Carb. Cooling fan questions. (1 Viewer)

[ThePostman3]

Hey guys so I have pretty much gotten her running in top condition but I think my cooling fan for the carb. Didn't work I have read some threads on it but I need a few questions answered and prob a few pics.

So she runs off the cooling system I get that but is that connected to the temp gauge circuit board?

Also I need pics of the sensor placement for the fan on the intake manifold and which wire it is in the wire loom. I haven't seen any and my wire has broken, so I have no idea where it is or which wire.

Thanks for the help!

 

[roadstr6]

The carb cooling fan is meant to be triggered by a sensor on the manifold. Many times the sensor fails or the wire snaps off. In the cluster of wires that go to the idle fuel circuit on your carb (the electrical connector on your carb) there is a blue wire. Take that blue wire and splice on an extension with a ring at the end. Remove a screw or bolt in the vicinity (pretty much any one will work) and ground the blue wire. This will take the temp sensor out of the equation and will allow the cooling fan to run for 30 minutes after shutoff. You may think 30 minutes is a long time but the fan takes very little amperage to run. It won't drain your battery.

 

[Output Shaft]

There's lots of info on this. Here's a thread.

Should There Be a Relay Here (Carb Fan)

Search "carb fan sensor"

 

[ThePostman3]

Once I've replaced the wire when is it suppose to be blowing air?

 

[Output Shaft]

The fan should turn on when the engine is shut down and the key is in the OFF position after it warms up.

 

[zprovo]

When the wire to the manifold sensor broke on mine, I grounded it to the body. It blows for 30 minutes every time I turn the key off. It's been this way since 2003. Only issue I've ever had is co-workers sometimes tell me "something is running on your truck"

 

[Speen Shaytan]

How necessary is the cooling fan? My wiring disintegrated years ago and has never really worked. I haven't had any issues...that I know of.

 

[roadstr6]

If you have to really wind on the starter to get a hot engine started the fan will help tremendously. If you are not having a problem then don't worry about it. My fan wasn't hooked up and my 60 required a lot of coaxing to get it to fire up when it was warm. It would always start but it acted like it didn't want to. I didn't give the fan much credit. It seemed like a dumb afterthought on the part of Mr. T (and maybe it was?). However, once I got the fan back working again, the truck starts right up no matter if it's hot or not. I continue to be amazed at how much of a difference it made on my truck. Again, if you are not having issues don't bother.

 

[Speen Shaytan]

If you have to really wind on the starter to get a hot engine started the fan will help tremendously. If you are not having a problem then don't worry about it. My fan wasn't hooked up and my 60 required a lot of coaxing to get it to fire up when it was warm. It would always start but it acted like it didn't want to. I didn't give the fan much credit. It seemed like a dumb afterthought on the part of Mr. T (and maybe it was?). However, once I got the fan back working again, the truck starts right up no matter if it's hot or not. I continue to be amazed at how much of a difference it made on my truck. Again, if you are not having issues don't bother.

Good to know, thanks.

 

[gregnash]

Yeah I apparently lots my carb fan sensor all together sometime between the beginning of the year when I finished the topend rebuild and about a month ago. Have ZERO clue where and when but the truck operated just fine in all that time, mind you it had about 2months off of normal usage as I was laid up with a busted leg. But even still it wouldn't have seen that much more usage as I normally bike to work and only use if I am driving somewhere outta town.

 

[Zack1978]

Is the manifold sensor still available new from Toyota?

 

[Output Shaft]

No

 

[houstonfj40]

Is the manifold sensor still available new from Toyota?

Zack1978,

I picked one up from CrusierYard priced right. SOR has them but $.

Marc

 

[ScottT]

I undeerstand that they are a bimetallic switch to ground and die frequently due to the heat. Wired mine to ground instead. Still didn't work. Hot wired the motor as a test and it worked. Found a break in wiring in drivers side kick panel. Works.

 

[Mestenorides]

Good to know, thanks.

Carb cooling fan is also not working on my 87 FJ60 which is hard to start in hot weather. Just started working on my Cruiser which has been sitting idle for a number of years. Bought new in 1987.

The wire to my sensor is broken but I can't identify the green-colored cylindrical part in a holder that is located upstream from sensor (see image). There is another one of these up by the fan before the wiring enters the bundle. Some type of relay or fuse? Tested my fan with DC power and it's good.

 

[OSS]

Just get rid of the Toyota plugs & wire (or crimp) a new wire to the sensor from the wiring harness near the fan. Plugs are convenient when removing the manifold, but wire cutters work just as well. Use wire designed for high temps. High temperature insulation.

 

[Elbert]

many threads about that wire getting cooked and a way to "hot-wire" the fan where it then comes on every ign cycle for "X" amount of time. The location of the temp sensor is just asking for another wiring meltdown if you use the sensor.

 

[OSS]

Elbert is right -

but there is a long term solution >

One wire you can use to connect to the manifold heat sensor is not really 'wire' at all. You can use stainless steel braided bicycle brake cable. It will never rust or corrode and last "forever". Heat won't affect it. You can crimp a non insulated eye terminal to the sensor end (or splice a little eye loop like I did) & crimp a WeatherPak plug to the other & a WeatherPak plug to the harness. Or skip the plugs & just make it a little longer & crimp it to the harness.
The SS brake cable conducts electricity fine. Fan/sensor works fine.

For the length that is running from the harness down towards the manifold (but not all the way to the manifold) you can slide a piece of OEM vacuum tubing over the cable to insulate it to prevent it from touching other metal. The last several inches leading up to the sensor are left bare of the vac tubing to keep it away from the heat.

I had my manifold heat sensor wired up like this with SS bike brake cable instead of copper wire for over 15 years (until the cooling fan relay died) and the wire was still as shiny & nice as the day I installed it. Vac tubing was fine too. Not affected by the heat because it did not run the full length of the "wire".
It worked great.

Just an option to consider...

 

[GeologistFelix]

My emissions computer died a long time ago (leaky windshield seal + pacific northwest + time = rusted-off legs on capacitors & resistors), so I've been putting together an alternative setup.

First attempt was to use the old manifold sensor/switch as a switchable ground for a relay to kick the fan on when things get hot (i.e. the same as the original setup, minus the 30-min timer). What I found was that the sensor, probably because it's old, doesn't close the circuit until it's >200 degrees (maybe 250?) and the exhaust manifold only gets to about ~190ish max from regular driving, but that's plenty to cook the gas out of the carb when I park after a longer drive. I was able to get it to switch on by blasting the sensor directly with a plumber's torch, but that just proves that the fan and the new relay are wired properly and working.

Next attempt is going to be to replace the old sensor with a 180 degree thermostat sensor. It was $20 and is supposed to come on at 180 F and switch back off at 165. I'm not sure where I'm going to mount the dang thing yet, but we'll see.

 

[NeverGiveUpYota]

I'll also add that even after pulling and thoroughly cleaning the innards of my fan it would not run hardwired to the fender and then wired it the right way direct to the manifold and still nothing. Then I found a guy (serendipity) who had an extra working cooling fan relay (located in the right side kick panel) who hooked me up. I pulled the stock one and added his and voila! working fan! I kept my old one and looked close at the lead connections... nothing looks cracked but who knows. I have yet to do any soldering to reflow the connections but could be that is all it needs.