Hard Starting 912

[Ian]

Is the Fuel pump you tallk about a special one for priming or just a normal back-up one. (Like the ones so many guys have fiited just in case?)
If not, them what do you do WITHOUT the pump?

Its an American automotive pump, in line with the fuel line. It's the back up. The mechanical pump on the motor is gravity fed - hi wing with tanks in the wings.

Cheers ian

[Stephan van Tonder]

Yup - good old facet diaphragm pump. Most decent spares shops stock them.
http://www.aircraftspruce.com/catalog/e ... tpumps.php

[Morph]

Friday or Sat I planned to install the electric pump, but at 37 deg celsius, you couldn't take longer than 20 minutes in the hangar

Sunday morning I decided to rather fly, pulled her out. MAGS OFF- I hand rotated the prop to pump the oil back into the reservoir so I could check levels eventually "Buurrrppp". The 10 or so turns did nothing to get rid of the air bubble in the fuel filter. I then checked the battery voltage before starting 13.4V. Mags off, throttle and choke closed, cranked her for 10 seconds, to get oil pressure up. Mags on, throttle closed, choke open, "Clear Prop" urgh- ahuh-uhuh-uhuh-uh-frikken-huh

I took a battery booster out of the car, even though the new plane has a new battery and a new rectifier. Plugged in in parallel to the battery, "Clear Prop", urgh- ahuh-vroooooooommmmmmm . once started and warmed slightly, restarts easily.

Ok so to me it is still inconclusive I still suspect that it is not the battery per se but that little boost just got her cranking quicker to get the fuel to the carbs quick enough.

Now this Friday I will install the electric pump, yes a Facet, initially inline with the rest of the fuel system, if that doesn't help then I will install it in parallel ala, Mogas' design.

Until then, frikken sh!t wind, hazy conditions and Saturn is not lined up with Uranus

[Stephan van Tonder]

Perhaps do a voltage drop test over your wires to the starter. You might see that 13.4 sitting at the battery but I have often seen a fairly huge drop over the wires on older wiring in cars before. Even a slightly bad earth connection can cause a massive drop. So do the voltage test at the starter with the mags off and see what it falls to while cranking.

[Morph]

Perhaps do a voltage drop test over your wires to the starter. You might see that 13.4 sitting at the battery but I have often seen a fairly huge drop over the wires on older wiring in cars before. Even a slightly bad earth connection can cause a massive drop. So do the voltage test at the starter with the mags off and see what it falls to while cranking.

New wiring, plus less than 20mm between the battery (back of the firewall) and the starter. But worth a check

BTW once started the voltage os measured at 14.5-14.7 V, as expected so a nice charging voltage. Also the starter does not sound like it is dragging at all, cranking the motor lekker

[bluesmancoops]

to my non-technical mind it definitely sounds like fuel problem - I think the pump will solve a lot of the problem if not all of it.

[German]

Cant you clip off the bowls and check the fuel level before starting?

[Trikenut]

So, this is the pump like the one, John Young and all the others installed?
Also, is it reccomended to fit a fuel pressure gauge to a 912 trike? (If you have panel space of course!)
Ciao
Ross

[Ian]

Also, is it reccomended to fit a fuel pressure gauge to a 912 trike? (If you have panel space of course!)
Ciao
Ross

Yep, the 2 instruments that make me comfortable (apart from airspeed ) is the fuel flow and fuel pressure. You watch the fuel pressure guage as you switch on the elec pump on a hot start, watch all the gasses get out then once it's stable you know the 912 will start fine.

Cheers ian

[John Young]

to my non-technical mind it definitely sounds like fuel problem - I think the pump will solve a lot of the problem if not all of it.

Hi,

I agree. Not quite a year with my 912 yet, but getting the hang of it.

I screwed-up twice (you twit) by having my right foot on the throttle just enough to have the enricher bypassed when I cranked. This is not the case with Morph da Boss and it most certainly won't happen to me again - you twit.

Recently, I have very consciously keep my foot off the throttle but ready and "wallah" - starts within half a revolution.

Morph da Boss - for info, with no flying for a week, facet pump will run for 3 secs before quietening with pressure. That's a lot of fuel. No flying for 1 day, facet pump will run for 0.5 secs.

Hope this helps.

Regards
John ZU-sEXY

[Trikenut]

Thanks Ian!

[tandemtod1]

Hi Morph,
It sounds like you are making all the right moves to solve your hard starting problem and I am probably going to tell you about things that you already know, but just in case, bear the following in mind:
The battery voltage is not as important as the cranking speed of the engine, Below 220rpm you won't get a spark. I have generally found that below 300rpm the engine is not a good starter. Check your rev counter while you are cranking to verify that you have 300rpm or better. If it's cranking well but still won,t start, then it simply is a case of insufficient fuel. If the engine starts well when it is warm, then the problem can only be the starting carburettor. To isolate the problem, take the air filters off prior to the first start of the day and sqirt a good dollop of petrol into the throat of each carb, replace the filters and try a start. If it fires up OK then you know it.s your starting carbs. About four or five years ago a whole bunch of choke arms were manufactured by Bing with the dot stamped on the wrong side so all of these carbs were assembled with the chokes farce about ace. These engines were very difficult to start when cold and the solution was to reassemble the chokes backwards. You can get more info on this from the chief Apache at Aviation Engines. If all this checks out, then the jet in the float bowl that feeds the starting carb is blocked.
Hope this helps because nothing ticks me off more than a frigging engine that won't start on cue.

[priester]

Apache

[Low Level]

Sorted ??

[Morph]

Not yet,

I have installed the standby electric pump. Switched the pump on THUMP THUMP THUMP THump Thump thump thump thump

"Clear frikken prop" Ur-huh huh huh huh huh huh huh huh"
try again "VROOM"

So nothing definitive yet