2000 Chevy Blazer 4.3 Vortec Bogging Rough idle and stalling

[Ryan Jones]

Hi i am pretty new here and i am just trying to diagnose problems with a 2000 chevy blazer 4.3 i recently picked up on a trade.

Idle is low and really rough and sometimes stalls

Bogs when accelerator is pressed down

has a backfire sometimes through the intake.

 

 

 

 

I recently hooked a fuel pressure test to the car it gets around 54-55 when key is turned on and off.

once it is started the fuel pressure gauge flickers from around 45ish - 52ish as seen as it is bouncing around when you give it more throttle it doesnt go up very much sometimes going down and after idling and bouncing around it dies and the pressure stays at around 46-48. until you turn key off and then back on then goes to around 54-55 i did do a leak down test and it holds the steady 55 and sometimes goes up a little after sitting 10 minutes. will a weak fuel pump be causing it to do these kind of things.

 

PS my gauge is brand new and i tested it on a 5.3 2000 Vortec and it does not flicker like the 4.3

 

Ive read that it should go up to 60 when key is cycled from on to off.

 

Thank you.

[silverlite]

Here's a link to get some help:

Blazerforum.com

 

It's one of the best sites I've found & may already have your answer listed in one of the threads.

 

YouTube is also an excellent source of help since Blazers, Jimmys & S-10 have been around a long time.

 

I'm not a mechanic by trade but manage to get by ok mostly using these 2 sources & a couple of friends.

 

Presently own:

1999 4dr 4X4 (parts)

2004 4dr 4X4 (parts or repair...) Haven't had a chance to check it over enough to decide yet but I got it for a steal, 2002 4dr 4X4 bought running but with needs, present project that will become my daily driver

All 3 of mine are LS models with the 4.3 L Vortec V6 engine

 

Some things I've learned in the past several months:

 

All 2002 and old Blazers have a throttle body with single fuel injection spider assembly with individual poppets

These poppets tend to carbonize & get brittle. Mess in the manifold after that. Plus, they get clogged up.

2003 forward GM went with the throttle body & a spider assembly that includes 6 individual injectors, 1 to each cylinder.

 

Amazon & EBay sell the complete new injection kit for about $225. Top 2 choices are ACDelco and Delphi. It's a direct drop in to replace the old poppets & gives a slight improvement on gas mileage too.

 

On a friend's 1998 Blazer with the 4.3L Vortec I checked the throttle body & it was pretty carbonized. Used throttle body cleaner on it & also pulled the MAF sensor body & sprayed it with MAF sensor cleaner. Also dumped a $10 bottle of Lucas deep clean fuel system cleaner. It's a white bottle with dark blue front label. Not the basic cleaner, deep clean. It did help his idle smooth out. However, there is also an IAC (Idle air control) valve that is good to also check for cleaning or replacement. And of course, fuel filter & fuel pump are other items that may need replacement.

 

On EBay: Complete fuel pump with fuel pressure sensor & tank gasket runs about $40. Local auto parts stores charge $200 to $280 for fuel pumps.

 

The Blazerforum.com is an excellent starting point.

 

If your skill is past most of my notes then please consider them friendly reminders. Wish you well with your project.

[silverlite]

Another part I forgot to mention is the fuel pressure regulator.

[Ryan Jones]

Ya I've read about all of the common things on these 4.3 gonna order the regulator and fuel pump. monday I'll let you know if either works thanks for reply

[silverlite]

You're welcome. Happy to help. I'm in the process of getting my 2002 Chevy Blazer roadworthy. Lots to do yet but it's a rust free 4 door LS 4X4 in pretty decent condition. Paid $800 for it last fall.

 

Parts installed so far include: new water pump, severe duty fan clutch, new thermostat. Used but excellent alternator. Used rear hatch switch. Scissor jack equipment from parts Blazer. New battery from Walmart... No receipt needed even though it came with the Blazer when I bought it. It went bad 3 months after I bought the Blazer. Under full warranty so I got the new battery totally free. Tires all match at about 65% tread. Spare great too. About 176000 on the odometer. Loaded with options: Leather, heated power seats, sunroof, heavy duty trailering/suspension package, roof rack, etc. It even has an aftermarket Pioneer radio system.

 

Things still needed: install the new fuel pump ( came with new fuel pressure switch & the tank gasket. Just under $39 from EBay. Change out the metal block that the oil filter & lines connect to. New hinge pins on front doors. Install the used lower transmission line from my parts Blazer & the right rear passenger triangle window (storm busted out the old one). Driver's side door master switches need to be replaced & possibly some of the other door window switches. Needs a few suspension bushings (well worn but not busted out yet). Needs new shocks & struts pretty soon too (EBay). I'm sure there are a few other things I've missed that are on my to do list...

 

We have 3 LKQ pick your own parts nearby as well. Whatever I don't have they sell really cheap. They also don't care how you get to the parts you need... Just have to pay for whatever you haul out. They don't charge for the oddball small stuff either.... screws, small rubber elbow, etc. Already sold enough stuff from my parts Blazer that anything else is free money. Money to spend on my good one.

 

Please let me know how yours comes along. I'm curious as to what the repair solution turns out to be.

[Ryan Jones]

I changed the regulator yesterday when it came and cleaned the injectors. same symptoms i only got 40 psi for fuel all the time now fuel pump will be in monday should fix my problem ill be back thanks.

[silverlite]

You're welcome.

I'm hoping to finally change out my fuel pump sometime this week. It's been waiting forever for me to finally get around to it. Thankfully the tank is low on fuel & a plastic tank..... Hate to accidentally drop it on myself...

Less weight is safer.

[Ryan Jones]

Well i changed the fuel pump got it to start wont idle put if you keep on gas it runs. i changed the regulator already maybe i got a bad regulator? or is it these spider injectors bad i also checked fuel pressure at it read 90 psi key on key off what would cause this.

[Ryan Jones]

It ended up being the fuel pump

[Patrickrobbins25]

Hello I have a question to anyone who can help I have a 98 blazer some how water or something got in the fuel I pumped out a gallon and half of wat looked like water from tank but anyway I ended up doing a fuel pump and I got a Carter p74000 witch is for a older gm but got it all hooked up and put in and still wudnt start and I also clean the injectors and I checked the psi and it only read 20 psi so I don't know if a wire is crossed or if that's all that fuel pump will put out any suggestions is greatly appreciated thanks

[stonum]

Be sure to clean the MAF sensor as silverlite suggested if you haven't already. My '99' Jimmy was bogging when I 1st pressed the gas pedal. I cleaned the MAF, and now the truck jumps forward without hesitation when I press the pedal down. I used CRC Mass Air Flow sensor cleaner.

[will975]

I'm having some trouble with my zr2 sonoma I just put a fuel regulator in feared it was leaking had gas in oil I had just put manifold gasket kit in a month before. And cleaned the intake as well so couldn't see signs of intact leeks cuz it was already clean intact also clean injectors and tb with carb cleaner I didn't take the sensors out I sprayed them down as well I got cleaner down in the intake buy accident had to suck it out with a pump put it back together now it bogs when give it gas also if I take the cold intake off while it's running it will die did the cleaner eat up the new intake exhaust gasket causing a vacuum leak or did it foul the plus or did I destroy my sensors.i had some trouble with the new regulator I was putting it as well I had to file the spacer down for it to fit is that the problem or a combination of everything it was as running perfect before I did that to it. But I am getting gas in my oil I don't know if that was the problem since I jut change oil to and only drove it once since I put the parts on yesterday . Any thoughts