looking for rocket owners experience

[goodyFAB]

I hate to be the guy who posts a bunch of silly questions but I've got to ask since I have searched and have not been able to find an answer. The answers i've gotten locally really haven't answered my question. 

to the rocket owners:

when starting your engines do you find the engine needs much more fuel / prime than the starting procedure calls for ?

for example, when starting my cold tsio520NB last night I did my pre flight, which involves sumping the tanks and gascolator for me as I like to see what accumulates in my tanks before every flight (I mention this because I wonder if doing the gascolator allows fuel from the engine driven pump to leak back down thus creation air in lines or hard to prime situation), after the pre flight the engine fires right off, maybe a couple blades after a 6-10 second prime, mixture full forward, prop fine, 1/4" throttle. 

then comes the fun... I have to keep bumping the primer to keep the engine running, I saw my FF #'s lower than normal during this time, they did even out once it smoothed out but this took quite a few bumps until she evened out and ran fine. I made some high power run ups to confirm I wasn't going to go for a swim before dinner and off I went. However, if I didn't bump the fuel primer the engine would have died. this has me wondering if this is a sign of something more with the engine driven pump or its a standard operating procedure for the tsio520?

do any of you guys running the tsio520NB see this kind of thing as an issue or something that is normal for your plane? I have not owned this plane long enough to have an opinion so im looking for insight from people who have. last night was really the first cold start, any colder I would have pre heated it. 

[Yooper Rocketman]

I saw that exact same issue after my engine tear down and reinstallation this fall.  Having flown the plane for 17 years my first go around I knew this was unusual.  I suspected it was because there might have been air in my fuel lines from the R&R of the engine.  After enough starts this issue should have gone away I started looking over my fuel lines and found the line going through the rear baffling to my fuel spider was just finger tight.  It wasn't leaking fuel but on shut down it apparently was allowing air into the fuel system and the fuel was running back the supply lines.  My starts are completely back to "normal".

I would look for something allowing your fuel to run back from the engine.

Tom

[goodyFAB]

1 hour ago, Yooper Rocketman said:

I saw that exact same issue after my engine tear down and reinstallation this fall.  Having flown the plane for 17 years my first go around I knew this was unusual.  I suspected it was because there might have been air in my fuel lines from the R&R of the engine.  After enough starts this issue should have gone away I started looking over my fuel lines and found the line going through the rear baffling to my fuel spider was just finger tight.  It wasn't leaking fuel but on shut down it apparently was allowing air into the fuel system and the fuel was running back the supply lines.  My starts are completely back to "normal".

I would look for something allowing your fuel to run back from the engine.

Tom

I will take a good hard look, thank you 

 

[Guest]

6 hours ago, goodyFAB said:

I hate to be the guy who posts a bunch of silly questions but I've got to ask since I have searched and have not been able to find an answer. The answers i've gotten locally really haven't answered my question. 

to the rocket owners:

when starting your engines do you find the engine needs much more fuel / prime than the starting procedure calls for ?

for example, when starting my cold tsio520NB last night I did my pre flight, which involves sumping the tanks and gascolator for me as I like to see what accumulates in my tanks before every flight (I mention this because I wonder if doing the gascolator allows fuel from the engine driven pump to leak back down thus creation air in lines or hard to prime situation), after the pre flight the engine fires right off, maybe a couple blades after a 6-10 second prime, mixture full forward, prop fine, 1/4" throttle. 

then comes the fun... I have to keep bumping the primer to keep the engine running, I saw my FF #'s lower than normal during this time, they did even out once it smoothed out but this took quite a few bumps until she evened out and ran fine. I made some high power run ups to confirm I wasn't going to go for a swim before dinner and off I went. However, if I didn't bump the fuel primer the engine would have died. this has me wondering if this is a sign of something more with the engine driven pump or its a standard operating procedure for the tsio520?

do any of you guys running the tsio520NB see this kind of thing as an issue or something that is normal for your plane? I have not owned this plane long enough to have an opinion so im looking for insight from people who have. last night was really the first cold start, any colder I would have pre heated it. 

I’ve never worked on a Rocket, but have worked on enough 340,414, 421 series over the years.  I would say your not priming enough.  Throttle full open, mixture full rich, prime, pull the throttle to idle, crank the engine, it should start in a few blades.  All this of course depends on your ignition system being healthy and the engine fuel system being set up correctly.

[goodyFAB]

1 minute ago, M20Doc said:

I’ve never worked on a Rocket, but have worked on enough 340,414, 421 series over the years.  I would say your not priming enough.  Throttle full open, mixture full rich, prime, pull the throttle to idle, crank the engine, it should start in a few blades.  All this of course depends on your ignition system being healthy and the engine fuel system being set up correctly.

Mags are newly overhauled maybe 15 hours on them now- 

How long do you prime for ? (Duration)

[Guest]

2 minutes ago, goodyFAB said:

Mags are newly overhauled maybe 15 hours on them now- 

How long do you prime for ? (Duration)

4-5 seconds or until a good flow rate is shown on the gauges.  Generally Continental engine are more tolerant of and can use additional fuel, Lycomings less so.

[Red Leader]

I've got a K and have found the best procedure is to put the mixture full rich, prime for about 5-7 seconds then turn on the high-boost pump for the same amount of time. It seems to be the best method (for me) as my engine starts in the first revolution or two - much longer if I don't use the boost pump. Also, like you, if using the primer only, I also have to bump the switch a few times to keep it from stalling. My boost pump procedure seems to have resolved almost all my starting issues. Still hard to start when hot.

[goodyFAB]

40 minutes ago, Red Leader said:

I've got a K and have found the best procedure is to put the mixture full rich, prime for about 5-7 seconds then turn on the high-boost pump for the same amount of time. It seems to be the best method (for me) as my engine starts in the first revolution or two - much longer if I don't use the boost pump. Also, like you, if using the primer only, I also have to bump the switch a few times to keep it from stalling. My boost pump procedure seems to have resolved almost all my starting issues. Still hard to start when hot.

im sorry but we have one electric pump after the fuel valve in our planes.

what does the HIGH BOOST do differently than the prime ?

 

[Red Leader]

I believe the high-boost can take the place of the engine driven fuel pump should it fail in flight. Someone correct me if I am wrong.

 

[aviatoreb]

46 minutes ago, Red Leader said:

I believe the high-boost can take the place of the engine driven fuel pump should it fail in flight. Someone correct me if I am wrong.

 

I have heard - but I do not know if it is true - that the high boost pump is the original high boost pump from the original TSIO360 installation, and the fuel flow from it is for that smaller engine - so it is pretty low power for the bigger tsio520nb.  I am unsure if its enough to keep the engine running and maintain altitude.  Anyone know?

[aviatoreb]

3-6 seconds of prime with full rich and full throttle.  Then throttle to just cracked open a bit.  Mine starts in less than a half turn and I am in a habit of paying attention to the rpm's since if my cracked open is a tad too much which it may be I don't want to let the engine roar to life to more than 1000rpm so sometimes I find I am quickly backing it off a tad before the rpms spin up.  It all happens pretty quick.

[Yooper Rocketman]

The only time I ever needed to prime more than 6 seconds on a cold engine or turn on a boost pump after starting (in 1700 hours of Rocket time and hundreds of hours on big bores in Bonanza’s ) was when there was a leak in the fuel delivery system allowing air in the fuel lines.  

Just my experience!

Tom

[carusoam]

Probably a good time to read the documents for the engine…

This is a tough one…

Because the priming system of the M20K has been changed and updated over the years…

And… the Rocket uses a different engine….

 

By design… Mooney uses one pump, and labels switches for Hi and Lo… 

If you have a mechanical fuel pump failure… your electric pump is your go to source for getting fuel for T/O power…

 

In the ovation Hi is about 3X the output of Lo, maybe more…. The POH describes priming time ranges for both options…

PIC has to know what the OAT is and adjust the timing accordingly…

 

On a cold day… it may require running the Lo switch for a few seconds after start, to keep the engine from starving out….

 

Some a Rocket Engineering documentation is really good….

 

Some mechanics really know how to set up the fuel system in continental engines…  find that guy.

 

PP thoughts only, not a mechanic…

Best regards,

-a-

[Fly Boomer]

On 11/16/2022 at 10:44 AM, goodyFAB said:

then comes the fun... I have to keep bumping the primer to keep the engine running, I saw my FF #'s lower than normal during this time, they did even out once it smoothed out but this took quite a few bumps until she evened out and ran fine. I made some high power run ups to confirm I wasn't going to go for a swim before dinner and off I went. However, if I didn't bump the fuel primer the engine would have died. this has me wondering if this is a sign of something more with the engine driven pump or its a standard operating procedure for the tsio520?

Others will respond, but I have read that this is common.  Some use quick touches on the high boost switch to keep it going until it warms up a bit.  What was your ambient temperature, and did you pre-heat?

[Chessieretriever]

Check the external spider vent line for fuel drips once you are operating (someone outside has to do this). It does happen that once you have a small tear on the diaphragm of the spider plunger you are just not moving the same mass flow of fuel (dumping some overboard which can be seen on the vent line) and requiring the idle mixture to be richened to keep it idling or overcome this lower flow with intermittent primer pump squirts when richer mixture is required to operate (cold). This is not very common but has happened before  and it can be masked by tech's simply adjusting the fuel system pressures to compensate for the leak and provide idle speed stability (but not sufficiently off-setting the lower flow at priming conditions).

[goodyFAB]

just wanted to follow up with you guys, no fuel leaks found.. 

however , a good plugging in on the reiffe engine heater and its alleviated all my starting issues. when cold, this engine loves fuel.