Bad gas

svyolo

svyolo

Junior Member
Out practicing T&G's today I got a fuel pump amp draw warning. My EFI pumps normally draw 5-6 amps. I have a warning set for 9 amps, and they are on 15 amp fuses. Both pumps were drawing the same amount of power (9-10) when I switched, I was guessing clogged filters. I have a 40 micron filter before the pumps, and 10 micron after the pumps.

When I got on the ground and parked, the pumps were definitely louder than normal, and vibrating more than usual. There was definitely debris in the 40 micron filter. I will clean them with car gas in the morning.

I thought about a diff pressure transducer, or an ammeter. I chose the ammeter as it was simpler. Seems like it worked as I had hoped.

This would also work on a boost pump for Bendix style FI.
 
Definitely had a dirty 40 micron pre-pump filter. 10 micron post filter was clean. I drained the left wing tank, through a 10 micron filter to see if it was dirty, and filter it. Good news it was filtered. But it does NOT appear to be bad or dirty gas.

I cleaned the fuel lines quite a bit before the first flight, and cleaned the filters. I also cleaned the filters at 10 hours. I think that is the last I cleaned them. I am at 83 hours now.

There was a small amount of metal slivers in the filter I cleaned. Mostly very small particle black stuff. Could be either fuel line muck, or fuel pump impeller.

EFI is a return system, in my case to a 2 liter header tank under the left front seat. At cruise the fuel probably makes 4-5 round trips through the fuel system. Cold side of the firewall is aluminum tube other than 8 inches in the wing root which is Aeroquip. Everything north of the firewall is Aeroquip lines.

Reinstalled and ran the pumps. Back to 6 amps draw. I wonder if it was the fuel lines, or impeller. Annual coming up. Maybe replace one pump, the one I have been running on, and take it apart and check the impeller. EFI pumps are cheap, 130 bucks last time I checked.

I have been running only 100LL. I was just about to make the switch to MOGAS.
 
5-6 amps is normal. I set the alarm for 9. Fuse is 15. I only have an ammeter on the primary pump, but I also have one for total bus amps.
Switching pumps the total bus amps was the same so i knew it wasn't the indication or pump.
 
how are you getting your amp reading? Are you using a VPX, or did you set up a stand alone amp meter on the fuel pumps?
 
Stand alone Hall Effect thru a GRT engine monitor, displayed on GRT 10 inch screen. VPX or similar allow for really easy amp/volt troubleshooting. SDS doesn't recommend VPX or similar as they haven't tested it. Software interacting with other software. I kind of agree. NOthing against VPX of other Electronic Circuit breakers. I like them. Actually I like them a lot.

My electrical system is a Littlefuze fuse/relay panel. Airplane circuit logic. Aeroelectric Connection.

My 40 Micron filter was clogged, although not easy to see visually. 10 micron post pump filter was clean.
 
You must log in or register to reply here.
Back
Top