I have a Scag STT61V-29DFI Turf Tiger....Kawasaki 29HP motor. (I’m new to engine troubleshooting so excuse any incorrect wording). I can’t get my mower to run without hot wiring it. Fuel Pump works great when hot wired, but not getting power to the fuel pump from fuel pump relay without the hot wire. I’m stumped. There is 12v going into the fuel pump relay at the top 87pin, there’s 12v registering on the right #87 pin of the relay (which is piggy backing off of the 87 pin I just mentioned), there’s 12 volts on the left pin #86 ( The wiring diagram says this goes to the engine), BUT there is NO power on the bottom pin (#30) which goes directly to the fuel pump. Like I said, I can attach a hot wire from anywhere registering 12v ( whether that’s the battery itself or any of the hot pins I just mentioned) to the 30pin which runs to the fuel pump or even the 87a pin in the middle, and the fuel pump turns on and allows me to mow. I tried replacement relays, but it’s always the same problem, no power getting to the 30 pin or the 87a pin. If I take the relay off and plug it into the main relay jacket right next to the fuel pump relay, this relay makes the clicking sound to show it is working properly. But none of the relays I have are making the clicking sound when I plug them into the fuel pump relay jacket. All of the wires are clean and making good contact inside the jacket that the fuel pump relay connects into. Any ideas as to what is keeping Power from moving that 1 centimeter over to the 30 pin or 87a pin? I don’t think it is a relay problem. Could it be the electronic control module (Denso 21175-2059)? Would there be something within this module telling the relay not to provide power to the fuel pump?
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Scag fuel pump relay help
- Thread starter 1holdwick
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Export threadbertsmobile1
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For a relay to work it needs to have power to one trigger wire & a ground to the other
The interlock module switches the GROUND to control the pump relay
To be of any assistance to you we need the model & serial number off your ID tag so we can get the parts manual which is a FREE download from Scag so you should have one as well.
The last pages of the parts book have the circuit diagrams and we need them to give you specific help.
Ground switching seems to confuse people but in any circuit you can switch either the + or the - it makes no difference if the item ( like your relay ) is insulated from the frame.
The interlock module switches the GROUND to control the pump relay
To be of any assistance to you we need the model & serial number off your ID tag so we can get the parts manual which is a FREE download from Scag so you should have one as well.
The last pages of the parts book have the circuit diagrams and we need them to give you specific help.
Ground switching seems to confuse people but in any circuit you can switch either the + or the - it makes no difference if the item ( like your relay ) is insulated from the frame.
Is the Interlock module theElectronic Module??
That’s only thing I have not tried yet and it’s definitely not Getting Round to relay one thing I also know this is I always thought that the engine light came on when you tried starting it and it does not it’s that helps
That’s only thing I have not tried yet and it’s definitely not Getting Round to relay one thing I also know this is I always thought that the engine light came on when you tried starting it and it does not it’s that helps
Sorry talk to text, but is the Interlock module theElectronic Module??
That’s is the only thing I have not tried yet, and the relay is definitely not switching to Ground also one thing I also noticed is I thought that the engine light came on when you tried starting it mower and it does not if that helps any but thanks for your reply
That’s is the only thing I have not tried yet, and the relay is definitely not switching to Ground also one thing I also noticed is I thought that the engine light came on when you tried starting it mower and it does not if that helps any but thanks for your reply
bertsmobile1
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YEs.
Every maker calls them some thing different
Eventually all ride one will either be fuel injected or electric as emission regulations get tighter
So I can see the new models all being designed for electronic control.
Nearly all of the modules switch grounds not power .
Every maker calls them some thing different
Eventually all ride one will either be fuel injected or electric as emission regulations get tighter
So I can see the new models all being designed for electronic control.
Nearly all of the modules switch grounds not power .
I have a Scag Turf Tiger 2011 Scag STT61V-29KA-DFI, Serial # F5900234. (Kawasaki 29 hp DFI)
It has had the intermittent fuel pump operation problem which causes it not to start. When the key is turned on the fuel pump normally can be heard to run for a short while. If it doesn’t run the mower will not start.
The problem in my case seemed to be the fuel pump relay located below the right side of the radiator. There are two relays there. On my mower the fuel pump relay is the forward relay. The relay behind it is the Main relay. (Song Chuan Mfr. #:896H1CHD1SWR112VDC (Mouser $5.56)) This is not an exact replacement relay. It is the waterproof version. The plastic clip on the plug does not line up. I removed the clip on the plug. It is held together with a zip tie as it previously was. These relays are fairly easy to replace by removing the four screws holding the oil cooler and moving it forward enough to reach the relays while reaching under the battery with your other hand.
To diagnose the problem I unplugged the three conductor connector located near the upper right side of the radiator. When looking at the end of the connector that connects to the fuel pump I turned the connector till the middle pin was on the right. Then I grounded the lower pin (or pin closes to me) with the key turned on. This should cause the fuel pump to run. In my case the relay would click but would not supply power to the fuel pump. (bad relay)
I will attach a schematic but this is how it seems to work.
When the key is turned to run it supplies power to the main relay. The main relay closes supplying power to the fuel pump relay contact and coil. The other lead coming from the fuel pump relay coil needs to be grounded to cause the relay to close. This grounding is done by the engine controller through the three conductor connector that I described above. When the lead is grounded it closes the fuel pump relay contacts supplying power to the fuel pump. Obviously if any of the step described here fail then the pump will not run.
Note: I think the main relay is an identical relay to fuel pump relay.
It has had the intermittent fuel pump operation problem which causes it not to start. When the key is turned on the fuel pump normally can be heard to run for a short while. If it doesn’t run the mower will not start.
The problem in my case seemed to be the fuel pump relay located below the right side of the radiator. There are two relays there. On my mower the fuel pump relay is the forward relay. The relay behind it is the Main relay. (Song Chuan Mfr. #:896H1CHD1SWR112VDC (Mouser $5.56)) This is not an exact replacement relay. It is the waterproof version. The plastic clip on the plug does not line up. I removed the clip on the plug. It is held together with a zip tie as it previously was. These relays are fairly easy to replace by removing the four screws holding the oil cooler and moving it forward enough to reach the relays while reaching under the battery with your other hand.
To diagnose the problem I unplugged the three conductor connector located near the upper right side of the radiator. When looking at the end of the connector that connects to the fuel pump I turned the connector till the middle pin was on the right. Then I grounded the lower pin (or pin closes to me) with the key turned on. This should cause the fuel pump to run. In my case the relay would click but would not supply power to the fuel pump. (bad relay)
I will attach a schematic but this is how it seems to work.
When the key is turned to run it supplies power to the main relay. The main relay closes supplying power to the fuel pump relay contact and coil. The other lead coming from the fuel pump relay coil needs to be grounded to cause the relay to close. This grounding is done by the engine controller through the three conductor connector that I described above. When the lead is grounded it closes the fuel pump relay contacts supplying power to the fuel pump. Obviously if any of the step described here fail then the pump will not run.
Note: I think the main relay is an identical relay to fuel pump relay.