Outer Limits 4x4 Board

Hi All,

I've got a '90 sierra with standard 1.3L carby and idle set to 1000rpm. On-Road is fine from 0-80kph, although it takes forever to get from 80 to 100kph.

After some weekend wheeling up some rutted hills I found the idle was dropping out all the time and stalling the car. I have done this track before without this problem. It appears to happen when i bounce around as I had no problems restarting the car at angles etc - just whenever I went over harsh bumps/ruts. I've also gone over some kerbing at work recently which bounced me around and had it stall there as well.

I had a full tank (filled up 3-4km from hills) so dont think it was starvation. I tried setting the idle-up to 1500rpm to see if that helped but it didnt. I dont think its a fuel filter issue because idle is otherwise fine but I'll be replacing it anyways. I've checked the carby isnt loose so the mixture shouldnt be changing. I've tried a new air cleaner in case the old one was rooted but no change.

Any suggestions? I'm not very mechanically minded but can attempt most basic things.

Other things I'm going to check:
- bypass idle-up solenoid in case its cutting in&out.
- blow out jets to make sure they're clear.

Kyle

try the fuel cut solinoid....

these will affect idle..

THATS WHAT I WAS SEARCHING FOR IN MY VACANT HEAD YESTERDAY!!!

on mine, pre-weber we bypassed a heap of wires... one of which included modifying the solenoid! Doh! how could i forget that!? it took weeks to discover that was the problem =) hehe

cant remember what we did to the wires though, i know we made a new earth for it cos that was what kept shorting out with mud... then my solenoid itself was coated in electrical tape to seal it.

I had a similar problem going uphills (on and off the road) and found that if i drove the car in reverse up step climbs (its scarier than it sounds) there was no problem. I found the fuel pump to be the problem, i replaced it with a second-handy and had the carb rebuilt overall cost was about $300 but havent had a problem since.

Stay on flat roads .. problem solved ..

yamadafaka wrote:I had a similar problem going uphills (on and off the road) and found that if i drove the car in reverse up step climbs (its scarier than it sounds) there was no problem. I found the fuel pump to be the problem, i replaced it with a second-handy and had the carb rebuilt overall cost was about $300 but havent had a problem since.

I dont have a problem up hills on-road (although I sometimes struggle to maintain speed), but I'll check the fuel pump anyways.

Kyle

I had a similar problem found the accelerator cably was lose and wen i had my foot down was half way on the carby not sure if that was the problem as havnt been able to try it after been fixed

mud4b wrote:try the fuel cut solinoid....

these will affect idle..

''

hi all i have a sierra 92 soft top and ive just started to have problems with it idling.
ive changed the fuel and ir filter cleaned the sparc plugs and it is still running like crap and stalls whenever i take my foot off the acelerator. ive adjusted the acelerator cable so it isnt loose also. i also bought some fuel additive which is suposed to clean the carby and injectors.

where is the fuel cut solenoid anyone got a pic of it?

has anyone got any other things i could try?

thanks

Double check all you spark plug leads are tight.

Mate had this problem, it was just loose ends on his leads.

ill try that tomorrow
could it also be the distributor cap?

SIERRA BANDIT wrote:ill try that tomorrow
could it also be the distributor cap?

Possibly. The problem my mate had, when he revved it was OK, I guess because of strong, fast sparking still getting across the loose connection. As soon as he went to idle, leads started flogging around with the slower vibration and spark wasn't getting through.

Would be good practice to check you rotor button and distributor cap at the same time.

so if the accelerate cable is loose will that cause a idle problem. how do you tighting it ? cheers

mine does the same thing, float level maybe??

There is usually two nuts on the carby end of the accelerator cable , undo the closest one to the end and pull the cable tight then adjust the second nut , clamping them together , leave a small ammount of slack so it returns properly.

Every carby thread you read generally involves crap in the carby , the standard filters are not fine enough to remove the crap from the fuel , and a builup of small particles will block up the carbies , use a EFI fuel filter as they have a finer micron filter which will remove the smaller particles , Cheers Paul.

Nice old thread to dig up dave...

time for a 1.6 conversion..... problem solved!

Or get a mighty 1ltr!

Or change down from 5th...

one ltr dosent have 5th so no worries!

Its a zook thing they all do it. Don't muk around with bits of the carby get it completly overhauled by a pro. Other wise you will keep wasting money. Or try the easy carb clean...swap over the middle two spark plugs and start her up, this wil back fire and may clean out the carb. Been doing this for years. Of course this is just a temp try for the trail, it works sometimes.

Zooks ya gota love em