Ok, so i know i have not been around here much these last few months, been busy with other cars and not had any problems with the 4runner.

But i have an odd problem now.

So last night i was driving, perfectly fine, not a single problem and lots of power. Came home parked it and that was that.

Today i go out, hop in, start it up and start to drive. And as soon as i press on the gas at all the engine stutters, like fuel cut.

Looked at the fuel gauge and it was about 1/8th, i usually can run it down MUCH lower and still have lots of gas. so i limp it to the gas station by basically letting it idle in gear.

Fill it up, and still have the same problem.

Limped it back home, did some basic checks and that is where it sits now.

All gauges are normal, oil pressure is good, no lights, no CEL.

Everything seems normal until you try to touch the gas, then it starts hicuping and acting like fuel cut.

I am lost, the only thing i can come up with are:

Eletrical problem of some kind, this is my best guess but no clue what it could be or how it would work fine last night and not today. plus no codes is odd.

Spark problem, possible i guess but i just got all new plugs, wires and all that stuff 5000 miles ago.

Fuel problem, possible as well but how and what? and how would it come up over night?

Too dang hot to work during the day so going ot mess with it a little tonight and then this weekend.

Any ideas?

Going to reset the ECU first and see if that does anything.

 

You know what's gonna happen TA is you're gonna go out there tomorrow, start it up and it will run fine, never again to have this problem. Sounds like something freaky like that is going on.

 

I bet you are right.

I know it makes NO sense why it would work perfectly last night and not today.

 

clogged fuel filter? Has that been changed? Same thing happened on my motorcycle. The thing started but ran extremely rough, and when you would give it gas, it would struggle even more. I got some bad gas at a Mobil 1 station and that clogged my filter all-togther.

 

I thought of that as well, the filter is new a 5000 miles ago though. And u have not filled up in over 2 weeks. So it doesn't make any sense that it would run perfect last night and be clogged today.

That is possible though.

 

vacuum leak will behave like this on occasion. Check for leaks, or air bypassing the MAF. I had a similar problem after a tune up before realizing I forgot to connect some stupid hoses.

 

Never thought about that, never seen a vacume leak act like that but that is possible. Will check that this weekend.

 

Ace,

If you can't figure it out take it over to Lexutech in Fort Worth. They should be able to diagnose it for you. These guys are awesome!

 

And they cost money, which i don't have. Either i fix it or it don't get fixed lol.

I am sure it is somthing small as the engine itself seems fine. The hard part is tracking down what the problem is.

 

someone mess with it?

 

I almost wounder but there is no indication that someone did.

 

Uhh, probably melted/clogged cats.

 

X2 I'd say. My MAF plug was loose and I couldn't give it hardly any gas to go anywhere until I figured it out. Also, the woodruff key on the crank could be the culprit. I had an issued but only at passing gear it would act like a stutter box at the drags at about 4000 RPM so who knows man. Sorry to hear about the issue but it's prolly something simple that you'll have to track down.

 

Possibly, but you would think the motor would be getting hot if that was the problem.

 

Not the problem i know 100%, no cats on the truck.

Another good idea. I will check that as well. Started to go out a few mins ago to check on some thigns but 105 degrees, 80% humidity and me don't get along too well unless we have to. In this case we don't so i will wait until later.

Got to install an engine in the 300zx tomorrow, if i finish early i will check out the truck.

 

Would a fuel pump do this if it's not up to the correct PSI?

 

Yes, i had thought of that as well, i had an RX7 do this once due to a bad fuel pump but it also acted a little differnt. This one really seems like some kind of sensor/eletrical problem.

Wish i had my wideband working (bung came out a few months back and never got around to having a new one put in).

 

check the MAF, check the intake hose for rips or cracks, check the plug on the MAF, check that tha clamps that clamp the MAF to the intake pipe are tight

if all of that is good then check the fuel pressure

if it is low then check the regulator, pull the vacuum line off an see if there is gas in it or if you can smell gas in the regulator. if you have a vacuum pump and gauge then test that the regulator holds vacuum.

if the regulator is good, but the fuel pressure is low then i would test the voltage at the fuel pump. make sure you have 12+ volts. if you do then throw another fuel filter on it just because it is cheaper than a pump. if that doesn't work then your pump would be the problem. I've seen them get weak but keep running before


if the fuel pressure is good then check your air filter and intake pipe, throttle body. etc...

make sure a mouse or squirrel hasn't made a nest in there


doesn't sound like an ignition problem

 

All good ideas, i also think it could be fuel related. As i said i had this same type of problem with my old RX7. But in the RX7 case the pump died slowly over about a week. kinda strange this would die overnight and the pump is practically new, only 2000 miles on it.

Plan to reset the ECU first and se if that does anything, then do a quick check for spark. If that checks out then going to move on to what you have listed above.

Today i am in the middle of getting the 300zx running (got the engine in yesterday, need to get it running today so i can get it back in the drivway before tomorrow when the code enforcer will write me up)

 

Fuel Filter x? this is where I would start other than the MAF plug! and intake tube.

Crap can back out of the filter then when you go to start it clog it quick.
usually this issue is the intake or the fuel filter could be the air filter though
Rare but it could be!

Vacuum can usually be heard if it is the instigator!