hard starting, increasing stalling issue with 04 Taco

hey guys, I'm hoping for some help diagnosing an issue with my truck - a 2004 Tacoma 2.7 3RZ-FE with 199k miles that has been stalling and hard starting very frequently

the first symptom two weeks ago was very minor, the truck felt like it stalled for a split second but then carried on for the day no issues - seemed harmless

next day experienced the first of many hard starts - although the truck started second attempt

following day the truck stalled for the first of many times, started right back up

from this point forward the hard starts and stalling progressed more each day, sometimes it stalls multiple times in a short span, sometimes only once, sometimes it won't have any issues for a day or two

sometimes the truck will start right back up after a stall, sometimes it takes 10-20 minutes

sometimes the truck sputters pathetically before finally stalling out, then when trying to start back up there is a distinct clicking sound coming from the throttle body area - I noticed the A/T Temp light flashes in unison with the clicking sound while the other dash lights stay illuminated

I can sometimes hear the clicking first thing in the morning when I turn the keys to ON, it will click anywhere from 5-20 times maybe

I also noticed the truck will not start while the clicking is occurring - perhaps a coincidence, but maybe worth noting

I changed spark plugs, battery, checked MAF sensor, relays, and reset ECU by disconnecting battery for 20 minutes and allowing truck to idle for 10-15

the majority of the stalls occur soon after driving for the first time that day, or after a long stop - once the truck is running it pretty much stays running - it has not stalled on the highway, or over 35mph

I don't know anything about cars or trucks with all the electronics, but if it were my motorcycle I would say it was a fuel delivery issue

any help would be greatly appreciated, like many of us my truck is my livelihood

no codes, no CEL

 

Perhaps a plugged Fuel Filter, Get a scan tool see what codes show up.

 

granted I have a generic obd2 scanner but it hasn't popped any codes yet

I will order a new fuel filter now and see what happens

thanks

 

Next time she doesnt start immediatly, slide under the truck and locate the skid plate under the fuel tank, with a rubber mallet, a piece of wood etc, smack the bottom of the tank/skid plate. As the fuel pumps gets towards its end of life it will get intermittant, jarring the pump via vibrations from the mallet/stick will move the armature on the electric motor enough to make good contact.

 

there is some kind of clicking from that black box and then it also clicks/vibrates at that green clip

truck will not start while it clicks, once clicking stops it will start up

no idea what this means

 

Change the fuel pump, it's at the end of it's lifespan with that mileage. I dropped and removed the tank to do mine, wasn't that difficult, in about two hours.
Some say it's easier to remove the bed and get to it that way, you just need to slide the bed back a few feet from what I've read.

 

VSV Valve Location | Tacoma World


Probably not your problem....

I first started having stalls, then hard starts,
then am2 fuse started blowing

keep getting worse over the month......then finally , a tow


Mine ended up being ignition switch slowly going bad

really those should be replaced like fuel pump for sure after 160K~180K
then every 150K there after

around here you cant leave a tacoma on side of the road....
they will hook up and steal it in less than a day



Start with simplest stuff first......bat cables connections....solid grounds

then move on to fuel.....like filter....open circuit relay....lastly pump

 

well I replaced the fuel filter and fuel pump today and everything seemed fine until I stalled out again

truck starts right up and idles well otherwise after not starting for two days prior to swapping pump and filter

 

you need to scan your fuel trims and try to find whats amiss

 

I just went for a drive with the scanner hooked up

short term 0%
long term 4.7%

 

How many miles on the fuel pump

has the engine ever been compression tested

low compression would show up as harder and harder starts

I know its kinda a crap shoot......but you test everything several times before going for a $100 part

 

the fuel pump has like 10 miles on it, just replaced it today along with the fuel filter

 

What about fuel reg.....vac or smoke testing

damn strange it idles.....but cant handle load

if confident of fuel supply....i'd look at vac problems next

if you pinch off booster vac line ...does that help


1st 1st is always check battery connections and grounds.....before you even get out of bed.........clean maf would be next

and check the maf numbers grams/sec

 

I'm just a young feller without lots of experience, but here's a few things I would eliminate. Since you have a scanner, what are you're O2 sensor readings? Sensor 1 should hover around 500 millivolts when the engine is warm. (O2 sensors would probably mess up the fuel trim, but I'd check it anyway.)
Also, are you sure your coils and the power supply to them are good? On my truck, the voltage to the coils was 10-11 volts with the engine off, ignition on. (A service manual will tell you which two wires in the plug are for power supply.)

 

@O'Silver_Taco I'm not confident in anything I don't know what I'm doing tbh


edit


Air Flow Rate from Mass Air

Flow Sensor

3.15g/S

 

@FarmerFred

oxygen Sensor Output

Voltage (B1-S2)

0.040V

this was at idle, not sure if that matters


edit

oxygen Sensor Voltage (B1-S1)

3.207V

 

Starting to rule out the cheap simple stuff...

wondering what the throttle position sensor says thru range
same on maf range.....anything weird


starting to get into obscure stuff.....like stuck/clogged egr and or its port..
or the acc sensor on the carb(TB) or even its motor going out

03/04 have the electro mechanical Throttle bodies

and they have the rear evap system which is prone to leaks ...and deteriorates much faster than pre 02's

 

well I just saw there is a stored p0401 code but no CEL

there was also a line disconnected but it was right above where the fuel line connects to the fuel rail - where I was working all morning

not sure if the code is related to that

I'm positive the line was disconnected today tho

 

using the code I discovered the source of the clicking sound I hear after the engine stalls...

the Vacuum Switch Valve

just ordered a replacement which will be delivered today, in the meantime I will remove and clean the EGR valve

 

Your O2 sensor readings are spot on, same with the MAF. I am thining that you might have a sticking EGR valve, that will definitly kill the motor at idle. Disconnect the vacuum line to the EGR valve, plug it and see if the stalling stops.