[dp87]

Hey guys this is my first post. I finally bought myself a 96 sierra.

just today it started to idle really high when it warmed up (2000rpm). and now its gone up to 2500rpm tonight.

when i turn off the ignition the motor diesels for about 5-6seconds before it finally dies.

anyone know what the problem is?
i thought it may be a vacuum line but i checked them and they seem ok. It just seems funny that all this has happened today.

any help will be greatly appreciated,
cheers Dan

[lump_a_charcoal]

I reckon your timing is too advanced.

[thompson_2986]

lump_a_charcoal wrote:

I reckon your timing is too advanced.

.
X2

[steak_knife]

thompson_2986 wrote:

lump_a_charcoal wrote:

I reckon your timing is too advanced.

.
X2

Why all of a sudden then??

[lump_a_charcoal]

The dizzy screw has come loose and it has turned due to spin ratios exceeding the width of the wheelbase, assuming the rear diff is a 3.14159265 ratio...






Simple.

[gravity_powered]

Air leak is my guess.

[dp87]

Thanks guys im amazed at how many replies ive got and its a friday night... wow...

il check the timing tomorrow and see if that changes anything. let you know how it all goes

[Zookin_85]

My guess would be a vacuum leak! Check all your vacuum lines for cracks, Make sure you check one at a time as not to get overwhelmed!

[nissvit]

wont a '96 sierra be a carby engine? first thought would be carby/ choke problem..
or even simpler, one of Royce's specials.... is the radiator full, as the choke is dependant on the coolant temp to come off..

[steak_knife]

nissvit wrote:

wont a '96 sierra be a carby engine? first thought would be carby/ choke problem..
or even simpler, one of Royce's specials.... is the radiator full, as the choke is dependant on the coolant temp to come off..

Now we have a thinker!!!

This would make a sudden change.

[Choppy]

nissvit wrote:

wont a '96 sierra be a carby engine? first thought would be carby/ choke problem..
or even simpler, one of Royce's specials.... is the radiator full, as the choke is dependant on the coolant temp to come off..

agreed this is what happened to mine, within a couple of days it started running spastic and ideling as you've described, it would either not idle when starting or bump up to 2500rpm. the choke had shat itself along with other things

[dp87]

Hey guys the i may have sorted the problem out.


i checked the water level and that was ok.
there were no airleaks in any hoses.

i let the car run untill it was idling at 2500rpm. then i disconnected at plug that i think is for the cold start. looks like a solenoid thing on the front of the carbie with a green wire going into it.

when i pulled the plug the idle went down to 1000rpm where and it stayed there, however the idle was really really rough.

i let it run like that for 2 mins until the car eventually stalled for some reason. i tried to start the car motor but it would not idle and just die.

so i reconnected the plug and it started fine, but this time the idle sat around 1000rpm and ran pretty smooth.

So now the high idle seems to have fixed itself.

HOWEVER, the engine seems to take forever to warm up and runs like a dog untill it is warm.
-AND the engine is a bit hard to start sometimes, Mainly when the engine is warm.

Any ideas as to whats going on??

[ck13488]

i have the same problem you have with the high idle, although mine is never hard to start and has only ever dieseled twice.

what would the actual problem he had been?...if its only removing/replacing a wire it would have to be a dodgey connection by my thinking?

hopefully ill fix it if it ever stops raining !!!!

[royce]

you unplugged the idle solenoid, which is supposed to stop dieseling

what I reckoned happened was the idle circuit was a bit blocked and the idle was fiddled to get it to work and now its cleaned itself out a bit and gone to shit

a good clean of the carb and reset might see it right

[suzibob]

royce wrote:

you unplugged the idle solenoid, which is supposed to stop dieseling

what I reckoned happened was the idle circuit was a bit blocked and the idle was fiddled to get it to work and now its cleaned itself out a bit and gone to shit

a good clean of the carb and reset might see it right

Second that.
If it is a 3 pin connector that you unplugged, the other wire that runs to the front of the carby is for egr / bring idle back slowly thingo.

[suzibob]

Also if your solenoid looks like this when you take it out, it may allow the car to keep running if your timing and mixture are out.

Effectively, when solenoid is powered, it contracts and allows fuel through the idle circuit. If it has been hacked at like this, obviously fuel is going to run through the circuit regardless of if its powered or not....

[dp87]

Yeh it was a 3 pin connector that i disconnected...

and i think the solenoid has a vacuum line to what i think is the egr???? is that right

how do i clean a carby lol?????? ive only ever owned fuel injected cars before. sorry for the noob question

[suzibob]

the vac line is for your idle up actuator. When lights or fan is on, it pulls the idle up a bit to compensate for the increased electrical load.

As for cleaning..... tin of carbie cleaner and try smothering the intake while the engine is running... if your problems persist, you'll need to disassemble the carbie

[suzibob]

Take the airbox off the carby, start the car and get a rag and smother the intake. Try not to let the car stall, so give it a few revs by the accelerator connector while your smothering it. The increased vac load as its about to stall sometimes sucks the crap out of the idle jet. If that doesn't work, the carby will have to come off (4 10mm bolts), disassembled and cleaned up. If your keen to give it ago, get a rebuilt kit for it first. - about $60.


Dont worry, I'm from the fuel injected field too, but didnt' I learn...