bgorham

Hi all ....

I have an Irvine .40 in my trainer, that up till now has run pretty well. I have put 3 gallons of fuel through it so far. I have two problems ...

1st is hard starting, after priming the engine by opening the throttle and turning the prop over 15 times, it is still quite an effort to get her to fire up. I have a known good glow plug and plenty of juice in my starter.

2nd is an event that happened this morning. At full throttle, I noticed at first that the engine was surging. Full rpms then less then full ... you know the drill. I flew the thing, and when I was practicing a touch and go, at full throttle for take off it bogged down to idle and died. It would start back up and then die out as soon as I advanced the throttle.

I tried adjusting the mixture ... no success, then checked all of my fuel lines and fuel filter. After I put everything back together it worked fine.

Hmmm ... I don't think I solved anything, and am wondering if you guys have any clues as to what could be wrong.

Thanks in advance.

Bo

KidVermin

My Feedback: (3)

Bo:

When you say you have a known good glow plug; do you mean
that the same plug has been used since new ?
After break-in, the plug coil gets a baked on residue on the coil.
It will still glow as if good, but that white color means it's time for
a new A3 plug. What you describe as symtoms are classic plug
changing time clues. When you advance the throttle and dump in
fuel that the plug is not hot enough to burn. Did you notice that
the engine slows or stops when you remove the ni-starter ?

Randy

bowbell

1st event
I have three Irvines that I fly on a regular basis and find them to be the easiest starting engines I have ever owned.
Correct priming procedure is to open the throttle , cover the carb intake with your thumb and flip the prop 3 or 4 times. Close the throttle and flip the prop twice more. Attach the glow driver and they start first flip every time.
15 flips with a wide open carb will achieve nothing.

2nd event
Glow pug on the way out or an air leak in the lines or tank.
Most likely an air leak.

bob_nj

My Feedback: (62)

Check the bolts in the backplate and the head. Make sure they are not working loose. Also check the carb hold down bolt and anything else that can be working loose, including the tank stopper and leaks in the fuel lines. Check the fuel lines with a metered vacuum gauge or under water. Air leaks will drive you crazy :stupid:

bgorham

Thanks for the inputs guys. I am kinda going to do all the suggestions. I went ahead and replaced the glow plug and the fuel lines. I also just wnet around the horn and verified the tightness of all of the bolts on the engine, and retightened the fuel tank stopper. I also had to replace my tail wheel and repair some covering .... but that is another story altogether!

I am looking forward to giving it another shot, hopefully one evening this week.

Thanks again ... Bo

KidVermin

My Feedback: (3)

Bo:

Let us know what happens on your next run. I didn't notice until
tonite that your location is the U.K. Well, that changes the rules. Don't fly in a heavy mist/fog. All that water goin in the air hole
will cause the symtoms you described.

brickwoodward

while trying all the great suggestions, you might also cut a piece of fuel tubing just slightly bigger than the space between the needle valve stem and the point where it screws into the carb....after a while that point can develop an air leak and drive you to want to try electric!!!!!! happy flying, bill in fla

bgorham

Bill - explain that one a little bit. Are you suggesting to put some fuel line as a gasket/sleeve on the stem itself to help seal where it screws into the carb? If I understand that right, you maybe onto something. My engine took a pretty hard knock a couple of weeks ago on a dumb thumb error (well the whole plane was nearly demolished) and since then the whole stem assmbly seams a little loose ....

I have replaced all my fuel lines, replaced my glow plug and tightened everything down. I am going to give it a try this morning. Will let you know how it goes.

Thanks ... Bo

KidVermin

My Feedback: (3)

Bo:

Just in case Bill doesn't get back to you in time. His idea is a good one. Cut a piece of tubing about 1/4" long to create an outside
o-ring to seal air from sucking in around the stem. One problem
you'll have is that it will be harder to feel if you fully bottom out
stem to start setting the 1 1/2 turns out. But it should start if you are at least close.
Good luck.

Randy

bgorham

Thanks Randy ... and all. I like that seal idea, I will give it a try. I did go flying this morning, and it is better after replacing all the fuel lines, but still not quite right.

I am still having trouble starting it. To get it to go, I have to pour some fuel down the carb. I don't seem to be able to prime it right by covering the intake, opening the throttle and flipping the prop over.

Even when it is warmed up, it is a fight to get running. Could one of you guys run me through priming and starting tips and hints?

Thanks for all the help!

Bo

KidVermin

My Feedback: (3)

Bo:

Try turning the low end screw counter-clockwise 1/2 turn. Sounds
like the low end is too lean.

Randy

KidVermin

My Feedback: (3)

Plan "B"

Also set main valve stem out 2 or 2 1/2 turns to see if you can't
get better fuel draw.

bgorham

Hey Randy ... et al ....

The low end mixture screw .... what is about the right setting, or number of turns out to get started. For giggles, I turned mine all the way in to see where it was set and it was around 3 and a half. I went ahead and backed it off to where it was and added another half turn.

My main is set around 1.25 out, and things seem to run pretty well at power. I have tried backing it out a half a turn to get it started and warm up, and then adjust it back when it settles down. I could try richening it up further.

I think you are onto something with the low end adjustment though. I have never touched that so far ...

Bo

bgorham

Well, I have been the rounds on this engine, and I think I finally know what the problem is. First off, I relaced all my fuel lines, new glow plug, RTV'd the carburator to the engine, and still had problems. Starting has been easier, and I can tell it is better, but it still is choking out reving up to full power from idle.

Today at the flight line, a mate and I were adjusting the carb, and we couldn't get it to richen out into four stroke. We were scratching out heads and I noticed that fuel was blowing out the main needle valve adjustment. I turned it a little bit and it stopped and ran right for a while, and then went back to it's old habits. So I tore the thing down and have discovered that the needle valve assembly is slightly bent, and I am not getting a decent seal.

I think what was happening was when I opened the throttle I was blowing fuel out into the air, instead of down the carburator.
So it is off to the LHS for me, and an attempt to find Irvine carb parts.

Thanks all for the posts to help figure out what was going on. I think I have this gremlin on the run now!

Bo

bgorham

Problem sorted. It was the bent needle valve assembly. I actually did an upgrade on the needle valve and seat/oriface. On the Irvine .40 that I have, there is no type of gasket between where you screw the needle and mixture control and the seat fitting. The Irvine .46 and bigger engines have a notch with an o-ring on the seat assembly. I installed the new one and wala .. all problems solved.

Thanks all for the help

Bo

KidVermin

My Feedback: (3)

Bo:

Good to hear that the problem is solved.
"We're all in this together."

Randy