So I recently acquired a 1995 Blazer on a trade for another vehicle, seeing as I was looking for a 4x4 for the winter. This truck just had the motor rebuilt, and was nearly complete - "just needs a coil & it's good to go!"

Well, needless to say; that statement couldn't have been further from the truth! This truck was in pieces, lots of pieces! But I've spent the last 2 weeks managing to get the majority of the truck back together, and finally tried to get it started. No luck! It just rolls & rolls, but never offers to catch.

I had to get a coil, bracket & module from the wreckers, and checked to make sure they were in good working order. There's good strong spark from the coil. We've pulled off a couple of plug wires & checked for spark; and everything seems good there as well. We tried a little gas in the throttle body, but that just caused a fireball to backfire out; and it still didn't start.

I thought maybe the distributor & rotor may have been installed incorrectly; so that's been checked & rechecked. (I was only able to find timing instructions for EDI engines, is that the same as the CPI that is in this truck?) The rotor is not perfectly aligned to the cast "6", but it's close. And I've tried a tooth either side & got the same results. So just to clarify, with the motor at TDC, the rotor should be pointing to the #4 plugwire?

And after ALOT of reading, I broke down & got a fuel pressure tester & this is where it gets weird... With the key in the ON position, but not started, the gauge reads 10-15 psi. No higher, and it holds at that pressure until I press the relief button. So I figured this is the problem, right? Well to make sure I was doing the test right, I went to a friends '96 blazer & checked his pressure - Key on, the gauge went to 60 for about 2 seconds, then quickly bled off to 0. No maintaining of pressure... but this truck starts fine! Is that normal operation? Also; maybe related, maybe not - should there be any power to that black round piece on top of the intake (I'm assuming something related to the injectors)? We checked & one wire is a ground, the other has nothing...

So in short, I'm at wits end! I'm thinking that something is wrong fuel related; but don't want to start ripping this apart if it's not the case. Is there a good DIY for this repair? Or perhaps a .pdf version of the Haynes manual available to download?

Any help would be hugely appreciated!

 

Pressure should go to 60psi and hold within 5psi after the key turns off. I would say that your problem may be a combination of issues...

If the fuel pump were your only problem, it should run with fuel or starting fluid into the throttle body. The fact that it back fires would lead me to believe that something in the valve train and/or timing is out of time with the crank. If you have timed the distributor correctly, but it still back fires through the intake, I would take a hard look at the cam timing. It is possible that it has jumped a tooth.

How far was the engine torn down? Have you checked compression?

The timing procedure may or may not be the same. It depends on which timing arrangement you have. If your plug wires are all horizontal on the cap, then you have the EDI ignition system. If they are vertical, then you do not have the EDI setup.

 

From my understanding, the motor was torn down , re-bearinged & gasketed & then re-assembled. So it is possible that there is an issue with the timng chain; although I have been in contact with the guy who did the rebuild & he assures me that the timing chain & gears were installed correctly.

is it possible that it is a fuel pump issue, and not a fuel regulator issue? Neither looks very fun to tackle. The plug wires are horizontal, so this is an EDI system? Am I correct that when the motor is at TDC the rotor is pointing towards #4 cylinder?

 

This thread will explain EDI Timing..https://blazerforum.com/forum/showth...=engine+timing

 

thanks for the link. we verified the timing using this; and I think everything checked out good.

Sorry to reask, but does anyone know of a DIY for the fuel pressure regulator replacement? Or an online copy of a repair manual?

 

The fuel pressure regulator is located under the upper plenum it is attached to the spider injector unit..its simple to replace...check this thread ..http://www.treasureboards.com/blazer/cpi/CPI11.html

 

Thanks again. Think I'm gonna have to look into this on the weekend.

Now about that black thing on the top of the plenum: any info on that & what is supposed to supply power to it, cause neither wire shows power, and for some reason that doesn't seem right.

Sorry for all the questions; but I'm really frustrated with this truck & the guy who caused all of my grief with this rebuild has been no help thus far.

 

what black thing?

 

Here's the part I'm talking about:

 

thats the manifold tuning valve. it has a flap under it that turn when necessary. but i dont know why its there, or what it really does. i took mone off today to look down the intake penuluim and i found a little fliud that smelled like gas at the bottom of the intake on both sides... why is it there? is this fluid supposed to be there?