AFS Fuel Pressure Problem?

Hello Everyone,

I got my AF-3500 hooked up temporarily today for the first time. It ran off ship's power and even accepted the data from my GPS496. The only problem was that the fuel pressure indication had a big red X through it. I had the correct wire connected to the fuel pressure transducer. I found that as I moved the ring connector on the transducer's terminal the X would disappear, then reappear intermittently. I thought maybe I had a bad crimp on my ring terminal, so I cut it off and crimped on a new terminal. Same result. The fuel pressure would work and read "0", then the gauge would get the red X through it again.

Have any of you had a similar issue? The ring terminal I crimped on is secure, but it almost seems like there is an intermittent contact inside the transducer itself. I used fuel lube on the threads of the transducer. Could that be interfering with the case to airframe ground?

Thanks for any help,

local ground

Maybe try temporarily grounding it externally, just to see if that's your problem?

Grounding Externally

I detached the transducer out of the manifold and let the case of the transducer rest against the manifold and firewall. The fuel pressure on the EFIS counted down to 0, then X'd out. That is the same thing it does with the transducer mounted in the manifold. When I attach the wire, the fuel pressure reading starts out high, counts down to 0, then the red X appears. I'm confused.

leak?

Sounds almost like there is an internal leak or problem with the transducer. I'd see if AFS will swap out the transducer.

The Gremlin is hiding.

I reattached the transducer to the manifold, reattached the wire to the terminal, and now it seems to work. I don't know if it will stay that way, because I can't say I did anything to fix it, but we'll see. I'll call AFS in the morning.