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Blue BlaZeR2 93

HELP fuel injector issue?

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I have a 2001 blazer zr2. Went to leave work the other night and when I started my blazer it was shaking really bad and had low power. No check engine light on though and drove a few blocks and it quit and went completely back to normal. Started it up to drive to work this morning (first time I had drive it since i had the problem) and it did it again this time the check engine light was flashing and then when it quit missing the light just stayed on but the motor quit shaking/missing and it had full power. 

 

Stopped by autozone on my way in to work and they pulled the p0200 and p0306 codes which are fuel injector circuit malfunction and misfire on cylinder 6 respectively. Car has 217k miles and no idea if it's ever had a tune up. I have the upgraded mpfi injector, full intake gasket set and bolts, spark plugs, and wires, cap and rotor, inigtion coil, and pcv valve in my cart now on rock auto. Before I go spending $400 right away is the injector at fault here? I know my cat is on it's way out as it is rattling but I would think it would be throwing a different code for that and have different symptoms. Are there any other parts in going to need for this?

I am going to try seafoam spray down the intake and running a can in the next tank of gas as well before I order everything. I'm sure it's over due for a tune up but don't really want to spend the money right now if I can help it.

Edited by Blue BlaZeR2 93

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Check the fuel pressure (there's a port near the back of the motor up top IIRC, someone will have to chime in on the correct pressure) just to rule out the fuel pump. Normally they just flat out quit (my experience) but, sometimes they can do weird things.

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27 minutes ago, Private_Ops said:

Check the fuel pressure (there's a port near the back of the motor up top IIRC, someone will have to chime in on the correct pressure) just to rule out the fuel pump. Normally they just flat out quit (my experience) but, sometimes they can do weird things.

I'll see about checking it in the morning. Drove it home from work tonight and it did great from start up til I got home. I really think the poppet for the cylinder 6 injector line was stuck open. I think age is finally wearing on an already poorly designed part but I hope someone with more experience can give me certainty. Going to spray a whole can of seafoam down the intake in the morning and fill it up and put another can in the gas and see if it comes back. I'm only the second owner and the previous owner supposedly replaced a lot of things on it going to try and get ahold of him or one of his sons before I drop a wad on a new injector and tune up.

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Did seafoam treatment today time will tell if it's going to need replaced sooner rather than later. Thinking back I've had off and on raw fuel smell since I bought the car earlier this year. If the poppet was stuck open and letting the intake fill up with gas left in the line would that have gave me that fuel smell on hot days?

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Blazer was normal driving to work and leaving it was shaking like it might have been misfiring for a short period but it never threw a ses light at me. Noticed yesterday doing the seafoam just how loud my exhaust rattle has gotten and it's only getting worse. Anyone know if a plugged cat could be causing my problems or has the injector leaking led to a bad cat so I'm looking at even more money for a proper fix?

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You could test the resistance of each injector coil with a volt meter.  I don't know what the impedance (in ohms) is off the top of my head...but you could have an injector coil  going bad.  That may be the P0200 code you are getting.  There could be other reasons like chaffed wires, broken wires, grounded wires in that harness, etc.

How many miles do you have?  If the cat is rattling...it should be replaced.  Did you do the fuel pressure test?  That would help with diagnosing a stuck/partially stuck injector poppet.  It will also rule out the fuel pressure regulator.  I had a poppet leak and only noticed after checking the fuel pressure.

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No I haven’t done a fuel pressure test yet. It’s been a regular occurrence the past few days. It will miss until the motor is up to temp ~190 degrees then smooths out and runs perfectly fine. I wouldn’t think it would be a ground wire. Since it’s running like crap until operating temp would an injector coil be a likely cause? Is the coil(s) going to be on top of the intake or inside it with the actual injector? If fuel pressure was a problem would it not cut out at higher rpm’s? It has 215k miles and is a 5 speed and has a lot of power down low but doesn’t ever make much power or wants to go above 3k rpm’s though I’ve never been sure if that’s because of the manuel shift or the cat going bad. I’ll try and do the fuel pressure test and report back but the way it’s acting leads me to believe it’s either the injector or something affected by the fuel tables like possibly a coil?

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I believe you can access the injector connectors from the top (where the large black harness is).  Remove the plastic "lock" (basically a plastic stick holding the clip) and unclip the connector.  Use a voltmeter with the resistance setting and measure across each injector coil.  Record your values and compare to OEM specs. I may be able to look them up if you can't find them.  Since you have a misfire on cylinder 6, pay close attention to what that value is.    If a coil is internally shorted it will throw a code. If there is any problem with the wiring to that injector coil it will throw a code.  There may be a weird situation where a wire or part of the coil is open (physically broken or separated) when cold.  After you reach operating temp, the broken wire or coil may make contact again (since copper expands with heat).  This may be why it runs normal after its heated up.  This is all theoretical though.  I have seen this in other situations (windshield wiper sprayers, etc).

The fuel pressure test may rule out if  you have a stuck/partially stuck poppet.  While looking at the gauge (key on engine off) you should see pressure and it should hold for about 5 minutes (+/- a pound or two).  If the pressure drops steadily then you MIGHT have a poppet stuck open.  This problem sounds intermittent, so the fuel pressure test may not show anything if the poppets are closing normally at that moment.

With the two codes you are getting something is obviously going on with cylinder 6, most likely electrical related to that injector circuit, which is causing the misfire.  Not only perform those tests but look for the obvious annoying stuff like chaffed wires and looms, partially plugged connectors or maybe even pinched wires.  You never know what the previous owner did or more importantly DIDN'T do correctly before you got it.  Let us know what you find.

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Ended up ordering a new fuel injector, complete tune up, new Magnaflow y-pipe and o2 sensors, and some odds and ends the car has been needing like rear glass struts. I’ll report back when everything comes in and I get installed. After talking with my uncle and having him look at it he seems convinced it’s the fuel injector so going to just replace all the known worn out parts and hopefully keep it on the road problem free for a while. Would really like to see a couple more years out of this car if possible. The only thing left that I’m not sure about is the fuel pump but I’ll cross that bridge when I have to.

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