[lukemc]

So...... my sierra has been running well lately, until the misses took it out yesterday to pick up mulch bags or some other such crap

Now it starts fine, the auto choke runs it up to about 2250RPM, all good, then as it starts to warm up, and the revs drop it cuts out

It fires back up first go, but will only run for about 5 seconds if that until the revs drop, if i keep the revs over 2000 its fine.........

Any suggestions of things to look at first? I have absolutely no idea about carbys, i do know where the idle speed screw is from searching but thats it

[abclarke]

Sounds similar as the problem mine had. Take it to Autoservice on Queen St. Only cost me $300 and was ready the next day. Mine ended up being a blocked idle jet i think he said.

[Zook_Fan]

Sounds like a blocked idle jet as well. Either grab a carby kit and clean every part meticulously as you pull it down or take it somewhere and around $300-$400 is the norm for a carby build

[lukemc]

thanks guys, I'm tossing up buying a webber bolt on kit instead and just getting that fitted/tuned.

The previous owner busted the threaded alloy section that accepts the stud that bolts the carby hat to the carby, destroying the threaded piece inside the carby itself. Ive had it to a few places to see if they can weld/glue/attach it somehow but no love, so at the moment if i remove the hat i have to silicone/sicaflex it back on to seal it.......less than ideal.......

Ive kept my eyes out for a carby for sale on here but they seem to be rare as hens teeth.....

[abclarke]

If you thinking about a weber, go to extreme fuel systems in campbelltown. They quoted me about $500 fitted.

[lukemc]

ab did that include the cost of the weber? or was that you providing the weber and them fitting it?

[abclarke]

Pretty sure thats including the weber, i was ringing around asking about getting mine overhauled and asked about getting one fitted. I didnt say i had one so id be pretty sure its everything. Dont quote me on it but

[lukemc]

Thanks mate I'll give them a bell.

[abclarke]

Imo if you have another car you can use just save the money for a G13B

[oozuk]

there is a round solonoid going into the top side of the carby with 1 wire coming out of it.
this controls the idle circurt and cuts the idle circurt when you turn the engine off to stop the engine running on, you will need a 12mm spanner to remove it and check it. on the end it should have a little black O-ring on the end of it's snout if that's missing that could be your problem as sometimes they perish and fall off into the carby port it sits in, also why you have this solonoid out get somebody to turn the ignition on and off whilst holding this solonoid on metal to earth it out, you should hear/feel it click with the ignition on and off, if this is not happening then the solonoid is faulty.

Last but not least has anybody tried to screw with your carby before ?? they have 3 seperate idle controls, 1 for choke idle speed, 2. for engine load idle speed compensation and 3. engine main idle speed (only works when choke is off) what should happen is when the engine is cold the choke cirturt should rev the engine to 1500rpm with the choke partially closed, as the engine warms up the wax pallet moves the choke mechinisim off the choke idle, opens up the choke butterfly and the engine main idle speed takes over to idle at approx 800 rpm.
it could be possible that this main idle speed is wound right off and when it comes off choke the throttle completely closes as there is no idle speed setting and causing the engine to not idle and die.

answer me this, can you hold the revs at 800-900 rpm when the engine is hot with your foot on the throttle without it stalling, if you can then it just needs the idle speeds set

[lukemc]

nah mate, it won't run at below 2000rpm at all.

At present when it starts up from dead cold it sits on about 1750rpm (well it did before this issue) then if you gave it a little rev it jumps up to 2200rpm and would run fine until it warmed up and the idle dropped to about 1000

Now i have to rev it at start to get it to jump to the 2200rpm, but as soon as it starts to warm up a bit and drops under the 2grand it cuts out, if you restart it and keep it revving over 2grand it runs, drop it slightly below and it cuts out.

[abclarke]

Sounds the same as my issue, you can still drive it if you keep the revs up? And just make sure you dont let it down at the lights?

[oozuk]

could be a couple of things.

A. the throttle plate bushes could be heavily worn (indicated by the fact when you rev it the rev's don't return to to the same before reving

B. Idle circuit could be blocked up try doing a poor mans tune up (follow steps below)

step 1: go to repco and buy a spray can of some good carby cleaner preferably one with a spray needle included (nulon one is good and smells pretty)
step 2: get the engine upto operating temp.
step 3: move the car off the nice concrete driveway as all sorts of shit will spray out of the tail pipe when doing this.
step 4: shut down the engine and use a 10mm spanner and remove the nut holding the intake off the top of the carby, unclip the airbox top and put it all to the side out of the way.
step 5: use some vice grips and remove the post from the center of the intake of the carby ( it unscrews)
step 6: look down the carby and identify the primary and secondary ports (primary has the choke butterfly in it and secondary has the little brass float breathers < REMEMBER THESE)
step 7: take your carby cleaner and using the spray needle insert it into one of the two float breathers in the top of the secondary ports and fill the bastard up until carby cleaner comes out the breathers, also whist your there spray it around in the primary and secondary ports whilst opening the choke with your fingers to get past the butterfly, you want to remove the varnish and see nice clean alloy inside these ports (now this is where it gets fun !!)
step 8: WITH THE ENGINE OFF !! reach down the back of the carby and pull it to Wide Open Throttle "WOT" and unflick the throttle cable off the throttle cam and bend it back out of the way so the carby can be controlled by hand (if this is not done and you rev it by hand it could possibly jam on WOT not fun pooing you pants whilst you rush to shut down your engine before things jump out of it)
step 9: get a friend to start the engine whilst you hold the throttle at 50%, Be prepared it will be hard to start and cough and splutter due to you flooding the carby with carby cleaner.
step 10: work the carby cleaner through the engine by reving the engine on and off the throttle. (now the cleaning starts)
step 11: with the engine running spray carby cleaner down the ports of the carby continue to hold the throttle open to sustain the engine revving.
step 12: not good if you have girly hands for this one!! after it has had a gutfull of carby cleaner you need to put it to work to do this directly after dumping a bit of carby cleaner down the ports of the carby (with the engine running) rev the living christ out of the engine to WOT say 5000-6000rpm (go by ear) then when it hits that point throw the palm of your hand over the carby to create a seal over the carby (still holding it WOT) effectively creating a massive vacumme in the carby and intake, and listen to the engine as the rev's die off to about 1500rpm (go by ear) let your hand off the carby and pump the throttle to keep the engine from dying.
step 13: continue steps 10-12 until happy, once done hold the engine at 1500rpm to allow the carby to clear itself and see if the idle improves (usually does if gummed up)

that may work for you it may not, at worst it costs you $12 for a can and some blisters on your hand (sounds like a night i had once)

don't be surprised if you go through a whole can of carby cleaner doing this

on another note... holy crap i think i've accually added "Tech" to auszookers !!!! what is this world coming to ?

[oozuk]

So did this help ?

[lukemc]

Mate to be honest I didn't try. With the damage to my carny I decided to replace it with a weber. Thanks for the time you took to write it up though.

Time will tell if I made the right decision

[oozuk]

lukemc wrote:

Mate to be honest I didn't try. With the damage to my carny I decided to replace it with a weber. Thanks for the time you took to write it up though.

Time will tell if I made the right decision

realistically the factory carb is a really good carb when it's running right, good luck with the webber.

[primejo07]

oozuk wrote:

could be a couple of things.

A. the throttle plate bushes could be heavily worn (indicated by the fact when you rev it the rev's don't return to to the same before reving

B. Idle circuit could be blocked up try doing a poor mans tune up (follow steps below)

step 1: go to repco and buy a spray can of some good carby cleaner preferably one with a spray needle included (nulon one is good and smells pretty)
step 2: get the engine upto operating temp.
step 3: move the car off the nice concrete driveway as all sorts of shit will spray out of the tail pipe when doing this.
step 4: shut down the engine and use a 10mm spanner and remove the nut holding the intake off the top of the carby, unclip the airbox top and put it all to the side out of the way.
step 5: use some vice grips and remove the post from the center of the intake of the carby ( it unscrews)
step 6: look down the carby and identify the primary and secondary ports (primary has the choke butterfly in it and secondary has the little brass float breathers < REMEMBER THESE)
step 7: take your carby cleaner and using the spray needle insert it into one of the two float breathers in the top of the secondary ports and fill the bastard up until carby cleaner comes out the breathers, also whist your there spray it around in the primary and secondary ports whilst opening the choke with your fingers to get past the butterfly, you want to remove the varnish and see nice clean alloy inside these ports (now this is where it gets fun !!)
step 8: WITH THE ENGINE OFF !! reach down the back of the carby and pull it to Wide Open Throttle "WOT" and unflick the throttle cable off the throttle cam and bend it back out of the way so the carby can be controlled by hand (if this is not done and you rev it by hand it could possibly jam on WOT not fun pooing you pants whilst you rush to shut down your engine before things jump out of it)
step 9: get a friend to start the engine whilst you hold the throttle at 50%, Be prepared it will be hard to start and cough and splutter due to you flooding the carby with carby cleaner.
step 10: work the carby cleaner through the engine by reving the engine on and off the throttle. (now the cleaning starts)
step 11: with the engine running spray carby cleaner down the ports of the carby continue to hold the throttle open to sustain the engine revving.
step 12: not good if you have girly hands for this one!! after it has had a gutfull of carby cleaner you need to put it to work to do this directly after dumping a bit of carby cleaner down the ports of the carby (with the engine running) rev the living christ out of the engine to WOT say 5000-6000rpm (go by ear) then when it hits that point throw the palm of your hand over the carby to create a seal over the carby (still holding it WOT) effectively creating a massive vacumme in the carby and intake, and listen to the engine as the rev's die off to about 1500rpm (go by ear) let your hand off the carby and pump the throttle to keep the engine from dying.
step 13: continue steps 10-12 until happy, once done hold the engine at 1500rpm to allow the carby to clear itself and see if the idle improves (usually does if gummed up)

that may work for you it may not, at worst it costs you $12 for a can and some blisters on your hand (sounds like a night i had once)

don't be surprised if you go through a whole can of carby cleaner doing this

on another note... holy crap i think i've accually added "Tech" to auszookers !!!! what is this world coming to ?

Mate this is an awesome write up! Should definately go in good tech, fixed my carby problems untill I can get it properly reconditioned

[primejo07]

oozuk wrote:

could be a couple of things.

A. the throttle plate bushes could be heavily worn (indicated by the fact when you rev it the rev's don't return to to the same before reving

B. Idle circuit could be blocked up try doing a poor mans tune up (follow steps below)

step 1: go to repco and buy a spray can of some good carby cleaner preferably one with a spray needle included (nulon one is good and smells pretty)
step 2: get the engine upto operating temp.
step 3: move the car off the nice concrete driveway as all sorts of shit will spray out of the tail pipe when doing this.
step 4: shut down the engine and use a 10mm spanner and remove the nut holding the intake off the top of the carby, unclip the airbox top and put it all to the side out of the way.
step 5: use some vice grips and remove the post from the center of the intake of the carby ( it unscrews)
step 6: look down the carby and identify the primary and secondary ports (primary has the choke butterfly in it and secondary has the little brass float breathers < REMEMBER THESE)
step 7: take your carby cleaner and using the spray needle insert it into one of the two float breathers in the top of the secondary ports and fill the bastard up until carby cleaner comes out the breathers, also whist your there spray it around in the primary and secondary ports whilst opening the choke with your fingers to get past the butterfly, you want to remove the varnish and see nice clean alloy inside these ports (now this is where it gets fun !!)
step 8: WITH THE ENGINE OFF !! reach down the back of the carby and pull it to Wide Open Throttle "WOT" and unflick the throttle cable off the throttle cam and bend it back out of the way so the carby can be controlled by hand (if this is not done and you rev it by hand it could possibly jam on WOT not fun pooing you pants whilst you rush to shut down your engine before things jump out of it)
step 9: get a friend to start the engine whilst you hold the throttle at 50%, Be prepared it will be hard to start and cough and splutter due to you flooding the carby with carby cleaner.
step 10: work the carby cleaner through the engine by reving the engine on and off the throttle. (now the cleaning starts)
step 11: with the engine running spray carby cleaner down the ports of the carby continue to hold the throttle open to sustain the engine revving.
step 12: not good if you have girly hands for this one!! after it has had a gutfull of carby cleaner you need to put it to work to do this directly after dumping a bit of carby cleaner down the ports of the carby (with the engine running) rev the living christ out of the engine to WOT say 5000-6000rpm (go by ear) then when it hits that point throw the palm of your hand over the carby to create a seal over the carby (still holding it WOT) effectively creating a massive vacumme in the carby and intake, and listen to the engine as the rev's die off to about 1500rpm (go by ear) let your hand off the carby and pump the throttle to keep the engine from dying.
step 13: continue steps 10-12 until happy, once done hold the engine at 1500rpm to allow the carby to clear itself and see if the idle improves (usually does if gummed up)

that may work for you it may not, at worst it costs you $12 for a can and some blisters on your hand (sounds like a night i had once)

don't be surprised if you go through a whole can of carby cleaner doing this

on another note... holy crap i think i've accually added "Tech" to auszookers !!!! what is this world coming to ?

Mate this is an awesome write up! Should definately go in good tech, fixed my carby problems untill I can get it properly reconditioned