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Grounding Pressure Senders

Bubblehead

Bubblehead

Well Known Member
I started having a problem with the oil pressure indication going high on my EIS 4000. I tracked it down to a poor ground from the case. Yesterday my fuel pressure started going up. I took the cowling off, disassembled the Adel clamp, scrubbed and cleaned the housing, re-clamped it and the problem is still there.

I have been using a small metal tab between the sender casing and the Adel clamp to attach a ground wire to. The tab has a hole drilled in one end to mount the ground wire to it.

Apparently my method is not very robust!

What are others using to ground the case of the pressure senders? Can the senders survive having a wire soldered to the casing? How about using a short length of grounding strap?
 
Bubblehead,

I installed my oil pressure and fuel pressure senders in a Van's manifold (aluminium thing with 3 lumps on it, each with 3 NPT ports) that is bolted to the firewall. The connection between the sender body and the manifold and the firewall has been satisfactory for around 300 hours.

Pete
 
Ground

penguin said:
Bubblehead,

I installed my oil pressure and fuel pressure senders in a Van's manifold (aluminium thing with 3 lumps on it, each with 3 NPT ports) that is bolted to the firewall. The connection between the sender body and the manifold and the firewall has been satisfactory for around 300 hours.

Pete
Click to expand...

Ditto above.

Grand Rapids generally uses VDO brand pressure sensors and in my experience they are not of the quality they once were. I had to replace my fuel pressure sensor and I did so with Grand Rapids high dollar alternative sensor.
($100.00+)

Make sure this is a sensor problem, not a grounding problem.
 
mannanj said:
Ditto above.

Grand Rapids generally uses VDO brand pressure sensors and in my experience they are not of the quality they once were. I had to replace my fuel pressure sensor and I did so with Grand Rapids high dollar alternative sensor.
($100.00+)

Make sure this is a sensor problem, not a grounding problem.
Click to expand...

I was on the phone today with Sandy at GRT regarding my fuel pressure sender which was sending an erratic signal. Search archives for recent thread. I found some debris that corrected it for a few days. But then it began reporting errors again. Sending 66 at engine start, then settled into ~16 in normal flight. Sandy said the $35 sender has a life cycle of 200-1000 hours. I had 400. She said it takes a lot of abuse. I ordered mine today. Sandy is excellent to deal with and shipping out today.
 
I also installed my pressure sender in Vans bracket. Oil pressure seems fine, but I had issues with the fuel pressure sender being erratic. I ended up temporarily using a short piece of wire with a ring terminal on one end (under a bolt head) and a cable clamp around the sender body holding the other wire end against the sender body. I have seen this other end soldered to the sender body in other installations, so one of these days I will probably do that also.

greg
 
Ground connection

I did the same as Greg. I stripped the ground wire and wraped it around the entire sensor and held it in place with an adel clamp. Fuel pressue is steady as a rock and no more low fuel pressure on climb out and high power settings.
 
Greg Arehart said:
I also installed my pressure sender in Vans bracket. Oil pressure seems fine, but I had issues with the fuel pressure sender being erratic. I ended up temporarily using a short piece of wire with a ring terminal on one end (under a bolt head) and a cable clamp around the sender body holding the other wire end against the sender body. I have seen this other end soldered to the sender body in other installations, so one of these days I will probably do that also.

greg
Click to expand...

I'm going to try this on the weekend before I install the new sender.
Will report back.
 
I used a ohm meter to check the ground on both the oil and fuel senders. The fround wire goes from the ground block to the oil pressure sender to the fuel pressure sender so I started at the oil sender. I got a good ground from the connection to the airframe so the ground wire was good, but I had a flaky ground between the sender case and the wire.

I soldered a pigtale onto the sender for oil pressure and connected it to the ground wire using a crimped connector and the ground got rock solid. Yesterday I flew for 2 hours and had rock solid and believeable oil pressures. It was a 70 or so degree day when I started the engine and had about 70 psi until the oil warmed a little. On climb out as oil temp increased pressure dropped to it's typical value of 63 during the climb out and stabilized at 65 to 68 during the flight with 210 degree oil. Very typical numbers.

The fuel pressure sender had a flakey ground too but I did not solder a pigtale on that sender. I took it out of it's adle clamp and used a "greenie" pad to clean the housing and metal tab that is supposed to ground the housing. When I reassembled it the ground was much better but still not great. I think I measured .1 ohm between the case and the ground wire. During yesterday's flight it was giving me close to normal readings but would fluctuate up to 100+ psi and then back to normal.

I gues it's time to solder a pigtale to the fuel pressure sender and see if that cures my problem. If not then it means I have a bad sender.

Perhaps instead of soldering a pigtale onto the case I could use a bulkhead type fitting and nut between the sender and the hose. I could use the bulkhead fitting/nut to clamp a piece of aluminum to use as a connection to the ground wire. I don't like soldering to the case because I don't know what damage I may be doing to the sender.

Any thoughts or ideas?
 
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