Bad fuel pulse damper? Wont rev past 1k unless a fuel pressure gauge is hooked up

Edit: It starts, idles great, but won't rev past 1k rpms now. Go to page 2

Edit: This has evolved, it starts now but dies, go to page 2.

Edit Note: These trucks have a coil on plug setup, resistance doesn't work to test whether they are good.

Trying to get my truck to start.

I cannot find the resistance spec for ignition coils on the 2UZ. I have one ignition coil that is non - oem, all the others are original denso. I checked the resistance of them all but I don't know what they are supposed to be.

- 5 of the denso test with 345 ohms at pins 1-2, and 2100 ohms at pins 1-4
- The other 2 denso test 345 ohms at 1-2, but then 4779 ohms at 1-4.
- The non-oem coil tests way off from all the denso- Pins 1-2: 380ohms Pins 1-4: 0L

I know I need to replace the non-oem, but I don't know about the denso ones. Anyone know the proper specs?? None of the coils have cracks.
I'm going to try the starter fluid in the intake tomorrow too

Also is rock auto going out of business?? Haven't been able to access their website for a while, which is unfortunate considering they have coils for $50 and everyone else charges $80.

 

Try clearing all your cookies and see if you can access the RockAuto website. That has worked for me in the past. I can log onto RA - no prob.

 

Unlike the Tundra 5VZ ignition coil that has primary and secondary coils to check for resistance, the 2UZ uses COP(coil on plug) design and the ignition module (transistor) is integrated on top of the coil, so you don't have a coil negative wire to attach to, meaning you can't measure the coil's resistance.

Good decision on replacing the non-OEM one.

 

Can’t help with specs but I can help by saying this.

One bad coil doesn’t prevent a truck from starting or running.

Two coils rarely fail at the same time, suddenly.

Cracks in the coils don’t cause misfires (but cracked or missing boots will).

You need to test for spark before you dig deeper. Starting fluid is your friend, as are spark testers. Both are cheaply purchased at the local auto parts store.

 

Ahhh interesting, good to know.

Thank you guys! At this point I have:
- Brand new camshaft sensor (Wires were fraying on the old one, thought for sure it was my problem)
- Cleaned off crank sensor, 2100 ohms (in spec)
- Clean maf, throttle body, air filter
- I can hear the fuel pump when key is on. I could smell fuel at one point when the engine was stumbling. Now its back to just cranking
- Cleaned battery terminals, battery has 12.4+ volts and 11 volts while cranking.
- Bad gas shouldn't be the problem, I was about 75 miles into a fresh tank.

I'm gonna verify for spark soon, and will update.

I did at one point get a P1126, but I believe that was because I left a sensor disconnected on accident. I will also rescan for that. I cannot find a single mention of it in the FSM.

 

P1126 is the throttle body circuit, if you unplugged the (4-pin?) harness on the (passenger side?) of the throttle body assembly, it would've done that, IIRC.

I'll ask it:

1. Did you pull the negative battery cable for 10mins after all those steps to reset the ECU and force relearn?
2. Did you try slapping the gas tank a few times to cause vibrations before attempting to start, just to ensure it doesn't fire up (failing fuel pump will often give another start or two with some tank slaps)?
3. Any prior work (engine swap or harness swap or similar) we should know about?
4. Any new codes to know about?

​

 

Just reinforcing what shifty' said. Check the basics first before loading up the parts cannon.
And maybe some specifics on the symptoms? Is it just cranking and no ignition at any cylinders at all? Does it start to run but not keep going?

 

Sprayed some starting fluid in there and she fired right up and then promptly died less than a second later!!

I unplugged one on the driver side, anyway the code is gone now.
1. Yes, I have had the battery completely out twice now to recondition and charge it.
2. Yes, no change.
3. None that I know of, but I wouldn't know. Bought the truck last year. Wouldn't be surprised if there was. Cylinder 3 (Non-oem coil one) has been re-tapped and uses a different spark plug.
4. No codes at all today. Did have a P0420 for a week or two before this.

Yeah, so I drove it 20 minutes to cal ranch and then it decided it wanted to stay there, was stumbling and trying to fire at first but eventually just cranking with no firing at all. Replaced my cam pos. sensor since the wiring had been chewed up. Still didn't start, but at first it did stumble, but now it is back to just cranking.
As far as basics go, I think fuses are the only big one left.

What steps now? The starting fluid means the issue is fuel correct, usually wiring related?

 

I'd try starting fluid now. Just to figure out if fuel delivery is your primary issue.

I'd be checking (at minimum) the EFI1 fuse under the hood.

I'd be checking the crankposition harness is correctly routed, behind its bracket, correct routing info here. And I'd be checking its harness (trace up from the sensor at ~4 o'clock from the big crank pulley) to be sure it's not damaged.

Starting fluid should tell you really quickly if this is a fuel delivery issue or not. And if it's a fuel delivery issue, the 2nd and 3rd things I recommended to try could both be reasons why.

Bad plug/poorly seated plug/bad coil on cylinder 3 won't cause no-run. Chances are this engine will continue running (albeit poorly) with 2, maybe even 3 cylinders having issues. You shouldn't run it in that shape, but ...

You need three things for a combustion engine to run: Air delivery, fuel delivery, spark delivery. If any of the three are missing, no fire for you. With EFI/Electronic Fuel Injected combustion engines, that upgrades to:

• Properly metered air (i.e. MAF and throttle body position, sometimes IAT and MAP sensor)
• Properly timed spark (i.e. plugs, coils are good and ECU is signaling fire in sequence, timing belt OK, timing is good)
• At least 35-40psi fuel delivery will get you firing consistently (i.e. fuel pump is working, fuel pump relay is firing and fuses good, all fuel lines are tightly together, each bank's fuel pressure regulators are working, fuel damper and vacuum to fuel damper are good, and in our case, the crank position sensor is good and its wire harness isn't nicked/damaged by a pulley/belt)
• ECU isn't totally fucked.

We've seen a wild variation in what's caused no start situations. Like, in older trucks, if the green-top coolant temp sensor (passenger side of throttle body) is shorted and reporting the engine is overheating, engine won't fire off. I originally thought this was because the sensor was broken or disco'd, but it's still really not clear to me.

tl;dr - anything you can due to rule out those four items is in your best interest. Clearly, if you spray a 2-3 second shot of starting fluid back behind the throttle plate, and it fires up, you know exactly which of those four bullets is [likely] the problem, and you know where to focus your attention.

All diagnostics, ultimately, is just as much trying to figure out which one it could be, just as much as whittling away what it couldn't be. In other words, if there are 4 branches of things it could be, and you can immediately remove 3 branches with one test, DO IT, and you've just made your major pool of suspects by 75%, and know where to be focusing your attention. Although it's worth noting ... ECU is the overlord of signaling the fuel pump relay, so absence of fuel delivery doesn't rule it out as a potential culprit.

 

Yes, I did the starting fluid and it fired right up and then died. Which means my issue is the fuel delivery. I did try banging on the gas tank to no avail. Is the next step to get a fuel pressure tester?

I did check the EF1 fuse and it looked good.
I tried starting it with my foot on the gas and that didn't do anything.
I will check that coolant sensor too next time.

 

If you are meaning key is in the IGN ON position, whatever you're hearing isn't the fuel pump.

Adding to what @Shifty said, we have to be cranking for fuel pump relay to energize. The smelling of fuel would be something to look further into also. I would consider checking fuel pressure if you're equipped to do that.

from Toyota Techinical Training....

• Engine start: During cranking, current from the ignition switch to the starter relay (ST) coil turns the relay ON. Current also flows from the ignition switch to the STA terminal of the ECM. When the STA signal and the crankshaft position signal (NE) are input to the ECM, Tr is turned ON, current travels through the coil of the circuit opening relay (C/OPN), the relay switches ON, power is supplied to the fuel pump and the pump operates.

Definitely re-check for that code and accuracy of your scanner because the 2UZ(V8) does not utilize a magnetic clutch but you would find that code in a 5VZ(V6)

 

Yes I saw that in the FSM and was puzzled. I did rescan for it and it was gone.
What do I do from here? Fuel pressure tester kit?

If the timing (crank position sensor) were bad, it would then not be operating the fuel pump so there would be no pressure?
And if I were to get pressure then something is causing the injectors not to fire right?
Sorry guys, just haven't dealt with this stuff before.

 

Perhaps I am doing it wrong but I am getting no fuel pressure at all.
i may have broken the fuel pump relay trying to check on it so will be replacing that.

I am now worried that the wiring fix I did on the harness that connects to the cam position sensor is still bad.

truck is trying a little harder to fire, not much but it’s intermittently trying stumbling not just cranking.

 

What method and at what location are you checking pressure ?

As for the relay, it's somewhat of a multi-purpose relay. If you have an Advanced Auto close by, they have the same type 12vdc 20A 5 prong relay type relay you could use in a pinch until you can order a Denso OE or get from Dealer after Holiday.

 

I ended up doing it the way he does it in this video, at the fuel line dampener https://www.youtube.com/watch?v=QEsuSWjMW88
When I took the dampener out there was a decent amount of fuel that wanted to come out. but when I took the tester out, it was dry.

I find it interesting that I could smell gas one time when the engine was stumbling.

 

I'm gonna grab this one from napa https://www.napaonline.com/en/p/ECHAR485
What things can cause the no fuel pressure?

 

Before purchasing try jumping that circuit

 

Brought the truck to my favorite local shop, and when the tech tried starting it, it fired right up. Which would indicate to me that it is the fuel pump since it got jolted pretty darn good when we were towin it. The tech did some testing on it, I tried explaining the timing dependent fuel pump situation on these trucks to him but I don't think he believed me. The relay is working as it should, and now it is once again not starting, and makes no fuel pressure. I'd think this all points to the fuel pump, and the shop agrees, but I'd like some opinions.

Not willing to pay $800 to have them do it so I'd do it myself, was going to go with a $190 delphi from napa since it has a lifetime warranty and I can get it today, but I found this denso one for $90 https://www.autonationparts.com/parts/denso-denso-electric-fuel-pump-9510002

Any recommendations?
Crank sensor harness is good, fresh cam sensor.

 

UPDATE: She starts and then dies off pretty quick.
Replaced fuel pump with the napa delphi, lifetime warranty. Checked the pump beforehand and it works, resistance is 350ohms. The old pump was definitely struggling. Resistance on it was all over place, it would only turn on sometimes when jumped to a battery. So I do feel like that was worth it. But now it fires up, idles normally for maybe 10-15 seconds ish when not on the gas.
To my understanding that means its running on the known good values at first, but then something is throwing it off. To my understanding that means it could be ?:
Timing sensors
02 sensors? Saw that in another thread, I did have a p0420 while it was running.
Maf or throttle body sensors? Maf and air filter were very clean, I cleaned the throttle body.
Alternator? Battery? Battery is 4 years old but has the volts, has been reconditioned and charged twice now.
Vacuum leak?

I'm gonna redo my wiring on the crank harness to ensure it's not that but I figured I'd update.

 

Worth getting the battery tested, but I doubt that’s your issue. The fuel pump is depending on some sensors to tell it that it is ok to pump. Have you checked all of the wiring including grounds? When you said you repaired the crank sensor, you replaced with OEM? Or you tried to repair the wires with splices or something? How’s the vacuum line situation? Old dry and brittle vacuum lines shouldn’t prevent firing off, but may prevent keeping an idle. Have you checked the fuel pump resistor?

 

Sounds like crank position sensor wiring repair may be in question. Its wires are shielded, so even regular repairs may be problematic.

But yes. If you pulled battery and haven’t cleaned MAF a throttle body with their respective cleaners try that first. Before anything else. But crank position signal has to be intact or the ECU kills the fuel pump, STAT.

 

I re-did the wiring up above where the cam sensor comes into the loom, above the driver side timing cover. A PO had those wires running at an extreme angle so they were exposed. The cam sensor is new, but I left the crank sensor in, since it is in spec (2100 ohms) and I'd prefer not to spend that cash unless necessary. It did have a lot of dust/ particles on it when it came out.

I haven't closely checked vacuum lines, they seem fine overall but I'll comb over them.

I put in a new fuel pump relay, where is the resistor?

I haven't really checked all the wiring, its really not my specialty. My neighbor is an electrical engineer who does car work too so maybe I'll ask him for some tips.

 

Drivers side fender well under the hood between the fuse box and brake MC.

 

To add to this, it’s the silver finned thing. On later years it jumps to the other fender well. It can be bypassed with a shunt or jumper, but it’ll force the pump to run in always-high pressure mode.

 

Is pretty quick meaning 10-15 sec ?

10-15 sec is long time when counting 1 1 thousand, 2 1 thousand. Have you attempted to help it a few rpm's ? It may be wanting to simply re-learn for a bit.

Speaking of the resistor, given it's in use during idle/light load and the fuel pump relay is energized at that time, you or your engineer neighbor could hook up your volt ohm meter leads to neg of battery and the positive lead to either one of the 2 conductors of the resistor. While keeping engine running at idle or just above @ say 1000rpm, you should see 12vdc at resistor. If it falls off, it's possible pump relay has de-energized, meaning ECU is no longer seeing the crank sensor and shutting down the pump.




Maybe this will help if neighbor enginner helps ya....

 

Tried it this morning and its more like 2-3 seconds before it shuts off, even if I'm holding the revs up. It's very consistent.

Great info guys, thank you all so much! I'll try that resistor test.

Vacuum lines seem to be in good condition.

I noticed that my wiring is actually purely on the cam pos sensor wiring, not affecting the crank wire. If the cam wire was the problem, I would expect a camshaft position code to show, considering its popped that code before without having started. Am I correct in that thinking?

 

Here’s a pic of the wiring, there is an extra wire, maybe a ground??, that was just tucked up into the heat shrink before so we left it the way it was but perhaps that is causing prollems. Anyone seen it before?

 

Update: vdc to the fuel resistor go up to 12-13 and then drop to 0 after maybe a second.

 

Suggest you re-read the High Speed Operation in the pic I posted above, in particular last sentence. My comment about your your initial 10-15 sec and 12vdc at resistor only applied because you were running.

Your newest 1 sec test circles back to what others have said, the crank sensor needs to be looked at because it appears the ECU is not seeing the crank signal and is not energizing fuel pump relay.

What sensor do those crappy wire connections and this ground you're speaking part of.

 

If I understood correctly those butt splices are on the bank 1 cam pos sensor.