The truck backfires alot when slowing down.It also blows black ex haust when first starting.And ocasionaly will choke and sputter,shutting off but able to restart later.It will ocasionaly sputter and act like its either flooding or possibly starving for fuel.It has only started this recently after a 14 state road trip in a month and a half but ran increadable with no problems the whole trip.The engine and carb are both new.I,m thinking the timing needs to be advanced and could use info. on how to do that as well as posibly leaning out the carb.Any suggestions would be greatly apreceated.Thank you.
2006-08-02 03:37:38 · 5 answers · asked by thomascrg 1 in Cars & Transportation ➔ Maintenance & Repairs
What you described sounds like the EGR valve is sticking closed it makes your engine backfire on deceleration and makes the engine run rich (the black smoke) to check to see if it is stuck slide your finger under the valve and try pushing up on the diaphram if it doesn't move then it's stuck closed. If the diaphram is bad you can check it with a vacuum gage! Start the engine and apply 18 inches of vacuum to the valve if the engine starts to die the valve is ok. If the engine doesn't die or the idle changes the valve is bad. Good Luck
2006-08-02 03:50:49 · answer #1 · answered by rookie 3 · 0⤊ 0⤋
New carbs are a royal pain... here are some suggestions:
Your choice:
Sounds like your choke is sticking, the body of the carb is warped, your bowl vent is plugged, float is sticking up or you have a vacuum leak.
These carbs are self regulating as to flow, etc., so the only adjustments are the idle mix. Even if the jets are too big the carb will only flow as much as the engine will take.
Take the air cleaner off (cold) and crank it up. Watch the choke plate and see if it moves. If it doesn't then you need to clean the plate, shaft and linkage with carb cleaner unitl it moves freely.
If you have an electric choke, you'll also need to check to see that it is operating. It should open up pretty quickly. These carbs are famous for blowing the electric choke.
If it's the old style divorced choke it should be okay once you free up the linkage - just make sure it opens fully when the engine is warmed up - you can use a pair of pliers to bend the linkage to get it to open up all the way.
While the cleaner is off, look for an obstruction in your bowl vents.
Take a screw driver and make sure all the screws that hold the carb together are snug.
Check all you hoses and make sure the PCV valve isn't stuck. Vacuum leaks can certainly make it backfire when you slow down. Too much fuel gets into the hot mufflers and you get you backfire.
As a last resort, wack the body of the carb with a hammer handle (not to hard) and see if it frees up the float.
Timing should be 8-10 degrees BTDC at idle and 30 degrees total advance at 2800 RPM with the vacuum advance plugged. Depends on your elevation - but these are good base numbers.
2006-08-02 14:27:15 · answer #2 · answered by Tim B 4 · 0⤊ 0⤋
Blsck smoke = too much fuel . sounds like stuck float in carb. Check fuel filter and needle valve in carb befor messing with other stuff. also check fuel pump. its a fuel problem
2006-08-02 10:45:41 · answer #3 · answered by Anonymous · 0⤊ 0⤋
I'd start with the basics. oil change, new plugs and wires and possibly distributer cap and rotor. If it still has problems then go from there.
2006-08-02 11:03:57 · answer #4 · answered by CJ 3 · 0⤊ 0⤋
sounds like ya got a vacuum leak somewhere it could be in your vacuum advance on the distributor. another thing could be your choke sticking
2006-08-02 10:43:30 · answer #5 · answered by Anonymous · 0⤊ 0⤋