Facet fuel pump

Currently doing a few mods to a-4. It had a Christen wobble oump as an aux pump for 25 yrs...since new. I don?t want to wobble if the engine mech pump fails. I?ve removed the pump, installed an elec Facet plus a new Van?s gascolator and selector valve. The Christen has all above parts as part of the pump. Also disabled the primer, as the Facet does that job.

PROBLEM: Now the engine won?t start.
QUESTIONS:
1. On average, how many seconds do you turn on Facet to prime before starting?
2. Do you hear a noise change in Facet when engine is being primed? I heard no change.
3. No gas ?overflow? on the ramp from carburetor .....as if the engine was flooded.
4. After priming for about 15 seconds, while trying to start engine it gave me a sensation of being flooded.......meaning the prop turned slower....as it seemed to be flooded/loaded up. Battery is good.
My friend on the ramp while I tried to start engine thinks the engine is not getting fuel, because there was no gas on the ramp. I ran out of daylight yesterday, so I put the plane back in the hangar.
Should I prime for 6-8 seconds and then see if gascolator has fuel by trying to drain via the quick drain?
The engine always started easily with the Christen pump setup....only used the primer when engine was cold.
What?s going on here? All comments/advice appreciated much.......Marv

How to ?prime a carb?

Boost pump pressure just assures the float bowl is full. I have a solenoid valve piped to #3 cyliber for priming while the pump is running. Prime 2 or 3 seconds with pressure and it always lights if I remember to turn on the ignition .

Is it possible your wobble pump was overpowering the float needle and effectively priming the same way accelerator pump strokes with the throttle would accomplish? Not that it is recommended for potential fire concerns, but it should start pumping the throttle while cranking if the float bowl has fuel. Do you know the facet is really pumping fuel ?

Just to follow-up. You noted that you disabled the primer. What type of primer was installed? The Cessna-style plunger?

As mentioned above, the fuel pump doesn't serve as a primer on a carbed engine. That situation only applies to fuel injected engines.

Hmmmmm. I'm confused. My primer setup has a primer nozzle inserted in the #1 cylinder intake at the threaded hole Lycoming provided for that purpose. I used to feed that with an Essex (Cessna-style) manual pump and it worked really well even in frigid weather. I had to blank off the Essex pump because it was allowing air into the cylinder and I didn't want to mess with rebuilding it. I plan to replace that pump with a "prime" solenoid fed from the outlet of my Facet boost pump which feeds the carburetor. So when I needed to prime I would turn on the boost pump then open the solenoid for a few seconds, which would squirt some raw gas into the #1 cylinder intake. From your description, it sounds like your boost pump is just boosting the pressure to your carburetor. That's not going to prime your engine at all.

snopercod said:

Hmmmmm. I'm confused. My primer setup has a primer nozzle inserted in the #1 cylinder intake at the threaded hole Lycoming provided for that purpose. I used to feed that with an Essex (Cessna-style) manual pump and it worked really well even in frigid weather. I had to blank off the Essex pump because it was allowing air into the cylinder and I didn't want to mess with rebuilding it. I plan to replace that pump with a "prime" solenoid fed from the outlet of my Facet boost pump which feeds the carburetor. So when I needed to prime I would turn on the boost pump then open the solenoid for a few seconds, which would squirt some raw gas into the #1 cylinder intake. From your description, it sounds like your boost pump is just boosting the pressure to your carburetor. That's not going to prime your engine at all.

Click to expand...

Your solenoid valve setup is pretty much the standard for Carb'ed RVs (from what I have seen). Mine is setup in a similar fashion.

Not to offend, but 1st be sure the Facet is pumping the right direction. It's not that hard to install one backward, if you get distracted.

2nd, be sure it's pumping and fuel is actually flowing. You made a lot of changes at once; verify that all the mods were done right by removing the fuel line at the carb & running the Facet while looking for boosted fuel flow. (With full tanks, you might get some flow without the pump running; with <~1/2 full tanks, no fuel will flow without the pump running.) Don't forget that there's a 'final filter' in the carb inlet fitting.

3rd, as others said, all the Facet will do is fill the float bowl. You can check for fuel in the bowl by simply 'pumping' the throttle (full strokes) repeatedly. If the bowl is (was) full, you'll see fuel dripping out of the cowl after 6 or 8 strokes of the throttle (accelerator pump in carb is squirting raw gas into the carb throat).

4th, in less than freezing weather you can usually use the idea from item 3 to prime the engine. Start cranking, then pump the throttle (full travel) 3 or 4 times while cranking.

Bonus item: Given that 1. the lowest fuel points in a -4 are the tank quickdrains, 2. the fuel (and any water/dirt) must go up to about 1/2 tank level to get past the selector, 3. the gascolator sits in the hot exit air from the cowl (very effective fuel heater), 4. I already have a fuel filter to protect my fuel flow sensor: After a very uncomfortable (and costly) vapor lock incident, I eliminated the gascolator from my -4.

Now, I'd never tell you to do as I have done, of course.

Charlie

In Canada it is a mandate to have a gascolator. In my 4 I had no primer. My carb had an accelerator pump. Always started fine even down to -8C (the coldest I have flown in, -14C at altitude). Never a vapor lock incident even in our occasional +30C days. I always use 100LL.

Cold starts in hot weather - Boost pump ON till fuel pressure indicating then OFF, 2 quick shots to FULL throttle while cranking. Cold starts in cold weather (engine always preheated) - Boost pump On till pressure indicating then OFF, 3-4 quick shots to FULL throttle while cranking. Would start every time in the 4 years and 450 hrs I had the plane. (O-320 with MS-4 carb). Since starting to fly my O-360 powered 7 with an MS-5, in July 2017, I start it in exactly the same way. It also has no primer. Through one full summer and winter and the start of another winter, 210 hrs so far, it has always started within a couple blades just as my 4 did.

When doing my preflight I always turn on the boost pump when I sump the gascolator. This pressurizes the system and is a good way to check for a leaking drain valve. You will hear a change in the pitch of the pump when the drain is open as you sump and you should get a good flow of fuel. I use a GATS sampler jar in order to get a larger fuel sample. FWIW.

Al

primer switch

In my setup I have a 2 position switch with the second position spring loaded to a primer solenoid valve which goes straight to the cylinder port. I turn on the facet pump and when it stops ticking (the carburetor bowl is full) I hold the primer position for about 4 seconds. I do this hot or cold and the motor seems to start pretty reliably.

I thought this was the standard setup so it is interesting to see all the other approaches in this thread.
Figs