Scott Hersha
Well Known Member
I need some help with a couple problems I’m seeing in my RV4. I have a 15 year old GRT4000 EIS, and a new GRT Horizon 10.1 EFIS in my newly updated panel. Here’s my issues:
1. First one is with my Hall effect current transducer not indicating what it should. I have it connected properly according to the manual, where it senses alternator output, as recommended. My indications are: after engine start I see 7-8 amps positive alternator output until the battery replenishes (way too low). After engine start and in flight, I see anywhere from zero to +2 amps, and every once in a while -1 amp. It should not ever indicate negative in my installation, and with everything operating, I should be seeing +12 to +15 amps in flight. This is the third airplane I’ve had with this Hall effect transducer, and none of them has ever worked. So it must be something I’m doing wrong.
2. Second issue has to do with indicated fuel pressure. I have a carbureted O-360 in my RV4, using a 0-30 psi VDO pressure sensor. It seems to be fine after engine start and while taxiing with only the engine driven pump supplying pressure, anywhere from 3 to 4.5 psi. On takeoff I turn on the aux fuel pump. After leaving the pattern I turn off the aux pump, still climbing at wide open throttle. The fuel pressure then slowly drops to zero - over about 30 seconds - and I get vocal and indicated warnings. If I turn on my aux pump, pressure comes right back up to normal - 2.5 to 4.5 psi. Turning the aux pump off again, still climbing, pressure falls to zero again. During this time with fuel pressure at zero, all other engine indications remain normal - EGT’s, CHT’s, fuel flow, and smooth engine operation. When I level off, with the aux pump off and pressure still at zero, the fuel pressure gradually returns to normal. Yesterday I replaced the VDO sensor with another one I had on hand that had seen very little use in my first RV8, and then went flying. This one behaved exactly the same as the original, except after leveling at 8000’ it just stayed at zero. I flew around for about 30 minutes and it stayed at zero. All engine indications were normal. When I started my decent, the pressure gradually stared coming back up, and by the time I was in the traffic pattern, it was back to 4.5 psi. Aux pump stayed off. My engine driven fuel pump witness tube has never had anything come out of it. I don’t want to buy and install a new engine driven pump if there is nothing wrong with mine. For one thing, besides the cost, getting that pump replaced is very challenging due to very limited access in an RV4. This problem has been discussed before on this forum, but I don’t know of anything ever being resolved.
If you have experience in either of these two areas, or can make suggestions, please do so.
Thanks....
1. First one is with my Hall effect current transducer not indicating what it should. I have it connected properly according to the manual, where it senses alternator output, as recommended. My indications are: after engine start I see 7-8 amps positive alternator output until the battery replenishes (way too low). After engine start and in flight, I see anywhere from zero to +2 amps, and every once in a while -1 amp. It should not ever indicate negative in my installation, and with everything operating, I should be seeing +12 to +15 amps in flight. This is the third airplane I’ve had with this Hall effect transducer, and none of them has ever worked. So it must be something I’m doing wrong.
2. Second issue has to do with indicated fuel pressure. I have a carbureted O-360 in my RV4, using a 0-30 psi VDO pressure sensor. It seems to be fine after engine start and while taxiing with only the engine driven pump supplying pressure, anywhere from 3 to 4.5 psi. On takeoff I turn on the aux fuel pump. After leaving the pattern I turn off the aux pump, still climbing at wide open throttle. The fuel pressure then slowly drops to zero - over about 30 seconds - and I get vocal and indicated warnings. If I turn on my aux pump, pressure comes right back up to normal - 2.5 to 4.5 psi. Turning the aux pump off again, still climbing, pressure falls to zero again. During this time with fuel pressure at zero, all other engine indications remain normal - EGT’s, CHT’s, fuel flow, and smooth engine operation. When I level off, with the aux pump off and pressure still at zero, the fuel pressure gradually returns to normal. Yesterday I replaced the VDO sensor with another one I had on hand that had seen very little use in my first RV8, and then went flying. This one behaved exactly the same as the original, except after leveling at 8000’ it just stayed at zero. I flew around for about 30 minutes and it stayed at zero. All engine indications were normal. When I started my decent, the pressure gradually stared coming back up, and by the time I was in the traffic pattern, it was back to 4.5 psi. Aux pump stayed off. My engine driven fuel pump witness tube has never had anything come out of it. I don’t want to buy and install a new engine driven pump if there is nothing wrong with mine. For one thing, besides the cost, getting that pump replaced is very challenging due to very limited access in an RV4. This problem has been discussed before on this forum, but I don’t know of anything ever being resolved.
If you have experience in either of these two areas, or can make suggestions, please do so.
Thanks....