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 gas it and it doesn't respond.

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 to ensure no leaks. I secured the hoses under the intake tube to make sure its not leaking there as well.

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....every once in a while it will respond and you can get rpms up to about 3k....but it won't get into boost at all. 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 if maybe its clogged or something (its about 1.5 years old). My plugs are all new (NGK's < 6 months ago). Sam @ Coastal tuned it with a Predator which i still have. 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 on finding the vacuum leak or anyone have similar problems?

 

Your 100% positive it was 87 octane. hopefully it wasnt mixed ( 2 cycle ). Im doing the Alt. on mine right now.

 

Yeah - 100% sure. He doesn't have anything that uses 2cycle...... It ran fine for about 45 minutes after I put the gas in also. I don't think it would've lasted that long with 2 cycle.

Couple guys from another board think that the clamps on my fuel pumps popped off (apparently that's a common prob with the 99-00).

 

Well sorry to hear about your problems. We all have as Im going through some right now. My alt. went out on me yesterday so I bought one at NAPA, threw it in today ran good for about 15 min. then my battery light came on and my volt gauge was only reading about 12 volts. The alt. started make a screachy whiny sound. So now I get to pull it out and get another one tomorrow. LMK when you find out your prob.
Tony

 

wow, if it ran for 45 minutes without problems i wouldnt think its the fuel, unless it had water in it and it settled in the tank and then you started it and sucked it up, i sucked up a little water in my old mustang once and it ran like that for about 5-10 miles then cleared up and ran better than ever.

 

+1

 

Thanks for the input guys. As soon as it quits raining, I'm going to change the fuel filter. My truck is too big to get into my garage so the rear sticks out. I don't feel comfortable backing it up onto the ramps in the garage, because my garage floor coating is slick and the ramps won't stick (plus I've already backed into the wall once LOL and I'd just assume avoid that).

On another board, some recommended that the clamps that hold the line onto the fuel pump popped off. Apparently they are weak and many 99-00 Lightning owners have this problem.

So....if its not the fuel filter, it looks like my ass is going to try and drop my tank and see if that's the problem. I know that is going to be one PITA. It has a little over 1/4 of a tank too....no way to get it out since these trucks have some kind of contraption that prevents siphoning....

 

You can test the f/p to see if one of the two outlet hoses has come off in the tank.
Most of the time when ^^that happens the truck will stll idle fine and run ok at low rpm's.

 

Had this problem with my DSM before, maybe reset the ecu?