Starting revelation! (Long)

I recently had N84MR in for it’s first real inspection (a mini-100-hr).
Everything checked out really well… until, after it was all buttoned up, I got a call from the Authorized Service Center asking “Do you have any special tricks to starting your engine?”
So I told them… Yes… I’ve found that if I get it good and warm (Reiff preheat), prime for a really long time (40 seconds), and “punch” the primer button repeatedly and frequently during cranking, it starts with no problem, although it takes awhile, and I can’t open the throttle beyond a crack for about two minutes without it coughing and often dying.
This got a response of “It shouldn’t be that way”. I hadn’t questioned the behavior because of all the previous discussion here about how hard it can be to start the engine; I was simply happy to have found a technique that works reliably.
The A&P told me that clearly there was not enough fuel getting to the injector manifold; and that maybe I need a new fuel pump. He would discuss it with Cirrus.

What he learned is that the fuel pump has an adjustable voltage limiting device on it, which may have been set too low (it was). He later explained to me that there is a poppet valve in the injector manifold, and the fuel pump was not generating sufficient pressure to lift it. If the poppet valve doesn’t open, it matters not how long you prime - no fuel will get into the manifold. The reason it worked for me is that with each “punch” of the primer switch, a little bit of fuel made it into the manifold as the pump first started, before the limiting circuit kicked in. With enough of those little squirts, the engine would start (but not run very happily at first).

The (happy) end of the story is that now my SR20 has gone from being among the most difficult of engines to start, to being about the easiest of all in my experience. This problem and fix may have been unique to me, but I suspect not. In any event, it’s well worth looking into.

  • Mike.

Hi Mike,
Wow, you’re really beating me now, I’m only up to about 50 hours!
Just a question for you… prior to this fix, were you having problems starting over the last couple weeks, now that the temperatures are getting warmer?
The reason I ask is that my starting experiences when it was cold sounds similar to yours (preheat then prime for a LONG time, although I didn’t have to keep punching the primer, just hold it down for a while), then it would start on the 4th or 5th try, and stumble for a couple minutes while I kept my fingers crossed.
On the other hand, now that it’s warmer (say 50 degrees or so), I can ususally get it started on the first try, with only 10 seconds of prime. I believe I’ve seen several other posts which have said about the same thing (no problem starting when it’s warm, but problems when it’s cold).
I guess I’m trying to figure out if your plane was hard to start even when it was relatively warm out (thus indicating maybe your problem was isolated), or whether your experience was pretty much the same as some of the others – hard when cold but easy when warm – in which case maybe your fix will benefit all of us with balky cold-starting engines…
thanks!
steve

I recently had N84MR in for it’s first real inspection (a mini-100-hr).

Everything checked out really well… until, after it was all buttoned up, I got a call from the Authorized Service Center asking “Do you have any special tricks to starting your engine?”

So I told them… Yes… I’ve found that if I get it good and warm (Reiff preheat), prime for a really long time (40 seconds), and “punch” the primer button repeatedly and frequently during cranking, it starts with no problem, although it takes awhile, and I can’t open the throttle beyond a crack for about two minutes without it coughing and often dying.

This got a response of “It shouldn’t be that way”. I hadn’t questioned the behavior because of all the previous discussion here about how hard it can be to start the engine; I was simply happy to have found a technique that works reliably.

The A&P told me that clearly there was not enough fuel getting to the injector manifold; and that maybe I need a new fuel pump. He would discuss it with Cirrus.

What he learned is that the fuel pump has an adjustable voltage limiting device on it, which may have been set too low (it was). He later explained to me that there is a poppet valve in the injector manifold, and the fuel pump was not generating sufficient pressure to lift it. If the poppet valve doesn’t open, it matters not how long you prime - no fuel will get into the manifold. The reason it worked for me is that with each “punch” of the primer switch, a little bit of fuel made it into the manifold as the pump first started, before the limiting circuit kicked in. With enough of those little squirts, the engine would start (but not run very happily at first).

The (happy) end of the story is that now my SR20 has gone from being among the most difficult of engines to start, to being about the easiest of all in my experience. This problem and fix may have been unique to me, but I suspect not. In any event, it’s well worth looking into.

  • Mike.

Mike - Our starting experience with N5841 has been almost identical to yours. Even the two mintute wait after it starts holding the throttle all the way back before it wants to run. Recently everthing was supposedly checked out to try to solve the starting problem including changing a mag. Still no change. Everyone has suspected that for some reason fuel was not getting to the cylinders. When priming sometimes we would get a blip in fuel pressure when first hitting the button but then it would stay at zero. Sometimes we didn’t even get a blip. I will have to check and see if your solution was tried.

I recently had N84MR in for it’s first real inspection (a mini-100-hr).

Everything checked out really well… until, after it was all buttoned up, I got a call from the Authorized Service Center asking “Do you have any special tricks to starting your engine?”

So I told them… Yes… I’ve found that if I get it good and warm (Reiff preheat), prime for a really long time (40 seconds), and “punch” the primer button repeatedly and frequently during cranking, it starts with no problem, although it takes awhile, and I can’t open the throttle beyond a crack for about two minutes without it coughing and often dying.

This got a response of “It shouldn’t be that way”. I hadn’t questioned the behavior because of all the previous discussion here about how hard it can be to start the engine; I was simply happy to have found a technique that works reliably.

The A&P told me that clearly there was not enough fuel getting to the injector manifold; and that maybe I need a new fuel pump. He would discuss it with Cirrus.

What he learned is that the fuel pump has an adjustable voltage limiting device on it, which may have been set too low (it was). He later explained to me that there is a poppet valve in the injector manifold, and the fuel pump was not generating sufficient pressure to lift it. If the poppet valve doesn’t open, it matters not how long you prime - no fuel will get into the manifold. The reason it worked for me is that with each “punch” of the primer switch, a little bit of fuel made it into the manifold as the pump first started, before the limiting circuit kicked in. With enough of those little squirts, the engine would start (but not run very happily at first).

The (happy) end of the story is that now my SR20 has gone from being among the most difficult of engines to start, to being about the easiest of all in my experience. This problem and fix may have been unique to me, but I suspect not. In any event, it’s well worth looking into.

  • Mike.

Mike: I was wondering - if you had the new Arnav engine monitoring equipment, would it had given you a clue as to the cause of this problem before your mechanic figured it out?

  • Steven, SR-22 #204

I recently had N84MR in for it’s first real inspection (a mini-100-hr).

Everything checked out really well… until, after it was all buttoned up, I got a call from the Authorized Service Center asking “Do you have any special tricks to starting your engine?”

So I told them… Yes… I’ve found that if I get it good and warm (Reiff preheat), prime for a really long time (40 seconds), and “punch” the primer button repeatedly and frequently during cranking, it starts with no problem, although it takes awhile, and I can’t open the throttle beyond a crack for about two minutes without it coughing and often dying.

This got a response of “It shouldn’t be that way”. I hadn’t questioned the behavior because of all the previous discussion here about how hard it can be to start the engine; I was simply happy to have found a technique that works reliably.

The A&P told me that clearly there was not enough fuel getting to the injector manifold; and that maybe I need a new fuel pump. He would discuss it with Cirrus.

What he learned is that the fuel pump has an adjustable voltage limiting device on it, which may have been set too low (it was). He later explained to me that there is a poppet valve in the injector manifold, and the fuel pump was not generating sufficient pressure to lift it. If the poppet valve doesn’t open, it matters not how long you prime - no fuel will get into the manifold. The reason it worked for me is that with each “punch” of the primer switch, a little bit of fuel made it into the manifold as the pump first started, before the limiting circuit kicked in. With enough of those little squirts, the engine would start (but not run very happily at first).

The (happy) end of the story is that now my SR20 has gone from being among the most difficult of engines to start, to being about the easiest of all in my experience. This problem and fix may have been unique to me, but I suspect not. In any event, it’s well worth looking into.

  • Mike.

Hi Mike,

Wow, you’re really beating me now, I’m only up to about 50 hours!

Hi Steve,

Actually, I did this inspection at 81 hours; knowing that I had a couple of long trips coming up. Right now, I have 92 hours on the Hobbs. By this time next week, if all goes as planned, I will have another 16 or so hours.

I guess I’m trying to figure out if your plane was hard to start even when it was relatively warm out (thus indicating maybe your problem was isolated), or whether your experience was pretty much the same as some of the others – hard when cold but easy when warm – in which case maybe your fix will benefit all of us with balky cold-starting engines…

When it was cold, I always managed to get it to run within the first 5 or so attempts; but I always preheated, so I didn’t expect any difference when the actual temp got warmer. No surprise there - it continued to behave the same way.

So the answer is that my airplane behaved consistently, hot or cold; mine may indeed be an isolated case.

Mike.

Hi Mike,

Wow, you’re really beating me now, I’m only up to about 50 hours!

Hi Steve,

Actually, I did this inspection at 81 hours; knowing that I had a couple of long trips coming up. Right now, I have 92 hours on the Hobbs. By this time next week, if all goes as planned, I will have another 16 or so hours.

I guess I’m trying to figure out if your plane was hard to start even when it was relatively warm out (thus indicating maybe your problem was isolated), or whether your experience was pretty much the same as some of the others – hard when cold but easy when warm – in which case maybe your fix will benefit all of us with balky cold-starting engines…

When it was cold, I always managed to get it to run within the first 5 or so attempts; but I always preheated, so I didn’t expect any difference when the actual temp got warmer. No surprise there - it continued to behave the same way.

So the answer is that my airplane behaved consistently, hot or cold; mine may indeed be an isolated case.

Mike.

I’m not sure yours is an isolated case, Mike. While true “hot starts” were never an issue for my engine, “lukewarm” starts (eg OAT 45F) continue to require 30 seconds of prime. I’ve experimented with 10 and 20 seconds prime and it just isn’t enough until the temp gets above 50F.

In 2 weeks I go in for an oil change (now have 230 hrs on the plane)and I’ll be sure to ask them to check the pump voltage. Thanks for the tip.

Definitely a defect of the species. The discussion was live some time ago and Joe had the intermediate recipe, LOOOONG prime and hoping some of the fuel reach the cylinders (most of it is jettisoned overboard).

The voltage cure is being looked into, as that was an idea the European distributor had too. Issue is, will the mod be a field installed and -approved retrofit and/or a Cirrus one at the source. I understand work is done on this. One of the concerns is flooding the engine while accidentally hitting and keep pushing the prime switch in-flite…

Cheers

Han

(220 hours in N144CD and enjoying all of it except the startup…)

Hi Mike,

Wow, you’re really beating me now, I’m only up to about 50 hours!

Hi Steve,

Actually, I did this inspection at 81 hours; knowing that I had a couple of long trips coming up. Right now, I have 92 hours on the Hobbs. By this time next week, if all goes as planned, I will have another 16 or so hours.

I guess I’m trying to figure out if your plane was hard to start even when it was relatively warm out (thus indicating maybe your problem was isolated), or whether your experience was pretty much the same as some of the others – hard when cold but easy when warm – in which case maybe your fix will benefit all of us with balky cold-starting engines…

When it was cold, I always managed to get it to run within the first 5 or so attempts; but I always preheated, so I didn’t expect any difference when the actual temp got warmer. No surprise there - it continued to behave the same way.

So the answer is that my airplane behaved consistently, hot or cold; mine may indeed be an isolated case.

Mike.

I’m not sure yours is an isolated case, Mike. While true “hot starts” were never an issue for my engine, “lukewarm” starts (eg OAT 45F) continue to require 30 seconds of prime. I’ve experimented with 10 and 20 seconds prime and it just isn’t enough until the temp gets above 50F.

In 2 weeks I go in for an oil change (now have 230 hrs on the plane)and I’ll be sure to ask them to check the pump voltage. Thanks for the tip.

Mike: I was wondering - if you had the new Arnav engine monitoring equipment, would it had given you a clue as to the cause of this problem before your mechanic figured it out?

  • Steven, SR-22 #204

Steven,

It’s a good question.

I haven’t seen the new ARNAV monitoring yet - I hope to fix that tomorrow at Sun 'n Fun - but no matter how good it is, the answer to your question is No, because I don’t turn on the Avionics until AFTER the engine is started.

  • Mike.