Archived Started missing & Bucking on way to work !!!!

[lcaruso]

Need a little help from the pro's out there... . About a month ago truck started bucking & missing like I had bad fuel. Took off the V/A box and all was fine. This morning on my way to work truck started bucking and missing again !!! Did not pick up new fuel. I'm almost afraid to ask: What are the lift pump symptoms?. Also, I have 39,000, don't tow (this is my baby, I mean toy. Is the lift pump covered under the 100,000 warranty?. It's 15 degrees here this morning but I don't thing that has anything to do with it. It's been this cold many days this winter. Fuel filter was changed 3000 miles ago... .





Thanks for your help

 

[Hohn]

Check the simple stuff first

There's a certain order in which I would recommend going about things. First, check the simple things. Change your fuel filter again, just to rule it out. look inside the housing to see if there's junk in there (from water in fuel). Make sure everything is tight- banjo bolts, injector supply lines, etc.



Once you spent that money, THEN you can really worry. It could be your lift pump, but most times lift pumps bail but there's no change in driveability. Nonetheless, what is your fuel pressure?



You DO have a fuel pressure gauge installed, RIGHT???



If you have ANY positive fuel pressure at all, then the LP is not the only cause of what's going on. In my mind, that leaves only two things left-- the injection pump, or the CPS (crankshaft position sensor).



LP is most likely culprit given your low mileage, but if it went bad a long time ago (and you didn't know it), the your injection pump is also at risk.



Check fuel pressure and let me know what you get...



Hohn

 

[lschultz]

Ditto on what Hohn said. I would ck all your connections too. Being that cold could be a connection.

 

[CstlEng]

dito on Hohn and Ischultz.

 

[AC]

What year and model?

Based on the mileage I'm guessing its an 01. We can help you better though if we know exactly what your driving. You said you unplugged your VA box but do you have any other mods like injectors and such?

AC

 

[lcaruso]

Thanks to all. Yes it is a 2001, no other mods (yet)... . Silly me for not keeping up with the latest goings on. Ordered my fuel pressure gage from genos today. Crazy thing, when it warmed up over the weekend, the problem stopped. Can't get it to miss again. I did tighten up all the clamps which were a pretty loose (third time now) and exhaust bolts which were slightly loose. Will post fuel pressure next week when I get the gage installed. Question, has any one else installed a booster pump in line?. Holly has one $99 on sale right now. Pre set at 14lb pressure thinking about it to be safe.

 

[Badunit]

Sounds like an iced up fuel line to me. Mine did the same thing this winter a day after buying fuel from a station I'll never visit again. I am assuming that, in my case, ice formed in the line then broke free and nearly plugged it. Was fine then next thing I knew it was bucking and missing. It would idle fine and run at low RPMs and low power but would buck otherwise. After a warm day it was fine. I ran the tank dry, got new fuel, and replaced the filter.