MEP-804B “No Fuel” Light Issue

[jake20]

Hey all,

Posting this as a live demonstration of the low fuel / aux pump float sender on a MEP-804B.

To sum it up, my sender keeps causing the panel to indicate “No Fuel” and shut the generator off. This can be temporarily field rectified by just yanking the plug from the sender if needed.

My issue seems to be that when the sender is submerged in fuel, thus causing the float to rise, it still causes a “No Fuel” light. When I remove the sender and manually lift the float by hand, the generator acts normally. Very bizarre and figured I’d post this to be somewhat informative. I’m still troubleshooting, I’ve tested with the same results on the original sender as well.

My thoughts are that it could be an issue upstream of the unit, or somehow the diesel conducts a tiny bit of current and closes the circuit in some way. It’s wire pair J12 as labeled, going to try to find and trace where it goes.

Here’s the video with the demonstration:

 

[jake20]

Figured it out!

Turns out these sender units are pretty flakey in terms of quality control, or maybe you're just supposed to tune it before installing it. Anyway, the lower of the two floats was allowed to come up too high, thus closing the circuit and tripping the "No Fuel" light. It was a little finnicky to continuity test at first but I was able to get the circlips on the shaft moved into the perfect spots to make it work.

Generator is now back up and running with the fuel sender working properly. Hopefully this helps someone, seems this is somewhat common.

Here's a video with a demonstration:

 

[loosegravel]

Hey all,

Posting this as a live demonstration of the low fuel / aux pump float sender on a MEP-804B.

To sum it up, my sender keeps causing the panel to indicate “No Fuel” and shut the generator off. This can be temporarily field rectified by just yanking the plug from the sender if needed.

My issue seems to be that when the sender is submerged in fuel, thus causing the float to rise, it still causes a “No Fuel” light. When I remove the sender and manually lift the float by hand, the generator acts normally. Very bizarre and figured I’d post this to be somewhat informative. I’m still troubleshooting, I’ve tested with the same results on the original sender as well.

My thoughts are that it could be an issue upstream of the unit, or somehow the diesel conducts a tiny bit of current and closes the circuit in some way. It’s wire pair J12 as labeled, going to try to find and trace where it goes.

Here’s the video with the demonstration:

Interesting! I thought that the 804A and B models both had mechanical primary lift pumps, and electric auxiliary pumps only? I can hear what sounds like an electric primary lift pump in your video though?

 

[jake20]

Interesting! I thought that the 804A and B models both had mechanical primary lift pumps, and electric auxiliary pumps only? I can hear what sounds like an electric primary lift pump in your video though?

I can’t speak for the 804A but my 804B has the same exact pump for primary and aux. Primary is located just behind the water separator filter, aux is mounted behind the fuel fill hole.


They’re both a simple Inline Electric Airtex E1074. That specific model doesn’t get manufactured anymore but the E8135 still is from what I saw. Similar enough to be a drop-in replacement if needed.