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 Post subject: R1 fuel sending unit
PostPosted: September 23, 2022, 6:23 pm 
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Does anyone know if the in-tank R! fuel sending unit will work on an aftermarket car fuel gauge? The fuel light has been blinking on the R1 cluster since the car was built.


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 6:01 am 
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Picture of the tank mounting would be good.

Short answer is no. It depends on your definition of "work" and the specific year model R1 sender and wiring. There is nothing universal about oem parts but there are ways around that. Aftermarket gauges are made for a specific range of ohms between empty and full and increasing or decreasing.

If the builder did not level the top of the fuel filler when installing the tank, then that is probably the primary problem. Lift what would be the seat side of the tank so the filler door is level like it would be when installed on the bike. This may also save you from damaging the fuel pump from sucking air.

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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 7:05 am 
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It's a 2006 R1, the tank is a custom-built unit by MK, using the stock R1 fuel pump and sending unit. In looking at the Haynes manual and the R1 owner's manual, the gauge does not show E-F, the warning light comes on when the tank gets to 1 gallon. Below is video of the first start that shows the tank, the original R! FP and sending unit is located at the bottom of tank.

https://www.youtube.com/watch?v=lKIw6pLIcSM


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 10:27 am 
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Found some good info on Locost uk site.




On the 05 R1 fuel level sender the resistance is in the range of 20-26 ohms at full and 134-140 ohms empty you need to measure the resistance of the sender you are using and see if it is the same. I don't think it will be the same which is why you have the problem with the light on. I have a racetech sender in my tank and that was not the same resistance so I am going to use the racetech fuel gauge as the R1 dash only has an indicator to tell you fuel is low.
To make the light go out on the dash you need to connect a resistor between the green/white wire and black wire that go to the fuel level connector on the fuel pump assy, I would think 100 ohm resistor would do it.

Not too sure if the 4xv is going to be the same resistance or uses the same fuel pump/fuel level assembly.


If it is the sort which makes a circuit when the float gets to a certain point it will not have a variable resistance throughout it's movement, it will just work like a switch. If this is the type you have then this will never work with the light as the float will be open circuit until the point of which the float moves far enough to activate and then it will be short circuit.

What the R1 dash needs to see is a variable resistance so it knows how much fuel is in the tank, when it gets to a certain resistance the light then comes on to warn you that fuel is low and that you are now using the reserve tank which is part of the bike tank. I think this is pretty basic and not much use in a car fuel tank as you would have to make it so the light came on with enough fuel in the tank to give you a reserve amount.

IMHO you are better getting a seperate fuel gauge and proper sender unit, then put a resistor in the bike loom to make the light go out. I am using the racetech gauge and sender, they are reasonably priced and this way you can see how much fuel you have.

They are easy to wire up and you only need one wire from the sender to the gauge.

You can test your float switch with a multimeter across it's terminals and see if it is variable resistance type or switch type.


I've put a 500ohm variable resistor in parallel with mine and connected it up to the tank sender (with a diode to stop it affecting the dash gauge). That way the low level light will still work. I can just adjust it to get the light on when I want.

A resistor in the 50 ohm region will stop the fault code. ECU expects between 20ohm (full tank) and 140 ohm (empty)


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 12:20 pm 
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A stand-alone aftermarket gauge and matching standard top mount sender could be installed. It can be a tube type or traditional float on an arm. VDO is a good gauge mfg. For the tube type, you need the tank depth.

A resistor spliced into the existing sender wire (wherever you have easy access) will give a false level indication to prevent the light from flashing.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 1:34 pm 
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Miatav8,MstrASE,A&P,F wrote:
A stand-alone aftermarket gauge and matching standard top mount sender could be installed. It can be a tube type or traditional float on an arm. VDO is a good gauge mfg. For the tube type, you need the tank depth.

A resistor spliced into the existing sender wire (wherever you have easy access) will give a false level indication to prevent the light from flashing.


:cheers:


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 2:14 pm 
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Another idea. I see no point in a low fuel switch that would provide variable resistance.

Unplug if possible or cut the sender wire (like you were adding the resistor), if it stops flashing, your done and the float switch is grounded when the float sinks.

If the float switch grounds the wire when floating, you may need to try grounding the wire instead.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 24, 2022, 2:38 pm 
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Miatav8,MstrASE,A&P,F wrote:
Another idea. I see no point in a low fuel switch that would provide variable resistance.

Unplug if possible or cut the sender wire (like you were adding the resistor), if it stops flashing, your done and the float switch is grounded when the float sinks.

If the float switch grounds the wire when floating, you may need to try grounding the wire instead.



I'll try it, as always, thanks


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 25, 2022, 11:00 am 
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Ok update--Tested the sender unit 1329 Ohms--disconnected the wires light still on-- I think in the wire diet during the build something was missed, and the cluster is getting a signal from somewhere. So I'll try to trace from cluster out to see if I can find the issue.


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 25, 2022, 11:52 am 
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Pickup a 10k ohm potentiometer like this: https://www.amazon.com/TWTADE-Potentiom ... s9dHJ1ZQ==

Splice into the wires temporarily by stripping back and inch or so and twisting on to the appropriate eyes determined by putting a meter across them and checking the ohms while turning the knob or use alligator clips to hold the wires on the eyes.

Turn the key on, slowly turn the knob until the light goes out. Turn back until it comes back on then rotate slowly to where it just goes out. Remove and check the pot resistance.

Reinstall the pot, turn the key on, and turn the same direction until the light comes back on. Remove and check the resistance.

Install a resistor with a value half way between the two values that cause the light to come on.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 27, 2022, 7:34 pm 
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Joined: March 1, 2011, 9:50 pm
Posts: 119
geoz3 wrote:
Does anyone know if the in-tank R! fuel sending unit will work on an aftermarket car fuel gauge? The fuel light has been blinking on the R1 cluster since the car was built.


Have you been able to rev the motor to redline in gear? That light coming on typically causes a low redline enable from the ecu. I had to put a resistor in. Can't remember the resistance but can take a picture and you can get a measurement from the bands.


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 29, 2022, 7:16 am 
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gto7419 wrote:
geoz3 wrote:
Does anyone know if the in-tank R! fuel sending unit will work on an aftermarket car fuel gauge? The fuel light has been blinking on the R1 cluster since the car was built.


Have you been able to rev the motor to redline in gear? That light coming on typically causes a low redline enable from the ecu. I had to put a resistor in. Can't remember the resistance but can take a picture and you can get a measurement from the bands.



Ya, I have not tried redline but seems to rev correctly when driving, please load picture, in case.


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 29, 2022, 8:39 pm 
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1k ohm. Brown, black, red, gold.

If you have any questions related to the r1 let me know. I've swapped two in already. An 01 and an 02. I have a Haynes manual with excellent wiring diagrams that covers 98-03 I believe. A 2010 engine is going in this winter.


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 29, 2022, 8:40 pm 
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I believe fuel cut off with the light on is 8k rpm fyi.


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 Post subject: Re: R1 fuel sending unit
PostPosted: September 29, 2022, 8:57 pm 
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gto7419 wrote:
1k ohm. Brown, black, red, gold.

If you have any questions related to the r1 let me know. I've swapped two in already. An 01 and an 02. I have a Haynes manual with excellent wiring diagrams that covers 98-03 I believe. A 2010 engine is going in this winter.




Thanks, mine is an 06, and came with a manual, but not sure how the builder wired it in the car.


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