Well I dropped the airdog down today and installed my band new autometer electronic FP sending unit on the airdog today. Ran the wiring up spliced in longer line. Hooked the 12v ignition wire to the radio fuse. The 12v wire to illuminate the light is wired to the illum fuse. Then ground is grounded to the steering shaft mount. I crimped one of the grounds to the main ground wire, so I didnt have to run two lines. The gauge gets power goes through its start up cycle when the truck turns on but then slowly creeps to 100psi.

Anyone have any ideas on why its creeps to 100?

 

Gauge damping?

 

Air compresses, diesel might not, maybe bleed the air out and see what happens

 

Check your connector at the sending unit. If there is no connection, it maxes out the gauge.

 

Not sure what that means what gauge damping is. I had diesel coming out when I installed the sending unit so no air there. But I will double check the connections for the sending unit at the airdog maybe its not click in all the way.

 

Check the connection at the back of the gauge as well. I had that issue with my pyro when I first installed them. Start the truck cold and it idled at 1000 degrees. Start driving and it pegged out. The wire at the back of the gauge had come out of the connector and had a poor connection.

 

Probably talking about use of a snubber, the purpose of the snubber is to dampen the oscillations and thus provide a steady reading and protection for the gauge or sending unit.

Your situation almost sounds like the sending unit wire is grounded out. A typical sending unit uses a variable resistance to ground ( in ohms ) to determine the reading on the gauge, which has to have the same working resistance range. Old school way of checking electric gauges was to ground the sensor wire for a split second and watch for full sweep of the gauge to see if it was working or not.

 

Could splicing in the longer wire be the problem? If those guages use resistance to determine the reading, splicing in a longer wire would raise resistance. Connections on the splice could also raise resistance. I don't know for sure, just an idea...

 

Odd thing happened today. This morning the gauge was pegged at 100. Then stopped in at store came out, started the truck and the gauge did its start up sweep and then held at 17psi. Its been working ever since. I am still going to install a needle vavle on the electrical and mechanical fuel pressure gauges that I am using.

 

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RJ