Pneumatic Fuel Gauge

[LEB]

My 79 E25+ has a simple pneumatic fuel gauge made by Marcra Manufacturing of Costa Mesa California. I have no idea if it was original. I finally got it plumbed up with some 1/16" tubing but I can't get it to the zero and span set. I can only get about 30% pointer travel as i move the tubing from the top of a full tank to the bottom. There are two adjustment screws but fiddling with them hasn't helped much.

Wondering if anyone is familiar with setting these up or has useful documentation. I've had no luck searching for Marcra Mfg.

I like the simplicity of it and will be disappointed to replace it with an electric system.

 

[Glyn Judson]

Pneumatic fuel gauge.

Dear friend, I too origionally had the same gauge in our 1979 E31 and played with to no end because of its uniqueness. It turned out to be a real Pnenain in the arse and I finally replaced it with a standard electric one. I still have the device including the sending unit that I keep around for old times sake. The problem with it was that mine had a slight air leak and within an hour of setting it up, I'd come back to check on it and it would read E (empty). Such is life, maybe that's why they're no longer in business. If I were you, I'd be tempted to yank it and start over again with modern electrical hardware, as I did. Glyn Judson, E31 hull #55, Marina del Rey CA

 

[LEB]

would you indulge a couple more questions?

You mentioned the sending unit. I assumed that it was a simple dip tube. I gave up on that connection and stuck a new dip tube through a tee in the vent line. only then could i get the tubing to hold the signal for more than a day. Is it any more sophisticated than a simple tube?

Given the high probability that I will follow your example; did you have enough clearance between the cockpit sole and the top of the tank to perform the task with the tank in the boat?

 

[Glyn Judson]

Pneumatic fuel gauge.

Dear friend, It's a bit more than a dip tube. It has a 3" long, purpose-made PVC "bell" on the end of a 3/8" OD clear plastic tube. Email me back channel at glynjudson@roadrunner.com and I'll gladly send you photos of the thing. My tank is directly accessible from the starboard lazarette with plenty of clearance above it which seems not to be the case with your tank. Now that I think of it, we too had a 1979 E25+ hull #515 and that is right under the cabin sole. By coincidence I had to replace the electrical one in ours and remember having to remove it from its plywood base in order to slide it out enough to get room above the sending unit. Failing that, you could always install a nice beige Beckson plate directly above the sending unit. I'm sitting here looking at my Marcra sending unit and it measures exactly 12" in length, the same as any electrical sender would measure. Cheers, Glyn