Electric fuel pumps have an inherent tendency to burn up, which is the probable reason why Detroit Diesel did away with it altogether in their later models. It is from experience that Thermoking APU tripacs will running fine, until I do a pm. After changing the oil & all the filters, the apu won’t crank and it turns out to be a bad fuel pump. I often hear the criticism it was apu was working before I started working on it. This is what I surmised: The fuel pump was already weakening, but still running. Removing the water/fuel filter separator & the in-line filter interrupted the pre-existing continuous fuel pressure in the line. That means the pump has to work harder to re-establish the same pressure to recreate that same fuel draw, and is unable to do so because of its weakened state, thus it burns itself out. I’m sure there is someone out there who experienced the same & could relate.
Yes Ted, my fuel pump is original from 2007, it's 2021, lol.. when I change the filters I have to self prime by opening the apu fuel bleed screw and putting air into my passenger fuel tank, when fuel starts coming out the bleeder I tighten it up and off we go.. it stays primed till next filter change.. I'm changing the pump soon, lol
I just had same problem with mine. Changed oil and filters and now it won’t start. I Was afraid to burn my starter, so I used starting fluid. Now I realize what to change next since it’s common issue with those unit. TK want around 250 for it. Thank for posting this comment
The fuel pump kicks on when you first crank the engine to build up enough initial pressure to create that fuel draw. Once the engine started, the pump shouldn’t have to stay on after it created enough vacuum pressure to siphon the fuel from the tank. The fuel system may have some sort of pressure sensor that would turn on the pump if it senses a drop in fuel pressure & shut off when that pressure have been reestablished. If the pump ran all the time, you would be going through pumps all the time.
07 tripac issues here. Cranking until it kills the batteries. Replaced pump, filters, belt, reset switch and still having this issue. We've tried a little bit of ether as well. Bled the fuel lines but it's still not firing up. Can you do a glow plug replacement video?
Rightlanecowboy ok what I would do before swapping out the glow plugs I would look at the alternator. Usually there is a white wire that comes off the alternator that powers the glow plugs. It's common for this wire to break and cause your issue. If the wire is broken or shorted it's easy to replace and if you replace it make the new wire at least 2-3 inches longer. I would gladly make you a video on glow plugs but the truck won't be back in town until the 27th of this month. Once it returns I will make a video. Realistically though replacing glow plugs is easy. Just use no seize on the new plugs and change them one at a time to be 💯 sure no wires get crossed.
Great job,thermo king are thieves period.
What fittings did you buy from the hardware store to make that fuel pump work?
Thanks you for video.
Thanks for viideo, please add changing fuel pump to title, make it easier to search it
I will do that right now!
Thank you for watching!
Electric fuel pumps have an inherent tendency to burn up, which is the probable reason why Detroit Diesel did away with it altogether in their later models. It is from experience that Thermoking APU tripacs will running fine, until I do a pm. After changing the oil & all the filters, the apu won’t crank and it turns out to be a bad fuel pump. I often hear the criticism it was apu was working before I started working on it. This is what I surmised: The fuel pump was already weakening, but still running. Removing the water/fuel filter separator & the in-line filter interrupted the pre-existing continuous fuel pressure in the line. That means the pump has to work harder to re-establish the same pressure to recreate that same fuel draw, and is unable to do so because of its weakened state, thus it burns itself out. I’m sure there is someone out there who experienced the same & could relate.
Same wiring so it only works when the unit is on
Yes Ted, my fuel pump is original from 2007, it's 2021, lol.. when I change the filters I have to self prime by opening the apu fuel bleed screw and putting air into my passenger fuel tank, when fuel starts coming out the bleeder I tighten it up and off we go.. it stays primed till next filter change.. I'm changing the pump soon, lol
I just had same problem with mine. Changed oil and filters and now it won’t start. I Was afraid to burn my starter, so I used starting fluid. Now I realize what to change next since it’s common issue with those unit. TK want around 250 for it. Thank for posting this comment
Thanks for the video. Now I know what to do next
Thanks. I spent 18 hours at thermoking and $800. And they didn’t even fix it.
What fittings did you use driver.
@tyronet74 brass 3/8 pipe thread barbed 3/8 nipples
@tyronet74 also watch out the fuel pickup tube in the tank can snap off on you and it will drive you nuts figuring it out!
@@hillbillyholler516 thank you
Does the fuel pump run constantly? Or does it turn on and off when the apu is running?
The fuel pump kicks on when you first crank the engine to build up enough initial pressure to create that fuel draw. Once the engine started, the pump shouldn’t have to stay on after it created enough vacuum pressure to siphon the fuel from the tank. The fuel system may have some sort of pressure sensor that would turn on the pump if it senses a drop in fuel pressure & shut off when that pressure have been reestablished.
If the pump ran all the time, you would be going through pumps all the time.
07 tripac issues here. Cranking until it kills the batteries. Replaced pump, filters, belt, reset switch and still having this issue. We've tried a little bit of ether as well. Bled the fuel lines but it's still not firing up. Can you do a glow plug replacement video?
Rightlanecowboy will it fire at all off of starting fluid and air filter removed?
Hillbilly Holler no it won't.
Hillbilly Holler it will just crank but never fire up until it kills the battery.
Rightlanecowboy ok what I would do before swapping out the glow plugs I would look at the alternator.
Usually there is a white wire that comes off the alternator that powers the glow plugs.
It's common for this wire to break and cause your issue.
If the wire is broken or shorted it's easy to replace and if you replace it make the new wire at least 2-3 inches longer.
I would gladly make you a video on glow plugs but the truck won't be back in town until the 27th of this month.
Once it returns I will make a video.
Realistically though replacing glow plugs is easy.
Just use no seize on the new plugs and change them one at a time to be 💯 sure no wires get crossed.
Hillbilly Holler I'll give that a check tonight.
It is called a loom wire cover.
I'm getting code AL3, it run for about 4 minutes then shut off. I cant find no info online for that code.