03:19:57 AM »
If it is jammed try briefly alternating the polarity back and forth. Doing this sometimes frees them up. If this doesn't work try soaking the pump in vinegar for a few days to a week then apply power and briefly alternate the polarity. I've been running a Chinese pump since 2017 with no problems see link. http://www.motobrick.com/index.php?topic=10054.msg85798;topicseen#msg85798
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #4 on: August 08, 2023, 12:18:23 PM »
While I was applying voltage directly to the pump leads I alternated the polarity a few times, still just a click in either direction. Until I crack it open later today I won't know for sure but I'm fairly sure that little piece of filter material was sucked up and is causing the issue. I'm not sure vinegar is going to be strong enough to dissolve material that spends its life inside a gasoline tank. But I do appreciate the reply.

Will report back with my findings.

I'm not able to find any information about pump disassembly so I may just go ahead and document the process and write up a post about my discoveries. Oh, and I paid $360 for this pump back in 2016 from Beemerboneyard brand new OEM. It sat in the freshly cleaned and dry fuel tank for the past 7 years so I'm determined to solve the issue of this pump rather than buying aftermarket. At that price, this thing just HAS to be of higher quality and repairability, right? RIGHT?! Please someone tell me I'm right :cry:

Edit: I did find this great close-up video of a pump disassembly, it's different than the OEM pump I have but I'm hoping it will be similar enough to get me going. Link to the video in case others may find it helpful.

  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline The Mighty Gryphon

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #5 on: August 08, 2023, 01:14:33 PM »
Wow, that hole in the screen looks so nice and square. 
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #6 on: August 08, 2023, 01:21:27 PM »
Yeah, it's weird for sure. 2 of the edges look melted and the other 2 look ripped. I checked and couldn't find anything in the tank other than fuel. I'm guessing I accidentally ripped it when I was installing the pump years back and it just needed an excuse to come loose. The melted edges have me stumped, though.
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline frankenduck

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #7 on: August 08, 2023, 07:32:17 PM »
Here's how the early K fuel pump can be serviced:
http://www.dws.epizy.com/ktech/K%20Fuel%20Pump%20Repair.pdf
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
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Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #8 on: August 22, 2023, 02:27:11 PM »
In the wise words of a dumb man, “Well there’s your problem right there…”

Looks like a small chunk of the original blue paint somehow made its way into the tank, past the hole in the filter, and lodged itself in the fuel pump. One more problem solved, now time to jb weld the filter hole, put it all back together, and see if it runs again
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline The Mighty Gryphon

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #9 on: August 22, 2023, 07:03:43 PM »
Wow, it doesn't take much, does it?
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #10 on: August 23, 2023, 05:33:19 AM »
Wow, it doesn't take much, does it?

Surprisingly little, the price we pay for precision. Also, it’s a good lesson for the importance of that pump filter. I sealed up the hole using JB Weld and some mesh filament.

This turned out to be a blessing in disguise since it brought to my attention yet another tank leak. Has anyone had any luck with tank sealants with our aluminum tanks?
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline Duckbubbles

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #11 on: August 23, 2023, 09:52:31 AM »
I used a product called Kream (maybe Kreem) several years ago to seal a hole in the bottom of my '85 K100RS tank.  Covered the hole with some foil tape from the outside and filled the seam of the welds at the bottom.  Maybe 1/4 inch thick down there.  Like I said, it's been years with no ill effects.  It might be hard to find.  I got mine the Honda shop in San Marcos.

Frank
  • Austin, Texas USA
  • 1985 K100/1100RS
'85 K100/1100RS 38 years, 331,000 mi.
'23 R1250RS
'03 R1100S BCR #6/200
500,000+ BMW miles

Offline The Mighty Gryphon

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #12 on: August 23, 2023, 10:43:05 AM »
Is this the stuff you used?

https://www.kreem.com/fueltankliner.html


* Kreem.jpg (14.94 kB . 232x306 - viewed 325 times)

You can get it on eBay.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"
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Offline Duckbubbles

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #13 on: August 23, 2023, 12:18:53 PM »
Exactly that!  Used it maybe 40 years ago on a Kawasaki steel gas tank and a few years ago on my K-bike.  Make sure the tank is empty and absolutely dry inside.  I removed all the fuel pump hardware and electrical wiring.  Just used it on the bottom as the rest of the tank was very clean.

BTW- since you are in there, I would replace the screen as it's available from Euromotoelectrics.com.  No telling how the fuel will react with your fix.

Frank
  • Austin, Texas USA
  • 1985 K100/1100RS
'85 K100/1100RS 38 years, 331,000 mi.
'23 R1250RS
'03 R1100S BCR #6/200
500,000+ BMW miles
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Offline Duckbubbles

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #14 on: August 23, 2023, 12:51:27 PM »
P.S.- The website suggests you use part A first.  I would not use the part that etches the metal, that is intended to use on steel and no telling what it would do to the aluminum.  I just used the white Kreem by itself.

Frank
  • Austin, Texas USA
  • 1985 K100/1100RS
'85 K100/1100RS 38 years, 331,000 mi.
'23 R1250RS
'03 R1100S BCR #6/200
500,000+ BMW miles
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Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #15 on: August 23, 2023, 01:08:16 PM »
Hey that's exactly the kind of thing I was asking about! I've been looking for a more purpose built product than JB Weld for fuel tanks. Thanks for the suggestion.

I just shoved my phone inside the pump reservoir and noticed there is still some buildup that I could not see or reach before so I've ordered a cheapo endoscope off Amazon (yay same day shipping) and will get at the rest with some old dental tools when it arrives. I’ll order some of that tank treatment and give it a try
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #16 on: August 28, 2023, 11:01:16 PM »
It runs! I found a new connector for the ignition switch and switched it out, reinstalled the serviced fuel pump, and everything worked enough to go around the neighborhood a few times. Still no fan though.

I put alligator clips on the fan connector and ran voltage through them, the fan turns on and runs when voltage is directly applied. But after a 15-20 min ride the fan still won’t kick on and the temp on the Acewell still reads -L-•F

Am I supposed to set the Acewell for a certain temp before it reads? Does it control the fan? What’s the risk of running a k bike without a fan in the short term?
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline Laitch

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #17 on: August 29, 2023, 09:16:32 AM »
The fan won't operate until engine temperature triggers it to operate. Riding around the block a few times won't do it, even in Texas.  :laughing1: If you let it idle, it should start up in 15 minutes or so, especially in Texas.  :laughing4-giggles: Be aware the temperature bulb lighting indicates Overheating. The fan running just means the temperature is being controlled so it doesn't overheat.

The fan responds to inputs from the temperature sensing relay that the relay receives from the coolant temperature sensor, if there has been no interference with circuit. The relay, the coolant temperature sensor and the fan all need to function for the system to operate. The Acewell doesn't govern that process; it only indicates the coolant temperature.
There are threads galore here about Acewell struggles and management. No doubt somebody with experience is likely to come along.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Duckbubbles

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #18 on: August 29, 2023, 10:29:49 AM »
The temp sensing module in the electrical box provides a ground to the fan.  On my '85 RS I provided a separate ground through a rocker switch so I can turn on the fan when I want to- like when I know I will be sitting/going slow for a while.  If I turn it on soon enough the temperature stays constant, even in traffic.  I installed an Autometer direct reading (not electrical) gauge about 100 years ago so I know the temp at any given moment.

Frank
  • Austin, Texas USA
  • 1985 K100/1100RS
'85 K100/1100RS 38 years, 331,000 mi.
'23 R1250RS
'03 R1100S BCR #6/200
500,000+ BMW miles

Offline Laitch

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #19 on: August 29, 2023, 10:36:32 AM »
I installed an Autometer direct reading (not electrical) gauge about 100 years ago . . ..
Maybe you have some daguerreotypes you could copy and post of your Autometer in its location, Frank? That could be helpful.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #20 on: August 29, 2023, 10:52:02 AM »
Ok thanks Laitch, that answers a question I've had about if I'm using the correct temp sensor which you've confirmed that I am (mine was the RT model and so it had a temp sensor at the coolant stand pipe on top of the engine that I have connected to the BEP 3.0 and an additional temp sensor on the bottom of the engine near the pump that I've left disconnected)

My initial ride on Aug 6 was what originally prompted concern that my issue may be fan related, which lead me to believe the pump failure was due to overheating. That was a ride that lasted about an hour at 10am in Central Texas, so about 90-95 degrees Fahrenheit. I assumed it would have kicked on before then.

Based on what I'm gathering from other threads, is my next step in diagnosis to check the resistance of the pins in the Jetronic connector? Not sure what comes next after changing the fuel tank and ignition switch connectors like frankenduck had mentioned (unless he meant replace the entire ignition switch, key and all).
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline Laitch

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #21 on: August 29, 2023, 11:10:49 AM »
Remember that the temperature switch in the pump serves an entirely different function—it operates a temperature gauge readout.  There has been confusion around here about the pin numbering sequence in the Jetronic plug. The sequence is in the attached diagram.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Laitch

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #22 on: August 29, 2023, 11:16:14 AM »
. . . that answers a question I've had about if I'm using the correct temp sensor which you've confirmed that I am (mine was the RT model and so it had a temp sensor at the coolant stand pipe on top of the engine
All classic Bricks regardless of model have the coolant temperature sensor in that standpipe next to the radiator. If the system is functioning correctly, the fan will start at idle as I indicated. Start it up and have an iced tea while you wait.  :laughing4-giggles:
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline RetroTexan

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #23 on: August 29, 2023, 11:31:10 AM »
That's what I'm saying: I've let it idle, I've ridden it for 20+ minutes around the area, and still no fan.

At this junction, I'm assuming there is an issue that's causing the fan not to kick on (either a faulty temp sensor, connection, or something else but I know the fan at least works when voltage is applied). I'm asking for recommendations for next steps in the diagnostics. I've already replaced the connectors, I've searched the forums, and the only other thing I know to do is to check the Jetronic pins (which I'm still researching how to do if anyone has tips and tricks)
  • San Marcos, TX
  • 1990 K100 Custom Scrambler

Offline Laitch

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Re: Stranded (Fuel Pump shutoff from overheating?)
« Reply #24 on: August 29, 2023, 11:58:47 AM »
There are no tricks to checking the sensor via the Jetronic pins, although you could perform it doing a handstand if you want to create a challenge for others.  :johnny

A multimeter is used. There is a fairly active thread about the self-generated travails a member here went through doing that. You must have missed that and you probably should continue missing it for your own benefit. :laughing4-giggles: You have a cold engine reading and an operating temperature reading. They are 2.5KΩ@20ºC(68ºF) and 300Ω@60ºC(140ºF). The fan starts at 103ºC(217ºF). Pin #13 is ground; pin #10 is the sensor. Those are where you connect your multimeter leads to take the reading. If they are ambiguous, the sensor can be removed for a cold-to-hot water test. 
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

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