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Tach not working

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Old Jun 25, 2017 | 05:41 PM
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Tach not working

Hello I have a 1993 Ford F-250 with a 7.3 nonturbo with a manual transmission. My tach has not worked since I bought it. When I start the truck up it works but then it slowly starts jumping around and then the needle goes all the way down. When I rev the engine up so far it comes up a little but no where near where it needs to be. Do I need a new tach sensor? I tried the one off my 1993 f-250 7.3 with a turbo manual transmission it threaded in but the plug would not plugin to the plug in the truck. Are the plugs different for the 7.3s with a turbo?
 
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Old Jun 25, 2017 | 10:44 PM
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Sounds like a faulty sensor, at least that's how mine failed.

I'm not familiar with the plugs but thought they were all the same, guess not.
 
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Old Jun 25, 2017 | 10:59 PM
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Originally Posted by DarkOverCast
Sounds like a faulty sensor, at least that's how mine failed.

I'm not familiar with the plugs but thought they were all the same, guess not.
They look the same. Maybe one of the prongs are a little off and not lining up right. Will try again tomorrow.
 
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Old Jun 27, 2017 | 10:09 AM
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If you determine the connectors really are different, just splice in the connector from the faulty sensor. I don't think polarity even matters. Make sure to insulate the splices well, as stray signals can throw off the signal to the tach.

But it's more likely just a case of a bent or misaligned terminal.
 
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Old Jun 27, 2017 | 10:16 AM
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Originally Posted by madpogue
If you determine the connectors really are different, just splice in the connector from the faulty sensor. I don't think polarity even matters. Make sure to insulate the splices well, as stray signals can throw off the signal to the tach.

But it's more likely just a case of a bent or misaligned terminal.
The first picture is the connector off the 7.3 non turbo the second picture is the connector off the 7.3 turbo.

 
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Old Jun 27, 2017 | 01:04 PM
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These tach sensors are so simple, often problems can be cured by removing the sensor and cleaning up the business end and reinstall. They pick up a lot of debris over the years (I believe they are magnetic?) and cleaning is many times the cure.

There's a couple of links in the FAQ to some simple ideas of making a new sensor, but like said above, you can just splice on the proper connector.
 
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Old Jun 27, 2017 | 01:36 PM
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Originally Posted by Chevy_Eater
These tach sensors are so simple, often problems can be cured by removing the sensor and cleaning up the business end and reinstall. They pick up a lot of debris over the years (I believe they are magnetic?) and cleaning is many times the cure.

There's a couple of links in the FAQ to some simple ideas of making a new sensor, but like said above, you can just splice on the proper connector.
Will splice the proper connector on. I tried cleaning it it worked great for a whole 45 seconds. Ordered a new one should be here Thursday.
 
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Old Jun 27, 2017 | 11:58 PM
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There is a few threads on a cheap fix instead of buying the pricy Ford dealer sensor.

Here are some listed on flea bag. and a few threads
https://www.ford-trucks.com/forums/1...placement.html

https://www.ford-trucks.com/forums/1...er-sender.html

Honeywell Variable Reluctance Speed Sensor | eBay




Hope this helps, not sure if this is what you are working on.


Charlie
 
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