M923A2 Starts only with Ether, and stalls when put into gear

[98G]

Just using a small, say 1 gal. tank and line direct to your IP can tell you if it's a fuel issue. Bypass all of the potential leaks.

.

This sounds like far less work, with a much higher chance of yielding a usable answer than jacking up the truck and spinning the wheels.

Although I'd go so far as to say that the chances of replacing the soft lines fixing the issue are high enough to just replace them anyway. Consider the replacement to be a diagnostic tool. New lines won't hurt anything....

Not to mention the safety issues with having 23,000lbs with wheels spinning just waiting to jump off the jackstands and go on a killing spree....

 

[simp5782]

This sounds like far less work, with a much higher chance of yielding a usable answer than jacking up the truck and spinning the wheels.

Although I'd go so far as to say that the chances of replacing the soft lines fixing the issue are high enough to just replace them anyway. Consider the replacement to be a diagnostic tool. New lines won't hurt anything....

Not to mention the safety issues with having 23,000lbs with wheels spinning just waiting to jump off the jackstands and go on a killing spree....

nvm I'll be nice

Sent from my SM-G965U using Tapatalk

 

[scrump]

Hello All,
Turns out my transfer case does of course have a neutral. However, there's no mention of it in the USAF/US Army Maintenance manual...therefore my thought that it didn't have one...so...it's just like the other "69,998" of them
I put the transfer case in neutral (the sticker is worn off the lever, meaning it took a little searching and stalling to find it).
When I did find neutral in the transfer case, I ran the truck through the gears. When going into 1-5 or 1, there was a momentary loss of RPM, from 1000 to 800, then it went back to 1000 and the engine stayed running. (Yes I know I should idle it lower). Seemingly ops normal for the transmission when transfer case in neutral...running it though all positions on the shifter.
Can I RULE OUT the torque converter at this point? Is the loss of RPM when shifting into gear the torque converter doing its job? Or because it's not "loaded up" with trying to move the truck does the torque converter allow the engine to keep running with the transfer case in neutral but would stall it if the transfer case was in high or low? I could feel the gears moving in the transfer case when I went from neutral to high ("If ya can't find 'em, grind 'em"). I had to let it wind down before going into high again. Point it, it's obviously working if the truck lurches when it's engaged and it selects into neutral as well.
FUEL: I have been running out of a 5 gallon can, with CLEAR LINES. No bubbles visible.
I just replaced the transfer/lift/primer pump today, with new. No change in starting habit, nor any other change.
Only one fuel tank on the vehicle, no tank selector valve, running off the 5 gallon tank would have bypassed that anyway.
The ONLY location that hasn't been bypassed (or replaced) in the fuel lines since I have been running from the 5 gallon tank is essentially...like TobyS says above, between the output of the fuel water filter (comes out of the case) and the Injection pump. Those lines are METAL and haven't been touched. No indications of leaks.
98G: Specifically, how is my fuel frothing?
Perhaps the Injection pump is failed, if it's "fuel", that's my only last thought of where the problem could be.
Specific troubleshooting advice from 98G would be appreciated, since you're certain "it's fuel". I appreciate the help. Specific troubleshooting advice from other is of course welcome as well. This is a great forum with lots of great minds. It's helping me learn my truck so there's plenty of good coming out if it already!
mark

 

[scrump]

...and oh, one more note that was interesting to add to the above, when the transfer case was in neutral, and I shifted into Reverse, there wasn't the commensurate 200 RPM drop, just a very minor burp in the RPM before it shifted into Reverse and the shaft started moving...
This is interesting that (as mentioned earlier) when the truck is on the ground, transfer case in high, putting the truck in forward will always stall the truck even with higher RPM. The truck WILL go and drive in Reverse if I keep the RPM up to about 1000...why is this?..I assume the torque converter does the same work in Reverse as it does in first gear. Not sure if this helps the troubleshooting or not. Still trying to "hear the sounds of the horses and not zebras"

 

[scrump]

...and of course I was very wary of running it and engaging the gears while it was on the jacks...simply the torque of those wheels spinning could have certainly taken it off the jacks. The truck is in an open field (on top of a hill)...the "killing spree" was a concern but the truck was heavily blocked on the front tires and my hand was full time on the manual kill cable pull. If it fell off the jacks it would've stalled anyway probably before I could have pulled the kill cable. But all good thoughts, always thinking "how do I prevent another YouTube video from going viral?"...well, don't do stupid stuff is always a good start...

 

[simp5782]

Top of the IP. Pull the 3/8" allen head plug out. Use a 3/8" deep well socket. Loosen the nut inside. Turn the fuel screw counter clockwise 3 or 4 full turns with a flathead screwdriver. tighten the nut back down. That will give her more fuel than what she is getting at the moment. Apparently she is starving. See if she will fire off. Make sure that the shift linkage will still move after you back that screw off you should be able to see it down below the nut when you do it... I took a minute to read thru all that garbage with the "online mechanic" till i went cross-eyed.

On another note....do you have your electric fuel shutoff solenoid hooked up still? If so. take it off and throw it in the brush.

I did have one that would fire on ether with the solenoid on. and run afterwards like it was sucking air. Then i learned if i pulled and pushed in the fuel shut off handle 2 or 3x it would spin over and start normally. also a great anti theft. Also make sure the arm on the pump is returning to the open position.

The 5 ton up on jackstands. if it fell off and did it's thing , that is called darwinism for putting it up on the jackstands and not knowing your -10 for the operation of the transfer case.

 

[scrump]

Simp5782, thanks. Seems like an easy attempt. Now to identify what you're talking about and find it.
The electric fuel solenoid was in the brush years ago, thanks! So is the solenoid for the 5th gear lock up...that's for trucks with winches or cranes only I guess.

 

[simp5782]

Simp5782, thanks. Seems like an easy attempt. Now to identify what you're talking about and find it.
The electric fuel solenoid was in the brush years ago, thanks! So is the solenoid for the 5th gear lock up...that's for trucks with winches or cranes only I guess.

The fuel screw adjustment port is right there above that shaft for the fuel shut off lever. When you pop the throttle make sure it returns to it's position or it can get hung up. I have seen people leave that jam nut loose and the fuel screw just back out and out and out and the truck wont idle.
Yeah for future reference Memphis equipment doesn't have a clue what they are talking about on a "bypass" You simply need to cut the wire that comes off the solenoid and goes to the plate right beside it. It is not a good enough ground. Cut the wire. splice a longer wire on it and ground it to the bellhousing bolts. That solenoid IS used when you want to shift on the fly for your transfer case from High to Low. Otherwise you can't do it.

 

[Shirehorse]

Sounds like you have two different problems. A fuel delivery problem and a torque converter lockup problem.

The torque converter lockup solenoid is a known failure point for this kind of issue. The wires and their placement make them an easy target for mice and/or fraying. Check from the transfer case lever all the way to the lockup solenoid on the transmission.

Does it seem like a torque stall, or a starving stall from lack of fuel? Does the truck lurch when you put it into gear?

The test on the jack stands with no resistance where it stayed running tells me your torque converter is locked in.

 

[Swamp Donkey]

I also believe you have 2 different problems after your last round of troubleshooting.

I'm not up on the 8.3L fuel system since I have the NHC250. I seem to remember a thread about a regulating valve in the return line though. Something about the spring would get weak, which would cause low rail pressure after the pump. I also seem to remember that you can run your return line back to the jug you're already pulling fuel from to see if air is entering the pump itself. Memory is on the downhill slide these days though so I could be wrong on both points.

On the 5th gear lock-up solenoid, it's a very simple system. The button on the T-case shifter only completes a ground. The actual most common problem in the system is a sticking or failed shifter button. Some silicone spray will normally free up a sticking button. The second most common problem is the wires coming through the floorboard to the handle get pinched by the shifter arm where it passes through the floorboard. A short in one of those wires completes the ground without the button being pushed, engaging the lock-up solenoid when it's not needed. If the solenoid is engaged and the truck is put in gear, a engine stall will occur. Simplest thing to do here is to unplug the wire at the solenoid to eliminate the switch and wiring. If the stall goes away when placed in gear then you have a problem between the wires and shifter handle. You can do this test in a couple minutes with tires on the ground.

As Wes said, if you want to shift High/Low on the fly then you will need the lock-up solenoid working. Other than that, it's not needed. A bad ground at the solenoid itself would cause a constant unlocked situation instead of a locked situation though.

 

[scrump]

Hey Guys (and Gals perhaps)
Summary: (since I don't expect everyone to read the whole thread, start here...)
Truck needs very small shot of ether to start.
Truck lurches but does not move forward, with higher idle, can go backwards without stalling.
Big picture: the truck had been run on biofuel and there was debris in the fuel system from the fuel coagulating over the colder months, some of the debris got beyond the fuel filter because when I ran it from a bucket I could see the debris leaving the fuel injection pump. Other than having to start with ether, she runs and idles SMOOTH. The fuel is CLEAN.
Fuel filter (inline filter and fuel water separator) were both changed more than once. Same model units that have worked on the truck for years.
Simp5782: no change with the adjustment of the screw inside the Injector Pump.
The fuel transfer/primer/lift pump (whatever your terminology preference is) has been replaced.
The vehicle has been run from a 5 gallon fuel tank, both the feed and return line. The ONLY section of fuel line that wasn't tested or replaced was between the fuel filter and the injection pump.
The 5th gear lock up solenoid is removed
The electronic shutoff solenoid has been removed for years (I shut it down with the kill cable, and have for years. The valve that is operated from the kill cable and the former electric shutoff solenoid operates smoothly and does not shut the engine down inadvertently.
The truck lurches when put in gear. Run up the engine and shift into forward, lurches, stalls. Run up the idle and go in reverse, it goes backwards and STAYS running and going backwards, this begs the questions:
-Does the torque converter work in reverse? If so, why will the truck go in reverse (albeit with a high idle required) but not forward?
-Why would it be complete fuel starvation in forward but not complete starvation in reverse?
The truck was put on jacks and run up to 1500 RPM, no load on the wheels and it didn't stall. It will stall with the wheels in the air and the parking brake on when put into forward or reverse.
The truck was then kept on the ground, transfer case in neutral and run through the gears. There was a momentary 200 RPM decrease when put into a forward gear. Virtually no idle decrease when put into Reverse.
The Air Fuel Control tube was clear. The engine was run with it disconnected as well. No change.
thanks all...

 

[WillWagner]

I agree with the two above posts, BUT, no low fuel pressure can cause the same type of issue. The lack of "lurching" when put into gear with the drive train disconnected is only because there is no load on the engine/trans. My gut says a trans issue. You need to check the low pressure fuel....find the wiring diagram for the trans and use a DVOM and check the circuit at the trans, this will confirm S. Donkeys suspicion of a shorted shift circuit short. Both checks will be easy to do. Troubleshoot man, the issue could be one or two of a dozen and only YOU will be able to verify by troubleshooting and not just relying on questions asked here

 

[scrump]

"The torque converter lockup solenoid is a known failure point for this kind of issue. The wires and their placement make them an easy target for mice and/or fraying. Check from the transfer case lever all the way to the lockup solenoid on the transmission. "

SDonkey, during my troubleshooting, upon advice, I removed the TRANSMISSION 5TH-GEAR LOCKUP SOLENOID VALVE, I believe this negates what you're talking about. Please advise if not.

 

[snowtrac nome]

those trucks all lurch when put into gear, I would check timing its simple, just bar the engine over till the timing pin drops in, than remove the inspection window on the pump and see if the little flat is centered in the window. using thicker off spec fuel could have spun the gear on the shaft especially if some one had changed it and not torqued the nut to 120 ftlbs.

 

[Swamp Donkey]

"The torque converter lockup solenoid is a known failure point for this kind of issue. The wires and their placement make them an easy target for mice and/or fraying. Check from the transfer case lever all the way to the lockup solenoid on the transmission. "

SDonkey, during my troubleshooting, upon advice, I removed the TRANSMISSION 5TH-GEAR LOCKUP SOLENOID VALVE, I believe this negates what you're talking about. Please advise if not.

Well, I think you'll agree that the first post is a bit much information to swallow, and after that the eyes start to get blurry, lol. Yes I missed you had removed the solenoid. I'm at work now and can comment in more detail later this evening, but here's a few thoughts to ponder...

Troubleshooting is a process of elimination. The more systematic it is the more successful it will be. I write troubleshooting procedures at work and in my opinion you're trying to troubleshoot too much at one time. Start with the most basic problem.

You haven't been able to successfully determine whether you have 2 different problems, or just 1 problem with several symptoms. You have an engine symptom and a possible transmission symptom. Focus on one symptom at a time or else you can't eleminate things completely. At the very basic level the engine should not need ether to start in these temperatures, plain and simple. I'd focus on that symptom, fix it and see what else changes down the line. Once you have the engine right without putting it in gear, start working on why is stalls in gear.

Reverse is a much lower gear ratio than forward. It might not stall in reverse because of this.

I need to go back to the manual and see if the lock-up solenoid is NC or NO in resting position to answer your question. I can't check at the moment.

 

[tobyS]

"The ONLY section of fuel line that wasn't tested or replaced was between the fuel filter and the injection pump."

That is the section that gives me the most trouble because the engine vibration on one end and the fixed connection to the filter on the other. If your not 120% sure that hose is crack free, replace it....or if you have to, cut it off and put hose clamps on it. They get small cracks at the IP end. That is the worst line there is for cracks.

Although you have ran the engine up and had it in gear, I doubt you have ever made it out of first or second. I think the valve body tries to lock up after 3rd, giving a 3L (locked) position and both 4th and 5th are locked. I'm not sure about how to go about unlocking it, but that sounds like it may be a problem.

The electric lock for the torque converter would be closing a valve in the valve body to supply higher pressure in the torque converter to make the clutch that is inside of the TC engage. Some blockage of (release of) hydraulic pressure may be happening.

 

[Floridianson]

"The torque converter lockup solenoid is a known failure point for this kind of issue. The wires and their placement make them an easy target for mice and/or fraying. Check from the transfer case lever all the way to the lockup solenoid on the transmission. "

SDonkey, during my troubleshooting, upon advice, I removed the TRANSMISSION 5TH-GEAR LOCKUP SOLENOID VALVE, I believe this negates what you're talking about. Please advise if not.

You removed it? Sorry I was not clear in the PM as you just needed to unplug the wires. Is it N/O or N/C.

 

[simp5782]

Or you can cover my cost for a flight and hotel room and rental car and I'll tell you what's wrong with everything in a few hours

Sent from my SM-G965U using Tapatalk

 

[scrump]

Floridianson,
The Lock in Solenoid was removed, and lines 4 and 8 in the photo were capped.
Troubleshooting: The goal always has been to try to get the engine to start without ether. Perhaps that "fuel problem" will correct the transmission problem. However, when some say these problems are interrelated, and some not (and you agree you're not sure) then troubleshooting with some organization of all options is best. I'm approaching it from steps I can take (cleaning of fuel system, replacement of filters, line replacements, removal of solenoids, change of fuel primer/transfer pump, bypassing the fuel tanks and fuel lines by running it from a bucket, running it through the gears while on jacks, running it on the ground while transfer case in neutral)...all of these things are "on the cheap and having not solved the problem, hopefully gaining information as to what the problem is. I'm no mechanic, but I'm smart enough to know the more data that can be gathered is a better find to the problem. Sure, I can now replace the transmission (torque converter problem) and replace the injection pump (contamination problem)...both have been identified by others more qualified than me as the problem. I have moved from "most likely" to lesser and lesser likely causes. I have also approached it from least costly to more costly. I think it has been a logical approach. Please advise how much more troubleshooting is left before I take the next BIG steps of Injector pump replacement (perhaps that'll fix the start problem) or digging into the transmission PERHAPS fixing the "can't drive it" function: From my perspective all has been exhausted except: 1. Replacing the metal line between the fuel pump and the injection pump. There is no sign of cracking or leakage when it is not pressurized. I doubt this is a problem, but IF it is the problem, it's an easy solution, but I haven't taken it on because there is NO evidence that I need to do so. But I will of course. 2. Check the timing of the pump. But how could the pump simply rotate? The mounts ARE torqued down and there is no sign of slippage (one could see if it had moved from the original location). Simply trying to loosen those bolts is difficult, and one is only accessible if other equipment is removed. I'll have to access those same bolts for timing if I take off the fuel injector pump in any case.
I really appreciate all the guidance here, but as one can see, in my summarized post above, I tried to reiterate complete details so I don't keep on going down the path of wasting guys time getting recommendations of things that have already been done. I really appreciate the time and effort everyone is putting into this.

 

[Swamp Donkey]

If I sounded condescending in my last post, it wasn't my intention. I'm only trying to point out that, yes, you've done a lot of work to figure this thing out. Yes, you've done a great job at posting your findings in great detail. You've been split testing the engine and the transmission at the same time though. It muddies up the results because you can inadvertently create false negative and false positive results. This creates even more work and can mask the original problem.

From the first post I can tell that you've been working on this long before you even posted here. I get that...I really do. But you haven't been able to rule many things out in my eyes and you've created some results that had nothing to do with the original problem.

For instance, removing the lock-up solenoid introduced a lurch and a stall when you placed the transmission in gear, when there was only a stall before the solenoid was removed. I get this from post #10. You've created a change here but what has been proven? What can be gathered from the change? The new lurch hasn't answered anything but it has added another variable to the equation. That's fine but the engine can't stay running to be able to test this path further. So a dead end.

On the other hand, the transmission can't require the engine to need ether to start. This is your one symptom that is related to a single system. This is why I suggest starting here, no pun intended. Put all efforts on that symptom. When you have it worked out, see what's changed elsewhere.

In post #7, Will asked for some specific information and gave detailed instructions on how to obtain it, to include timing and line pressures. I've seen none of those questions answered here. You really need that information. To check timing you don't have to remove the pump. It's really easy to check on the 8.3 engine. Those are critical missed steps because if timing has slipped out then resetting the timing might clear all of this up without the need for any parts or further testing. Pressures can give you a good idea of system performance without having to remove things. Will knows diesel engines. He can be of great assistance and he knows what he needs from you to be able to help.

Keep in mind that we don't get to see, hear and feel what we are trying to help you fix. We are relying completely on what you find and post. This can be very frustrating on our end as well. We are honestly trying to help.

Back to the lock-up solenoid since it is already out now. While you have it off, see whether it is in the open or closed position. Then supply 24v and a ground to the proper wires and insure that it changes positions. My fear here is that removing the solenoid and capping the ends has placed the torque converter in permanent lock-up. This would explain the new "lurch" after removal, which is also a symptom of a stuck shifter button. A stuck shifter button or grounded wires presents with a lurch then an engine stall.

From the -10 Operator's Manual:


The solenoid manually places the transmission in 5th gear. The torque converter is unlocked in 1st and 2nd gears and locks in 3rd, 4th and 5th gears. The torque converter locks as a result of the transmission being placed in 5th gear and is not directly controlled by the solenoid.

What is not clear is whether the solenoid is in line before or after the govenor system. If it's before the governor system then the solenoid is NC and will open to supply pressure. If it's after the governor system then the solenoid is NO and will close to create pressure. The operators manual just gives a basic understanding of how the system works. I won't rely on that description above to assume NO or NC.

The easiest thing to do at this point would be to test it to insure that it changes when power is supplied and returns when it is removed. If it's working, I'd reinstall it on the transmission and just leave it unplugged for now. If it's not working then you have verified 2 problems instead of just an engine problem. We already know you have a dedicated engine problem given the need for ether. Check the operation of the solenoid while it's out to make sense of the new "lurch" as well since it started when the solenoid was removed.

Don't forget post #7...