Multiple misfires after rebuild ** FIXED **

Just restating… when I turn the key on the fuel pump doesn’t pressurize the fuel rail. When I try to turn it on with my Autel scanner I can hear it make a noise but there is no fuel going to the rail.

is there anything I should check before going to the fuel filter and maybe the pump?

 

Forgive me here as it’s been a short while since I’ve been under the hood of a FGT and played with a 4.7L, but the lines connecting the fuel rails use banjo-bolt fittings, do they not? If yes, are you 100% sure that a drilled banjo bolt wasn’t substituted with a solid bolt from somewhere else? This would block the flow of fuel from one rail to the other, of course.

 

That was going to be my question. You should crack the bolt and let it try and pump fuel up to the rail and see what’s going on there.

 

Yep.

Again, this may or may not be useful to you.

But last winter my fuel pump went out and I replaced it. One thing I learned is that the OEM 2000 Tundra fuel pump, is identical to the a 2000 Subaru outback fuel pump.

Now, the reason this is possibly relevant is that about five years ago my subaru left me stranded ontop of a 6600ft mountain with symptoms of a bad fuel pump. They thing was, I could HEAR the fuel pump turning on, but no fuel was getting to the rail.

I called up the neighbor kid and got him to pull a fuel pump from my parts car and bring it up to me on his dirt bike and made it home.

But the part that may interest you, is that the fuel pump itself had not failed, what had happened was that a blocking cap for an unused in fuel tank filter cartridge, had broken and blown off the fuel pump assembly, so that no pressure could build and the fuel was just getting pumped back into the tank.

Now, my Tundra does not have this same type of fuel pump assembly, but there are in tank connections that could in theory come apart and allow the pump to run, without actually getting any fuel out of the tank.

 

Yes, I am sure they are the correct banjo bolts with the holes. And I put new copper crush washers on them.

 

I put my fuel pressure gauge on the passenger side where the fuel comes into the fuel pressure regulator and it read nothing.

 

That is good info, I guess there is no way to know but to drop the tank, which does not excite me. I think I will take the fuel filter off, hook up a piece of hose to a bucket and try to turn the pump on and see if any fuel comes out.

 

I believe the fuel pump only pumps when turning the key to start the truck and when running. It does not pump with the key just in the on position.

 

Yes, I was not very excited either to drop mine as it was the middle of winter here and I don't have a garage. I would certainly do the fuel filter thing first. In my case I knew for sure it was the fuel pump as my truck died, wouldn't start, had no fuel at the rail, and then only started after I gave the fuel tank a thump with a hammer.

I would however, spray your fuel tank strap tensioning bolts with some Pblaster right away....I broke one of mine off and dealing with that was half the battle of the whole job.

 

Bad FPR? Or am I misunderstanding where you're saying the gauge was attached?

Cylinder order taken from another post, ignore the red. I'm trying to remember how fuel is run. And maybe it's different on earlier. I thought it was pump => engine bay / FPR => bridge between rails => left and right rail.

As mentioned prior, absence or insufficient fuel to the injector will cause misfires. But I'd find it strange if the fuel pump was sending adequate pressure to one rail and not the other.

 

In my truck it looks like the fuel pressure regulator sits on the passenger side fuel rail. So I would think it is:

pump - engine bay/fpr - left fuel rail - cross over pipe - right fuel rail - out back to the tank?

does that seem correct?

 

Yep. Sounds right the last time I checked.

 

This looks like the feed line, correct? When I crank it fuel should shoot out?

 

This is where it comes into the engine bay. Nothing came out when I cranked it.

 

I’d have to take a look at my engine to confirm. I only looked at the left rail, that looks like the right side.

 

This is the passenger side.

I loosened the engine side bolt on the fuel filter and cranked it. Lots of fuel came out, so I don’t think it’s clogged. If that’s the case then could there be a problem with the fuel hard line? Could it be blocked? I don’t Understand how fuel could be at the filter but not through the pipe. Unless that is the return line and not the feed line.

 

Can't answer if it should shoot out but that is your fuel pressure regulator that's part of the return line that if you follow it goes to what you circled in yellow. What I circled in red is the feed line and if you follow it, it goes to fuel rail banjo(pulsation damper).

 

Yes! The fuel is not getting passed the pulsation damper for some reason. I did drop the little notched gasket thing but I used a small crush washer instead. Why would the fuel not get passed the damper?

 

This still remains a good clean download of an 00-03 Factory Service Manual. As some know, there is very little difference from 00-03. If you do a search in that PDF for the words "fuel return", you can see other areas dealing with Fuel and troubleshooting for fuel delivery.

Index of /Toyota/Tundra/ (aitnet.org)

 

I’m an idiot. I put a washer on the top of the damper which got lodged inside it and blocked the flow of fuel. Unfortunately that didn’t fix my misfire issue. That is still happening but at least it starts now and I can get back to working on that issue.

 

Deep breath and keep patience handy....TGIF !

 

For sure. I am going to have to pull the drivers fuel rail again. I have an injector leak. Maybe that is causing the misfires now. The live misfire count is very low. So that’s good.

 

Well, in the process you ruled out another possible: Fuel pump is working, both rails have adequate pressure in the 40-44psi range.

If you didn't alter or change the injectors (which I'm assuming you didn't) fuel delivery isn't your problem.

Next sanity check: Maybe try swapping the O2 sensors from bank to bank if not difficult and you have the tools?

EDIT: Just saw your note. I suppose you could also swap injectors side to side, see if it follows.

 

Has that extender been put in place and does it do away with your splice ?

 

I actually have the 12 hole injectors from dirty deeds.

 

I haven’t installed it yet.

 

So I finally got all the injectors to stop leaking. My live misfire count is very low. The idle is still really low. I disconnected the battery again last night so I assume it will take some time to relearn idle?

 

The idle did get better, about 650. I have all the misfire codes like usual. I am thinking about swapping all the plugs on that side and maybe get a new crank position sensor. I’m about out of ideas.

 

Maybe I missed something but what happens if your rev it? Does the misfire count go to zero or get much less?

Have you ruled out water in the gas? Was it raining the night before or did you fill it the day before the problem showed?

Just throwing things out there.

 

The misfire counter keeps going when I rev it. It has been in the garage since I did the rebuild.