MEP 701A fuel cutoff solenoid

[kipman]

I am not getting any power to the fuel solenoid, took of the plug and checked it with the switch to on, not sure were the power should come from. I read if the fuel tank is to low, it will do this, I have 1/4 of a tank.

 

[ETN550]

Most likely a bad connection. Or you need more fuel.

You have no voltage on the connector to the solenoid.

Open the tank and use a long stick or coat hanger or threaded rod or what have you and lift the bottom float up and down. That is the float that provides the shutdown for low fuel. Note that the float needs to be almost submerged before it rises. You may unplug the 5 way connector on top of the float assembly and further diagnose the float switch. The float switch is a magnetic reed switch and is sealded from the fuel and outside world and is normally maintenance free.

Next up is the relay on the control board that is on the left side of the control box. I have to get my notes to see which one it is. The relays are sealed Air Pac units and usually reliable. The relay is a double relay but only one side is used. If the relay is bad it can be flipped upside down and reinstalled to get the 2nd half to do the work. In esssence it is a self contained spare. They cost $150 BTW and are no longer made but can be found used or NOS.

Check the wiring for shorts. I have seen repairs and chafing as a lot of the wiring is unsupported. In the control box the wiring is up against surfaces where it can wear through.

Does the solenoid work if you put 24vdc directly on it?

Does the rest of the panel work? Does the aux fuel pump work?

You can test the float switch and you can short the harness at the connector for the switch to see if it is the switch.

You can also jump the relay to see if it is the relay.

Could also be the main run switch which can also be shorted or jumped to see if that is the culprit.

I do not think it could be anything else.

Of course there is power at the control panel 24vdc push button breaker.

Although these controls seem intimidating because everything is made of simple components it is quite serviceable on a small pice by piece scale.

Even components on that control board can be replace if you have the patience to do resoldering.

Let us know how this goes. I had the same issue once and it was just a connector on the solenoid. I did not realize that until I went through all the other stuff!

Doug

 

[kipman]

Thanks, everything else works fine, will try your ideas.

 

[derf]

On some MEPs you have to hold the switch in the start position for a few seconds until the oil pressure builds enough to keep the low oil shutdown from killing the solenoid. There is a starter disconnect so you aren't killing the starter by holding the switch in the start position. I now the MEP-003 has this feature but I'm not sure about the 701A/016B. My point is the switch in the on position doesn't always send 24V to the solenoid. There may be other variables in the circuit.

 

[ETN550]

On some MEPs you have to hold the switch in the start position for a few seconds until the oil pressure builds enough to keep the low oil shutdown from killing the solenoid. There is a starter disconnect so you aren't killing the starter by holding the switch in the start position. I now the MEP-003 has this feature but I'm not sure about the 701A/016B. My point is the switch in the on position doesn't always send 24V to the solenoid. There may be other variables in the circuit.

On the 701A and 016B the main fuel shutdown solenoid is energized and enables fuel as soon as the master switch is set to run aux or run, prior to cranking. It is only de-energized in the off and preheat positions.

It makes a rather loud snap or clack noise when energized and de-energized.

Another thing the 002 and 003 do when oil pressure is met is they disable the starter and allow the switch to remain in the crank position and they flash the field until the crank switch is released. I'm not totally sure but I think the 016B and 701A also flash the field when crankng but do not lock out the starter so one has to get off the starter switch as soon as it starts. For extended cranking or flashing the fuel solenoid can be unplugged and the unit will crank but not start.

 

[derf]

Don't the 016Bs have low fuel and/or oil pressure safeties? That is what I meant by other variables. There is a board in there with relays that do something.

 

[ETN550]

Don't the 016Bs have low fuel and/or oil pressure safeties? That is what I meant by other variables. There is a board in there with relays that do something.

Yes, you are correct. They have both.

 

[derf]

The 016Bs do have a starter disconnect circuit with Zener diode. The instructions call for:

Roate master switch to START position and hold until voltmeter reads normal
operation.

 

[Speddmon]

We had a chance to work on Kips 701 this past weekend and got the situation resolved.

Thanks to all who posted good ideas. When I got to his place he had the schematics printed out for me and we got to work. It was indeed the low fuel shutdown float in the fuel tank causing the issue. We removed the entire float stem and had to physically free the float from the bottom of the stem. The float was stuck pretty good to the stem.

For anybody who needs the information or for future use, the pins of the connector on top of the float stem for the switch are Pins "D" and "E". A quick continuity check of those pins with a full tank of fuel and you'll know if your float switch is working or not.

 

[kipman]

Thanks Tom, she runs great and makes power.