HELP!!!! this one is interesting

[zach78k5]

all of a sudden my blazer started running poorly. at idle it feels like it is running on about 7 cylinders(shaky really rough idle). When I stomp the gas, though, all power is there. While cruising though, the truck will sort of sputter as if it were getting no fuel for a quick second. it will do this sputter two or three times and then is fine. If i use very little gas i dont have this problem. What could this be. my wild guess might be fuel pump or fuel filter but this just began half way on my way to work today.

 

[xswede]

You might want to check your vacuum hoses. Make sure you don't have any leaks.
Good luck,
Dan

 

[zach78k5]

ttt

 

[rockink5]

Is this for the 85 in profile? Sounds like the same problem I chased for YEARS. It turned out to mainly be the EGR. Not sure how to check it, but the EGR solenoid went bad and was not letting the valve operate correctly. Idled crappy, had somewhat ok takeoff, but had poor cruise characteristics. Check that solenoid! /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif

 

[mud390]

Have you checked your fuel filter? Maybe its partly clogged and only allowing gas to get through at higher RPM's.

Kris

 

[Blazer1970]

EGR valve stuck open. The '78 may not have a solenoid, it might just be operated off a ported vacuum port on the carb. The EGR valve itself might just be carboned up. The EGR valve should always be closed at idle.

 

[zach78k5]

I will try that as well as the fuel filter. Where is the EGR solenoid located?