My Jab won't run cold

[bushpilot]

Thanks C/S.. I'll try it. The technique that works on mine is: full choke for 1 min; then open throttle to about 1700rpm; then close the choke..

 

As you say, I guess they are 'all' a bit different...

 

 

[Jabiru Phil]

For those who have not read my post on cold starting.

 

We have no electricity at the hanger. I take a thermos (saves heating with the gas burner) of HOT water and pour over the carbie, works every time.

 

Phil.

 

 

[Jabiru Phil]

Sorry, to clarify I only use

 

on very cold mornings.

 

Phil.

 

 

[Guest Cloudsuck]

Just driect hot air up from the nosewheelarea witgh a blower

Nup, that won't work, he hasn't got a nose wheel area (its a Tailwheel Jab) ;)

 

 

[Harthy]

Fuel Enricher Valve

 

Hi Qwerty,

 

This is something worth looking at. There is possibly a problem with your Fuel Enricher Valve. It has been found on a couple jabs. My jab is displaying similar symptoms to yours, but mine will run fine just needs alot of choke on cold mornings, I then need to raise the revs to 1500rpm after a minute or two and then push the choke in quickly and it runs fine.

 

The possible cause is easy to check. I will be checking mine today.

 

On the right side of the carby is the enricher valve. it is held in with 4 phillips screws (about an inch square plate with the choke lever coming out of the centre of it) The valve shaft is located in the choke lever on a 8 o'clock 2 o'clock position. On the end of the shaft is an indexing mark which should be lined up to the 8 o'clock position. if it is lined up to the 2 o'clock position it needs to be rotated 180 degrees.

 

This may be worth a look.

 

Harthy

 

 

[Guest brentc]

This behaviour must be catching. Is started mine on sunday and it ran like crap for about a minute. It was like half of the spark plug leads have fallen off. It was quite cold which may help to explain it.

 

 

[lambousc44]

you need to check your needle and jets in the carby and advise , eg... clip position , main jet and idle jet size these can be found to reference to on the jab web site , they have had a ned ad for this i think may 2009 , check and see , if not call Keith rule at cessnock he is very very good on jabs .

 

 

[Guest Qwerty]

OK, an update

 

I take it that the mixture enriching valve is the "choke" the choke works, it was tested by a mate blowing through a plastic tube into the pickup tube on the carbie while I worked the choke cable. It switched on and off OK.

 

I started it cold today for about the tenth time since I asked about this. With carefull use (jiggling) the throtle, I can get the choke off reasonably quickly and it runs fine once I have dumped the choke.

 

I will check the jet sizes and needle position next time I've got the cowls off. There is still something wrong with it. There are several 4cyl jabs here and they start fine. Simply start and then dump choke no fuss no problems and reliable. I WILL get to the bottom of this.

 

FYI, this thing really screams. I forgot to look at the VSI but with full fuel, GF onboard and 2 stages of flap I turned cross wind at 500ft AGL about half way along the strip. The strip is 1000m long. She was going up like an express elevator. I was climbing at 70kn, I wish I knew what the VSI indicated. I have climbed it before at MTOW at 90 kn at 1100 fpm. I know that I was probably buring 30+ l/hr but I don't care, this is an amazing a/c. It cruises at 115 kn at 2800 rpm at about 21-22 l/h and this is with the climb prop. This won't make it any easier to part with my beloved lightwing.

 

 

[Guest Cloudsuck]

Good to chat on the phone today qwerty. It depends on the day but solo I could get 1800 fpm out of it sustained. It is an impressive machine.

 

I used to get some people come up to me and say, "Oh yeah... I flew a J160/170, it wouldn't climb etc etc" I would reply that this is no J160/170. They tend not to believe you with regards to the performance of the aircraft. Even the instructor on my airfield was big on bagging Jabs till he flew your tailwheel.

 

 

[Guest Qwerty]

I like to keep the fuel full to reduce or avoid moisture in the fuel system but I am in the process of using it down to 15 or 20 l. I want to fly it light on a cold still day at QNH about 1030. I'm looking forward to seeing how well it will go under ideal conditions.

 

I was out in it solo today, I havent done much time in it solo. It is crisp.

 

It was a bit of a bugger to keep running. It typically runs for about 10 - 15 seconds and then just sort of fades away. It did this 5 time before it kept running. Its bloody infuriating......but its worth it, it flies beautifully.

 

 

[Yenn]

Quite a few Jabs at Bundy had starting problems at the weekend, including my Jab engine. The show organisers had a Land Cruiser kept busy jump starting them.

 

 

[Guest Qwerty]

The battery is fine, the ignition is fine.

 

It starts in less than 1/4 turn EVERY TIME. The bugger just wont run, it goes for 5 or 10 or 15 seconds and then just sort of fades away.

 

I am convinced that it is a fuel problem. I'm thinking maybe mixture or atomisation problem. It runs perfectly even if is only a bit warm.

 

I appreciate everyone's interest and contributions.

 

 

[jetjr]

Just a point of view but maybe theres ice being formed very fast, mine doesnt stop but does stuff around a bit in cold weather

 

It seems as soon as theres warm air coming in its all OK - i run carb heat from straight after start until takeoff and you can hear the ice melting and the rpm altering even seconds after starting - might be why the heater/thermos idea works well.

 

With all that aluminium sitting there it can suck temp from fuel pretty fast, add some air velocity and its solid.

 

Just an idea

 

JR

 

 

[facthunter]

Icing .

 

I have had the same experience with motorcycles that have the carb. a fair way from the port , (douglass's).and Volkswagens, where the heater pipe from the exhausts has become blocked by carbon. It is probably exacerbated by the enricher (choke) not enrichening enough or the main tapered needle being a bit "fat" at the top, which is where it will operate when idling, and just above idle. Nev

 

 

[bushpilot]

I wonder if there is any difference between Jab in a hanger and Jab outside, overnight? I only seem to have a problem with cold starting when she is left outside.. (My hanger is only metal - no insulation..)

 

 

[Jabiru Phil]

Did my BFR today. My Jab needed the hot water trick. The other 230 started after 4 tries but a couple of hours later.

 

Both in shed similar to yours.

 

Temp was about 6 deg and then around 12 for the other Jab.

 

I guess that it may be a bit warmer in the shed than outside as we have old thick carpet on the floor, also no wind factor.

 

Phil.

 

 

[Guest The Bushman]

When the Factory fit the Economy kit the idle jet is drilled out to allow extra flow of fuel throught the carb check with don and make sure passage is drilled could have been missed ??

 

This would not allow the extra Fuel to get through and make it hard to start

 

The other day at Bouke the Aircraft J170 was parked out side all night 1/2 inch of ice on the wings 2turns and away she goes that third ignition realy works

 

James

 

 

[Guest check-in]

By the look of my plugs my 2200 solid lifter Jab engine is set up slightly more rich than it could be. However, it seems to make for easy starting. When cold, after pulling prop through 8 compressions, throttle then just a poofteenth off the stops (to give about 1000-1100 rpm), NO choke, I crank on the starter with ignition OFF for about 4 turns of the prop, then while continuing to crank, throw the ignition ON. So far, so good - it fires up 1st time and idles OK. Two minutes of that and it quite happily accepts a gentle burst of throttle to get moving. Tailwheel also, so I don't think that part has anything to do with it.

 

I have only ever pulled the choke out from curiousity with the cowls off to see if it is actually connected to anything .

 

Could be worth a try, except for a six pull it through 12 compressions with ignition off then crank it for about six revolutions of the prop before giving it ignition. But the 6 may be a different animal to the 4, so it may not work at all.....but if it does it's a very kind way to treat both the starter (less cycles) and the oil system (because pressure is built up slowly but is there when it fires).

 

 

[Guest Qwerty]

I'll try it and let you know how it goes.