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05 4.7 hard starting

Discussion in '1st Gen Tundras (2000-2006)' started by bmc02, Aug 24, 2020.

  1. Sep 18, 2020 at 10:56 AM
    #31
    bmc02

    bmc02 [OP] New Member

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    UPDATE. truck was still occasional hard starting, but less frequently and by hard starting I mean turning over for only an extra second or two before firing. Not a big deal, but not normal so I kept at it.

    I replaced the fuel pump resistor, as previously discussed. this made no change. When I tested old vs new the readings we're slightly different, but not by much.

    So I finally did what I should have from the get go, bought a fuel pressure gauge. Hooked it up, which the banjo bolt adapter it came with needed modified, so that took a bit of work. while running it was at 40psi pretty consistent. As soon as I turned off truck it would quickly fall to zero. Which is not good. That could be injector, regulator or pump.

    I would think an injector bleed would take longer to bleed down from 40 psi. Along with the findings previously posted I ruled out an injector issue.

    The regulator would not change pressure reading when I unhook the vacuum line. which I would think that it would so I figured it was bad. Nothing I can find in the FSM has any info on testing this item. so I bought a new one for $80 from the dealer and I have installed it. Pressure goes to 40 still, but now when I shut it off it only drops a few psi and stays there. After 5 min it is still holding so looks like the regulator is to blame. good news! A lot cheaper and easier then a fuel pump.

    What still has me scratching my head is the pressure doesn't change between vacuum line on or off, idle or 3000rpm. makes no difference on pressure reading. Also the vacuum port on the air box/resonator is very small and I can't feel any vacuum. Blew air through it and it is not clogged. I should just leave it alone, but if anyone has any input on their regulator behavior I would be interested in hearing it. thanks.
     
  2. Sep 18, 2020 at 11:19 AM
    #32
    Professional Hand Model

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  3. Sep 19, 2020 at 3:56 AM
    #33
    tvpierce

    tvpierce Formerly New Member

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    Thanks for posting back with the results.
     
  4. Sep 19, 2020 at 2:53 PM
    #34
    SouthPaw

    SouthPaw The headlight guy

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    Interesting and good find. Fuel pressure regulators are pretty common on GM stuff for similar symptoms. Usually will cause a misfire as well but every make is different.

    Either way, sounds like you either fixed it or it’s on the right track.
     
  5. Sep 20, 2020 at 3:36 PM
    #35
    bmc02

    bmc02 [OP] New Member

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    ugh... It's back, didn't last long. after replacing the regulator had a few short drives, seemed all good. Today I took the family fishing so had a bit of a drive with the boat, ran fine. on way home after truck sat for a couple hours, every start has been extended crank. So when I got home, hooked the pressure gauge back up, and sure enough its no longer holding pressure at shutdown. I don't understand!

    Had no pressure at shut down, replaced the regulator, maintained pressure at shut down. figured it was fixed. now there is again no pressure at shutdown.

    my only thoughts are when I replaced the regulator and checked pressure the truck was only idle warm. Today it was a bit of drive while towing boat warm. I will test pressure again later tonight or tomorrow morning, to see if pressure will be maintained when its cold...

    Any ideas? Must be injectors or fuel pump... Thinking in a couple weeks after my hunting trip I'll get injectors cleaned/tested.
     
  6. Sep 20, 2020 at 4:28 PM
    #36
    SouthPaw

    SouthPaw The headlight guy

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    Well I am still semi new to these trucks, I haven’t heard of many injector failures. If it was bleeding off, that is quite a bit in that short of time. Fuel pumps are a semi common issue with these trucks and know to cause hard starting.
     
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  7. Sep 20, 2020 at 4:31 PM
    #37
    Festerw

    Festerw New Member

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    If it nearly immediately drops to zero I'd say the injectors would be ok. I'd think more of the fuel pumps internal check valve would be the culprit.

    Had a Jeep with that issue it's not really going to cause any harm it's just an annoyance.

    Try for a week for so just turning the key 'On' without actually starting it, then back to 'Off', then try starting it. Doing that the 1st cycle will help prime the fuel system.
     
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  8. Sep 20, 2020 at 4:35 PM
    #38
    FrenchToasty

    FrenchToasty Desert rat

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    I’ve hard sort of a similar issue, when it sits at work all day and I go to fire up at 3pm it sorta has an extended crank. I’ve replaced all the things you did and then some. I asked around if leaky injectors would cause that, I was told misfires would be present if the injectors were leaking by. Like @Festerw said it might be the check valve in the pump assembly itself. I have tried priming the pump before starts and it does seem to help but not 100%
     
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  9. Sep 20, 2020 at 4:43 PM
    #39
    bmc02

    bmc02 [OP] New Member

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    If i'm not mistaken our fuel pumps only run when the truck is cranking. so I don't think we can prime. I know I can't hear the pump turn on with the key to on position.

    I wouldn't think injectors would bleed down that fast either. the check valve on fuel pump is a good possibility. I just can't wrap my head around the fact that the regulator immediately fixed the issue. then couple days later its back. Unless its just a crazy coincidence... The problem I have with changing the fuel pump is I never replace parts with anything other than OEM, i'm that guy... But the factory ones are double a good aftermarket brand, so I'll probably go the cheaper route, and hate myself for it. haha. So really trying to rule out everything before the pump.

    Is the injector cleaning/testing such as through witchhunter.com worth it? I plan on keeping my truck forever, or at least it will stay in the family, so if its a worthwhile maintenance, regardless if it fixes my problem, I'd give it a go.
     
    Last edited: Sep 20, 2020
  10. Sep 20, 2020 at 4:47 PM
    #40
    bmc02

    bmc02 [OP] New Member

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    yeah, I'm not having any issues besides the occasional extended crank. But it went 7 years before it started doing it, so I will not give up trying until it is gone.
     
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  11. Sep 20, 2020 at 4:54 PM
    #41
    bmc02

    bmc02 [OP] New Member

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    when I turn key to "ON" without starting the fuel pressure gauge does NOT come off zero. So there is no pressure at the rail until cranking begins. that confirms my previous statement that we can't "prime the pump" like some vehicles are able to do.
     
  12. Sep 20, 2020 at 4:58 PM
    #42
    Festerw

    Festerw New Member

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    Interesting. I wonder if this is something that changed through the model years, could be wrong but I could swear I've heard it run on my 04.
     
  13. Sep 20, 2020 at 5:07 PM
    #43
    bmc02

    bmc02 [OP] New Member

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    probably true. I believe 05 is where they went to vvt-i, so maybe that was part of the change. I also know some of the older first gens have an inline fuel filter, where my 05 doesn't.
     
  14. Sep 22, 2020 at 1:16 PM
    #44
    Professional Hand Model

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    2002 key in ‘ON’ position without engine turning (RPM is zero) the Fuel Pump is pumping.
     
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  15. Sep 22, 2020 at 2:32 PM
    #45
    tvpierce

    tvpierce Formerly New Member

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    Interesting.
    My 2000: key in the on position, no fuel pump running. :confused:
    The plot thickens.
     
  16. Sep 22, 2020 at 2:40 PM
    #46
    Professional Hand Model

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    I can hear mine running. Maybe?
     
  17. Sep 22, 2020 at 7:10 PM
    #47
    bmc02

    bmc02 [OP] New Member

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    I can't get past the fact that when I installed the new regulator my truck was for the first time (since I got a tester) holding fuel pressure when off, then 2 days later it's no longer the case. So I've ordered a new cheap regulator online and will compare them/test to see if it works. Doesn't seem likely that a new Toyota OEM regulator would fail almost immediately but I have to be sure.

    In a couple weeks after my hunting trip I am going to get my injectors cleaned/tested. at 110k and 15 years old my truck could use that service regardless.

    If i still have no pressure at shut down I'll change the fuel pump. Something I've know all along I'd probably end up doing, but as a last resort.
     
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  18. Sep 22, 2020 at 7:14 PM
    #48
    FrenchToasty

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    I pulled my resistor to let it cool off in the house and check it’s resistance. I’ll leave it jumped for my journey to work tomorrow and see if I see any difference.
     
  19. Sep 22, 2020 at 7:15 PM
    #49
    bmc02

    bmc02 [OP] New Member

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    all this talk of fuel pump behavior is interesting. mine isn't building any pressure until it begins to crank. But my rail isn't holding pressure like its supposed to, so I guess i'm not one that should be saying how the fuel system is supposed to be running... haha.

    but pretty sure the 05/06 models had several changes with the vvt-i addition.
     
  20. Sep 22, 2020 at 7:22 PM
    #50
    bmc02

    bmc02 [OP] New Member

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    I've already ruled out the resistor. I measured my original one and posted the results previously. The reading actually jumped around a bit for me. I'd like to hear if yours does the same thing. I ended up buying a new OEM one to compare, it tested pretty much the same. I didn't want to go through the hassle of returning so I just installed it.

    The resistor does affect how the pump runs, but wouldn't be the cause of losing fuel pressure when off. If I would have bought the pressure gauge prior to coming to resistor conclusion I could have saved that $80. oh well, live and learn.
     
  21. Sep 22, 2020 at 7:42 PM
    #51
    FrenchToasty

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    I keep forgetting you’ve been at this for a while.
    Where do you call home? Average day time temps? I’ve also heard a engine temp sensor can cause weird starting issues, but mine SEEMS like it would be acting normal, I guess I’d have to look up the testing method for that.....
     
  22. Sep 22, 2020 at 7:54 PM
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    bmc02

    bmc02 [OP] New Member

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    i'm in the inland northwest. when the issue first happened it was 100+ (which is not that common). seems to be worse when its hot and engine is hot. but I have experienced it recently, where the temps are only in the 60s.

    I'm pretty certain it's due to the fact that my fuel pressure is not holding when I turn off vehicle. It should maintain 20+ psi for 5 min after shutdown per FSM. it is not doing that except for when I replaced the regulator, but 2 days later it was back to no pressure. So either regulator, injectors, or fuel pump... Unless I'm missing something, which is why the forums are nice, get some other opinions.
     
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  23. Sep 22, 2020 at 7:57 PM
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    bmc02

    bmc02 [OP] New Member

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    and yes I have been at this for a while... I was biking to work quite a bit as I usually do over the summer, and also working from home few times a week, and this problem isn't all the time - so its been a slow process of ruling out one thing after another... delaying the inevitable of changing the fuel pump.
     
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  24. Sep 23, 2020 at 3:55 AM
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    bmf4069

    bmf4069 Yup, that's car parts in a dishwasher

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    I'd look at prices/down time on cleaning vs ordering 12 hole injectors from dirtydeeds. I think the price is roughly the same, and they install in a few hours instead of having your truck OOC for a week or more.
     
  25. Sep 23, 2020 at 5:38 AM
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    Professional Hand Model

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    This^^^
     
  26. Sep 23, 2020 at 7:23 AM
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    bmc02

    bmc02 [OP] New Member

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    I'll look into them. Thanks.

    There is a well regarded injector cleaner locally that has a turn around time of a week or so. I could manage 2 weeks without my truck pretty easily, so I'm not too concerned with down time.
     
  27. Sep 24, 2020 at 6:40 AM
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    bmc02

    bmc02 [OP] New Member

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    yesterday was rough, several long cranks. one was probably 5-7 seconds. Was supposed to get new regulator in the mail, but its running late... of course. Hopefully get it today. Although I don't expect it to fix the problem and i'm ready to admit defeat and change the freakin pump, just have to burn off 3/4 tank of gas first. right now timing is not good with work, family obligations and a 9 day hunting trip coming up. But i'll sneak it in somehow.

    Looked into Dirty Deeds 12 hole injectors. Although it will cost $200 more then simple cleaning, sounds like a worthwhile upgrade. So I am going to order a set of those. Plus I won't have to be down and can install them whenever I get the time, that will be nice. Shouldn't need any other parts, gaskets etc to install these new ones will I? I'm a capable mechanic but injectors is one of the few things I don't have experience with.
     
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  28. Sep 24, 2020 at 7:15 AM
    #58
    FrenchToasty

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    If your pulling off the fuel rails to put on a pressure port and installing a new regulator, it’s not much more work than that, just don’t loose the banjo washers on the fuel rails.
     
  29. Sep 24, 2020 at 7:20 AM
    #59
    bmc02

    bmc02 [OP] New Member

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    thanks. I've already gotten familiar with the banjo bolts/washers installing and removing the fuel pressure gauge.
     
  30. Sep 24, 2020 at 2:14 PM
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    Professional Hand Model

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    You got this.
     
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