MEP-803A Fuel Tank Switch

[superman4283]

The fuel tank switch on my mep-803 does not seem to be working properly. Do you guys see any reason that I can't run the generator with the switch unplugged without harming it? Or do you know of a cheap replacement? Thanks in advance for any help.

 

[kloppk]

Fuel tank switch?

Which switch are you referring to?

 

[superman4283]

This is what I am asking about.

 

[superman4283]

Also I do not use an auxiliary fuel tank.

 

[kloppk]

The lower float on that assembly is for detecting a No Fuel situation. If the tank gets really low it trips the Low Fuel fault shutting the engine down.
The upper float is for the Aux Fuel pump automatic operation.
If you totally disconnect that assembly you will loose the ability of the generator to shut itself down before totally running out of fuel.
The generator will run with it disconnected.

 

[superman4283]

Yes I understand how it works but it's shutting itself off with plenty of fuel still left. I have looked for a replacement but they all seemed very expensive. I've never ran out of fuel and keep a very close eye on the fuel level. Judging by the manual I should be able to just unplug it and the generator should run just fine. If the generator does run out of fuel I assume I could just add more fuel and restart the generator without any problems. I just wanted to check with the experts on here before I tried it. By the way you're a remote start system really comes in handy.

 

[2Pbfeet]

Yes I understand how it works but it's shutting itself off with plenty of fuel still left. I have looked for a replacement but they all seemed very expensive. I've never ran out of fuel and keep a very close eye on the fuel level. Judging by the manual I should be able to just unplug it and the generator should run just fine. If the generator does run out of fuel I assume I could just add more fuel and restart the generator without any problems. I just wanted to check with the experts on here before I tried it. By the way you're a remote start system really comes in handy.

That's great that you plan to keep a close on eye the generator.

Running a diesel engine out of fuel is not great for the injection pump(s) as the injection pump relies on the diesel for lubrication. Being a very tight tolerance mechanical item, it doesn't take much to trash an injection pump. Even if the injection pump doesn't get damaged, you still would have to prime and bleed the whole fuel system.

To me the risk is pretty high for momentary distraction. If it were me, I would replace or repair the sensor. (Have you checked that the floats float, and they move freely on the stem?)

All the best,

2Pbfeet

 

[Ray70]

Out of curiosity, what have you done to test the existing dual float assy? The problem could be as simple as a stuck float or a bad component on the float control module.

 

[superman4283]

The generator had been running fine but shut off one day with the no fuel light on. I assumed it was out of fuel so when I Went to put more in I realized it had plenty. I noticed the tank looked a little dirty so I pulled the tank and cleaned it. I also changed all the fuel lines and fuel filters. When I did all this the floats seemed to be moving correctly on the assembly. After reinstalling everything I added more fuel and the generator crank and ran for about 30 minutes before stopping with the no fuel light on. I would be happy just to replace it but I'm not willing to pay hundreds of dollars to do it. If anyone knows of a cheap replacement I would love to know about it.

 

[Ray70]

You're jumping to the conclusion that the float assembly is bad before testing it to verify.
It's a simple switch mechanism, I'd suggest you use a multimeter and check continuity on the 2 wires for the lower float.
The issue could be with the float control module rather than the float itself. There is also a possibility that the float is oriented in the tank incorrectly and rubbing against the side wall of the tank, causing it to falsely trigger the low fuel light.
Test, determine root cause then implement the solution, don't blindly throw parts at it

 

[kloppk]

It could also be the Fault Monitor itself. They do go bad.

Ditto on the A9 Float module. They go bad too.

I'm working on something to replace the A9 Module, Float Switch assembly and Fuel Level sender. It's not ready to be sold yet. I need to do some tweeks to it and do some more testing.

 

[superman4283]

I'll double check to make sure the float is not touching the tank but it wasn't when I reinstalled it. It'll probably be a few days before I can get to it but thank you for the help so far. It is very much appreciated.

 

[Ray70]

Verify the float assembly with a multimeter while you're in there. check both pairs of wires, aux fuel switch and the low fuel switch.

 

[superman4283]

Verify the float assembly with a multimeter while you're in there. check both pairs of wires, aux fuel switch and the low fuel switch.

That is my plan.

 

[Guyfang]

If you are going to test the switch, take it out of the set. Have someone hold it upright. Both sets of contacts should be open. Turn the float switch upside down. Both sets of contacts should be closed.
1. Pins A&B are for the Aux fuel pump system.
2. Pins C&D are for the Low Fuel Shut off.

If the readings are right, then its probably the A9 module.

 

[CallMeColt]

If the switch is indeed dead, you can run without it and get some sort of switch of your own likeing to wire into the proper circuit set & install it in it's place. On top of it running dry being bad for the engine, the main reason why this switch was there was to avoid surging & sputtering with a closed contractor. This will stress out the voltage regulation system & anything hooked up to the generator getting power. I'd also remove the auxiliary fuel pump from the tank area, along with the plumbing for it & have it as a spare for the main fuel pump.