OK, before I shoot this darn Blazer, I'd appreciate a little help.
It's a '96 Blazer LT 4 door, 4.3L, auto trans., 4WD, with 212834 miles.
I have been chasing what I thought was a TPS related issue, and I started another thread in the past regarding that.
I replaced the TPS, but it still sets the MIL with a P0122 - Throttle Position Sensor Circuit Low Voltage.
I have traced the wiring to no avail.
I searched for the PCM grounding issue that the '96 was known for, but this one has the part number that is supposed to be fixed from the factory.
The symptoms would come and go, but of course they gradually got worse.
Now the truck runs really bad, occasional strong gas odor, and mileage practically non existent.
And now there appears to be gasoline in the oil.
So, is it likely that the fuel injection spider is the culprit?
I did the fuel pressure leak down test, and it failed.
I haven't done the test by blocking the fuel line at the filter to test the pump only, but I did replace the pump assembly back in Nov. '08 at 181572 miles. (I know, I know, but I didn't know any better and used an AIRTex E3925M pump....but so far it's been OK)
but now, with the gas in the oil, I'm thinking the spider has bitten me...(pun intended)
So, before I drop a bunch of dollars into this truck, again, am I on the right track?
Thanks a bunch for any advice.

 

Just pull the upper plenum and look close at what happens when you key on.

 

Aah...very good.
That's what I'll do, and post back what I find.
Thank you very much for the suggestion.

 

its easy to tell if the fpr is leaking or the nut kit look for a fuel wash on the lower half

 

1995 and older, (CMFI) have the nut kit. No nut kit on 1996 & newer, (CSFI)

Pettyfog is spot on perfect again! You should be able to see any external leaks when the pump is activated. However, after you remove the plenum, you'll need to reconnect the lines to the injector assembly before activating the pump. If there are no visible leaks, the components in the plenum will need to be isolated* from the rest of the system to figure out exactly what's leaking.

This is all assuming that your "failed leakdown" problem is actually in the plenum, and not in the tank. Fuel pump maximum output pressure & leakdown should actually be checked first, (especially knowing it's an Airtex pump). The clue here is you have fuel in the oil, and leakdown failed, so chances are the leak is in the plenum. If it's the regulator, it can be serviced separately. If it's the spider, it comes with a new regulator!

*Requires the fabrication & temporary installation of 2 shut off valves.

 

Thanks for all the suggestions so far guys.
As for the leak down test, funny thing is that after my reply to pettyfog, I went out and ran the test again, and this time it passed.
It showed about 62~64 psi while the pump was running, dropped down to about 60 psi when the pump stopped, (as soon as the pump stopped I turned off the ignition), and never dropped below 54~56 after 20 minutes or so.
This is the first time since this truck has been acting up that it's held that kind of pressure like that.
Apparently whatever is leaking is intermittent.
I'm also going to replace the lower intake gasket while I have it apart, because as I was looking at it yesterday I noticed a bit of seeping at the very front of the intake.
Are there any pitfalls I should watch out for as I'm taking this thing apart, or anything special I need to do during reassembly?
Also, is GM Parts Direct a good place to shop for the parts I'll be needing?
Thanks a lot for the help folks, I do appreciate it.

 

Fuel regulators can give intermitent results. Sometimes with the plenum off they will show no signs of leaking exept for a clean spot, then you hit them with compressed air. Leaking all over the place.

 

Look at Rockauto and also look for discount code. Advance on line has discounts.

There's a lot of good info on doing this both on here and several on youtube. Use the ones that seem common sense.
Lining up the distributor is key to a successful job. Remove the accessory belt and distributor cap. Turn the crank CW till the rotor lines up with the number stamp on lip of base and use straight edge and sharpie to make exact mark. When you pull the dist, do it straight up without turning base and make another mark where rotor stops turning -- that's where it needs to start on reinstall.
- use premium intake gasket set to avoid re-do. Felpro premium is most folks choice. I'd think Victor Reinz prem should also be good
- Look closely at the intake torque specs... INCH POUNDS! Dont forget!

 

Funny that you should mention that....
I pulled the plenum and reconnected the fuel supply and return lines.
I located the fuel pump prime connector so I could manually operate the fuel pump from under the hood without the ignition being involved in the testing, and so I could watch for any leaks.
Pressure is about 62psi with the pump running, and I don't see any leaks.
No signs of any fuel washing that I can see, everything is equally filthy.
I'm going back out there now and hook up a vacuum pump to the regulator and see if the diaphragm will hold a vacuum, that may tell me something I suppose.
Where do you apply the compressed air to test the regulator, and at what pressure?
Again, thanks for the assistance.

 

Thanks, I hadn't thought of RockAuto.
I have been searching here and everywhere for information, but I always seem to land here, for obvious reasons.
If the spider assembly shows symptoms of failing, is the MPFI upgrade recommended?
I've decided to put off the lower intake gasket for now, but I will do it in the near future.
Thanks for the tip on marking the distributor, particularly this part "make another mark where rotor stops turning -- that's where it needs to start on reinstall"...It had never occurred to me, but it makes perfect sense.
I always just kept dropping them in, pull it back up, turn it a skosh, drop it back in, repeat, etc.
Your way sounds better.