So here’s my problem - one day a couple months ago I noticed my blazer starting to sputter. It did this on and off for a week or so. I quit driving it and have been trying to pin point the issue, one fix at a time. I bough the thing for $100 two years ago because the kid was mad that he couldn’t figure out how to replace the fuel line. I fixed that and it ran great until recently. Now it constantly sputters any time you rev it up, in park, neutral or drive. I have replaced the cap and rotor, plugs and wires, coil pack and ignition modulator tested bad so I replaced both of those, has a new fuel filter, starter and battery. This thing has had more new parts than most of my vehicles combined, but I’m stumped as no other right now. There is no check engine light, fuel pressure test stayed around 55PSI (key on) after 10 minutes it went down to 54PSI. I have read on here that a lot of people where having fuel pump issues, but their pressure was also around 40/45PSI (key on). I don’t want to keep replacing parts if they are not going bad but at this point the only thing left to replace is the motor haha. Any help would be appreciated!

P.S. - there is no check engine light at all either. I thought maybe a plugged cat?

 

Mitchell
Does it idle well? Any chance wires are crossed? When I came across a restricted exhaust several times in pass; would idle but not come up to speed. You can disconnect the exhaust or perhaps pull an oxygen sensor before cat.
You didn't say how many miles were on it. Did plugs, wires, cap and rotor make any change at all?

 

Ebbervonfloyd,

180k miles are in it. It will idle fine, this only happens when giving it gas. I did have someone come down and it gave an error showing 2 and 3 cylinders were misfiring I am now leaning towards injectors. It also showed there was back pressure to the motor.

 

I guess you've tried cleaning the mass airflow sensor? Sounds simple, but it made a huge improvement on my '99'. No stumbling at all now.

 

Ill have to give that a try today

 

Also, the plugs, wires, cap and rotor didn’t make any difference at all

 

I used this stuff..

 

What do you mean by “showed back pressure to the motor”?

Why are you leaning towards injectors?

is it always the same cylinders that are misfiring or is it random? Did you look at a live misfire counter?

When you try to increase rpm and it stumbles do you have 1” of strong blue spark?

George

 

EGR valve is pretty easy to take off and clean, take gasket to parts store and show them to get the right one. I was having random misfires and I did check it. Turns out my AC Delco wires had a bad end. Cut off about two inches and reattached the end. I worked silicone grease around the boot and was able to slide it up the wire. I found the problem by looking at wires at night. I have new original wires to install but have not done so at this time. Ramdom misfires are gone.
L