GregP

Is anyone else having problems with Gaffrig Red Line gauges failing? I am having recurring problems with my redline oil pressure gauges. I e-mailed Gaffrig (both of them actually since I can never remember which Gaffrig is which), but only got a reply from the one who doesn't make my redline gauges.

Last fall I had the first gauge failure. The gauge would read off the scale for high pressure and the low pressure light would illuminate at the same time. The gauge would do this as soon as electrical power was applied, with or without the engine running. I "verified" it to be the gauge as if I connected another gauge into the same circuit (even did it at the same time) the other gauge (also a redline oil) would read normally. I also have a mechanical pressure gauge on the engine which showed the pressure was normal. As a final test, I bypassed all the boat wiring and ran a jumper wire direct from the sender to the gauge with the same results.

Since I was pretty well convinced it was a bad gauge, I replaced the gauge and it worked for about 4 running hours last season. This spring, after about 2 hours of running time, the new gauge has started reading about 25 psi high (I can compare it to my engine mounted mechanical gauges, also it will read 25 psi when the engine is not running but electrical power is switched on), again with the low pressure light also illuminated. Just for grins and since I had one on the shelf I put in a new Gaffrig sender. The problem went away ... but came back on the second run out on Sunday. Since the problem appears to be intermittent I restarted the motor several times to see if it would correct itself, but kept getting the bad readings.

Knowing that the oil pressure was really ok (I checked my mechanical gauge) I went out for a short run with my daughter anyway (just can't say No to your kids, can you). Made the usual idle out and a couple of minutes after getting on plane the gauge suddenly started to read "correct" pressures and the low light went out. It worked fine the rest of the time out and during the idle in. Did a couple more re-starts during the engine flush and it kept working fine.

This gauge failure is slightly different than the first, as it does "react" with true oil pressure variations, but reads high. The prior gauge just read off the scale with no movement with actual oil pressure levels.


Is there any signal value which should cause the gauge to read both low warning and higher than true pressure at the same time? Has anyone similar problems with this gauge series?

One of my fuel gauges also has this intermittent off-scale high combined with low level warning light behavior (it will also sometimes read suddenly empty), but I have always attributed it to a bad sender. I have never tried to replace the in-tank unit to check it. I am beginning to believe that this is more likely also a problem with the gauge now that I've seen the same behavior with the oil gauges. I have run a bypass wire from the tank at the dock to see if it was a bad connection or wire, but everytime I did "anything" it would fix the problem for a while, then come back.


The first gauge had a couple of years of use before failing, the latest gauge is essentially brand new. If I can't isolate and eliminate these problems I will have to switch out the entire panel to some other more reliable gauges as I'm getting tired of never being able to know for sure if they will work or not when I want to go out for a ride.

-Greg

Budman

Did you also run jumpers for the hot and ground terminals? This would rule out a problem with one of those circuits. I know you would expect to see all of the other gauges acting up as well, but sometimes electrical problems are weird.

GregP

No, I only bypassed the signal. All the grounds and hots tested ok with my digital VOM, and all the gauges are tied together at the panel for that engine.

At one time I had the grounds for both electrical systems tied at both the motors and at the panel, but I measured a couple mili-volt difference at the panel when I removed the tie so took it off to eliminate the possibilty of a ground loop.

Since the oil gauge and fuel gauge both act up, but at different times, and the water temp, oil temp, tach and volt gauges all stay ok, I guess I find it hard to believe it is a power or ground problem.

-Greg

Mbam

Assume nothing

arks

My money is on a bad ground to the gauges.

GregP

But why only one gauge, and it checks good with the meter? I'll take another look at the pins in the engine connector but don't expect anything. Guess I can take the old gauge and hook it up to power and signal and no ground just to see if that makes it read high and low at the same time.

-Greg

Helmwurst

Make sure that the gauge wiring on the ground side has a clean connection all the way around the ring lug. Even a small bit of shrink tubing or corrosion can make just that one gauge fluctuate.
You may also have a cooroded or partially broken wir on the ground side that is effected by the vibration.

Helmwurst

Also make sure that there is no teflon tape or pipe dope on the threads of the sending unit.

GregP

There is no tape or dope used on the sender threads.

All the gauge grounds are daisy-chained at the panel and the oil pressure is in the middle of the chain. All the panel wiring is new from when the panels were changed about 2 years ago. I checked for a loose terminal crimp, but they all look ok. All terminals are ring bolt type, so it isn't a loose "plug" terminal.

The wires might be long enough to swap the ground from the oil gauge with another to see if it migrates ... although since I can't always reproduce it it is hard to tell what "works" or not.

-Greg

Scott

I have the same problem with one of my oil gauges. This has been an on going problem for me. I have tried most of the above and come up with nothing. I have talked to Gaffrig and they don't have an answer. What I can't figure out is why would the light come on when it is set for 10lbs or less while the needle shows presssure all over the place. I of course have run a machanical gauge to make sure that I do have normal pressure. I have switched the senders I have replaced the gauge. The only one thing I have noticed is that it seems to only act up when heated up and running. If I shut down and restart it may go away for an hour or may come back right away (very intermittent). I plan on sending one of my defective gauges back to Gaffrig. I may copy this thread and send it along with the gauge.