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-   -   93 4runner rough idle/vapor locking (https://www.yotatech.com/forums/f116/93-4runner-rough-idle-vapor-locking-294150/)

deltazlt 03-21-2016 08:24 AM

93 4runner rough idle/vapor locking
 
I've got a 93 4runner that is running rough and vapor locks if left off for more than ten minutes or so. I've done quite a bit of searching and can't find a definetive answer anywhere. It just had the head gaskets replaced as well as new valves. Any help would be greatly appreciated.

millball 03-21-2016 08:56 AM

Not likely to be vapor lock on an engine that has relatively high pressure fuel injection.

Check the fuel pressure under different conditions.

I'd guess you more likely have a flooding issue than a weak fueling problem.

Maybe the cold start injector, or regular fuel injector is leaking down after shutdown.

deltazlt 03-21-2016 10:38 AM

Normally I would agree, except in order to get it to start after sitting for a few is to crack loose the fuel line at the rail and nothing but vapor comes out, and then it will start right up. But still runs like crap no matter what.

scope103 03-21-2016 11:21 AM

The Fuel Pressure Control system http://web.archive.org/web/201503060...ne/99fuelp.pdf is there to deal with vapor lock. You might as well check that.

Don't forget that EVERY time you "crack loose" a fuel line you must replace the two crush washers. They are one-time-use. Not a place to tolerate a leak.

deltazlt 03-22-2016 02:40 AM

Checked that, nothing obvious wrong, which vsv is it though? Seeing that there are several under the hood. The only sensor that hasn't been replaced is the maf.
However driving home yesterday it kept shutting off as I came to a stop.

scope103 03-22-2016 06:34 AM


Originally Posted by deltazlt (Post 52314165)
...
However driving home yesterday it kept shutting off as I came to a stop.

That doesn't sound like vapor lock. Have you checked basic igntion timing? Are the plugs still firing right up to when it dies?

deltazlt 03-22-2016 07:53 AM

It only vapor locks after being shut off for a period of time, and yes when it would cut off it start right back up and be fine until I push clutch in again to stop.

deltazlt 03-22-2016 05:17 PM

I installed a intake on the truck this evening in doing so had to mess with maf, and when it was all said and done the truck is idling fine now so I'm suspecting a bad maf as at least part of my issue. From what I research about the vapor lock is that no one has truly found a solution to the issue


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