The mystery fuel leak
 

Well as you all know I have been having trouble with a small hesitation. I found out why well sort of., I did a fuel pressure test on my truck yesterday and lost about 7 psi in 10 minutes(4.3 v6 02 model) Well that lead me to believe that it was leaking in the plenum considering I had not seen any fuel under the truck. And no leak! I can watch the gauge go down and so I then looked right at the spider and again, no leak . Then I crawled under the truck and followed the fuel lines, and couldn't see a leak anywhere!! I know its leaking fuel somewhere though. I can smell it almost overwhelmingly. Any ideas of where the leak could be?? I just put a new fuel pump on it not even 3 or 4 months ago, if that. I just don't get it, what am I missing???:icon_confused:

I think we need some perspective... the odor is one thing, rate of pressure drop another.
Liquids dont compress. If the fuel filter has been on the truck a while, then the air pocket in the filter at installation is gone, losing 7 lbs pressure might equate to a few drops of gasoline.
-That's why if you've just put a filter on or drained it then depressing the valve blows gas all over but after some use, only gets you a dribble.

There's a video on youtube that shows a bad Fuel Pressure regulator that could only be seen by blowing air across the vacuum inlet port.
I dont know if that has anything to do with oyur hesitation.. have you tried driving with MAF disconnected?

+1, don't assume its leaking somewhere. It may be the filter restricting flow. Also, make sure its not leaking from the test port. That will give you a false reading.

I hope the pump you put on wasn't an Airtex, if so, that may be the problem. If the hesitation isn't fuel related, like fog said, look at the maf. You might want to also look at the cap,rotor and plugs.

I don't remember what brand the fuel pump was, but I got it off the internet. It's losing about 10 lbs every 15 minutes or so. And will go all the way down to 10 lbs. I left the tester on overnight,and this morning it was 9lbs. I tried driving without the MAF and it didn't change the hesitation. I actually just replaced the MAF sensor this weekend as well as the spark plugs, wires, distrubtor cap and rotor. All AC Delco parts!! Never will buy anything not AC Delco again. The first thing I tried was the fuel filter about 2 weeks ago, and I am testing from the test port under the hood and there's no leak there. I'll be able to explain more when I get home from work....Thanks for the input guys. Any help is much appreciated. I am at a loss of ideas.:confused:

Well, IMO, still not enough leakdown to cause the problem, assuming you dont have starting issues, usually but ya never know.. things are weird sometimes..
now you get to do the head pressure leakdown test at fuel filter:
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https://blazerforum.com/forum/tech-a...agnosis-23038/

Ok so today when I got home I put a leak down test on the truck, and found that the spider assembly I installed in October had started leaking from underneath were the legs start anyway I put an old spider assembly on the truck I had just laying around and it stoped leaking but now its saying miss fire cylinder 6. (p0306) which that's what it said when that assembly was in there last. so I found my leak fixed it and now have an even worse problem any hoo my Question is can I take the two spider assembly's and make one Or just bite the bullet and go get my second spider assembly since I started driving these trucks a year ago?

Yes you can combine them, just use new o rings when putting it back together.