1996 3rd gen 4runner 3.4 v6 keeps dying or stalling

[96tacorunner]

Can anyone help me figure out why my 3rd gen 4runner keeps stalling/dying. So car was sitting for about a month or so because I was welding spindle gussets on my runner to reinforce it. When everything was ready to go my battery was dead so I got a new battery and she started right up. Everything was normal for like a week then I went out one day and then she shut off on me while driving. Wouldn’t start up right away but after waiting maybe 10-15 min she started up and I was able to drive home. After getting home I let the car idle in the garage and revved the engine a little. Sure enough it stalled out again. And again wouldn’t start until letting it rest for a while. Next thing I thought was it’s the alternator but I checked with multimeter and alternator was charging fine and voltage was all good. No lights dimmed all electronics still working fine. So I did some searching on google and forum. Checked with code reader and I got a code saying it was my iacv changed the iacv still no luck still stalling. Changed crankshaft position sensor yesterday and still no luck but this time I was able to drive around the neighborhood for a good while maybe 30 min and it never died on me while driving. But when I would get home it would idle rough and it would struggle to stay on and it would catch it self. And it would stay on if I revved it up but if I just let it be it would die out. I’m stuck and not sure what to do next. I’m thinking it could be something with fuel or spark plugs or coil packs but not sure what the next step should be. Any advice or help would be very appreciated thank you guys

 

[jgue467]

I'd start with basic intake cleaning such as the MAF, IAC (even though you changed it) and check all hoses leading up to metal intake runner for any cracks/air leaks.

If that still doesn't help, I'd move onto a minor tune-up, plugs first then wires if they don't help.

Others will chime in....Luck.

 

[4runnerfiend]

check for Vacuum leaks also.

 

[RandyBobandy]

This sounds like what was happening when the fuel pump went out on a mustang I used to have, would stall and refuse to restart until the pump cooled off for a little bit.

I know the factory service manual way of testing fuel pressure is a pain but I wonder if you could splice into the soft line going to the fuel pressure regulator and get an idea of pump health that way

 

[96tacorunner]

This sounds like what was happening when the fuel pump went out on a mustang I used to have, would stall and refuse to restart until the pump cooled off for a little bit.

I know the factory service manual way of testing fuel pressure is a pain but I wonder if you could splice into the soft line going to the fuel pressure regulator and get an idea of pump health that way

Yes I was gonna change fuel filter first since that was the cheaper thing to do and if that still doesn’t fix it then probably try to change the fuel pump

 

[96tacorunner]

check for Vacuum leaks also.

Been looking for past couple days and I think it’s safe to say that there’s no vacuum leaks that I could find

 

[96tacorunner]

Quick update on the runner. After work today I tested each coil pack with multimeter all of them seem to be good. Spark plugs and wires are less than a year old so not too sure if they need changing but if all else fails I’ll change them. Checked tps sensor with multimeter everything is good. But just wondering how do I clean maf sensor? I know might be a dumb question but I clean the connection with the electronic cleaner but how about inside the intake? Where the maf sensor is? I also cleaned the throttle body when I changed the iacv so not the throttle body. Went out for a test drive around the block and it died on my again but this time was sputtering and misfiring really bad to the point where I can’t even accelerate anymore car was backfiring too. Was able to start car but would just sputter and die. Wouldn’t even stay running for more than 10 sec. So my best bet now is that it’s something with the fuel but still open to anymore advice. I minus well change spark plugs and wires while I’m at it but not too sure on coil packs because they still seem to be good checked all connections with coil packs too nothing loose or anything. Thank you for advice you guys

 

[96tacorunner]

Another quick question when I put the 4Runner on the “ON” position should I be able to hear the fuel pump priming or am I the only one that doesn’t hear anything I only hear like couple clicks from the engine bay please lmk

 

[RandyBobandy]

The fuel pump doesn’t prime in the on position line some vehicles, which is why 4runners have a somewhat long cranking time normally. I highly doubt it is your plugs or wires, doesn’t hurt to change them if they’re old or have a lot of miles but I doubt it will fix your issue. Is it throwing a code for the maf? If I were you I’d figure out a way to do a fuel pressure test, harbor freight sells a kit that works fairly well that you may be able to adapt to work with the 4Runner

 

[snydmax]

With the intermittent starting, I doubt it’s your MAF... could cause the rough idle and stalling out but should not prevent starting.

When it is running, what happens if you apply throttle? Does it rev out normally, hesitate, fall on its face?


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[AntleredRuin]

The best way to test if is the fuel pump going bad is to have it stall out and then see if you can get it going again by spraying some starter fluid in the air intake.

Our fuel pumps have a check valve that fails closed when its warm (after running for a few minutes) that then releases once it's cooled off.

Your symptoms sound very similar to mine when my pump failed a few years ago. When mine stalled or failed to start, starter fluid got it going each time, I guess because it forced the engine to turn over and draw fuel, which forced the valve back open. I just feathered the gas to keep RPMs around 1000 and kept some starter fluid in the car with me while waiting for a new pump to be delivered. I was never stranded once using this method.

 

[spartacus]

Its either'the fuel pump not keeping pressure or a vacuum leak. Also check the charcoal canister and connecting for'cracks.

 

[96tacorunner]

The fuel pump doesn’t prime in the on position line some vehicles, which is why 4runners have a somewhat long cranking time normally. I highly doubt it is your plugs or wires, doesn’t hurt to change them if they’re old or have a lot of miles but I doubt it will fix your issue. Is it throwing a code for the maf? If I were you I’d figure out a way to do a fuel pressure test, harbor freight sells a kit that works fairly well that you may be able to adapt to work with the 4Runner

The only code that it’s throwing is a P0505 which I thought was iacv

 

[96tacorunner]

With the intermittent starting, I doubt it’s your MAF... could cause the rough idle and stalling out but should not prevent starting.

When it is running, what happens if you apply throttle? Does it rev out normally, hesitate, fall on its face?


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So when I start it when it’s cold it’s starts up perfectly but it runs for a while and I could actually drive it for a while but random if I’m driving it when I gas it it won’t accelerate it’s seem like it’s not getting enough fuel and it starts to backfire when I press the gas. Then it will eventually just die and then when I try starting it up again sometimes it’ll start but just die right away then sometimes it wont start at all but it will crank. Which leads me to thinking it might be fuel. Do 3rd gen 4Runners have any fuel relays? Because I had this problem on a Toyota pickup and it was a fuel relay.

 

[RandyBobandy]

Have you done anything to address the iacv code? Since you have a code I’d work on that first, although I don’t think your iacv is the culprit I’d get one off eBay or a junkyard and put it in to see if it helps

 

[Pears4R]

So you need to take the MAF out of the air intake pipe clean it with a brush and the right sensor cleaner look up Timmy the tool man on u tube

 

[Bad Luck]

So you need to take the MAF out of the air intake pipe clean it with a brush and the right sensor cleaner look up Timmy the tool man on u tube

DO NOT CLEAN THE MAF WITH A BRUSH Do not clean sensitive electronics with any sort of brush/cloth/etc. Use MAF cleaner spray and follow the directions on the can.

 

[AntleredRuin]

So when I start it when it’s cold it’s starts up perfectly but it runs for a while and I could actually drive it for a while but random if I’m driving it when I gas it it won’t accelerate it’s seem like it’s not getting enough fuel and it starts to backfire when I press the gas. Then it will eventually just die and then when I try starting it up again sometimes it’ll start but just die right away then sometimes it wont start at all but it will crank. Which leads me to thinking it might be fuel. Do 3rd gen 4Runners have any fuel relays? Because I had this problem on a Toyota pickup and it was a fuel relay.

This sounds like the FPR (fuel pressure regulator) issue that I had when I first bought my truck. I completely forgot about it, or I would have mentioned it in my earlier post above.

Does your truck have an aftermarket air intake system, or have you done the ISR mod? If not, then you have an easy way to test if your FPR is failing. The FPR maintains its pressure from the air intake, and when the check valve in it fails, it will begin to dump fuel INTO the air intake through its attached vacuum line. If you have the stock airbox, this fuel will wind up pooling in the airbox, and will be very noticeable if you remove and shake it around. Makes for an easy diagnosis.

Unfortunately, the FPR is a real SOB to get to, as it's at the rear driver's side of the fuel rail underneath the air plenum. It's also held on with those crappy brass Toyota screws so they will strip out easily unless you can apply good pressure to them, which is near impossible without removing the entire fuel rail and clamping it in a vice to hold it down. If I had to do it again, I'd think hard about getting a Milwaukee M12 Right-Angle Impact driver to see if it would fit back there. If it would, it would be well worth the price of admission.

I opted against using a new OEM or aftermarket, and went with a used one from eBay with (supposedly) only 60k miles on it, as this is a relatively rare piece to break and they often go 300k plus. I've put a good 110k miles on it and it's still working fine. It only cost $30 (not including the injector I broke when removing the fuel rail).

 

[96tacorunner]

This sounds like the FPR (fuel pressure regulator) issue that I had when I first bought my truck. I completely forgot about it, or I would have mentioned it in my earlier post above.

Does your truck have an aftermarket air intake system, or have you done the ISR mod? If not, then you have an easy way to test if your FPR is failing. The FPR maintains its pressure from the air intake, and when the check valve in it fails, it will begin to dump fuel INTO the air intake through its attached vacuum line. If you have the stock airbox, this fuel will wind up pooling in the airbox, and will be very noticeable if you remove and shake it around. Makes for an easy diagnosis.

Unfortunately, the FPR is a real SOB to get to, as it's at the rear driver's side of the fuel rail underneath the air plenum. It's also held on with those crappy brass Toyota screws so they will strip out easily unless you can apply good pressure to them, which is near impossible without removing the entire fuel rail and clamping it in a vice to hold it down. If I had to do it again, I'd think hard about getting a Milwaukee M12 Right-Angle Impact driver to see if it would fit back there. If it would, it would be well worth the price of admission.

I opted against using a new OEM or aftermarket, and went with a used one from eBay with (supposedly) only 60k miles on it, as this is a relatively rare piece to break and they often go 300k plus. I've put a good 110k miles on it and it's still working fine. It only cost $30 (not including the injector I broke when removing the fuel rail).

I have stock air intake and I don’t think I did ISR MOD I don’t even know what that is tbh haha but what do you mean I would see fuel? Like I there would be fuel on my intake?