The Project Pad

Hey guys, I believe this is my first post on this board but I've been lurking for a bit. Most of you know me from Motorgeek for my 02 UrS4 or my old 88 90Q. Right now I'm asking for assistance on my wife's vehicle, 2001 Chevy Blazer, 4.2l V6. I replaced the spider injector with a MPI spider injector and now I have a misfires and even some back fires. I am sure I have the injectors in the right cyl as it's all labed.

So after having problems last night I fired her up this morning, started right up no problem! I thought, "Wow! This is nice! What happened?" Then it started misfiring again.
I went down and picked up a fuel pressure gauge so I could verify the pressure. I had my wife turn on the battery and I have 62PSI for about a second then drops to 54PSI. Fires up and goes up to almost 60PSI. Then starts to miss and back fired once. When it backfired I saw the pressure spike over 70PSI.

Any ideas? I need to get this working asap so my wife can use her when I got to work tomorrow. Thanks again in advance.

Amazon link to the spider injectors: http://www.amazon.com/ACDelco-217-3028-Fuel-Injector/dp/B000NW8ES0/ref=au_pf_ss_1?ie=UTF8&Make=Chevrolet%7C47&Model=Blazer%7C420&Year=2001%7C2001&carId=002&n=15684181&s=automotive
Forum/thread I found info: http://www.s10forum.com/forum/f107/scpi-to-mfi-upgrade-kit-324166/

I had some experience working on the 4.3 v6 (If they are the same thing) If the psi is fluctuating there is probably a really bad ground or bad voltage regulator somewhere. Does the FPR look ok? Definitely sounds like the two correlate to each other.

I was just looking and noticed that the PCV valve (pn: acdelco cv769c) is not plugging in where it should and is crazy loose/won't stay in place. I'm wondering if this could cause it as it's the crank case breather valve? I'm going to replace that today but anyone else have any thoughts?

Okay, she runs now and learned a new lesson...

When you are putting things back together (especially if you can't see the back/under something), also massage it into place gently making sure everything is in place where you can't see.

Apparently, I had one of the spider's legs (furthest back injector line) pinched under the housing and I couldn't see it till I had it all off and was looking at everything. She's up and runs now. Appreciate the help Themagellan and Dave.

Glad to hear it was somthing kind of stupid. I was thinking about htis for quite some time after we talked. I couldnt figure what wouldhave been causing the issue. Glad you have it fixed, and your wife has wheels again.

Yeah... I just wasn't very careful was all... I'm just glad it didn't cause any permanent damage to the unit, I didn't want to spend another $200 due to my own stupidity. lol

I had everything pulled apart last night and didn't see it till I was putting everything back together again and boy did I feel stupid when I found it. And the relief I felt when it turned over and ran well.

Next is to get her ISV (whatever Chevy calls that thing) cleaned for her. Then I will change out most of her electric system. After that, she'll have a reliable car that I won't have to worry about for her. Then comes some loven for my car!

GM calls them an idle control motor. Same thing different name.