Mep 003 cranks but will not run. not a fuel problem.

[Rene M]

I was reading in the TM on operation of the DC system that during cranking it receives 24 volt positive and ground to that solenoid during cranking. then will transfer over to the safety system once cranking has ended. another words the temperature switch oil pressure switch that's the one will then pick up the power supply for the governor solinoid.
Is that correct ?

I have no supply of power or ground during either.

 

[Guyfang]

Roger, correct. When the S1 is in the start position, the safety switches are bypassed.

 

[Guyfang]

S1-26, wire number P66D goes to TB5-8. That is the circuit that bypasses the safety switches.

 

[Rene M]

Good test information. I will hit when I get back to the house this eve.

 

[Guyfang]

Roger.

 

[Guyfang]

When you get home, take a frontal picture of the starter so I can see just what terminal the cut off wire goes to. Thanks!

 

[Rene M]

Looks like the j3 was cross-threaded and didn't allow it to seat so none of the pens made contact which is why everything dead ended right there it took some doing to get it off to some of the Cross them the **** out of it.

 

[Rene M]

I could have never figured it out without you guys I've been banging my head against it for quite some time.

 

[Guyfang]

Glad you got it going. Take care and wish you luck.

 

[1800 Diesel]

Guyfang--I am having similar issues with an MEP-003A with the fuel shutoff solenoid not engaging during cranking. The unit will crank right up when the solenoid plunger is pushed upward off the governor linkage.

Reading through the TMs and your excellent posts on this subject I've narrowed things down to the A1 terminal group in the upper RH corner of the control box. On the LH side I'm not getting power to terminal #1 during cranking. The wire number on this terminal is P66E16. I also compared a known good unit in my shop & this terminal "lights up" during cranking.

Other items checked:

1. Verified no power to solenoid during cranking.
2. Removed solenoid, cleaned, lubricated and tested with direct 24v & it functions properly.
3. Jumpered TB5-8 to TB5-9 and solenoid functioned properly during cranking.

4. Verified all functions & terminals on S1 switch--in particular 24v is coming out of #28 during cranking.

5. Verified proper voltages on the 2 solenoids inside the control box with S1 in cranking & run positions & all match the known-good unit I have in my shop.

Have not checked the diodes behind the A1 relay and have not checked the fuel level switch (if that would have an impact).
BTW, also having a similar problem on an MEP-016B but will address that one on another day.
If you can shed any light on what else I should do I would greatly appreciate the assist! Thanks!

 

[Guyfang]

Let's start with this.

Is this machine new to you? Or did it run right before, and suddenly stop running right?

3. Jumpered TB5-8 to TB5-9 and solenoid functioned properly during cranking.

I assume you mean the fuel cutoff solenoid, K5? Does this mean the set started?


Reading through the TMs and your excellent posts on this subject I've narrowed things down to the A1 terminal group in the upper RH corner of the control box. On the LH side I'm not getting power to terminal #1 during cranking. The wire number on this terminal is P66E16. I also compared a known good unit in my shop & this terminal "lights up" during cranking.


If you have 24 volts on the number 28 terminal of the S1 WHILE it is in the start position, then you need to check at TB5-9 for 24 volts, WHILE cranking. The wire that runs from S1-28 to TB5-9 is P66D16.

If you have 24 volts at TB5-9, then unscrew J2. Measure at pin J2I, WHILE cranking, for 24 volts. The wire from TB5-9 to J2I is P66F16.

If you have 24 volts at P2I, Screw J2 back in place, and Unscrew J3. Measure at J3a WHILE cranking, for 24 volts. The wire from J2I to P3A is P66G16.

If you have 24 volts at P3A, then screw J3 back in and measure at K5, (fuel cut off solenoid, or GOV SOL) The wire from J3A to K5, terminal1, is number is P66H16.

If you have voltage up to a certain point, and not after, you have a loose connection or broken wire. Can't be anything else. It's just wires a terminals. Nothing else.


I'm not getting power to terminal #1 during cranking. The wire number on this terminal is P66E16. I also compared a known good unit in my shop & this terminal "lights up" during cranking.

If the starter is turning over, you HAVE to be getting 24 volts at the A1, terminal 1. K1 is the start relay.

 

[RIrvin]

Unclear on importance but by jumping TB5-8 to TB5-9 isn't the safety feature of S4 (oil press)and S5 (temp) being modified. S4 looks like it should be open to run???

 

[1800 Diesel]

Let's start with this.

Is this machine new to you? Or did it run right before, and suddenly stop running right?

I've had the machine for over a year. Originally is was partially seized up as received from the Seabees and I've had the cylinders soaking in diesel up until recently when I was able to get the engine to turn. At the present time, the engine will start, run at governed speed and the generator produces electricity--as long as the fuel solenoid is manually pushed up during cranking. After the engine lights off, the circuit that provides voltage to the fuel solenoid functions properly since the plunger pulls up on it's own shortly after engine light-off.

3. Jumpered TB5-8 to TB5-9 and solenoid functioned properly during cranking.

I assume you mean the fuel cutoff solenoid, K5? Does this mean the set started?

Yes K5.


Reading through the TMs and your excellent posts on this subject I've narrowed things down to the A1 terminal group in the upper RH corner of the control box. On the LH side I'm not getting power to terminal #1 during cranking. The wire number on this terminal is P66E16. I also compared a known good unit in my shop & this terminal "lights up" during cranking.


If you have 24 volts on the number 28 terminal of the S1 WHILE it is in the start position, then you need to check at TB5-9 for 24 volts, WHILE cranking. The wire that runs from S1-28 to TB5-9 is P66D16.

If you have 24 volts at TB5-9, then unscrew J2. Measure at pin J2I, WHILE cranking, for 24 volts. The wire from TB5-9 to J2I is P66F16.

If you have 24 volts at P2I, Screw J2 back in place, and Unscrew J3. Measure at J3a WHILE cranking, for 24 volts. The wire from J2I to P3A is P66G16.

If you have 24 volts at P3A, then screw J3 back in and measure at K5, (fuel cut off solenoid, or GOV SOL) The wire from J3A to K5, terminal1, is number is P66H16.

If you have voltage up to a certain point, and not after, you have a loose connection or broken wire. Can't be anything else. It's just wires a terminals. Nothing else.



I'm not getting power to terminal #1 during cranking. The wire number on this terminal is P66E16. I also compared a known good unit in my shop & this terminal "lights up" during cranking.

If the starter is turning over, you HAVE to be getting 24 volts at the A1, terminal 1. K1 is the start relay.

I will double check the A1 terminal readings this morning but I'm fairly certain of the readings I took yesterday. The relay has 4 connections on the left (facing the inside of the control box) and 4 connections on the right. LH connections are numbered 1 thru 4 the top LH one being #1 & RH connections are numbered 5 thru 8 with the top one being #5. During cranking on my known-good machine, #1 & #4 terminal both light up & on the test machine, #4 lights up but not #1. On the RH side, all 4 terminals light up [#5 thru #8]. #3 terminal on both units seems to be the 24v input voltage as this terminal is energized with the S1 switch being in any position. Again, I'll check this info again this morning.

I'll go through the remaining troubleshooting directions you provided in a short while.
Thanks again and will report findings later today.

 

[Guyfang]

If you pull out K1, and look at the side of it, it should show you the function of the relay, and which little leg, connects to the contacts. When you look at the bottom, the little legs sticking out, one has a blue, (I think, its blue, but has been a long time since I looked at it) ring around it. That pin is the A1, pin 1, for the coil. The A1-2 pin is kitty corner to it, on the other side. You should be able to see it printed on the side of the relay. You can test this relay by applying voltage to the A1-1 and A1-2, and measuring to see if the contacts open and close.

 

[Guyfang]

Unclear on importance but by jumping TB5-8 to TB5-9 isn't the safety feature of S4 (oil press)and S5 (temp) being modified. S4 looks like it should be open to run???

Yes, jumping around the two switches is accomplished by connecting TB5-8 and TB5-9. That's the same thing that happens when you place the S1 in the start position. Notice the wire above the S4 and S5 switches. It goes from S1-28 to TB5-9. If you don't have this function, the set would NEVER start. Every gen set in the army works this way.

S4 is the Temperature Switch, and S5 is the oil pressure switch.

Schematics always show switches and contacts in the unpowered state. That's why the S5 is open. The engine has to build up pressure before it can do its job. When the oil pressure is built up, and the switch is closed, then voltage flows through it and S4 to keep the set running. If you lose oil pressure, or the engine temp gets too high, then they break the circuit and the K5, gov sol loses power and the engine dies. That's why I need to know the answer to this question.
3. Jumpered TB5-8 to TB5-9 and solenoid functioned properly during cranking.

I assume you mean the fuel cutoff solenoid, K5? Does this mean the set started?

 

[Guyfang]

Here is a diagram of the K1 relay that I spoke of.

Pins 3 & 6 are the coil pins. The coil causes the contacts to open and close when 24 volts are applied to the K1. No matter HOW you insert the relay into the socket, the 3 and 6 pins are always positioned right to function as the coil contacts.

Pins 2&4 and 5 &7 are the closed (or more properly called Normally Closed contacts) and they are in a closed position when the relay is unpowered.

Pins 2 & 4 and 1 & 7 are the Open ( or more properly called Normally Open Contacts) and they are in an open position when the relay is unpowered.

When you apply 24 volts to pins 3 and 6, the Normally Closed contacts, (2 &4 and 5 & 7) will open up, and the Normally Open Contacts, 2 & 8 and 1 & 7 will close.

You can test the relay, easily. I clamp it a small vice. Then measure ohms between the normally closed contacts to see if they are closed. Then measure ohms to see if the normally open contacts are open. Then you apply 24 volts to pins 3 & 6. Repeat your measurements, but now you should get the opposite measurements the second time around.

View attachment Übungsleiter_C_Lizens_Info0001.pdf

 

[1800 Diesel]

Update with good news!

I didn't have to go very far down your list. When I checked connections on TB5-9, Wire # P66D16 was not found--only P66E16. Noticed 3 wires on the RH row of TB5-8 and sure enough, found P66D16 connected there instead. (Three wires were connected on the RH side terminal.) Removed P66D16 from TB5-8 and connected it to TB5-9. Set S1 to start (bumped only) and got instant fuel stop solenoid function. Also checked LH side of #1 terminal on K1 relay & it's also getting power.

I then finished changing fuel & oil filters and primed the fuel system, filled up crankcase and cranked her right up! Put a small load on her and ran about an hour. I can't thank you enough for your help!

One thing I did notice is that the AC voltmeter is reading high (180V in L0-L3) switch position. I checked main output lugs and adjusted voltage control to 120V L0-L1 or L3 and then read 240V L1-L3. Frequency held steady. I'll swap out the AC voltmeter & then I'll do a load test for at least an hour & see how the engine holds up.

Thanks again for the great help--I appreciate it more than you know!

Kevin

 

[Guyfang]

No problemo! That's what the SS Forum is all about!