MEP-701A / 016B Fuel solenoid and control box questions?

[leedawg]

So at last I have finally gotten a bit of time to start working on my Mep-701a I picked about 3 weeks ago. So I got power connected to the DC system and it appears to be working properly. The starting circuit works fine I can hear the hour meter running in the run position and the aux fuel pump works when the switch is in the aux fuel position.

I have a couple questions for you guys that own these units I am not familiar with it at all I have a mep 005 and an 003, and just picked up this one along with an 002. Oh I was searching around the forum and went to the TM section however I could not find the TM's for this machine. Do any of you guys have a nice little link to them or perhaps I need to hit up the google and look out there was hoping for a PDF file of them like the 003, 004, 005.

Any way I have been slowly going through things and noticed that when the start is engaged the fuel shut off solenoid is not contracting to allow the injection pump to start sending fuel to the injector. So I figured well maybe its a bad solenoid so I pulled the connector off of the solenoid and put my multimeter on it and moved the starter switch to the start position and saw no voltage across the pins of the connector. This brings me to my first question.

When the starter switch is switched to the start position and the starter engages should the fuel shut off solenoid be contracting or does the motor have to crank for a bit before this happens? I have not yet cranked it over for more than about 2 seconds since I have just been testing the electrical system at this point then going to move on to adding oil and fuel. Hopefully it will just start up I dunno though

So I decided to open up the control box just take a peek at the starter switch. Wow lot of stuff in there much more than the bigger units. So I decided to take some wonderful pictures for you guys that have these to compare to and tell me if anything looks amiss. So the voltage regulator looks rather open and there is a large screw on connector on the right side with nothing attached to it. I do not see the cable that would usually have this connector so I assume that it is not used in this machine is this correct? Again I have no other units to compare mine to. How does the internals of the control box look to you guys just from the photographs? I also noticed that the top FUse I think its F1 is soldered to the two plugs on the front and then the one below It I think its F2 is not hooked to anything just like the spare is not hooked to anything. Is this how its supposed to be?

Next question when taking the sides off this unit most of the screws came out no problem. A couple of them however the blind nuts just spin in the square tube frame. This is a horrible design because you cant get the freaking screws out. So I just ground the heads off the bolts with the grinder. Are these blind nuts rivited in somehow? What are they made out of aluminum like the square frame tube? If it is im debating running a small bead around the collar to weld it to the frame so that I can put a torque to get these screws out. Or do you guys have a source for these and just drill them out and rivit new ones in? Really bad design in my opinion what if you were a soldier in the field and one of these things just spun on ya would be a major pain in the arse to get the panel off. So just wanted to know what your guys thoughts were on this. I posted a picture of one of the blind nuts with the ground of bolt I was talking about.

Thanks again guys in advance

Lee

 

[Triple Jim]

There are a couple manuals here:

http://www.google.com/url?q=http://...sQFjAA&usg=AFQjCNGxm0DqVPoL4aZfqrqVknkgNdaSPQ

http://www.google.com/url?q=http://...sQFjAA&usg=AFQjCNEpeS838K-GNKwHS0asMvHH3Y6dbA

The only fuses like that I found were two for the convenience outlet on page 4-95 of the 016B manual. It shows both the hot and neutral fused.

 

[leedawg]

Ah thanks Jim. that makes sense the fused both sides of the convenience outlet. Looks like somebody bypassed it on my unit. Well I am going to go peruse the Tm's for a bit on this thing and see if I can learn more about the fuel shot off solenoid.

Thanks for the links Jim again.

 

[Triple Jim]

You're welcome, Lee. I've found quite a few on Igor's site. Strangely, some are under "Military Generators" and some are under "Other Generators": http://igor.chudov.com/manuals/

 

[leedawg]

Answered my first question with the TM appears as though the solenoid is supposed to be energized when the switch is in the run position so guess im going to have to start tracking down why there is no power to the shut off solenoid. I assume these machines have safety circuits like their bigger brothers that shut the motor down when say there is no oil pressure or no fuel etc. However id think it should be overridden if the switch is in the start position.

 

[leedawg]

Nice im going to have to bookmark that place they have tons of manuals on there. I just need to find a wiring diagram now so I can track down the solenoid circuit on this thing. I wonder if there is a depot level maint manual like there is for the bigger units somewhere. Thanks again for all the help Jim.

Think I just found it if anybody else is looking

http://www.ko4bb.com/Manuals/11)_Stuff_Not_Sorted/Military Gas Generators/fastmenu/062761.PDF

 

[Triple Jim]

Wiring diagrams and schematic start on page 4-94 of the first manual I posted too.

 

[ETN550]

Lee,

Turn the switch on, raise and lower the lower float in the tank to see if that makes the solenoid work. The plate on the control box cover with the wiring diagram is the only one I have seen that incorporates the wiring on the outside of the box. Use it to troubleshoot. The manuals only show the box wiring. One of the relays on the left side board controls the fuel solenoid. The relays are labeled K1 through K4 beside the relays but on the rear side so you need to stick your head in the box or use a mirror. They are not labeled in order, which drives me crazy. You can meter most everything off of the big terminal strip and the one on the left side board. basically, battery goes to the switch, then to the relay, and I think, if I remember, the float switch grounds the relay coil and allows the main contacts to put juice to the fuel control solenoid coil. If the relay is clicking, listen with a screwdriver to your ear, then it is probably a bad float switch or ground. The relays usually don't fail. If the float is bad you can jump a ground from the lower terminal strip to where the float comes in on the board. Although this is not your particular issue the spade connectors on the plug that goes into the fuel solenoid get loose or corroded which is another issue. The female spade terminals can be removed from the plastic plug and made to grip tighter by closing a little with pliers. They can also be replaced with standard female spade ends if the plastic plug is abandoned altogether.

 

[leedawg]

ETN550

Thanks for the tips. I was just thinking perhaps its cause I have no fuel in the tank right now. I am going to go out right now and try that and see if raising the float allows power to go to the starter solenoid. Thanks again I will report back.

lee

 

[leedawg]

Well moved the float up with the switch in the run position still no voltage to the coil, so much for the easy stuff going to have to start working on it more next weekend when I have more time. Thanks for the input.

 

[Crawdaddy]

Did you move the lower float up or the upper float? You can also jump out pins D and E on the cannon connector to simulate the float being up.

 

[leedawg]

Did you move the lower float up or the upper float? You can also jump out pins D and E on the cannon connector to simulate the float being up.

As I recall I think there was only one float. I will have to go out and take a closer look at it tomorrow. I know one of the MEP 005a has two floats one for low fuel the bottom one and the upper one for the fuel transfer solenoid. I will probably just jumper the pins over as you described D and E. Thanks for the input appreciate it.

 

[ETN550]

Regarding those pesky rivet nuts that spin in the frame...

Grinding them off is the only way to get it opened up. Since the military uses washers on all their fasteners careful grinding will get through the screw head and the washer will protect the housing cover from grinder marks.

I usually replace the rivet nut in the frame. Keep grinding carefully and when it gets real thin it can be knocked into the frame with a punch leaving the hole in the frame. Tool stores sell kits to fix this and it is handy to have this blind fastener capability around anyway. The nuts are like pop rivets and the tool is similar, except the tool has a stem that threads into the rivet nut and pulls it tight then simply unscrew the stem and the blind rivet nut remains. Because the aluminum frame is rather thin try to find the style that has serations around the OD to grip better.

Otherwise, I was running a tap through a few of those rivet nuts that the screws did come out of when my tap started turning the rivet nut! I wanted to save the tap so I tried making 6 dimples by placing a sharp center punch at the edge of the flange on the rivet nut and struck it sharply with a small hammer leaving decent prick marks half in the aluminum and half in the steel rivet nut. This worked good enough to back the tap out. I doubt this would be strong enough to get a cut off screw out but it might be worth a try before grinding the old rivet nut out and installing a new one. Provided some vice grips could get a hold of what ever is left of the screw.

You can find the rivet nuts and tools in McMaster-Carr. Just be sure to order ones that are larger than the hole existing in the frame. The thread size is #10-32. Mc-Master-Carr also has a good selection of stainless screws as well.

When going back together use antisieze on the screws, as stainless does not rust but it does gall and stick which is part of the problem to start with. the screws do not have to be real tight anyway.

If you don't care one or even two missing screws on the side panels presents no problem. One missing screw on the end panels is no problem either.

 

[leedawg]

Thanks so much for the info ETN550 I am going to have to order up the rivit tool for the blind nuts as you suggested and see if I cant work that bolt out or possibly grind it out as you mentioned. I like your idea of using a punch to sort of pinch the flange to the frame rail to try and get some traction so it does not spin in place. Thanks again for the suggestions and help.