Kent
Bronze Member
So the snap-on 30 amp inline fuse carrier flaked out (took a day to trace all the wires to find it but minutes to put in a new water tight one from AdvancedAuto) and in the process I accidentally broke off the temperature sensor wire. This is a thermistor. The engine's ECU uses the temp to adjust the mixture and to shut power off to the fuel pump if the engine overheats.
The temperature sensor doesn't show up on any Subaru parts diagram. I wrote in to their web "contact" form and was called back pretty quickly by the parts guy "Ron" who couldn't find the wire either. I asked him if maybe it was part of the ECU, so that lead him to find that the sensor wire is actually part of the EFI wiring harness 1, part number 20K-73101-01. Goes for $185. Ouch!
So I tested the old thermistor and it appears to be a 10,000 ohm one. I'm ordering one from Mouser Electronics - Electronic Components Distributor made by US Sensor (USUR1 | U.S. Sensor Corp.)
803-USUR1000-103G-06
About $13.
By the way you can now order parts directly from Subaru at Small Engines | Pumps | Generators | Subaru Industrial Power. Prices are the same as other places I order from, Lawn Mower Parts | Small Engine Parts - Jacks Small Engines and Subaru/Robin Parts.
Anyway, in talking with Ron I mentioned that the engine started running rich a few months back, and is it possible that I had broken the thermistor at that time and would this cause it to run rich, and he was convinced that would be the case.
He also felt it very important to replace the temperature sensor to keep the engine from burning up (only the EFI model has it).
According to Ron, if any of the the Subaru engines like the EH72s are mounted in the open they have seen no overheating problems, but when put into any piece of equipment with constricted space (two or more sides like a welder or pump) they burn up all the time (kind of like our PTs). Also at one time they had a muffler from a third party supplier that used slightly smaller diameter tubing and had some welding slag in the flanges, and again, burned up some engines. Reconfigured the muffler design, found a new manufacturer, and that problem went away.
The temperature sensor doesn't show up on any Subaru parts diagram. I wrote in to their web "contact" form and was called back pretty quickly by the parts guy "Ron" who couldn't find the wire either. I asked him if maybe it was part of the ECU, so that lead him to find that the sensor wire is actually part of the EFI wiring harness 1, part number 20K-73101-01. Goes for $185. Ouch!
So I tested the old thermistor and it appears to be a 10,000 ohm one. I'm ordering one from Mouser Electronics - Electronic Components Distributor made by US Sensor (USUR1 | U.S. Sensor Corp.)
803-USUR1000-103G-06
About $13.
By the way you can now order parts directly from Subaru at Small Engines | Pumps | Generators | Subaru Industrial Power. Prices are the same as other places I order from, Lawn Mower Parts | Small Engine Parts - Jacks Small Engines and Subaru/Robin Parts.
Anyway, in talking with Ron I mentioned that the engine started running rich a few months back, and is it possible that I had broken the thermistor at that time and would this cause it to run rich, and he was convinced that would be the case.
He also felt it very important to replace the temperature sensor to keep the engine from burning up (only the EFI model has it).
According to Ron, if any of the the Subaru engines like the EH72s are mounted in the open they have seen no overheating problems, but when put into any piece of equipment with constricted space (two or more sides like a welder or pump) they burn up all the time (kind of like our PTs). Also at one time they had a muffler from a third party supplier that used slightly smaller diameter tubing and had some welding slag in the flanges, and again, burned up some engines. Reconfigured the muffler design, found a new manufacturer, and that problem went away.
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