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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: guitbiking on November 30, 2019, 04:19:29 PM

Title: Fuel level sending unit question
Post by: guitbiking on November 30, 2019, 04:19:29 PM
I have a fuel level sending unit that has wires broken off at the connectors at the base of the unit inside of the tank. I'm not concerned with losing the fuel level function (can use odometer like other bikes). But, I need to power the fuel pump. The ground wire is still intact, but the power to the fuel pump wire is not only broken off, but there is no nib to solder it to.
 It would seem that the base plate could be drilled such that the two fuel pump wires could be routed through it using a fuel safe grommet and sealer. Much like the little plastic original connector accomplishes.
I'm thinking other applications of in-tank fuel pumps must accomplish getting the wires to it in a similar fashion, without including a 200 dollar fuel level attachment :(
Before I do an lengthy search, has anybody done this type of repair? Thanks!
Title: Re: Fuel level sending unit question
Post by: Laitch on November 30, 2019, 05:13:13 PM
Before I do an lengthy search, has anybody done this type of repair?
Somebody must have done it to have created a market for fuel-tight grommets. Give it a go and show others a path out of this condition.
Title: Re: Fuel level sending unit question
Post by: guitbiking on December 01, 2019, 10:57:30 AM
I came up with this item that might fit the bill. https://www.summitracing.com/parts/abt-cfd-504/overview/ (https://www.summitracing.com/parts/abt-cfd-504/overview/). Usually for the top of a fuel cell. But I was thinking of running PTFE insulated wires through it and putting a little JB Weld Steel Stik on the connector for good measure.

The other option would be to run a bulkhead stud through. Then connect wires to the outside and the inside of the stud. Probably only one for + and use the existing ground post on the sending unit plate. As I doubt there is room for two studs in the plate without weakening it.

Any thoughts on the legitimacy of my thinking? It would be about a 50 dollar fix.
Title: Re: Fuel level sending unit question
Post by: volador on December 01, 2019, 11:17:42 AM
I came up with this item that might fit the bill. https://www.summitracing.com/parts/abt-cfd-504/overview/ (https://www.summitracing.com/parts/abt-cfd-504/overview/). Usually for the top of a fuel cell. But I was thinking of running PTFE insulated wires through it and putting a little JB Weld Steel Stik on the connector for good measure.

The other option would be to run a bulkhead stud through. Then connect wires to the outside and the inside of the stud. Probably only one for + and use the existing ground post on the sending unit plate. As I doubt there is room for two studs in the plate without weakening it.

Any thoughts on the legitimacy of my thinking? It would be about a 50 dollar fix.

BADA BOOM
pm sent
Title: Re: Fuel level sending unit question
Post by: guitbiking on December 01, 2019, 11:56:30 AM
Bada Boom, like in Boom?


https://media3.giphy.com/media/oe33xf3B50fsc/giphy.webp?cid=790b761120d9549842a68e71cd194e354f5e139080f28e56&rid=giphy.webp (https://media3.giphy.com/media/oe33xf3B50fsc/giphy.webp?cid=790b761120d9549842a68e71cd194e354f5e139080f28e56&rid=giphy.webp)
Title: Re: Fuel level sending unit question
Post by: Laitch on December 01, 2019, 12:26:25 PM
Any thoughts on the legitimacy of my thinking? It would be about a 50 dollar fix.
Your thinking seems reasonably dispassionate and analytical. There's always this (https://www.ebay.com/itm/BMW-K100-8V-RS-RT-LT-FUEL-GAS-PETROL-TANK-LEVEL-METER-SENSOR-SENDER/293348062769?hash=item444ce83631:g:AX8AAOSweRpd3BvV), too. It would likely give you a pump connection you could strengthen; function of the fuel level sender would still be questionable.
Title: Re: Fuel level sending unit question
Post by: guitbiking on December 08, 2019, 05:10:04 PM
All for naught. I was able to melt the plastic around the post enough to solder a wire to it. I was also able to clamp the wire so that there is no tension on the solder.
Happy trails to you.
Title: Re: Fuel level sending unit question
Post by: Laitch on December 08, 2019, 06:57:33 PM
All for naught.
Which was the all and which was the naught.
Title: Re: Fuel level sending unit question
Post by: The Mighty Gryphon on December 08, 2019, 07:22:15 PM
So you're telling us your repair didn't work?
Title: Re: Fuel level sending unit question
Post by: Chaos on December 09, 2019, 01:09:33 AM
No, I think he's saying posting here was an exercise in futility.
Title: Re: Fuel level sending unit question
Post by: Laitch on December 09, 2019, 09:48:25 AM
I think he's saying posting here was an exercise in futility.
Probably. I think his innate genius will carry the day wherever he goes.
Title: Re: Fuel level sending unit question
Post by: guitbiking on December 09, 2019, 10:20:35 AM
Holy crap! I just meant that I was able to melt the plastic on the original part such that I could attach the wires and solve the problem without having to do a work around as I thought was my only option. I reached out for help and was encouraged to try it.
 Perhaps a poor choice of wording on my part in the follow-up, by trying to be brief. But did it really seem that I was being arrogant or offensive?
I don't often ask questions, because I do extensive research on this and several other sites before asking. I am grateful for all of the helpful information.
Title: Re: Fuel level sending unit question
Post by: Scott on December 09, 2019, 10:37:55 AM
Holy crap! I just meant that I was able to melt the plastic on the original part such that I could attach the wires and solve the problem without having to do a work around as I thought was my only option. I reached out for help and was encouraged to try it.
 Perhaps a poor choice of wording on my part in the follow-up, by trying to be brief. But did it really seem that I was being arrogant or offensive?
I don't often ask questions, because I do extensive research on this and several other sites before asking. I am grateful for all of the helpful information.
I understood what you did and you also were able to take the strain off the repaired joint as well. Good job in this throw away and buy new culture.
Title: Re: Fuel level sending unit question
Post by: The Mighty Gryphon on December 09, 2019, 11:32:08 AM
Your wording led me to think the repair wasn't ultimately successful.  Very glad to hear it worked well. 

Is it possible to post a photo of what you did?  I have a tank connector with a similar issue and would like to try your repair.
Title: Re: Fuel level sending unit question
Post by: guitbiking on December 09, 2019, 12:42:32 PM
It is under a gasoline filled tank at this point. I will try to illustrate with a found photo. [img] [ Invalid Attachment ] [img].
The metal post continues down into the plastic nib, the green line. (Actually it is the wire on the backside, but looks the same.)
I melted the nib with the solder iron until I had enough metal showing to solder to. I then ran the wire through the old float mechanism and pinched the wire with the tab, red line.
A bit of a hack, but it did the job.
Title: Re: Fuel level sending unit question
Post by: Laitch on December 09, 2019, 12:48:31 PM
Thanks for the illustration.
Title: Re: Fuel level sending unit question
Post by: Scott on December 09, 2019, 12:53:22 PM
I did the same sort of thing on my xt500d, about five years ago on the rectifier diode, I guess it's fixed.

Title: Re: Fuel level sending unit question
Post by: The Mighty Gryphon on December 09, 2019, 01:16:13 PM
Nice job!
Title: Re: Fuel level sending unit question
Post by: Chaos on December 09, 2019, 01:39:41 PM
Holy crap! I just meant that I was able to melt the plastic on the original part such that I could attach the wires and solve the problem without having to do a work around as I thought was my only option. I reached out for help and was encouraged to try it.
 Perhaps a poor choice of wording on my part in the follow-up, by trying to be brief. But did it really seem that I was being arrogant or offensive?
I don't often ask questions, because I do extensive research on this and several other sites before asking. I am grateful for all of the helpful information.

Don't take it personally. If we're not out riding we're sitting around making obtuse remarks online.  Glad you got your dilemma fixed!
Title: Re: Fuel level sending unit question
Post by: Past-my-Prime on December 10, 2019, 09:39:58 PM
Hey I understood "All for Naught"!

It means "All the drama for no big deal" which implies that after the help, you were able to find your way through.

Good job mate!
Title: Re: Fuel level sending unit question
Post by: volador on December 12, 2019, 07:11:32 PM
Hey I understood "All for Naught"!

It means "All the drama for no big deal" which implies that after the help, you were able to find your way through.

Good job mate!
Surprisingly you did not mention "splines"
Title: Re: Fuel level sending unit question
Post by: Past-my-Prime on December 13, 2019, 10:25:08 PM
"splines splines everywhere the splines,
do this don't do that"

Sorry, back to your usual programming. I've been into the rum and eggnog this chilly evening.