I bought the 170 a year and a half ago, it has an O360 Lyc, it started easily, just followed what the book procedure said and started usually on the first try (cold or hot)
Book Procedure is
Battery ON, Alt ON Fuel pimp ON, 5 shots of primmer, 25% throttle in, left mag ON, press start button.
Plane started easily but in cruise at low power setting ran bad, hiccups, rough, after trying a few things that did not helped, we replaced the carburetor, now it runs very smooth, that problem was fixed, but now it is very difficult to start, specially when cold, I follow this same book procedure and it wont start, also tried 6 primmer shots, 5, 4 and 3 and does not want to start, carb idle is as should be , also I get the rpm rise before the engine stops, when shutting down.
Now it starts after many tries and waiting a few minutes, pumping the throttle, while starting, or leave more than 25% in works after many attempts.
Any ideas on a fix for this? Definitely the book procedure does not work anymore.

Long stroke primer or short stroke primer?

Larry, the engine wants lots of fuel to start and wants to idle and run as lean as practicable. I leaned to max RPM at any DA, and even when air temp was cool. When hot, advancing the throttle more than what you normally do is allowing more air, and that is fine. If cold and you are having to advance the throttle after six primes, you have actually put too much fuel in and the open throttle is letting the butterfly get more air, the same as the hot start.

I ran the 0-360 in the Cardinal on the pipeline when a 172 was not available. I drank coffee all day and had a small bladder, so lots of hot starts. I primed about four shots when cold and pumped the throttle at least two times. When hot, outside or engine, I just pumped the throttle one or two times and did not prime. In high wing like Cardinal, the fuel pump did not matter as it was gravity feed. Like most smallish engines, getting fuel air mixture just right takes some iterations to get what that particular engine wants exactly, but once you have cold and hot parameters, you are good forever. Marvel Schebler is a good carburetor.

Just for fuel efficiency, we used 2500 rpm and 21 inches manifold pressure. We needed rapid transitions, so high rpm, but 21 inches got us just a bit more than 8.5 gph. You also need rapid transitions in your low altitude work. Fuel savings?

A1Skinner wrote:Long stroke primer or short stroke primer?

Long stroke primmer

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contactflying wrote:Larry, the engine wants lots of fuel to start and wants to idle and run as lean as practicable. I leaned to max RPM at any DA, and even when air temp was cool. When hot, advancing the throttle more than what you normally do is allowing more air, and that is fine. If cold and you are having to advance the throttle after six primes, you have actually put too much fuel in and the open throttle is letting the butterfly get more air, the same as the hot start.

I ran the 0-360 in the Cardinal on the pipeline when a 172 was not available. I drank coffee all day and had a small bladder, so lots of hot starts. I primed about four shots when cold and pumped the throttle at least two times. When hot, outside or engine, I just pumped the throttle one or two times and did not prime. In high wing like Cardinal, the fuel pump did not matter as it was gravity feed. Like most smallish engines, getting fuel air mixture just right takes some iterations to get what that particular engine wants exactly, but once you have cold and hot parameters, you are good forever. Marvel Schebler is a good carburetor.

Just for fuel efficiency, we used 2500 rpm and 21 inches manifold pressure. We needed rapid transitions, so high rpm, but 21 inches got us just a bit more than 8.5 gph. You also need rapid transitions in your low altitude work. Fuel savings?

Will try less throttle when doing cold start, I agree , is a matter of finding the right procedure then will be good forever, however when I replaced my carb in the 182, and after we put the new one, it started exactly as the previous one.

Yes, most models do pretty much the same. Just a little fine tuning for some. It was so much easier when even little engines were usually propped. Outside you can hear and smell mixture very accurately.

What do you have for mags? If they are slicks the first thing I would check is the internal timing. Slicks are notorious for starting problems even with only 15 hours on a rebuild. Could also be sticky impulse coupling on the left mag. Fuel can be part of a starting problem but it is most always a spark issue. Check the mags, start with the left. If you need to be replaced get Bendix!! DENNY

4 cylinder primer? All lines good to cylinders?

Ya that is also a good point my cub was starting a bit slow and it turned out to be a broken primer line. DENNY

First of all, I would NEVER open the throttle 25 % for ANY start.

I use a quarter to a half inch open throttle for start. I hope that's what you meant.

Cold, I use three to four shots of prime, long stroke primer. Open throttle quarter to half inch open, and crank. fires right up every time. Every O-360 I have met (twenty or thirty I'd guess) starts fine that way. You should NOT have to pump the throttle in a cold start.

Hot Starts: I define this as any time the engine's been running in the last hour or so. Here, I NEVER prime the engine. It is VERY easy to flood these engines when they're hot. Crack the throttle a half inch, and start to crank. WHILE cranking, pump the throttle ALL the way to the stop and back TWICE FAST, and immediately bring it back to about a quarter to half inch open.

DO NOT pump the throttle like this UNLESS you are turning the engine over with the starter. As in NOT EVER. You might dodge the bullet, or you might burn your plane down, Not worth the risk and frankly pumping the throttle before cranking defeats what your'e trying to do.

Frankly, it sounds to me as if your new carburetor is not set up right. I'm not a Marvel Schebler expert by any means, but while these things are sorta simple devices, there are LOTs of ways to screw them up. Get someone knowledgeable to look at that carb and get it set up right.

Set up right, and with a pilot who knows how to start them, these engines should start second or third blade EVERY time. Anything else means there's something wrong with the carb.

MTV

I actually just fixed a carb on a 360 that was acting similar. Extremely hard to start. Like run the battery dead almost every time. There is 2 types of accelerator pump check valves, and if you have the style with no spring and it doesn't seat properly you'll have a he'll of a time starting it. I switched it over to the spring style and plane had started easy peasy ever since.

Here's something you might try. Forget the primer and give it 3 strokes of throttle and pull it through by hand 3 or four blades with mags off----very carefully. Get in and see if she pops off right away. If it does, then the mag should be good.

180Marty wrote:Here's something you might try. Forget the primer and give it 3 strokes of throttle and pull it through by hand 3 or four blades with mags off----very carefully. Get in and see if she pops off right away. If it does, then the mag should be good.

Please do not do this.

The Marvel Schebler carburetors are UPDRAFT carburetors, which are generally equipped with an accelerator pump. This pump is installed as a sort of squirt gun to pump a big dose of fuel into the engine when you shove the throttle up fast. This prevents the engine from stumbling from too much air (the carb is an air device too.) and not enough gas.

The accelerator pump is essentially a squirt gun, which squirts raw fuel into the throat of the carburetor. The UPDRAFT carburetor. Which means if you activate that accelerator pump while the engine is not turning over, much of that raw gas just drips down into the air box. That gas does you no good, BTW.

What it does do is create a potential fire hazard IF you get unlucky and get just the slightest backfire. Granted, backfires are not very frequent in these engines, but it only takes one induction fire to ruin your day. I’ve watched it happen.

So, the PROPER way to use an accelerator pump for starting is to crank with the starter, THEN pump the throttle twice. Now THAT fuel will be sucked up into the engine, where it belongs and where it may actually accomplish what you hoped it would.

But please don’t pump the throttle on an engine that’s not running.

MTV

I hadn't thought about it but as MTV explains is how I have used the accelerator pump. Crank and pump. The lack of accelerator pump on small Continental engines 65-90 hp made propping where you could see, hear, and smell what was going on the easier way to start.

My 0-360 in cold weather or warm weather, 2 primer strokes and 1/4 inch of throttle and mag on left push starter button and it fires up right away. I have never tried anything different.

Mike,It actually squirts up into the induction system and that is why you pull the prop through---Carefully like hand propping---- and it sucks the fuel well into the intake system. Even with a primer on my old 180, I prime and pull the prop through a few blades. This newer 180K doesn't have a primer so I have been doing 3 pumps, pull through 4 blades, get in and crank and it usually is running immediately. I don't like to do many blades of cranking before it gets fuel. This procedure is for the first start of the day and not when it is hot. Also, you don't stand around talking to your friend, you do the three strokes and get right out there and pull the blades through.

180Marty wrote:Mike,It actually squirts up into the induction system and that is why you pull the prop through---Carefully like hand propping---- and it sucks the fuel well into the intake system. Even with a primer on my old 180, I prime and pull the prop through a few blades. This newer 180K doesn't have a primer so I have been doing 3 pumps, pull through 4 blades, get in and crank and it usually is running immediately. I don't like to do many blades of cranking before it gets fuel. This procedure is for the first start of the day and not when it is hot. Also, you don't stand around talking to your friend, you do the three strokes and get right out there and pull the blades through.

The issue is the accelerator nozzle squirts up by by the time you get out to spin the prop it's ran back down into you airbox. Especially in a C180 it really doesn't get into the induction, it squirts up out of the carb and falls right back down unless you are actively cranking the engine amd sucking it in. I've seen to many air boxes that are blackened up and I highly recommend only using throttle pumps while cranking... but it's your airplane so you can do as you wish.

A1Skinner wrote:[The issue is the accelerator nozzle squirts up by by the time you get out to spin the prop it's ran back down into you airbox. Especially in a C180 it really doesn't get into the induction, it squirts up out of the carb and falls right back down unless you are actively cranking the engine amd sucking it in. I've seen to many air boxes that are blackened up and I highly recommend only using throttle pumps while cranking... but it's your airplane so you can do as you wish.

This is an interesting tangent. My O-320 has no primer on it. When it's cold, three partial pumps of the throttle and hit the starter. Usually goes fine.

However, one time it was moderately cold out (30°F ha! by my old Oregon standards) and the battery was dead. I couldn't get it to fire hand-propping it, probably because of the issue you noted which is the fuel runs back down into the airbox by the time you get around the front again. And it's not warm enough to get it vaporizing just from ambient air temp.

I just cranked mine up and thought I had the phone on video but didn't----just a still so of no value----maybe next time. It got down into the 30's last night so I plugged the Reiff in for three hours and it was nice and warm. Did my three accelerator pumps and pulled it through five blades. Got in, mixture rich, throttle cracked and turned the key. It was running within 180 degrees of crankshaft rotation----my kinda start. I did some figuring and I have owned this plane for just under two years and have started it like this about 180 times. If the battery was dead, this is what I would do except I would make sure the prop was positioned just right and make the mag's hot and I bet most times it would be running with one pull of the prop. Thought of this----I don't bother to get in as I'm just standing on the ground leaning in working the throttle so I can quickly get around to pull the prop to prime.

180Marty
Next time you have the cowling off pump your throttle 3 times and go look at your air box you will see gas leaking or or pooled in the bottom. The accelerator pump is in the middle of the cab it will squirt fuel upward but it all just falls back down out of the carb if the prop is not turning. As usual every plane/engine seems different. Understanding how your primer works is important. In a 170 with the 145 hp Continental the primer was in the Y above the carb. The effect of priming was quite similar to pumping the throttle without the prop moving you get a airbag full of gas and a nice rich mixture for start. It works fine and some never have a problem HOWEVER, as mike said all it takes is a backfire through the carb to start a fire. I have had two friends with carb fires from improper starting procedures. Lycoming tend to have primer lines run to the cylinder head as do several Continentals so priming without the prop is not a issue. As always look at YOUR plane and do you starting procedure in accordance to the plane setup you have. The OP had a carb issue with he first got the plane but that was fixed. He had a starting procedure that worked after that and he should stick to that. So something has changed. Broken primer line/clogged primer/mag or spark issue. My money is still on a mag issue but primer lines are easy to check. DENNY

Today I got an opportunity to compare my priming actuator to a Cessna 172, mine feels very easy with no resistance compared to this other plane.
So bought the O rings, and will try to change them tomorrow, it would be nice if this was the cause.