Long crank when warm - Issue after valley pan repair (1 Viewer)

[jmanscotch]

That definitely seems like a possible way.

I went ahead and looked it up and the FSM earlier and it says to disconnect two (2) fuel pump ECU connectors (on the frame by the rear sway bar it seems).

Then while disconnected, start the vehicle up and let it run out of fuel and stall (might store a lean code). Try cranking engine again to ensure it won’t start. Crack open fuel filler cap to depressurize the rest of the system and you’re good to go.

 

[jmanscotch]

Well, I replaced all 8 fuel injectors and the problem persist.

All rebuilt Denso fuel injectors, only had to do the job twice, of course I pinched one of the top o-rings on the rail and it leaked fuel the first time I put it back together.

Had a check engine light (P0348) along with many other dash lights come on after doing the job and found a wire on “Camshaft Sensor A, Bank II” had come out of the connector, so have to re-pin that connection now too.

There’s always the chance one of the rebuilt Denso injectors I got is having the same problem as one I pulled out, but damn that’d be a coincidence.

Doing my best to search the FSM for ideas, but a leaking injector or bad regulator really is the only thing I’m finding that fits my symptoms and it’s hinted at in there. There’s some mention of wiring issues for similar symptoms, but nothing that behaves like my rig and nothing that throws codes, it’s so baffling.

What other ideas am I missing?

 

[Acrad]

Unfortunately... there is some live data Techstream troubleshooting here that i am not familiar with.

 

[jmanscotch]

Yeah, I'm trying to read up on that some to see what I might be able to work through using the live data I can view versus what techstream would show me. Most the suggestions I see there are based on what CEL code it's throwing though, which mine isn't. So it's tough to know where to focus.

I'm also researching a few other items to troubleshoot that might be mostly similar in symptoms. While the fuel scenario makes the most sense, there are some sensors that could suffer from a hot-soak-no-start condition, while that doesn't really line up with my condition (where it DOES start). It's also unlikely as those sensors should definitely trigger a CEL if they're having signal/reading issues...but I don't know where else to go so need to explore more.

I could pull all the injectors and have them tested to ensure they're not still a problem, but I'd probably want to buy a second vehicle first as I'd be out my DD for a while. Not a big deal, I flip cars occasionally and could just find a ripe one for that use and make it work. If it wasn’t for snow I’d just borrow my friends motorcycle.

I'm probably a week away from dropping it at the dealership and letting them have a go at troubleshooting it. I'm not hopeful for that route, I expect a rather shallow look at things and an educated guess or unknown diagnosis, but maybe I'll be pleasantly surprised.

 

[jmanscotch]

A few additional notes:

I found a fuel pressure tester that'll work for the quick connect type fuel lines we have and is a reasonable cost.

Amazon product ASIN B07LF26ZTJ

I also wanted to share that to bleed off fuel pressure, before opening the system, I didn’t follow the FSM and disconnect the two Fuel Pump ECU connections on the rear frame rail behind the fuel tank. These connectors were somewhat abnormal and I simply could not figure out how to disconnect them without enough concern of breaking them, so I did what Acrad had suggested and simply pulled the Fuel Pump relay while the vehicle was running and let it die, worked fast and effectively.

I’ve seen all sorts of threads on similar issues, from MAF sensor, camshaft sensor and coolant temp sensor issues contributing to the problem and all sorts of things.

In my opinion, it still checks the most boxes and acts most like a specific scenario fuel supply issue. While I am a little suspect on the new rebuilt fuel injectors, I’m going to try to do some more detailed fuel system diagnosis before making weighted guesses any further.

- check fuel trim data (with a better understanding of what I’m looking for)
- check fuel pressure
- if pressure is low or bleeds off, try to determine what part of the fuel supply system is the weak link
- research the rigs fuel system setup and identify the parts and their functions to better understand what should be and what potentially isn’t functioning

 

[carlos33018]

Any update ?

 

[jmanscotch]

Any update ?

I have a fuel pressure tester now, but haven’t had time yet to use it. Hopefully this weekend I’ll get time.

My plan is to install the fuel pressure gauge in-line with the inlet of the fuel rail feed. The gauge setup I got has a shut off valve piped into it, so first I’ll confirm if I have fuel pressure bleed down over 1 hour (to match my symptoms) and if I find I do, I can run the test again, shut the valve and identify if the bleed down is coming from the engine side of the gauge (ie fuel injectors, regulator, a little bit of fuel line and the physical fuel rails themselves) or the fuel tank side of the system (so potentially a fuel pump issue).

If the fuel pressure test shows no leak down, my options get limited real fast, so I hope I find the issue there, even if it means needing 8 new injectors or a new fuel pump.

I investigated a bunch of the data stream information and found no obvious issues. All sensors are still operating within normal ranges, fuel trims and O2 sensors are just slightly off, nothing ultra smoking gun, and still no codes thrown.

 

[carlos33018]

There are no codes correct ?

 

[jmanscotch]

There are no codes correct ?

Correct, not a single one.

 

[jmanscotch]

Well, add one more hiccup to the mix, the fuel pressure tester I bought won’t fit on the GX connections.

The kits female quick connect fitting, that’s the correct size inside diameter at 7.89 mm, is too shallow to fully seat on the fuel rail male connection.

I have a shop I’m going to give a chance, take it to them and see how they do with troubleshooting the darn thing, see if they can do the fuel pressure leak down test as well and go from there.

 

[Acrad]

You probably came across this in the past... this is setup in FSM with PNs.

SST09268-31012 (90467-13001, 95336-08070, 09268-41500, 09268-41120)

09268-45014 (09268-41200, 09268-41220)

 

[jmanscotch]

Yeah I came across that but didn’t check the kit as I assumed it was quite pricey.

Looking now, I see a few from $300-600. For that buy in price, I’d rather just cave and have a shop handle it. Going to stop by a new shop after work today and see how they check out.

 

[r2m]

Yeah I came across that but didn’t check the kit as I assumed it was quite pricey.

Looking now, I see a few from $300-600. For that buy in price, I’d rather just cave and have a shop handle it. Going to stop by a new shop after work today and see how they check out.

I have to agree if you can find a reputable shop, that's a whole lot cheaper than $300-600 for a probable one time use tool.

 

[jmanscotch]

Well, dropped it off at the shop Wednesday morning and just picked it up. Not overly impressed with the shop experience, but not bad. As discussed, I’m general just picky and not easily impressed by shops. They did end up only charging me $107 for diag after 3 days of screwing with it, so I’ll try not to complain too much about the ordeal.

Basically, they check it over and are as stumped as I am. It was a lot of playing telephone while talking to the front counter guy, so I didn’t end up asking as many questions as I wanted to for clarity on what they found/didn’t find. Here’s their notes:

- “during extended crank, fuel pressure comes right up to 45 PSI”
- “fuel delivery from tank to engine is not causing extended crank”
- “suspect fuel system at engine is vapor locking or fuel injectors are causing extended crank”
- “seems heat soaking engine is causing extended crank”
- the tech mentioned, earlier today when we talked, that he called his master Toyota tech friend and he said it sounded like an uncommon issue he’s experienced where either the fuel pump and/or fuel control module were acting up. Said there wasn’t a solid way to prove or diagnosis this though,

Questions I have:

- Do our engines hold fuel pressure when off or somehow allow it to bleed off/return and only build pressure when running? Seems like a silly question, but I’ve seen several references to many Toyota engines not having fuel pressure when off and it being the normal operating condition. Their phrase “fuel pressure COMES UP to 45psi during cranking” has me questioning if it is low/zero and rises or what they meant in general.

- I didn’t consider vapor locking. I’m vaguely familiar with it, had an older Jeep that did it on extremely hot days (and at our 7,000 ft of elevation, it’s not crazy to consider) but it’s happening on very cold days, isn’t happening as soon after shut down as research says would be typical and overall the symptoms would have randomly started and stayed after this repair, which makes it unlikely in my mind. Thoughts?

- Part of their diag seems to fall in line with the idea of possible fuel leaking at the injectors, so I’m still focused there.

- the fuel pump/fuel control module idea was pretty glanced over but I’d consider throwing parts at it if nothing else cures it. Fuel pump is 111k miles old and wouldn’t be a waste to replace, fuel control module is $350 new but plenty of used ones for $80 or so (off wrecked GXs).


So, I guess I’m at a crossroad still. Do I drop $1,000 on new injectors to either fix or rule out the potential faulty rebuilt units? Do I drop the fuel tank, replace the pump and fuel control module for around $450? Do I chase the vapor locking idea? Do I redo my entire valley pan repair procedure (except the actual pan part) and verify all parts touched are not cracked, are sealed, connected, etc?

I’m strongly leaning towards 8 brand new injectors. It makes the most sense, still. Hoping to hear some of your guys opinions on what you’d lean towards trying if you were in my shoes, wanna make sure I’m not being irrational out of frustration here.

Jake

 

[Acrad]

IMO: I do tend to think recent area of work so I would side with the injectors

 

[jmanscotch]

Yeah, it’s definitely the most logical place to start. It’d just be a frustrating coincidence that I replaced leaking injectors with rebuilt injectors that are also leaking. Not unheard of, definitely not impossible and actually not that surprising...but definitely unfortunate and a heck of a wrench thrown in the mix of troubleshooting.

Oh and one more bit of interesting info I forgot to mention, my gas mileage has gone down. Typically the truck registers about 13 MPG (uncorrected) and it’s currently between 7 MPG “after refill” and 8.8 MPG overall lately. That suggest something is causing extra fuel usage. Could be injectors, could be sensors. Injectors still remains a common theme that checks the most boxes.

I only took note of this today when I realized I’ve gone 70 miles on half a tank of gas and took a look.

 

[jmanscotch]

I’ve been reading dozens of threads on the topic. From Tundras (same engine and different engines), Tacoma’s and other Toyota vehicles. I’ve come across several that have fixed the exact same issue with fuel injectors and several that haven’t.

If I remove my Tundra/4.6L/1UR-FE search terms and stick to more general Toyota searches, I’m starting to see many more threads about success with replacing the fuel pump to solve this exact same issue.

Here’s one example of someone on the Sienna minivan forums who had long cranks when the engine was warm (aka not immediately after shutdown and hot, nor when engine was cold from sitting) replaced injectors and no change, replaced fuel pump and problem solved.

Engine Starts Great Cold or Hot - Long Crank When Warm

www.siennachat.com

Pair this with the master Toyota tech note the shop gave me, the fact that I’ve already replaced the injectors, pressure regulator and checked over the connections and for leaks on the systems I've disturbed during repairs, I might be leaning towards doing the fuel pump now, instead of another round of injectors.

We go on vacation next week, so going to sit on it a bit and contemplate what the next move is when we get back.

 

[jmanscotch]

Alright, I've been contemplating and researching it all weekend and here's my latest theory on being ok with suspecting the fuel pump as a potential issue.

Say there's a bad non-return check valve in the fuel pump, on the supply line side (can't find a detailed enough schematic to confirm our setup has one, I presume it does and it's built into the actual fuel pump outlet itself).

To the best of my understanding, it'd exhibit symptoms like:

- When running, you get full 45 PSI to the fuel rails (as confirmed by shop) since the pump itself does indeed function
- When a hot engine is turned off, for less than 1 hour, the pressure is still held in the line, though begins slowly leaking down, back past the check valve
- Once engine has sat off, for over an hour, the fuel pressure has bled down considerably in the fuel supply line/fuel rail and now the lack of adequate pressurized fuel in the line allows for a vaporized fuel condition (primarily in the fuel rails where the heat exists and soaks) and causes the long crank condition. The shop *sort of* confirmed this scenario as they noted the "fuel pressure RISES to 45 PSI during the long crank condition", presumably meaning the fuel pressure at the rails had dropped and was starting from a notably lesser point before cranking.
- Once completely cooled off, the pressurized fuel supply line has 100% bled down, back into the fuel tank, removing the problem of a hot engine and vaporized fuel, instead overcomes the empty fuel supply line with the initial fuel pump prime.

In theory, it covers the symptoms and hasn't been ruled out by the other steps, parts and test that have been performed on the truck yet and in some ways it has been supported by the data known to me. My only hesitation is that it would be some seriously bad luck timing for that check valve to have started failing to hold pressure, on the exact day I finished my repairs. There was no opening of the fuel system during my repairs, so it shouldn't have stressed nor shocked the fuel pump components.

 

[Tex68w]

It sucks that you're still dealing with this. I hope it gets resolved soon and for little money out of pocket, this isn't the norm for these vehicles.

 

[jmanscotch]

Parts came in today and I made some time to get to it.

The end result of new fuel pump and new MAF sensor: problem still exists, unfortunately.

Started with replacing the MAF sensor, which didn’t fix the starting issue but did seem to correct the slightly stumbling idle, which was nice.

Then moved onto the fuel pump. Fuel tank removal isn’t horrible, but does include some extra steps. You have to remove the passenger side middle row seat, then some trim and such to be able to peel back the carpet and get to the fuel pump access panel.

Once you have the panel removed, you only need to disconnect the fuel pump electrical connection (leave the two fuel lines for now)

Connection undone:

Then move underneath and disconnect five (5) hose connections: two (2) fuel lines, a fuel filler neck hose, a fuel cutoff line and a vapor/emissions line.

Two fuel lines on front side of fuel tank:

Fuel cut off line (small) and fuel filler neck (large) front back side of the tank: