1989 gmc s15 pickup gives only 12 miles per gallon

[vikasintl]

Originally Posted by Myself

If the spring is not broken you're OK there. Timing jumping everywhere is usually a worn out distributor or sticking advance mechanism. Have you put in a new fuel filter? Are your plugs gapped correctly?

Fuel filter looked clean so I did not put a new one...I guess they are costly...

btw how do you clean fuel injectors?

Plugs are brand news AC delco..

I can check distributor but not sure how to check sticking advance...

Btw I checked again still timing is not steady at 8 ...it still jumps ...even though after correcting vacuum leak and replacing spark plugs.. it idles and runs smooth...



what else could be culprit?