HET M1070 Barely Moves, No Guts

[abfisher1798]

Starts just fine. On the open road with the pedal to the floor, the tach pegs at 1500 RPM, about 15 MPH (speedometer not working), barely moves down the road. It struggled to get over the small hump that railroad track straddles.

I thought that it's stuck in low gear. The transfer case shifts to neutral just fine. Seems to shift into high gear with the results described earlier. I also shifted it to low gear and there was no change in performance.

Transmission is brand new and shifts through all the gears. After 30 or so mins it began sputtering/surging but maintained speed. Check engine light is not on, and a diagnostics reader shows no error codes.

If anyone has any insight or guidance, I'd very much appreciate it.

Thanks.

 

[rd3war]

Check for clogged fuel lines or filters. Any debris at the bottom of fuel tank?

 

[simp5782]

Fuel pump more than likely. Hook up the scanner and check fuel pressure. I've had 2 of them do it in the past year

 

[abfisher1798]

Changed the primary and secondary fuel filter. I’m having trouble getting it primed. I used then hand pump above the left side tank to the point where diesel seeped from the water separator. Also filled both filters with diesel before installation.
How do I prime the fuel system? I can’t find the right TM.

 

[abfisher1798]

Can no one can offer guidance on how to purge/prime the fuel system?

 

[Shark Bait]

Can no one can offer guidance on how to purge/prime the fuel system?

It’s been a long time since I sold my HET. I had done it before and it wasn’t a difficult task but I do not remember the procedure right off hand. I do, however, think I remember the tanks being pressurized by the air system in order to be able to help push fuel to the height it needs to go to the pump for proper operation. Lol. I could be wrong though, it’s been many years since I’ve had mine.

 

[silverstate55]

Can no one can offer guidance on how to purge/prime the fuel system?

For DD 8V92

If your fuel tank has a vented cap near where your fuel suction & return lines enter tank, replace it with either a threaded air line adapter or quick disconnect (I use female quick disconnects, so fuel doesn’t shoot up & out of fitting when removing air line). Using compressed air, pressurize your fuel tank to 5-10 psi…be very careful not to over-pressurize your fuel tank; you want just enough air pressure to push fuel through fuel system. Make sure your Engine Stop lever/switch/button is not engaged, to allow fuel to flow through system. Depress your throttle pedal with something that will hold it down (most likely a piece of 2x4 wedged against pedal & seat base), this will allow fuel to flow freely throughout system.

Do this for an hour or two…it should purge the majority of air to allow the engine to start quickly. I’ve never had to crank more than 5-10 seconds before engine starts (dependent upon ambient temperature) using this method.

NOTE: excessive engine cranking without fuel flowing through system can damage injectors.

This method also allows you to check fuel hose connections for leaks or excessive seepage, and is why I prefer it.

When done pressurizing, before you disconnect the air hose please loosen the fuel tank filler cap SLOWLY to bleed off pressure….if your air supply device (such as an air chuck) has a pressure bleed off feature, expect the pressure in the tank to push fuel back through your air hose, just like a siphon.

If your fuel tank is non-vented, you may have to drill & tap your fuel tank cap for either a Schraeder valve or pipe adapter.

 

[davidb56]

ditto on the 5 psi. at 15psi you'll have a football shaped tank. I use 3 psi on my barrel transfer system or the ends will balloon out.

 

[87cr250r]

If you pre-fill the filters, the engine should self-prime on its own. No need to push the accelerators. Unit injectors move fuel regardless of rack position.

All of the talk of pressurizing fuel tanks on this forum is crazy.

 

[abfisher1798]

I pre-filled the filters and it ran for a short while then cut out.
Today I disconnected a couple fuel lines located after the secondary filter and did a couple dozen pumps on the primer. No fuel reached the secondary but a while lot was forced out of the top seal for the primary filter/water separator. I suspect there may be a kink or clogged line somewhere.

 

[87cr250r]

If your engine doesn't prime then you certainly have problems elsewhere. The unit injector DD engines are the easiest engines to prime.

 

[silverstate55]

If you pre-fill the filters, the engine should self-prime on its own. No need to push the accelerators. Unit injectors move fuel regardless of rack position.

All of the talk of pressurizing fuel tanks on this forum is crazy.

There it is for the second time. Not going to waste time/energy arguing about it, just going back to lurking & let the experts handle these issues. I’ve already explained why I do it, but I’m obviously crazy.

So, OP, go ahead and fill those filters full of fuel and crank away on the starter. Good luck.

 

[simp5782]

There it is for the second time. Not going to waste time/energy arguing about it, just going back to lurking & let the experts handle these issues. I’ve already explained why I do it, but I’m obviously crazy.

So, OP, go ahead and fill those filters full of fuel and crank away on the starter. Good luck.

Well according to your last psychological evaluation sir....... a few of us won't dispute that!

 

[bigmike]

I pressurized my system after rebuild and bled the system perfectly. It also identified two lines I failed tighten. If I recall correctly I needed 10 psi to push the fuel up to the engine.
sincerely, crazy Mike , formally big Mike.

 

[abfisher1798]

Sounds good. I have an extra fuel tank cap somewhere that can be drilled and tapped.
The pre-fill filters comment was meant in the past tense, done at the time they were changed. I always pre-fill the fluid filters when able.
Going to be an interesting Sunday. Will start at 3psi for 30 mins, then up to 5psi and continue until something happens.

 

[silverstate55]

Most of us here own trucks that are 30+ years old, and many times a seemingly simple issue is an indicator of either a larger issue or a multitude of issues. Most of our trucks/vehicles aren’t less than 10 years old & sent to a large maintenance shop with only 1 issue to be resolved; nor are we large fleet owners who can afford to keep throwing $$$ after parts while chasing a problem. We are usually not governed by book times per repair, and can find the time to properly diagnose/fix a problem.

Pressurizing the fuel tank is an alternative to excessive engine cranking, which at one time cost me a new set of 8 fuel injectors & a starter…turns out these Mechanical Unit Injectors don’t like being turned over without fuel in them. The starter was old & worn anyway, but still… that was money out of my pocket and I don’t want the OP having to go through the same experience.

OP you can also use the tank pressurization method to see if you have a collapsed or obstructed fuel hose. While the system is pressurized loosen connections one at a time to see if fuel leaks out, or you can disconnect the hose and have it drain into a container to get an idea of fuel flow rate through the hose, also checking for debris as well. Heck I even had the suction tube (“draw straw”) fall off into the tank on one truck while driving it.

If your fuel hoses are as old as your truck, and living in a dry climate as you do, there’s no telling what condition they’re truly in. If you have to replace more than one, I’ve found that it’s best to replace them all. But YMMV.

 

[Micmada]

Can no one can offer guidance on how to purge/prime the fuel system?

As said above... I just pressurize gently the fuel tank after rigging the fuel cap with a ball valve I adjust to fit a pneumatic hose. It can be done with a bike hand pump too. I then untighten all the fuel line connections and filters all the way to the pump until everything drips as fuel grades up. I tighten as the leaks start in places.

The fuel pump might have a way to open its chamber and you can add diesel in there too. Kerosene might be an easier start. Then I push the gas down and try and start it. If it does not go as a last resort I use starter fluid to mechanically pull the rest of the bubbles.

Could be the loss of power is due to a turbo leak somewhere. Careful. Dont want the dreaded runaway oil turbo thingy. Have a Co2 extinguisher just in case.

 

[abfisher1798]

I may have found a contributing factor. I obtained a Napa filter/water separator using a filter cross reference guide, which was not at all accurate. The replacement installed just fine, but I now see the open end is slightly wider and the gasket is not making a full seal. That explains why my hand priming efforts pushed diesel out the top of the separator. Sheesh.
I ordered an original OEM filer/separator and bowl as well. Once they arrive, I'll give it another shot and I'll bet some of my woes will be alleviated.

Thanks for all your help.

 

[87cr250r]

We had to stop using Baldwin primary filters on our John Deere 6081 engines. The top of the filter has a tapered metal seat and the angle on the Baldwins is wrong. It touches metal to metal before compressing the rubber gasket. When the fuel tank level would drop below the height of the filter the generator set would suck air and die. They never leaked fuel outwardly even with positive head pressure. That one took quite some time to figure out.

 

[abfisher1798]

Replaced the primary filter/separator with OEM today. A few dozen cycles with the hand pump and she started right up.
Went for a test drive and no change in performance.
During the drive, I shifted the transfer case to High, Low and Neutral and the truck continued to drive as it has been. Being that it drove while in Neutral has aroused my suspicions. My next course of acton is to attempt shift at the transfer case. I found what I believe is the shift cable on the t-case. Once I have another hand, I'll have them cycle the shifter while I watch and see what happens.