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803 shuts down with “no fuel” light on ... but tank is full?

BA in CO

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My 803 has been working fine since major engine work couple years ago (bent push rod) ... has run the whole ranch a few times ... was testing yesterday and during cool down it shut off with the “no fuel” light on ... gauge read 3/4 tank, I topped off the tank good clean fuel... now starts fine and runs for about 5 minutes then shuts down. I replaced the spin on fuel filter but no joy... to be honest I am not terribly mechanically inclined so will likely take it to my farm mechanic now. He knows diesel motors well so I suspect he can trouble shoot fuel system problems OK but if you have some advice on most common places to look that might be related to the 803 safety switches etc. we would appreciate the where to look advice!
 

kloppk

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Basically there are two components and their wiring that detect a Low Fuel fault. That being the Low Fuel Float switch and the A9 Float Switch module.
The Low Fuel Float Switch FL1 is inside the fuel tank. It' comprised of 2 float switch's. The lower one FL1 detects a LOW Fuel situation. The upper one FL2 is used to turn the Aux Fuel pump on and off. The wires from FL1 and FL2 go to the A9 Float Switch Module. It's located to the far right slightly above the fuel tank.
To get to the float switch assembly and A9 one needs to pull the access panel off the end of the genset.
The FL1 float switch contacts are wired to the A9 Float Switch Module. When the A9 senses a Low Fuel signal from FL1 it in turn causes relay K19 to close. When K19 closes it sends a signal to the A2 Fault Monitor which in turn triggers the Low Fuel Fault Lamp to illuminate and cause the engine to immediately shut down.

Low Fuel Fault.jpg

Float Switch and Module.jpg

Float Switch and Module Locations.jpg
 
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BA in CO

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Ault, CO
Thank you for taking the time with the detailed answer ... I think I followed some of it but as I said not my strong suit ... I did understand that the sending unit it the most likely culprit and I will share that with my mechanic friend ... I have a couple 802s so if that part is interchangeable I could try changing it out before buying and replacing parts (module) ... love these gensets but wish there was someone local in Colorado who liked to work on them ... many thanks
 

jmenende

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The first thing I do is put on a glove and get my hand in the fuel fill hole. There are two floats, one on the very bottom and another in the top. You need to fondle them both but in particular the bottom one. Sometimes they will get stuck due to varnished diesel or the rod was set a bit too close to the wall. If that does not work then take off the back panel. The float sensor has a nut on top you can take off and that will allow you to turn, lift and push the sensor. It should be about 1/8 off the bottom. If that does not work, break out the multimeter and start testing what klopp listed.
 

BA in CO

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Ault, CO
Sorry one more question before I start palpating my fuel tank ... before you start the motor when the master switch is in the prime/run position should the fast clicking stop after 10 or 20 seconds or just keep clicking? I seem to remember it should stop but now it just keeps clicking... could this mean my “no fuel” shutdown is a fuel lift pump problem not a float/switch problem? Had to ask ...
 

DieselAddict

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Sorry one more question before I start palpating my fuel tank ... before you start the motor when the master switch is in the prime/run position should the fast clicking stop after 10 or 20 seconds or just keep clicking? I seem to remember it should stop but now it just keeps clicking... could this mean my “no fuel” shutdown is a fuel lift pump problem not a float/switch problem? Had to ask ...
To add, there is a different sound when the pump isn't pushing its normal fuel flow. Before the system is fully primed and pressurized, the pump sound will have more high frequency components. It will sound a little more rattly. Once the system is fully primed it will sound a little more dull or muted. Once you learn the difference in the sounds you can tell pretty quickly if you have the system primed enough to run properly.
 

BA in CO

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Ault, CO
Sorry it has taken so long for the follow up … I replaced the float switches in the tank and that seems to have fixed the problem… easier said than done, took lots of jiggling and figuring to get it out and back in but I finally got it … almost thought I had the wrong part as the mounting screws in the flange that holds it in place are not evenly spaced and I had it rotated wrong but in the end I got it! thanks for all the advice!
 

loosegravel

Just a retired mechanic who's having fun!
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Sorry it has taken so long for the follow up … I replaced the float switches in the tank and that seems to have fixed the problem… easier said than done, took lots of jiggling and figuring to get it out and back in but I finally got it … almost thought I had the wrong part as the mounting screws in the flange that holds it in place are not evenly spaced and I had it rotated wrong but in the end I got it! thanks for all the advice!
I've had to replace FL1 on several different units. It's item #10 in Kurts drawings above. I'm not really sure what fails in these sending units. They utilize a magnetic type of float rather than a resistor type like in FL2. Maybe fuel gets inside of the tube and messes with the electronics? Anyway, it's always good when something works correctly after you've replaced some parts isn't it? And you're right...there's nothing easy about working on these 5kw and 10kw fuel tanks and related parts. Even knowing what to expect, I still get tested whenever I have to repair something on them. Good job(y)
 
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