fuel filter/pressure

Hi all,

I'm still having P0300 errors. i've replaced plugs, injectors, and coils.

I'm looking for a way to test the fuel pressure, but I don't see a shrader valve. also I fitured I would replace the filter but I don't see the either. I can follow the fuel line from the tank all the way to the injectors and I don't see a filter.

Any thoughts?

 

Nope, no point to easily tap into fuel line. There are some threads in the forum about making or buying an in-line adapter.

Not sure of filter location, hopefully not integrated in the fuel pump located inside the fuel tank.


Greg

 

ended up pulling the high pressure line and attaching a T-fitting. I'm getting 0 static and 10 PSI idle. probably explains my P0300 errors. As soon as I turn it off, it drops to 0. New pump or is there a pressure regulator I need to look into?

 

Ok. I replaced the pressure regulator but it's still doing the same thing. guessing it's the fuel pump? any way to test this before I spend big bucks on a mechanic? thanks

 

I put a clamp on the fuel line and the PSI jumped up to 70 PSI. So the pump is good, fuel regulator is new. what could be causing the pressure to be at 0 when the key is on and idle at 10 PSI?

 

I have a Haynes Manual that states that the fuel pressure at idle should be 38-44 psi. Residual fuel system pressure (five minutes after engine turned off) 21 psi.

 

thanks. Any diag for low pressure?

 

All that it really says is:
"Check for a restriction in the fuel system (kinked fuel line, plugged fuel pump inlet strainer or clogged fuel filter). If no restrictions are found, replace the fuel pump module."

 

Any way to test the fuel pump module?

 

Not that is offered by the Haynes Manual. Here's another little tidbit that I found though:
"Sit inside the vehicle with the windows closed, turn the ignition key to ON (not START) and listen for the sound of the fuel pump as it's briefly activated. You will only hear the sound for a second or two, but that should tell you that the pump is working. Alternatively, have an assistant listen at the fuel fill cap. If the pump does not come on, check the fuel pump fuse labeled "F/PMP" and the relay labeled "F/PMP". If the fuse is okay, check the wiring back to the fuel pump. If the fuse and wiring are okay, the fuel pump module is probably defective. If the pump runs continuously with the ignition key in the ON position, the Powertrain Control Module is probably defective."

 

ok. Just to level set, the fuel pump is working.

I can get her to idle but she runs rough and gives me P030X errors. those are random.

I put on a pressure gauge and with the key on it read 0 PSI BUT if is start the truck it goes up to 10 PSI and idles rough. as soon as I turn the truck off, it goes back to 0 PSI instantly. While at idle IF I give it some gas the pressure will go up to 20PSI

I clamped the fuel line and I read 70 PSI at the fuel pump, and the pressure stays steady.

I did replace the fuel pressure regulator but nothing changed.

my current GUESS is one of the injectors is stuck open and just leaking.

I do get smoke when I start the engine and IF I romp on the gas.

 

I would think that you might get hard starting (flooding), the odor of raw gasoline on startup, and possibly rich codes from the ECU specific to one engine bank or the other (I'm not sure what the threshold is for setting that code though, I don't know if the ECU is capable of leaning out the other injectors enough to not set a rich code). That might be indicated by one spark plugs looking nastier than the others.

 

ok. replaced all the injectors. started at 20 PSI, started better, but after a little while it started to shake and got down to 10 PSI again. It's almost like something is lowering the pressure or something.

Got P0300 this time the codes were for only 4 cylinders. 304, 306, 307 and 308.

 

It may just be the pump...

 

Could be, but why is it when I block the line to the pump I get a stead 70 PSI and it stays 70PSI even with the engine off. Somehow going from the pump to the rail, regulator, and out I get down to 10 PSI

 

I don't know, I'm kind of out of ideas...

 

Same

 

Ok. I was checking the return line. it has 42 PSI. that sounds right.

I've changed plugs, coil, injectors, pressure regulator. Compression is in the 200 range for all cylinders. Still getting P0300 errors. what am I missing?

 

Poor quality gasoline?

 

possible but we're not in afganistan. Any way to test this?

 

Have you tried cleaning the MAF sensor?

Battery connections tight and free of any corrosion?

No other codes than the missfire codes?

 

The sniff test isn’t really reliable, but I can’t remember why.

 

@landphil thanks for the tips. cleaned the maf and it's down to P0300, P0304, P0306 and P0308

no other codes.

BTW. What's that thing over cylinders 5 & 6? they look like EGR connectors or something.

 

If you're getting pressure with the line blocked, but low pressure otherwise, it sounds like a clogged filter (part of the fuel pump assembly). You have pressure, you just don't have volume, so it sounds like flow is restricted somewhere.

I installed a fuel pump kit from URD and bypassed my internal filter and installed an external filter (it comes with the kit). Alot of gunk and debris came out of the internal filter. It was way cheaper than a complete fuel pump assembly from toyota, and I have a fuel pump with a better flow rate now.

 

Hi, I have several tundras and my older one had some fuel issues..last year it died and it was the fuel pump, toyota seems to have issues with the denso pumps....then about 2 months ago it died and i thought it was the fuel pump, I pulled the pump and bench tested it and it ran,,,so now the search went deeper..behind the drivers side wheel in the frame rail is a fuel pump control module, it controls the fuel pump..speed, pressure and so on...so you may want to look at that, as that was my second fuel issue and about $400 bucks for a new one and all runs good now...