Binh

Hi guys,
I've been having trouble with my 1996 tacoma 2.4 automatic lately. After reading a lot I think it may have a bad MAF sensor even though I replaced the old one with new that I bought off ebay for $70, could be crappy, it throw a P0171 code which is running clean, but I can tell it's running rich because of the smell of raw fuel and also the spark plugs is black and get very bad MPG. If I accelerate it I heard a pop pop sound from the front and car stalling and have no power, after a while it will settle down and run ok. I did change bank 1 sensor 1 O2 sensor and Coolant temp sensor but no help. In the morning when the car is cold, it will start up, if I press down the pedal fast it will "hiccup" like I said above, if I stop for gas or food when I come back it would not start, must wait 10 or 20 minute to start back up even the outside temp is 50 F. I did check the fuel pressure, in the morning is 0psi, when idle 10-20psi jumping up and down, when stop pressure 20 psi, come back after food 40psi, start it back at 20psi and no start at 20psi. Spark is good new spark plugs, wire and ignition coil. And one more thing, I can not see any fuel in the return line, if I unplug the return line i can see fuel flow backward, I mean fuel not flowing from the regulator to the return line but flow from the return line to regulator, my fuel pump is only 1 year old. I have order fuel filter and pressure regulator, I will replace it this weekend. Thank you for any advance.

luisugueto90

If your fuel pressure is out of whack, why not just change the pump and filters??

My 2.7 had a hiccup on acceleration as well and changing out the fuel filter solved it.

I would rule that out..

Also, Have you cleaned your throttle body???

Binh

I have checked throttle position sensor, it's good, but throttle body I have not. I did replace the fuel pump so I hope it would be the fuel filter.
Thanks

Binh

So i have change Fuel filter with no help, any idea. Thanks

Jomoka

The fuel pressure symptoms sound a bit bizarre. But it can seem bizarre because the pressure is actually relative to the manifold air pressure, not the outside air pressure. So as the idle vacuum level varies, a gauge will show the pressure fluctuating as well.

Is the engine running smoothly otherwise? I.e. it's not constantly running on 5 cylinders is it?

Binh

ok, after replaced fuel filter my pressure seem to be stable at 20psi at idle. when I accelerate i seem to drop 2 psi, accelerate really slow if i accelerate quick it just pop pop and no power. It seem to me a have a leak or some problem that make the fuel pressure seem low and that is the reason no fuel at return line cause my regulator set at 45 psi.
Any idea what should i check? thank you

raretaco02

I'd say filter or pump cause 20psi is low period ,and the filter, pump ,regulator is the things that cause it . Its one of the three I'm sure lol

Binh

What is the recommended pressure for my truck 1996 toyota tacoma 2.4l standard cab

Binh

Hi, I have checked my fuel pump, it's seem in working order voltage drop only .2, good amount of fuel come out when pump is activated, check resistance at 3.6ohms, i don't know is this in spec or not but i don't think the low pressure problem is because of pump or filter.
Thanks

Binh

the problem fixed, the fuel pump is weak only give 20psi the new one give 60 psi at outlet, replaced it run good but have some hiccup at certain speed but that is other problem.
Thank you

raretaco02

What kind of hiccup does it have , is it at a set rpm or throttle position?

Cesar Prieto

I had the same problem
Replace several components,
Fuel filter
fuel pump
egr valve
egr actuator
Air MAF sensor
clean entire intake manifull
clean valves
Clean fuelinjectors
New sparkplugs amd wires
clean distributor cap and check for crack
And the problem still there
after one day I drove 200 miles on highway
the A/C clutch,pulley or coil got burned
making a wining noise after .
the noise bother me so y cut the A/C belt out after
that my problem was fixed no more hesitation or hiccups
(I guessed the clutch was getting stuck causing a pull to the idler whit the belt
hope this help !’

PeteT

I am sorry if I am posting this wrong or in the wrong place. I am new here and hoping someone could help. I purchased a 1995 Tacoma with the 2.4 with only 131,xxx miles. I purchased it knowing it had issues with the fuel delivery system. It would only run sometimes and even then it struggled. I replaced the fuel pump and the filter. I am getting a strong flow of fuel to the filter but now it will not start at all. It will start by shooting fuel into the intake hose. I tried pinching the return line from the regulator but still nothing. All and all the truck is pretty clean but needs paint. I am looking for a fix or to get $1,200 out of it. Please let me know if you have any ideas of what might be going on or if you are in the Charlotte,NC area and are interested. Thanks.