I was doing a general look over on my 2000 blazer 4.3L and noticed that the air intake was a little dirty so I sprayed it down with some carb cleaner. When I started it up it started to run VERY rough. While running I sprayed some more into the intake and it started backfiring and running rougher, like it was way out of time and it now has white smoke out of the tail pipe and absolutely no power. I checked and cleaned the plugs, they weren’t in to bad of shape, and got the same results. Checked the fuel filter, it is fine. Fuel pressure seems adequate. All of the spark plugs are firing. I’ve tried unplugging all three oxy sensors and the MAS to set it into default, no luck. Unhooked the battery and reset the computer, no luck.

If anyone has any ideas I would REALLY appreciate the input.

Thanks

 

I would run a compression check. You might have blown a head gasket.

 

Start the truck up and watch the coolant tank. If there's any bubbling coming up through the coolant...that's bad. Also check the oil...if it looks brownish and chocolate milkshakey....again..bad.

EDIT: Although, when I cleaned out my throttle body, a little white smoke comes out from the carb cleaner and the loosened carbon...and the backfire could have been the carb cleaner igniting...have you driven the truck for a mile or so to clear out all the cleaner?

 

I thought of that but there is no coolent in the oil and it looks more like gas coming out of the tail pipe, so much so that it killed the grass along side of the driveway under the tail pipe in about a 3 ft circle. After doing some research, some of the symptoms I had prior to this sugested a faulty fuel preasure regulator. Hard starting after it warmed up and a slight gasey smell after I shut if off. It will start up and idle fine for a few seconds then starts running rough again, like it's starved for fuel. Also it hasn't been overheating. Also when I'm idling it if I shoot compressed air into the intake it will smooth out. I also took out a plug at a time and ran it, compression seen fairly uniform. When I try to rev it up it runs like there is a couple of plug wires turned around or it is out of time. Could I have plugged something up when I sprayed Gumout?

Looked at what is coming out of the tail pipe again and it's definatley gas vapor. If i try to drive it very far I can't get it over 3000 rpm and I get a blinking SES light. Checked the coolent and there is no bubbling.

 

If that is the case, then a fuel pressure test would show you if you have a FPR failure on your hands. It is possible that the backfire blew out the diaphragm in the FPR. By pressurizing the fuel system and watching the fuel pressure after the pump shuts off, you can quickly determine if it is a fuel leak that is causing your problems.

 

Ok, that makes sense. Thank you VERY much for the help.

Tim

 

I've kinda got the same prob right now. Not trying to thread jack, but I have a 95 blazer Vin"W" and I am experiencing the same. I changed my FPR and while I had the intake off, I used throttle body cleaner to clean the manifold. Although i sponged up all the cleaner I could see, I obviously didn't get every last drop(nor did I expect to). When I fired it up I've experienced exactly the same. I have drove mine about 3-4 miles with no result. Maybe we can figure it out together.

 

What I found on mine when I removed the upper intake
manifold was that the fuel lines running from the
spider to the injectors were leaking. They looked
like they had caught fire, or at the least had gotten
very hot. I tried spraying part of the line that was
still good with carb cleaner and put a lighter to it
and couldn't get it hot enough to melt, it would only
melt if I put a propane torch to it. Beats the hell
out of me. Basicly 5 of the 6 lines were pouring fuel
into the air intakes and flooding the engine. Hope
this helps. Good luck!!

Tim