TexJJ

So some of you may remember that I have been spending the past year tracing a mysterious jerk that would randomnly hit my '91 4Runner 3.0. We've replaced the coil, igniter, wires, distributor cap, plugs, etc, checked the resistance on the dizzy, upgraded the power and ground wires to the system all the way around.

The problem was spurratic at best, usually occuring once or twice every 300 miles, but never under the same circumstances. Generally the truck would be running normally, say on the highway, then all of the sudden jerk, the tach would read a sudden drop in rpm to say 100 (WHICH DID NOT HAPPEN IN REALITY AS I HAVE A MANUAL) then before you could react everything would go back to normal. The engine would jerk as if someone killed the ignition for a breif second, but 12vdc would remain constant, no spikes monitored on the digital voltmeter I rigged into the system, lights would not flicker, no other symptoms.

SO, this weekend I take the vehicle on a quick trip camping and pull up to the ranger's station to get my permit. Everything was working fine while I was driving. I leave the truck running as I talk to the ranger and when I am returning to the 4runner notice green fluid begining to trickle then POUR out of the right hand side. I immediately shut down the motor and see the temp guage is pegged at H. CRAP. I try to pop the hood, but too much hot fluid is erupting out. I grab a glove and carefullly open the hood. Rather than pressure blowing from the radiator cap, fluid is boiling out of the plastic resevoir. WHAT THE HELL???

I then note that my Flex-A-Lite fan is not running at all. I let things cool a bit (well let the eruption of fluids from the resevior cease) and look around. THe fuse from the battery to the electric fan is not just blown, IT IS FRIED. The rubber fuse housing is totally melted. My dad (a very meticulous man) had made sure to run the wires and zip tie them so that they would not be near any heat sources, so I know it was not ambiet heat that melted this, it was current. So now what. I am a good hour from town and no fan.

I camp the night and the next day refill the radiator hoping for the best that I did not warp my heads. I then try to rewire the fan via another 15 amp fuse I had put in the vehicle for the rear power supply. I know the fan won't turn on until the relay/temp sensor hits a pre determined temp so I start up the truck and get to 50 mph as soon as possible knowning (or aat least hoping) that my dual fin high capacity radiator will be able to dissapate the heat sans fan with the ambient air flow at speed. The vehicle hits operating temp, but does not creep into hot. However when I finally stop I check and the fan still is not working. I take the chance and connect the hot leat directly to battery, NOTHING. Hmmm the fan must be bad.

So now I am home and dealing with a post mortum. I am supposed to go on a multi-week offroad trip to interior Mexico in two weeks. I may postpone because I have yet to have any reliability out of this vehicle. (New engine, still consuming oil, now overheat.) ANYWAY, next weekend we will go back to the clutch fan and try to buy a shroud (the original owner must have had the clutch fan explode on him because the shroud was shreaded when we got it.)

Do any of you have any experience with the flex a lite causing WEIRD electrical problems? It dawns on me, that the problems with jerking began with the addition of a new timing belt and the electric fan. Does it stand to reason that the fan could become a generator as the air flow pushed it causing a reverse flow of electricity that may cause weird problems. The best description of our jerk was like a capacitor at times just built up a charge and bang the system shut down then refired up.

Any advice, comments will be greatly welcomed. Perhaps this 4Runner is jynxed at it is time to trade up, but I really enjoy the syle of the 2nd Gen, and it has been a great deal of fun working on it (altough I am getting tired of field repair.)

Thanks guys!

JJ

^VooDoo^

Ive had this jerking before but with my Celica, Ive read the same happening to many generations of 4R and 4x4 On this site.
Mine was a bad Fuel pressure regulator for EFI engines.
On my Celica it caused alot of overheating I belive from running to lean.
Though I still have the clutchfan, I suggest staying with the electric.

midiwall

I've had a few things happen... I'll give you two, one exactly the same as yours.

I was on a trail, we'd been moving slow for a while, and ... hey lookit that, the temp is PEGGED. Pull over, pop the hood, the fans aren't running... and the fuse holder is melted to the point that it's fallen apart, the fuse has fallen out, and of course - no fans. I wired in a new fuse holder and continued on that day without any other trouble.

Last July was my latest issue, and after this I pulled the fans.

I was running a local set of dunes, bouncing around and all that (note my avatar pic). I'd done a couple of big jumps that day, and "at some point" (not sure just when), I hit hard enough that I broke a blade on one of the fans, it wedged into the housing, and jamed the fan motor. Not good but that's what fuses are for, right? Well, instead of blowing the fuse, it blew the controller. (yes, the fuse was the right rating)

That wouldn't have been a "huge" issue with a mechanical controller, but this was the THIRD controller I had gone through in 2 years - 2 mechanical and... this one was an electronic from PermaCool - about $70 and potted (can't open it up). I went back to a mechanical setup as soon as I could get a fan.


I like the idea of running electric fans, I agree with the performance gains, but I've dropped $350+ into trying to make it work and while sometimes it's been awesome, most of the time I've been the hold-up on the trail.

ChickenLover

The same exact thing happened to my flx-165. Of course, on a hunting trip 70 miles from anything that resembles civilization. Rewired it and continued on. This fan has been a pain in my ass.