Low Fuel Pressure Indication

The fuel pumps are constant displacement pumps.
This means that it is theoretically possible to produce enough pressure to blow the walls out of the hoses or the casing off the pumps.
If you replaced the fine filter with a pressure gauge, you dead-ended the pumps and the 90 psi you saw was the internal pressure relief valves within the pumps bypassing to save the pumps.
The pumps are good!

You have a sending and/or display system problem.
The UMA N1EU70D sender should be 0-70 psi (0.5-4.5v) with 0psi=0.5 volts and 70psi = 4.5volts output.
Easily confirmed with a Voltmeter.

Are you sure the Garmin is configured for a 70psi sender and does not think you have a 50 psi sender?
4.5v =50psi?

Bill,

I think his pressure reading was correct for the first 100 hours, and then recently he saw a steady decline in the reading, now down to 16 PSI. So, I don’t think it’s a programming problem.  I do agree though that it’s probably the UMA sender or possibly (less likely) the Garmin GEA-24 interface that is failing.  I had a GEA-24 that developed an error in the 5v reference voltage, which had dropped to 3.5 volts causing a similar error.  Garmin replaced it and problem solved.  

Jeff,

When you had the Garmin unit failure, was it just fuel pressure indication failure or did you see other engine parameter issues?

Scott

Scott,
It was only fuel pressure, and I was seeing about 36 psi when it was actually 43 psi.  Your problem is much more likely the sender or the wiring to it,  and it’s much easier to start there. With a simple DC volt meter you can check the both the reference voltage on the GEA-24 and the output voltage of the UMA sender, but if you don’t have access to a mechanic/tech who knows how then you may be stuck with first replacing the sender and going from there. I hate replacing perfectly good parts, but in your circumstance it may be the lowest cost approach.  

The sender is on its way now from the USA, along with the pins and crimper tools to remove and replace the weather pack connector wiring.

I should have the parts here in Jamaica next week.

I had planned to leave Jamaica two days ago and fly to Florida for the Sun n Fun show.

I'll miss the show this year.

Really hoping that this part fixes my problem.

Thanks again for your advice!