Quote:
Originally Posted by Zilverado
Sorry for the lengthy post here, but I need your help. In an attempt to fix a rough running/stalling condition, the following parts have gone in:
- Plugs
- Wires
- Dist. cap
- Rotor
- Air filter
- Air breather
- PCV
- Fuel filter
- and of course - - oil and filter change.
So I start it up to fill the oil filter. Runs great, oil light goes off, and I shut it down to top up the oil. Start it up again, runs great for about 15 secs, then starts to slow, eventually loping badly (rich exhaust). Rev it up and things clear slightly, but very quickly she slows and eventually lopes to a stall. Starting again is difficult and even reving up is rough.
Before anyone suggests it, I'm pretty confident I got the plug wires in the right order - and this condition existed before the work was done. 
So does this sound like a carburation issue? I was thinking of maybe removing the top of the carb and cleaning things up a bit (as opposed to a full rebuid - due mainly to time). How can I tell which carb I have - I have attached some photos? Where are the fuel mix adjustments?
Again sorry for all the questions, but just want to get this fixed. Thanks. |
Zilverado your carb is a M4ME Qjet, first thing is get a big can of carb cleaner and spray the outside of the carb and get all that gum and varnish buildup off as well as spraying really well down the PRIMARY THROTTLE BORES working the butterflys, looking at the Chevy Factory manual under Carb troubleshooting it states these as possible culprits
Loose,broken or incorrect vacuum hose routing.
Choke valve not operating properly
Choke heater system malfunctioning
Fast idle speed low when cold
Choke valve sticking or binding
Fuel pump
Malfunction in accelarator pump system
Choke valve not closing
Insufficient fuel in bowl
Clogged or malfunctioning PCV system
Air leaks into carburetor bores beneath throttle valves, manifold leaks and or vacuum leaks.
Good way to find those vacuum leaks is to start the truck and spray Carb cleaner around the base of the carb and around the various vacuum lines and see if the RPM changes, if it does you have found your leak.
The idle mixture screws are located on the bottom front of the carb beneath the fuel filter, you might have plugs over them, easy to pop off then you can make your adjustments, if you adjust, turn them all the way in C/W then back out 3 complete turns for the initial adjustment then adjust each one to obtain your best idle. If all else fails it 's probably time for a carb rebuild, and it's best to keep the old carb. Hope this helps.
John