Replaced 6 Injectors on Toyota 3.4l Now Only Popping and Dies

Hi there,

Thanks for taking the time to read and hopefully help me out. I either hooked something up wrong, or I have wrong injectors, or I seated them poorly. Someone may have been in the same spot.

Here is details:

1. Truck is a 2001 Toyota Tundra w/ 3.4l (same as tacoma)

2. Was getting a p0300 random misfire. I had done fuel filter, spark plugs, valve cover gaskets, added injector cleaner (this would help then it would come back). Figured I would just replace all 6 injectors since truck has 370,000 miles on original engine and it seemed one injector was leaking fuel into cylinder after shut off (leading to 300 code after hot start misfiring).

3. Bought injectors off ebay. Matched the ones I took off in number and name (arran or some brand like that). Injectors have a 4.5-5 star rating on ebay.

4. Removed upper and lower intake manifold. unbolted four bolts holding down fuel rail. Lifted fuel rail up to get enough room to remove the injectors (didn't mess with anything on the fuel pressure regulator)
a. did I knock something loose on the FPR?
b. Could the injectors all not be seated down properly? I took special attention about this and pushed each one back into the engine first then seated them individually on the rail. I don't see any fuel leaking .

5. Could fuel pump fuse be blown? Where would it be located?



Thanks!

 

Okay Alfa,

Let me see if I understand this correctly. You were getting a P0300 code from the ECU, which is a random misfire code. You then went ahead and did some good homework, and replaced a bunch of parts. First of all, what lead you to believe that the misfire problem was a fuel delivery problem. Please don't think I am faulting you for replacing the injectors. With that many miles on it, that was definitely a good idea. The thing about a misfire code is that it is more than likely an electronic problem before a fuel delivery problem. The culprit could also be a sporadic problem with the coils or a bad spark plug wire. You did, however, determine that you are leaking fuel into a particular cylinder after you shut the engine off. Please also take note that I have done absolutely no research on this code prior to writing my response. I am just taking your word for what the code means.

You say the engine is now popping and dying. Does this mean that it does start and run for a little while before it dies? I don't think replacing the injectors has anything thing to with your current symptoms especially when you take into consideration on how much detail you practiced when installing them. I think you indirectly damaged something else while you were installing them or one of the other parts you installed.

Blowing the fuel pump fuse could indeed be the culprit because if you blew it, the fuel pump would not pump fuel to the engine at all. You, however, were not working in this area at all with the work you performed. This is an easy thing to repair, though. You just have to replace the fuse.

The fuel pressure regulator is not something I know enough about to help you. I would go ahead and replace your spark plug wires while you are doing all of this work.

Good Luck,
Paul

 

Paul,

Thanks for the response, however I don't want the thread to go down to many rabbit holes. For now, I don't really care anymore about what caused the p0300 misfire at idle. Bad injector or not. Now I have a truck that starts pops and dies now. I just want my truck to be running again p0300 or not.

a. I just took some photos of the injector seals on the engine block. Looks like some may have some damage on the seals. However no gas leaking and they seem fully seated in the fuel rail.

b. Truck doesn't prime when turn ignition to on, but tacomas and tundras don't. Is there some way to push power directly to fuel pump so I can make sure i am getting good pressure and no air bubbles or anything?

c. What is the proper installation sequence for injectors? To push them into the manifold first then seat the fuel rail up top? I don't want to take apart the fuel rail and don't think it is necessary there is plenty of space if you just take off the upper and lower manifolds.

d. so yes truck starts fires revs up loud then shuts down. Like it is flooding.

1. Injectors just all not seated properly and causing fuel dripping down into cylinders?

 

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A dying injector will almost always throw a code for a particular cylinder. Injectors were needing to be done anyway but doubtful that was the source of the po300. You did not mention plug wires in your list of parts. Did you replace plug wires at the same time as plugs?

If the injectors weren't seated well you'd have either bad fuel leak you'd see and smell or a terrible vacuum leak and throw a lean code. I'll bet you're fine.

I'd want to test the MAF if possible. A dying MAF will definitely cause the popping and dying you're experiencing. The 2001 should be a drop in style MAF readily available from a parts store. Just try it, and return it if it doesn't fix it.

A dying fuel pump could cause similar issues as well. To test that, you need to get a banjo bolt adapter for your fuel rail to be able to connect a fuel pressure gauge to. YOu can rent this kit at AutoZone or similar. It includes the adapter. Do not speculate on a fuel pump... it's a PITA to replace so test it first.

 

Only reason I think it has to do with something i messed up on install is because truck was running fine before I did injectors. I only did injectors at that time. I didn't mess with anything else however I did have to remove upper and lower intake and unbolt / un do a lot of stuff vacuum lines etc. The injectors were only variable I changed.

 

p0300 was the only code. If it was telling me which cylinder it was then I would've just replaced one. I have not done plug wires but I don't think they would suddenly fail all of them at same time right after I install injectors when before they were working fine. I am not going throw parts at it like that without a better theory. Going to try starting truck with MAF disconncted and see

 

Oh, gotcha, then YES it was probably something you did. Check to see the MAF, coolant temp sensor, and ignitor are even plugged in. Check the TPS sensor connection too. If you left a vacuum line off, you'd get a lean code quickly.

 

It will not run with the MAF disconnected. The old 3.0s would, but 5vz will not. Yes, don't replace any more parts, it's something you've simply overlooked.

 

yeah basically before I take everything apart again I just wanted to see if anyone has seen this problem before. Starts revs hard then dies. Doesn't run long enough to throw a code. no smell of gas and no leaking gas that I see

 

Sounds like a fuel issue to me, if it starts up fine but immediately dies like it's not getting any fuel. You mentioned checking the fuel line/fuel pressure regulator, I'd start there since that had to be moved when you did your injector work.

 

thing is i didn't touch it i just unbolted four bolts hold down fuel rails and pulled up on both at same time. Didn't unbolt anything else to do with FPR or things toward rear of engine on the fuel rail. Could I of messed something up by doing it that way?

 

Hard to say for sure but it can't hurt to check your fuel pressure just to confirm. I think you can rent the gauge at any auto parts store (or buy it, I don't think they cost very much) and check your fuel pressure if only to rule it out, since it does sound like a potential fuel issue.

 

This is hard becasue there is no schrader valve to test you have to take apart fuel rail

 

SOLVED UPDATE:

INTAKE MANIFOLD LOWER was not seated properly leading to big intake leak. Was just taking it apart and realized that it hadn't seated properly and that was causing the problem this was due to a piece of broken hose or plastic that had wedged itself inbetween gasket and manifold. Be extra careful with this!

Thanks everyone she purrs now.

 

Awesome Glad to hear it was a relatively easy solve/fix, and thanks for posting an update; too often people make threads like this and never post their finds/solutions for others to read who might right into the same issue. Enjoy your healthy truck!

 

Yeah and what hsould of been red flag was that the bolt for the engine hoist point (i am assuming that is what it is) wasn't lining up with the lower intake manifold. It was close but just wasn't right. That should've been first sign (i just left it off)