Hello,
I went out and looked at a customer's 95 Blazer today. The complaint was that it wouldn't start and when it was running, it was running rough. The customer said he had to keep his foot on the gas to keep it from stalling at a stop in gear. Upon arrival, i inspected the vacuum hoses, plugs, wires, coil contacts, checked fuel pressure (25lb after several cycles of the fuel pump relay) Clamped off return hose- still 25lb. pulled fuel filter(blew air through no problem) Reinstalled filter with new o-rings. Noticed that gas guage was in the red- added 2 gallons of gas (60lb or pressure) and engine fired and ran(fuel pressure was still 50lb 20min later after shutting it down). Engine is running like it has a bad vacuum leak- rough idle lots of missing, hesitation off idle, try to hold RPM at 2000 and it will wander up and down from about 1600 to 2300. Checked TPS- voltage is .60 and sweeps smooth to 4.5V. Checked IAC- worked pintle down and reinstalled to see if engine would idle high- engine started high and went right down to wandering around 750rpm, so IAC is good. I noticed a hissing noise coming from the EGR and after some research, noticed that these are problematic in the 4.3 vortec. I sprayed some electronic cleaner on the EGR to see if the idle would change- no idle change but the hissing noise changed to a gurgling noise so Im sure that is where it is comming from... the hissing is comming from between the EGR solonoid and the footplate that attaches to the intake. Has anyone else observed this noise? Is it normal? I read the post about cleaning the EGR ports in the intake and will be doing that when i go back. Do you guys think i should replace the EGR at the same time?
Thanks,
Derek

 

Alright, i guess if no one knows, ill just replace the EGR. I was hoping someone could just listen to their good running engine and tell me if they could hear a hissing noise at the EGR. do they hiss when they get stuck?