Okay - I'll try to explain what is going on the best I can.

My L is a 99. Mods are 2lb lower, 2.8 upper, REM intake tube, Long K and N, MAC exhaust.

Today a buddy and I finished up completely swapping out my brakes. We put in Rotorpros rotors all around and HPS pads. We bled the brakes numerous times and they finally felt "okay". I was in a hurry to get over there yesterday and was on "E" when I arrived. The next day when we were testing the brakes and bleeding them and after we started the truck numerous times, I realized it needed fuel badly. he suggested using some gas he had in a tank (about half a gallon) - was only sitting there a few weeks but was 87 octane. I'd done something like that before in a pinch and quickly filled up with 93 octane and had 0 probs. So, after I left, I immediately filled up with 93 octane.

So, we get done with the brakes and I leave - having 0 probs with the truck. I get home and leave a few hours later. I get about 20 minutes up the road and the truck starts sputtering, not wanting to go and it dies. I get it into a parking lot and try to restart it giving it gas, and it keeps sputtering and idling REALLY rough. I try to back up and the truck really starts bucking and wanting to die.

I get a friend to bring over some tools. I take off the IAC and clean it up really nicely. I take off the K and N and clean it. Still same problem. I thought maybe the gas so I pour in fuel injector cleaner, doesn't help (I knew that wouldn't but I was praying at this point). I also cleaned the MAF and removed the entire air assembly (intake tube, maf, filter) and put it all back on tightly. I secured the hoses under the intake tube to make sure its not leaking there.

I tried spraying it down with carb cleaner to find any vacuum leaks, but its now dark and I can barely see. I did notice something interesting....when I pop off my air filter the truck starts to run MUCH nicer....but still bogs when you give it a little gas. Pop the filter back on and it either dies or drops to 300rpm and barely runs.

I plan on changing the fuel filter tomorrow to see if that helps. My plugs are all new (NGK's about 6 months ago). I know I didn't blow a spark plug out of the cylinder head because I've done that already and it doesn't sound like that at all. I'm thinking fuel filter or vacuum leak somewhere.

Any suggestions>?

 

Sounds like you blew the hose off the fuel pumps. All 99-00s have that problem, it's just a matter of time. The factory crimp clamps are indequate. Drop the tank, and replace them all with regular worm clamps.

 

you covered all the basics except the chip has a loose connection on the PCM (if you have one).

Did you use a non-residue leaving spray to clean the MAF?

Over oil the filter?

Some of those pastic (non-flexible) vacuum tubes get cracks in them (almost impossible to see)

 

Thanks for the input so far. I will definitely try what you recommend Sal ...am gonna try the filter first praying that it does it...

I was actually able to get it running earlier just up and down my street and couldn't get it above 1500rpm. Would it still run if the pump clamps had gone?

I definitely didn't over oil the filter. That's the thing...the problem was there before I even cleaned or oiled the filter. I used carb cleaner to clean the maf which is what I've always used before with a problem. But again, the prob was there before I did that.

I don't have a chip - was tuned with a Diablosport Predator which I have. I ran a diagnostic with it and it pulled no codes also.

**edit** I'm going to check all of the hoses tomorrow to see if any are cracked....**

 

Well - all the hoses seem good so no issues there. I am going to replace the fuel filter as soon as it stops raining.....then plan on attempting to drop the tank and get to those clamps this evening.

I did a search to get some tips so hopefully that'll help. I'm just over 1/4 tank and from what I've read these trucks are siphon proof. Anyway to get the fuel out of there? That is going to be one heavy/awkward SOB with that much gas in it.

 

Ok - changed the fuel filter without a prob. I've dropped the tank and disconnected just about everything and am going to lower the tank shortly. Any additional tips on looking for the clamps?

 

Okay - dropped the tank and sure enough one of the hoses to the pump was barely on and the clip was loose. I replaced all of the crappy clamps with the worm clamps.

Unfortunately, there is a light blue colored sensor type looking device that connects to some black rubber hose that I broke. I was hoping it would still be functional since the end of it is all that broke (ie a tube that goes into the hose) but I don't think I can make it work after numerous attempts

So - anyone know what this is? I've tried prying it off to no avail and it doesn't want to twist. It appears that it has a pretty large slash on the top of it that maybe a really thick flathead screwdriver could fit into. Any help telling me what it is (so I can order one) and how I can get it off there would be much appreciated.