Outer Limits 4x4 Board

I was looking over the carbi in my sierra today, making sure all vac hoses were in good condition, and noticed one had been (by a previous owner) purposely plugged with a screw and then just fitted back into place, so it looked normal.

Can anyone tell me why this would be the case? Also, what does the hose activate? I operated it manually and at idle, and it made the engine idle at higher rpm. I removed the plug, and re-fitted the hose. I havent properly tested it yet, but so far it has made no difference. See pic below to see which hose was plugged.



Mike

thats the idle up solenoid for your headlights.

if its working correctly it should open up when you turn them on.

Taff wrote:thats the idle up solenoid for your headlights.

if its working correctly it should open up when you turn them on.

That is correct, and the idle up can be adjusted via the 10mm bolt below the screw. It's possible the previous owner did'nt know how to adjust it properly, causing the carby to hunt when the lights were switched on, and just plugged up the hose instead.

Ok i found why it may have been plugged.

The idle up works, it will idle at 1000rpm, but with lights on it sits around 1500rpm.
The problem i found was when i turn the lights OFF the revs dropped right down and stalled the engine. This only happened once (when i got to work this morn and turned lights off). I re-started the engine, and turned lights on again, then back off again. It didnt stall this time, but revs dropped very low, before picking back up to 1000rpm.

Can this be adjusted?

Mike