hey everyone, after a long time away from the forum after losing my 94 from a blown motor, Im back. I recently inherited my late Dad's 2000 Blazer. Driving it home from his house to mine roughly 90 miles, it used almost 3/4 of tank of gas. Plus it would have a rough idle at a red light and stumble off the line. Black smoke would come from the exhuast as well. I figured it needed a tune-up. I did plugs, wires, cap and rotor, air filter. I didnt do fuel filter, becuase he told me he had to replace all the fuel lines earlier in the year and they did the filter then. No joy, still had a little rough idle, drove it to work, figure it needed to run itself out and it still sucked down gas like it was nothing and ran worse as the truck warmed up.

So I figured I needed to replace the spider or the fpr. Brother in law hooked me up with a somewhat used MFI spider from his garage. But it is missing 2 of the clearish nipples or nozzles that are at the end of the injectors. I have searched Advance Auto, Rock Auto and Google searched and I cant find then anywhere, without having to buy individual injectors at 80 bucks each.

Anyone Know where I can find them. My next stop is junkyards, but finding a truck with the spider still and one with the MFI upgrade is going to be hard.

 

I dont think you are able to just buy those. those things get brittle over time. Before you go throwing parts into it. Have you done a fuel pressure and leak down test?

 

No I didnt do a fuel pressure test. I should have, but my brother in law said it was probably the spider. And with the way it was burning fuel, I figured he was right. I already have the manifold apart, it wasnt until I pulled the old out that I realized they were different and started doing some research and learned about the MFI upgrade.

Is it worth staying with the old spider and replace the fpr?

The inside of the manifold is completely black from carbon, except towards the back. I sprayed it down with carb cleaner and it started to brighten up a bit.

 

black carbon is a GOOD thing. it comes from the egr. If its got cleans spots,its leaking gas.(which of course its a cleaning solvent)

i may be at the yard tomorrow. there is a lower intake manifold laying in the back of like a 98ish blazer with the unit still in it. if you want i can look at it and see if its the new style etc. I might beable to fish out the lines without breaking em. Do they have the security bit screws like the old 92-95 spiders have? If so i dont have the bits

 

Newer style or not, all you need is flathead screwdrivers to release the unit from the bracket and pull it up and pull each leg out. At the end of each leg is the plastic nipple.

 

towards the back is where the regulator is. you need a spider assembly or at least a regulator.

 

ok, found the nozzles at the junkyard, only 3 trucks in the yard and only one had the spider, sure enough it was the mfi one. Score. snatched all 6 nozzles off it and went home to put the spider in.

put it all together twice, after not checking if everything was clear and I crushed a spark plug wire that was under the manifold. stupid me

started it up, had a noticeable rough shake at idle, rev'd the throttle body and it seemed to smooth out. Bunch of black smoke came out the exhaust, along with a nice blast of black gunk that sprayed the driveway the first few rev's. But it cleared up. Still had a shake at idle.

Threw the pressure gauge on. Key ON it shoots up to 64psi and quickly starts to drop. Running it holds at 58psi.

Thoughts and suggestions

 

Sounds like you still have a leak to me.. if it leaks down quick, could be a couple things, injector or nut kit leaking, or the check valve in the pump. you would have to check the fuel pressure at the fuel filter to rule out the pump.

 

the 2nd gen doesnt have a nut kit. But the problem with used injectors is you have to know why the vehicle failed. Lots of people get a leaky injector issue and keep driving it and let it get so much gas in the oil it wipes the crank bearings THEN they scrap it. You have to find the leak, that pressure needs to hold. If it keeps black smoking then its still a bad injector

 

yea, I know that pressure needs to hold. Co-worker that used to work as Chevy dealership mechanic for 15 years told me about the the leak down test. Where you clamp off the rubber fuels lines underneath after turning the key to ON and see if it holds pressure. Going to try that as soon as I can.

What is the ideal pressure at key ON and Running??