Make sure you don't have any leaks along the fuel lines and piping.

If you did an engine swap, it might be leaking from the fittings at the back of the manifold.

Did you replace all the rubber O-rings? There are two on the spider injector fittings and two more the same size on the fittings at the back of the manifold, where the lines attach there. Those rings are hard to find, and often gasket sets include only two, not all 4. CarQuest part # 27478 (also available through Advance Auto Parts now) is a kit with all 4 O-rings, two of the smaller ones for the return line fittings, and two of the larger ones for the supply line.

You have a leak in the pressurized fuel system, somewhere between the filter and the regulator. Leaking injector poppets are fairly common, and will cause your symptoms. A leaking regulator will also do it, whether it leaks into the plenum or down the return pipe. Obviously any fuel leaks in the supply line between the pump and the injector assembly can also cause you leak down symptoms.

 

Alright.


Yes I did actually replace the O-rings (I'm not notorious for replacing such things). There aren't any visible leaks but I'll double check. Thanks again!

 

I agree, the nylon line clips and O-rings are over looked a lot for fuel leaks. Mainly because from what I've seen they don't actually leak that much fuel, just drip every few minutes, making it difficult to catch.

If you do find the spider injector the culprit, me personally, will be doing the multi-port fuel inj. swap. The kit is actually cheaper than the OE single and snaps right in. Not sure of any computer programming issues or added wiring that may or may not need to be done with it though.

 

If you failed to do a Crank Sensor Relearn after swapping the engine, this is a probable reason for a false misfire code. Note that failure to do the crank sensor relearn will not cause an actual misfire, but will prevent misfires from being identified correctly. A SES light with a pending or hard P030x code will also prevent PCM from operating normally and engaging TCC as well as pulsing injectors sequentially and other things.

Often the presence of a misfire code simply makes you feel a non-existant misfire.

If you really have a performance problem and fuel pressure is good, then move on to the ignition. That is a troublesome area for Blazers. Cap/Rotor/Plug wires/Plugs and check the cam sensor retard to make sure it is 0° ± 2°.

P.s. I have found that 58-59psi is normal fuel pressure for many Blazers with Key On Engine Off. This is what mine is with the AC Delco Spider Upgrade and it runs just fine. Note that if you have the upgrade MPFI spider, there are no poppets and resulting minimum pressure to get an injector to deliver fuel.


Good luck.

 

Thanks for all the advice. This project has been on hold for a few reasons, mainly the sister in law's Neon. (Ugh). Tomorrow night is preschool orientation as well so we'll see..
You dudes are awesome!

 

Oh man, hope you're not having to do a timing job on that Neon! The worst I have ever done.

 

That was the first go-round. It broke a timing belt. AND!, about two months before I TOLD them they should probably replace it. So yeah, valves, a cam (didn't change the oil enough), head gasket etc., etc.,. Oh don't get me started... Haha!


This time it's just a wheel bearing and cooling fan wiring among some other little stuff.


Hopefully tomorrow I can get some time in on the Blazer..

 

Ouch! Yeah, We have a lot of those people around here as well. A bunch of, "I told you", moments lol.

10-4 man, keep us up on what you find. Completely understand, 99% of my interior is still out of mine due to lack of time.

 

Well I had a minute to work on it last night and I think I got 'er figured out.


First I tightened the lines by the firewall and actually that helped a lot. It went from 60-20 psi in about thirty seconds to 60-40 in about two minutes. This still didn't seem right to me and I was about to jump on here and ask what it should look like (still kinda wondering) when I decided a quick check would be to yank out the injector lines. Sure enough, cylinder 3 has a drip every five seconds or so.


That's about as far as I got last night but the next step is to swap spiders. I know I should replace it but this isn't my vehicle and I know this guy won't want to spend the cash. We'll see I guess!


Thanks again peeps.

 

Okay.


Swapped spiders and it started acting exactly like it was before. Fuel pressure drops immediately. Great. So I kinda fiddle with it for a while and after cycling the pump quite a few times it starts holding pressure a little better. Still not great by any means.


This morning I decided I would try a new FPR and look 'em up online. While looking, I see this little rubber o-ring on the very end. Now I guess there's a chance it's still in the housing (there is a chance, isn't there?) but it leads me to wonder how fuel pressure would act without that o-ring.


So before I go get a new one, I'm gonna make sure that o-ring is in there.


Too much fun...


On a side note, my four year old was "helping" me last night. When I took the spider assembly off, I show it to him and ask him,


"What's that look like?"


Before I hardly get the words out he says,


"A spider."


But then he asks,


"How many legs does it have?"


I tell him six.


"It's not a spider then. They have eight legs."


Some times he's to smart for his own good.