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Do you use your primer for startup?

AndyRV7

Well Known Member
I don't because I can't figure it out. I generally feed throttle in after I begin cranking. Usually it doesn't start until the second try. But it is pretty consistent. If the engine has been run, like after fueling en-route, I leave the throttle off and it will start without adding fuel, then I keep it running with throttle advance. This is in the winter or summer.

For some reason, once in a while, I feel like I should try the primer. I give it a quick squirt of about a second or two,, then crank the engine. It doesn't start so I move the throttle off the stop and it still won't start. But now, I am lost. I'm never sure at that point if I've flooded the engine or what. So it is all trial and error from that point on. And then I go back to not using the primer for a few weeks before I try it in vain again at some point.

Do you guys have a procedure that works? I'm carb'ed on an O-360.

Thanks. Andy
 
Yes

Andy
Same setup 0-360 carbed, I normally crack the throttle, turn on the boost pump and hold the primer switch for approx 4 secs, engine generally starts right up. I do this hot or cold. Just 1 data point.
Figs
 
Andy,
First off, find out and understand what primer system you have and how it works. Some are 1, 2 ,3 or 4 cylinders. so understanding how yours works will help.

I have a 4 cylinder system with the vans solenoid valve, my hangarmate has a 3 cylinder set up as well......when cold like 30 or below, we push the button for 3 to 5 seconds. when it colder, we will stroke the throttle while cranking if it doesn't fire off right away.
 
Do you guys have a procedure that works? I'm carb'ed on an O-360.

0-320 instead of a 360, but the process should be the same...

I found a crack in one of my primer lines right above a hot cylinder after about 100 hours of flying, fortunately before it could cause a scary mishap. I promptly removed the primer system entirely and have never looked back.

Even in cold weather flying, so long as I get the engine to 40-50F beforehand (the absolute minimum temperature I am comfortable starting with*), my carb'd 0-320 with slick mags will start right up. My procedure is to start cranking the engine, immediately follow with one full throttle application to activate the accelerator pump (still while cranking), immediately followed by returning the throttle to just barely open. Almost always it starts on the first try, just as I'm pulling back the throttle.

*(I'm not saying this is the only way to do it, but I follow Mike Busch's adage that goes something like "starting an engine without preheat below 40F is a misdemeanor and below 32F, a felony.")

Again, though, I've never regretted not having a primer system since I removed it. YMMV. Good luck.
 
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I've got a carbureted O-290-D2 and I capped off the (Essex) primer because it was leaking air into Cyl #1. When it was working, I would give it one squirt in 70F weather, and 4 squirts in 30F weather. It worked great. Since I've capped it off, I pump the throttle to get it started. It starts easily in warm weather but, at 30F OAT, once I almost drained the battery getting it started while pumping the throttle. These days I plug in my oil pan heater if the OAT is going to be lower than 40F. I hope this helps.
 
Thanks guys. Sorry, I thought we all had the same primer. Mine is an electronic 4-cylinder type that works off a momentary switch. I guess I am not missing anything by not using it. And I too have had the primer lines break off. I guess I don't use it much because of that. I'd hate to be dumping raw fuel into the cowl.

Next time I change the oil and have the cowling off I will try some of these suggestions. It take me a good 3 hours to change my oil, so the engine will probably be cold again. We'll see.
 
Primer

The four cylinder Lycoming with carb primes directly into the cylinder from above. So every shot of prime washes a bit of oil from the cylinder.
I do not have a primer on my 0 320 non RV. Engage the starter with the throttle at idle, as soon as the prop moves one quick pump of the throttle and then quickly to throttle barely cracked. All this has to be quick because the engine usually fires on the second blade.
 
Andy
Same setup 0-360 carbed, I normally crack the throttle, turn on the boost pump and hold the primer switch for approx 4 secs, engine generally starts right up. I do this hot or cold. Just 1 data point.
Figs
This is the same procedure I use with my O-360. The engine normally starts well before the 2nd turn of the prop. YMMV

:cool:
 
The four cylinder Lycoming with carb primes directly into the cylinder from above. So every shot of prime washes a bit of oil from the cylinder.
I do not have a primer on my 0 320 non RV. Engage the starter with the throttle at idle, as soon as the prop moves one quick pump of the throttle and then quickly to throttle barely cracked. All this has to be quick because the engine usually fires on the second blade.

Totally false information. The O-320/360 engines are not direct injection engines. The primer/injection port is located before the intake valve. No washing of the cylinder is possible.
 
Had an o-360 on my 6 and installed the primer to cyl's 3 + 4. Used #3 braided teflon hoses so as to avoid the cracked line issue. Only primed when cold. As in, first start of the day, and really only on cold days.

Fuel pump on,
primer pump momentarily on (3 sec or so).
Mixture full rich, throttle cracked.

Started first time every time.

Before that, I had a MA-3 carb on a Corvair engine in the Zenith. The MA-3 had a very effective accelerator pump, and so it was started by "priming" with two pumps of the throttle and occaisionally pumping the throttle while cranking. usually fired up right away too.

My $.02 is that either works fine, but I've never needed to do BOTH (inject prime AND pump), and didn't need either when the engine was warm. YMMV
 
I have an O-360. Boost pump for three seconds and then off. Engine starts within a few blades with no problem summer and winter.
 
Andy, have you looked into your ignition system?

Could that be the reason for your starting issues?
 
Andy, have you looked into your ignition system?

Could that be the reason for your starting issues?

Bill, I wouldn't say I have starting issues per se. At least not any I don't create myself with poor technique!!:D

I was really just trying to see if anyone else was using a primer system for starting the engine. More of a curiosity than anything else. But I got a lot of really good tips in here about starting in general and now I am looking forward to trying to improve my starts without having to use the primer on my engine.

I feel pretty good about my ignition though. I always get very consistent mag checks during run-up. Anything I can do to get it to fire up quicker has to be good for the battery and starter I guess.
 
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Andy - I am probably not much help. My 0320 on the Bucker has an Ellison which requires priming for cold starts. It?s plumbed to three cylinders and a manual plunger type primer. Three shots of the pump and it starts first blade every time.
It will not start cold without priming but that just might be an Ellison thing...
Good luck sorting it out.
 
Definitely inspect your priming system - that's a no-brainer, for many reasons. Definitely know and understand how that priming system works. Again, a no-brainer, as we should know how each system on our aircraft functions.

Once you've done the above, experiment with what works and what doesn't work. I've got about 120 hours on our "new" airplane, having operated it through two winters and one summer now. I'm STILL learning how it likes to be primed.
 
Thanks again guys. I just want to be a little clearer. I wasn't trying to solve a starting problem. My plane starts fine all the time. Maybe I could be a little better at the process but I don't have a "starting issue." I was more just curious about how to use the primer in other people's opinions, because I just never do use it.

I think half the reason is that I'm afraid of it. After you find a line or two has vibrated itself free of the engine, you really don't want to hope for the best every time you start sending fuel toward the engine. Also, unlike the Cessna plunger-type primers I used in my earlier flying days, you cannot tell if the solenoid is actually doing anything (or for how long it may have been doing something). That is, if there is any slack in the primer line before the fuel actually gets flowing, for example. You can never be certain how much fuel you are actually sending into the engine. Or worse, if the lines are even attached anymore.

As a byproduct of this thread, I am looking forward at trying some of the suggestions for improving my non-primered starting procedure!!

Thanks for all the advice!
 
Andy - I am probably not much help. My 0320 on the Bucker has an Ellison which requires priming for cold starts. It?s plumbed to three cylinders and a manual plunger type primer. Three shots of the pump and it starts first blade every time.
It will not start cold without priming but that just might be an Ellison thing...
Good luck sorting it out.

That's a really nice bird! Is that your daily flyer?
 
Thanks again guys. I just want to be a little clearer. I wasn't trying to solve a starting problem. My plane starts fine all the time. Maybe I could be a little better at the process but I don't have a "starting issue." I was more just curious about how to use the primer in other people's opinions, because I just never do use it.

I think half the reason is that I'm afraid of it. After you find a line or two has vibrated itself free of the engine, you really don't want to hope for the best every time you start sending fuel toward the engine. Also, unlike the Cessna plunger-type primers I used in my earlier flying days, you cannot tell if the solenoid is actually doing anything (or for how long it may have been doing something). That is, if there is any slack in the primer line before the fuel actually gets flowing, for example. You can never be certain how much fuel you are actually sending into the engine. Or worse, if the lines are even attached anymore.

As a byproduct of this thread, I am looking forward at trying some of the suggestions for improving my non-primered starting procedure!!

Thanks for all the advice!

Prior to completing my O-360 Powered 7 I purchased an O-320 powered 4 to learn taildragger. It was built in with no primer system. I flew it through 3 Canadian winters and 4 summers (450 hrs). Never a starting problem. Two quick shots to full throttle while cranking cold in summer and 3-4 shots cold (pre-heated) in winter. Started second or third blade every time. Just a quick half shot after a hot shutdown using idle cutoff.

I had intended on installing the primer solenoid on my 7 but removed it prior to completion due to my experience with the 4. The first 100 hrs was with a Rotec which requires a very different start/shutdown. The last 130 hrs with an MS carb through 2 winters on my 7, I start it the same way as my 4 and it starts just as easy every time. Both engines with dual mags...the 4 had Bendix and the 7 Slick with one impulse coupling.
 
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That's a really nice bird! Is that your daily flyer?

Ha!
It?s great on a nice warm summer day. It?s a hangar queen in the winter but I typically can get up once a month or so, but this winter has been tough.

The 6 is my workhorse. Almost twice the speed on less fuel and I have a heater!
However, the Jungmann is the only airplane I have flown that has better flying qualities than an RV, even a 3, (sacrilege! on this forum I know) although it can bite back on landing if you don?t show respect and you?re blind as a bat on take off and landing. RV?s are soooo friendly!

If I could only have one airplane, it would be an RV.
 
Ha!
It?s great on a nice warm summer day. It?s a hangar queen in the winter but I typically can get up once a month or so, but this winter has been tough.

The 6 is my workhorse. Almost twice the speed on less fuel and I have a heater!
However, the Jungmann is the only airplane I have flown that has better flying qualities than an RV, even a 3, (sacrilege! on this forum I know) although it can bite back on landing if you don?t show respect and you?re blind as a bat on take off and landing. RV?s are soooo friendly!

If I could only have one airplane, it would be an RV.

I understand completely. You really do need 3 or 4....or 7 planes to scratch all the itches!!
 
Two quick shots to full throttle while cranking cold in summer and 3-4 shots cold (pre-heated) in winter. Started second or third blade every time. Just a quick half shot after a hot shutdown using idle cutoff.

I've never been able to master this technique - it just cranks and cranks and cranks and I' afraid I've flooded it. Two questions:

1) How fast do you pump the throttle for those 2-4 shots?

2) what does the half shot at shutdown do?

Thanks
 
I've never been able to master this technique - it just cranks and cranks and cranks and I' afraid I've flooded it. Two questions:

1) How fast do you pump the throttle for those 2-4 shots?

2) what does the half shot at shutdown do?

Thanks

When I pump the throttle I do it very quickly. Both my engines start by the 2nd or 3rd blade. The trick is getting quickly to a nice 1000 rpm idle and not having a high rpm start. The half shot when hot gives it a little fuel for start since I ran out the fuel with the idle cutoff shutdown. Makes for a quicker start in my experience.

I have found in the past that weak mags will give starting issues. I don't overhaul both mags at the same time and always have them checked prior to the 500 hr requirement.
 
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When I pump the throttle I do it very quickly. Both my engines start by the 2nd or 3rd blade. The trick is getting quickly to a nice 1000 rpm idle and not having a high rpm start. The half shot when hot gives it a little fuel for start since I ran out the fuel with the idle cutoff shutdown. Makes for a quicker start in my experience.

I have found in the past that weak mags will give starting issues. I don't overhaul both mags at the same time and always have them checked prior to the 500 hr requirement.

Hi Al. Thanks for the replies.

When you pump the throttle, say 4 times for example, do you bring it back to idle during the first three pumps? Or stop short - somewhere near the 1000 rpm position?
 
yes, I do use the primer system... installed on cylinders 1 & 2, used only when engine cold.
Fuel pump 1 (or 2) on, mom sw 3“ ON (watch the decrease in FP on gage and take note of change in pitch of the rattling FP), crack throttle lever once, push starter knob :)
When hot, just push starter knob...

This for a O-360A3A with dual Plasma II

(Jet? No thanks, don’t wanna give up either grass fields nor my 6 hours endurance)
 
Hi Al. Thanks for the replies.

When you pump the throttle, say 4 times for example, do you bring it back to idle during the first three pumps? Or stop short - somewhere near the 1000 rpm position?

The idea is to reset the accelerator pump for the next shot of fuel. Not that critical exactly where you pull the throttle back to. It is easier and quicker to bring it all the way back and just go stop to stop. If you only go part way you will only get a partial shot of fuel which may then require more pumps. Even pumping in the middle of the range should get you enough fuel for a start and then back to idle.

I would suggest that if your engine is that hard to start, both hot and cold, that you have another issue. Would be worth checking the complete ignition system, plugs, wires, mags, timing.

We had someone on the field that had a start problem develop. He went through all the above. Plugs all checked out ok on a tester twice. Mags checked and one was overhauled. Still impossibly hard to start. Replaced the plugs and starts like a charm. He also has no primer, just the accelerator pump and uses the same technique I do.
 
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