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How To Fit a Modern Fuel Sender Unit To The 02 Gas Tank?


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I want to use a modern fuel gauge that operates at 240-33 ohms resistance, so I’ll also need to install a modern fuel sending unit.

I don’t see any units that will screw into the tank like the original BMW sending units do, so I’m wondering if anyone has successfully adapted a modern fuel tank sending unit to a 2002 tank?

Judging just by pictures, it would seem to require drilling and tapping 5 screw holes into the gas tank. If so, what’s the safest way to drill a tank? Does it need to be emptied of gas or would that make it more risky?

Tank was recently lined, so I don't expect to dislodge any rust or crud. I'm thinking any metal fragments from drilling could be pulled out with a magnet.

I would expect to use an inexpensive sending unit that is something like the one in this photo.

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I'm just trying to spruce up the gauges on a '74 daily driver (a 4-in-1 gauge and a GPS odometer / speedometer) and don't want to reinvent the wheel if there are some other obvious solutions.

Last alternative would be to install a new fuel cell with the gauges (and sell original tank and sending unit to pay for it). But that seems like an excessive effort to just make the dash look a little better.

Any ideas or suggestions would be appreciated. Thanks. 

Greg S. -

 

 

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Tank is constructed of relatively light gauge sheet steel, you cant tap threads into it. You would have to install a threaded backing plate somehow.

Hardly seems worth the effort just to spruce up the gauges  however good luck with your experiment.

Dont blow yourself up, I would never drill, cut or otherwise generate heat/sparks in a tank with gas in it or empty and uncleaned. 

Drain and remove it from the car to attempt whatever it is you are trying to accomplish. 

 

Edited by tech71
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Following with interest as I plan to fit an in tank pump. The one I think I will go with simply fits with self tapping screws, a gasket and some sealant. I think trying to get a tapped and threaded ring onto the inside is impossible as it would need to be larger than the hole itself.

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While I think it's overkill in this situation (see Tony's and my previous posts) here's a way to install a threaded fitting onto sheet metal.  It's a specialized pop rivet called a "Rivnut".

 

You set it like an ordinary pop rivet, but it's threaded internally so you can run a small machine screw (6 or 8 diameter) into the rivet's center.  I've used it to replace a hogged out sheet metal screw hole where I didn't want to use a larger screw.

 

mike

 

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1 hour ago, PhilC said:

Following with interest as I plan to fit an in tank pump. The one I think I will go with simply fits with self tapping screws, a gasket and some sealant. I think trying to get a tapped and threaded ring onto the inside is impossible as it would need to be larger than the hole itself.


You use a ring that is almost a complete circle and rotate it into the hole. 
 

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Be aware that the float/arm type level sensor may end up with a bouncing needle on the dash gauge.  I've seen this happening.

The original design and the late model in-tank pumps with level sensor have what is called a "stilling well" surrounding the float.  Fuel in the tank sloshes when cornering/accelerating and decelerating.  Fuel level at the float location will rise and fall.  The stilling well slows the rise and fall of fuel in it so the dash needle doesn't bounce.

Just my 02cents.

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Worth at least a dime, Jim.  Some capacitance across the circuit at the gauge input might kinda sorta simulate the de-sloshing effect of the surround, but there must be a good reason for the physical method, and circuit analysis or cut-and-try electrical engineering would be needed to determine how much C to install.

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20 hours ago, LindrelT said:

The Speedhut 4in1 allows you to program the fuel gauge to the existing sending unit…. easy process.  And yes, my speedo is GPS which covers getting correct speed with my 245 and 3.91 rear end.  In my ‘71:

 

432B5EBA-BF73-413B-BFC2-CB389F5E727D.thumb.jpeg.165d839dab1e1b1a5a4e2f85c97cc99c.jpeg

 

8D4E98C3-23BD-4DF1-BDA9-6CD1E869087A.thumb.jpeg.777bcdc1bd3489bd63648a3270b9d36d.jpeg

 

 

Are those canbus?

 

Answer ...no

 

Edited by Dudeland
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