Fuel delivery troubles

Hello this is my first post as a new member and I'm really hoping I can get some help from the tundra community.... so here are my tundra woes.. I have a 2003 access cab 4.7l 4x4 with way too many miles (347k) I've taken very good care of it but lately I've been running into what I believe are fuel delivery issues. When it first started it was only when going around corners at or above 30mph it would kinda cut out or stumble just a little bit. Just barely noticeable then over a couple weeks time it got slightly worse. Now it has started doing it while driving at higher speeds 45+ but only when I try to accelerate. So like when I try to speed up to pass. It will cut out but I can let off the gas for just a second then accelerate again and it stops cutting out and will run fine. I replaced the plugs and coil packs to no avail. I tried a fuel treatment and still no luck. Any advice on what I should look for or how to troubleshoot the issue would be greatly appreciated.

 

Ever cleaned the mass air sensor or throttlebody? No codes?

 

Has anyone ever replaced the inline fuel filter that exists on 2000-2004 trucks? Or is it still the (very free-flowing) factory filter?

The fact it happens during turns seems like a significant symptom, like the filter, has the pump ever been replaced?

If I were you, I'd be borrowing a fuel pressure test kit on loan from the LAPS and testing fuel pressure, both at idle, and while applying the gas pedal.

 

I have not checked the fuel pressure. I did look for an inline filter but was unable to locate one. The check engine light is not on and has not came on at all since the problem started. I was just talking to a buddy about possibly trying to clean the sensors to see If it helps at all. Today on my way home from work it has gotten substantially worse. Now it is cutting out when taking off from a stoplight or stop sign and also while going up hills. But whenever it starts to cut out if I let off the gas for just a split second then accelerate again it seems to run just fine. There's no rough idle or even when it's in park if I Rev it up it doesn't cut out at all. I'm going to try to clean the sensors tonight and hopefully that will at least help somewhat. I will post with the results

 

Yeah, that sounds like fuel delivery to me, like when you let off the gas and give it a sec to build up pressure again, then tap the gas when it's more-pressurized, it's OK.

But I hate throwing parts at things, and I've seen many a soul on here replace their fuel pump with one from the local auto parts store - even big-name brands - only to have them DOA, straight outta the box, or die within a couple weeks or couple months, so I'd never tell you to go straight to that. Nothing sucks worse than getting that "lifetime warranty" shit part from the local parts store, spending 2-3 hours minimum installing it, only to need to pull it out and replace it a short while later. It happens often enough I get frustrated reading about it.

If it were me, I'd verify fuel pressure at idle and under load, you want to be (ldeally) north of 38-42psi baseline, IIRC. If you're not, the pump is the issue. I'd recommend buying OEM, personally. About the only other brand I'd trust is Bosch, and frankly, I don't know if they make a pump for our trucks.

And ... avoid buying your auto parts on scAmazon/fleaBay/WallyMart. If it's not a knockoff, risk of issues is too high for comfort, knowing there are a couple of other vendors out there (like Summit Racing and Rock Auto) who can get the part to you at scAmazon-level pricing.

PS - I assume the V6 trucks have a fuel filter inline. It's normally inside the framerail, just under the cab, near the rear of the cab, I think. It's a friggin bitch to replace, and aftermarket are notorious for clogging, while OEM are pretty free-flowing.

 

I had another vehicle once, that would only misfire when stepping hard on the gas, turned out to be spark plugs.

 

Did you test it last night? What did you come up with? I'm wondering because my 2004 tundra is doing somewhat of the same thing.