Mep802a starts then shuts off

[Bassfishin114]

In your typing you tend to leave out entire words so that makes following your conversations hard. But from what you have said like the part about the two wires on the o/p sensor and asking if it were just a ground makes me wonder if you have even looked at a wiring diagram? And if not how did you rewire the ones that were off? Next question is do you know how to follow a wiring diagram and actually convert the picture on the paper into what you see in the machine? If you do not follow the troubleshooting procedures to the letter from start to finish you will never find the problem. You absolutly cannot skip any part of the trouble tree! Personally I have no experience with this machine, but some of the people answering you have a LOT of experience with them and you are not paying attention to what they are telling you. You are jumping around making your own "assumptions" in between them trying to give you solutions. You will find out real fast that this is the fastest way to lose very good help!

I am trying to give enough information without telling every troubleshooting step I am doing.

original problem was it would crank/start then shut off almost immediately.From what I am reading from the comments maybe I was not holding the start switch long enough to build oil pressure. While doing troubleshooting for that problem I found a total of 4 wires disconnected on the TB5. The numbers on the wires correlated with slots 1 and 2 on the TB5 according to the schematic. After attaching the wires to the correlating spots I would turn the start switch and it would not crank and the LOP light came on. Followed the troubleshooting for that and it advised to clean the sensor. Cleaned the sensor off and now I have no LOP light but still no crank. When testing the oil pressure sensor the troubleshooting says it should have “x” ohms but no matter what I tested I could only get it to read overload or 0 ohms. According to the comment above I can jump it to eliminate the sensor.

Engine starts and runs fine using the dead crank switch.

I am very familiar with mechanic diesel engines but not very familiar with military equipment and the electrical side.

 

[peapvp]

I am trying to give enough information without telling every troubleshooting step I am doing.

original problem was it would crank/start then shut off almost immediately.From what I am reading from the comments maybe I was not holding the start switch long enough to build oil pressure. While doing troubleshooting for that problem I found a total of 4 wires disconnected on the TB5. The numbers on the wires correlated with slots 1 and 2 on the TB5 according to the schematic. After attaching the wires to the correlating spots I would turn the start switch and it would not crank and the LOP light came on. Followed the troubleshooting for that and it advised to clean the sensor. Cleaned the sensor off and now I have no LOP light but still no crank. When testing the oil pressure sensor the troubleshooting says it should have “x” ohms but no matter what I tested I could only get it to read overload or 0 ohms. According to the comment above I can jump it to eliminate the sensor.

Engine starts and runs fine using the dead crank switch.

I am very familiar with mechanic diesel engines but not very familiar with military equipment and the electrical side.

What you think is giving enough information is not enough for us to even comprehend of what you are doing.
Since you have read the TM you should know that the dead crank switch only cranks the engine but it does not start the engine

 

[rickf]

I am trying to give enough information without telling every troubleshooting step I am doing.



Engine starts and runs fine using the dead crank switch.

I am very familiar with mechanic diesel engines but not very familiar with military equipment and the electrical side.

Here is the problem, When you leave out steps you have done you leave us in the dark. We have no idea if that step helped or harmed. If the manual says that the dead crank switch only cranks but does not start the engine but you are saying it does start the engine than it sounds to me like those cut wires are a clue that someone has been in there and made some wholesale changes. You are going to have to do a deep dive into the wiring diagrams and trace out every, and I mean EVERY, circuit from end to end. There are no shortcuts in situations like this. If you keep trying shortcuts you will eventually let the magic smoke out. Once the magic smoke is out then you can sell what is left for parts.
I strongly suggest you swallow your pride and listen closely to what people like Guyfang and Inova have to say. They generally do not say it over and over.

 

[Bassfishin114]

Here is the problem, When you leave out steps you have done you leave us in the dark. We have no idea if that step helped or harmed. If the manual says that the dead crank switch only cranks but does not start the engine but you are saying it does start the engine than it sounds to me like those cut wires are a clue that someone has been in there and made some wholesale changes. You are going to have to do a deep dive into the wiring diagrams and trace out every, and I mean EVERY, circuit from end to end. There are no shortcuts in situations like this. If you keep trying shortcuts you will eventually let the magic smoke out. Once the magic smoke is out then you can sell what is left for parts.
I strongly suggest you swallow your pride and listen closely to what people like Guyfang and Inova have to say. They generally do not say it over and over.

It will run with manual override of the fuel shut off solenoid using the dead crank switch.

I have no pride as I am extremely new to anything related to these things. I will work through the manual and if I have any further questions I will list every step I do.

 

[Guyfang]

OK, let try to get on here. The LOP, (MT7) is not your problem. That's why I have asked if you have the TM's. In the Operators TM, it explains that on start up, CB1 pushed in, S7 not engaged, S1 Turned to the START position, the gen set bypasses several safety functions. LOP is one of them. So you need to get that out of the equation.

Yes, you can start the set with the S10, (Dead Crank). But its not supposed to work that way. S10 is only to crank the engine over, and not to start the set. You are cheating the system by manually pushing the L5, (Fuel Cut Off Solenoid) to full fuel position. When you do this, you no longer have any safety circuits working to protect your gen set. This could result in damage to the gen set.

Since I was not there when it happened, the wires on TB5 being removed, I can only assume, and that's a mistake to do, but only assume, that the wires were removed to allow you to at least try and start the set. Because when you hooked them back up, it will not crank over but a milli second before kicking the starter out. Someone was trying to do just the same thing you did, cheat the system. The only difference is you are trying to fix it.

So, first look at the control cube. Look for cut wire ties. where that happens, is a good place to start looking at wire numbers and positions they are screwed into. Look all over. Make sure its all supposed to be where it is. That means using the attached document.

Do that, and then let us know if there is ANY differances between what you have and what you should have. Then we can go to the next step. Hook the L5 back up. Hook the MT7 back up.

Take a few GOOD pictures of the control cube. Post them. Maybe we can see something you can not.

Also check S10, to ensure someone has not tricked that.

 

[rickf]

Are they still demilling these sets by cutting wires and such like they used to do with the older 002 and 003 series? Or do they just flat out sell them without worrying about that anymore? I stopped being interested in them once they went to computer controls. To me, the whole idea of military surplus is simple, easy to fix anywhere, anytime.

 

[CallMeColt]

Are they still demilling these sets by cutting wires and such like they used to do with the older 002 and 003 series? Or do they just flat out sell them without worrying about that anymore? I stopped being interested in them once they went to computer controls. To me, the whole idea of military surplus is simple, easy to fix anywhere, anytime.

There is nothing computer controlled in the TQG's.

 

[rickf]

TQG's? Not an acronym I am familiar with but if you are talking about the 802 series they have LED screens don't they? Don't they have microprocessors controlling those screens and the functions those screens provide? I saw back in the beginning of the thread someone asked if there were any codes? Codes would be handled by micro-processors, computers.

 

[CallMeColt]

TQG's? Not an acronym I am familiar with but if you are talking about the 802 series they have LED screens don't they? Don't they have microprocessors controlling those screens and the functions those screens provide? I saw back in the beginning of the thread someone asked if there were any codes? Codes would be handled by micro-processors, computers.

TQG Tactical Quiet Generators. These are the 800 series generators and they don't have any computers as I said. It's all manual and electro-mecanical, just like the older air cooler 00x model's. There are more electrical systems on them then the older generation but it was to improve the system. They're pretty simple once you figure them out, but all the wires can be intimidating at first.

 

[rickf]

Ok, I went back through the posts and where I thought it said codes it was stating "Fault lights" . That was what got me on the computer path. I am not familiar with the 800 series since when I was looking at them they were just too expensive. Another of my things about "Surplus". Surplus items used to be a good deal when you got a running piece of equipment that was fairly cheap and got the job done without having to spend a ton of money on it. That all stopped with the 800's. Parts are proprietary and once gone they are gone and you are left with scrap. Sorry, rant for another thread. I hope he gets it all together and follows the manual and expert advice on here to the letter and gets his set going.

 

[Guyfang]

TQG Tactical Quiet Generators. These are the 800 series generators and they don't have any computers as I said. It's all manual and electro-mecanical, just like the older air cooler 00x model's. There are more electrical systems on them then the older generation but it was to improve the system. They're pretty simple once you figure them out, but all the wires can be intimidating at first.

Perhaps you need to look at the MEP-805B and the MEP-806B. They are also part of the TQG family. They have computers in them.

 

[Guyfang]

Ok, I went back through the posts and where I thought it said codes it was stating "Fault lights" . That was what got me on the computer path. I am not familiar with the 800 series since when I was looking at them they were just too expensive. Another of my things about "Surplus". Surplus items used to be a good deal when you got a running piece of equipment that was fairly cheap and got the job done without having to spend a ton of money on it. That all stopped with the 800's. Parts are proprietary and once gone they are gone and you are left with scrap. Sorry, rant for another thread. I hope he gets it all together and follows the manual and expert advice on here to the letter and gets his set going.

Rick,

Yes the TQG family has computers in them. The MEP-805B and MEP-806B are computer controlled. Below is a picture of the control panel, of a partly disassembled Gen set. Take note of the CIM screen.

 

[CallMeColt]

Perhaps you need to look at the MEP-805B and the MEP-806B. They are also part of the TQG family. They have computers in them.

I learned something today!

 

[Light in the Dark]

The A versions of each of the machines Guy listed were 'analog' style, though I'm not sure how many units of each were actually fielded before going to the B variants... but they are out there.

 

[Guyfang]

There are, I was told, more A models, then B models. But in my experience, I saw way more B models. @dewy38 might know the real numbers.

 

[Light in the Dark]

Color me shocked then... you dont hardly ever see the As across the block, as compared to the Bs. Not that I pay too much attention to the larger 3PH stuff... but its almost always Bs.

 

[Squarefour]

Recently acquired a mep802a and have been working through a few things to get it going. I found that the shut off solenoid when cranking pulls back but once the engine fires up and return the start switch to run the solenoid returns to the off position. This causes the engine to shut back off. It I hold the solenoid it will stay running. I replaced the solenoid and still having the same problem. Just trying to see where I should start. Start switch? Relay? Is there a specific wire at the switch panel that should be providing power to the solenoid?

IT HAS TO HAVE OIL PRESSURE AND THE GEN HAS TO SEE IT IN ORDER FOR THE RELAY TO STAY CLOSED FOR RUN

 

[Bassfishin114]

In your typing you tend to leave out entire words so that makes following your conversations hard. But from what you have said like the part about the two wires on the o/p sensor and asking if it were just a ground makes me wonder if you have even looked at a wiring diagram? And if not how did you rewire the ones that were off? Next question is do you know how to follow a wiring diagram and actually convert the picture on the paper into what you see in the machine? If you do not follow the troubleshooting procedures to the letter from start to finish you will never find the problem. You absolutly cannot skip any part of the trouble tree! Personally I have no experience with this machine, but some of the people answering you have a LOT of experience with them and you are not paying attention to what they are telling you. You are jumping around making your own "assumptions" in between them trying to give you solutions. You will find out real fast that this is the fastest way to lose very good help!

Finally was able to spend some time troubleshooting. Followed the fail to crank all the way to step 11 of testing the reverse battery diode set. It says to test ohms of r10-r13 which should be between 7-7.8 ohms. R10 had 1.4, r11 had 2.4, r12 had 0.8, r13 had 0.8. R14,r15,cr1,cr2 were all correct. Ordered new resistors per troubleshooting and installed. Found after install that they all have the exact same readings. Decided to test the original resistors while not connected to any wires and found 7.5ohms. Any ideas on what could cause this? Where should I go from here? Tracing every wire is the only thing I can think of.

 

[kloppk]

When testing resistors and other 2 leaded components one of the leads needs to be disconnected from the circuit before measuring.
If left connected other components in the circuit can cause the readings to be way off.

 

[kloppk]

Figuring out why the starter isn't engaging will require tracing the START signal from S1 to the starter relay coil K2.
I'll post up a sequence of measurements to check that path.