This gauge replaced a combo electric pressure/volt gauge that ground the sender via the engine and used one wire (via a threaded stud terminal) to go to the gauge. My gauge ground lead is going to a clutch cover screw, so it is a good ground. The GSX engine has very limited room below (not under) the ignition pickup cover- the OEM warning light sender does in fact mount under this cover internally. If I used a 16mm x 1.5 (main gallery plug thread) to 1/8 pipe adapter the bullet terminals would stick out too far. I used a 90 degree fitting on the prior sender but the new one is a larger diameter and longer due to the bullet terminals, so it just would not fit there. The -4 hose was the best solution I could think up given the space limitations. I used PTFE hose since I found a good deal locally for the hose assembly.
I tested the ground wire and got a solid ground. I tested the sender between the terminals with wires disconnected and got .4 ohms with the engine off, and then started the warm engine and ran it on fast idle at around 2500 RPM, which should give close to 100 PSI on the old sender. I got a reading of 23.58 megaohms. I looked up some common 0-100 PSI senders and the ones I saw listed were 240 ohms @ 0 PSI and 33 ohms @ 100 PSI. I tested the old sender and got 235 ohms (0 PSI). I suspect the sender is defective but will confirm the Revo numbers with the seller. If it uses a regular 240-33 ohm sender, I can use a spare unit I have here.
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