Truck is jumping almost always and sometimes violently :(

Fellow 1st gen Taco Owners! Specifically 01-04. I have a problem and would like some in input please. Has any of you ever had any issues with your truck like jumping while your driving. It's kind of hard to explain. Sometimes it starts doing it immediately and sometimes it'll start later on. & at various rpms also. Some times it'll get really bad and not want to accelerate past 30. Also, it's started and shut off immediately a couple of times aswell. There is also this faint knocking noise I can hear coming from under the hood. If anyone can relate please let me know if you have any ideas on what my problem could be.

P.S. Ive already removed and thoroughly cleaned my throttle body and also changed the fuel pump relay with no avail.

P.S.S. So, yesterday my truck officially took a shit. It shut off and won't start anymore. On the bright side it finally produced a code for me. However the code is beyond vague. Code it gave was:
P1071-Fuel Trim System Too Lean (bank 1)
https://www.kbb.com/obd-ii/p0171/
I put some fuel on a rag and held it to the air intake and it started! So, I'm betting on the fuel pump. Just bought one at the store for $60 after the business account discount was applied. Not too bad I think. Im about to install it but I don't know what the fuel pressure specs are for my truck and having a bit of difficulty finding the answer online. Any insight would be greatly appreciated.

P.S.S.S. For whomever want's to help with the proper psi reading I should get when checking fuel pressure Tigerlily is a '04 2.7l 4cyl Prerunner SR5 (not sure if SR5 is something you need to know or not)

Also does anyone have a complete pdf of either the FSM, Bentley, or Chilton Service/Repair Manuals that they wouldn't mind passing my way please?!? All the links I find online are deadends to nowhere -.-
!!I'll love you forever!!

 

Could it be bad fuel?

 

In my experience with my truck it was a blown head gasket when doing similar to what you're describing. I also had a bad engine coolant temp sensor plug that caused some jerking and stumbling at times. Maybe unrelated to your issue but a possibility.

 

CEL light? Check for codes?

 

From your discretion I'd say fuel related. Starving, bad/water (as suggested earlier). A fuel filter and maybe a pressure check wouldn't hurt.

Although my twisted mind went here 1st

 

Supercharged?

Sound like a defective MAF that intermittently shuts off and get re-energized.

 

When the truck is idling does the tachometer needle bounce a little or is it steady? Taco should love you long time.

 

When you said jumping I pictured the wheels leaving the ground.

either fuel or ignition has a intermittent problem allowing the engine to stall and reignite

 

So, i'm going to check fuel pressure today just finished getting everything of what I think I need to do the test. fingers crossed. But I think it'd help you all to know that I often refuel at the junk yard for free with fuel I pull from junk cars. :/ not the smartest idea, im aware.

 

I think this.

Occam's razor. eliminate the easy stuff first. I had a Jeep CJ7 do this on a road trip. it would surge..(surge is a better word than "jump"). surge hard.

my CJ7 was carborated, but it surged. it was similar to bad fuel for me. I had rust in the gas tank.

 

I super hope this is not the case. But just a question, shouldn't my truck have been overheating if the head gasket was blown? Also, wouldn't my truck have not survived much longer with a blown head gasket? Just wondering cause in my case, when I was 17, my '95 eclipse died due to me ignoring it constantly overheating until the head cast blew and got water in my pistons. I will make note to review both areas you suggested. This has become Tigerlily's most difficult issue to identify hands down. I've asked many people (most if not all of which work with cars) before posting here and almost everyone has given a different guess. Amongst the most mentioned were..throttle body and fuel pump. Throttle body was pretty gross with a decent amount of scum, but I've since then made that shit look brand new. Checked the fuel pump relay...all good. Now, on to check fuel pressure.

 

No lights or codes unfortunately. =l But, I do however have my OBD II reader always plugged in and can put it into live data mode if any one can make any suggestions on any specific functions I should review. =) Would greatly appreciate that!

 

e1222 211. 2

I will add this to the checklist. P.S. not supercharged. Should I still check MAF?

 

I had that same "bucking/jerking" issue when I had a 22rte that's why i asked. Under no load, no issue but once the engine sees boost, it jerk and the engine truck shakes. Turn out to be a bad MAF with a a dead spot, swap out it out and no more issue.

 

What do the fuel trims look like driving around?

 

So, the tachometer has had a very lazy mind of its own for what seems like maybe 1 year now. so, then answer is yes it does do what you've described but rather than little it bounces a lot . It, also revs at high rpm for too long before the car shift to the next gear. It will also flatline aka read 0 rpms. Of these 3 it usually just chilling steady on 0. lol I'd say my tachometer is trash.

 

Thank you for the vocab tip. Also what do you mean by "Occam's razor"?

 

Not sure what you mean...Is this a function I should monitor with the OBD II reader? If so, what would the exact name/label for this be on the reader?

 

Occam Razor is an idea that the solution to the problem is most likely the easiest or obvious one.

 

I see. How did you come to find out you had rust in the tank & were you able to clean it out or did you buy another?