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MEP-701A MEP-016B MEP-016E Engine Control Board, aka Assembly 3/A3 84-13178

jas671

New member
14
15
3
Location
Pennsylvania, USA
I have 3 of these generators that I am working on, two MEP-016E and one MEP-701A.

For those who are not familiar with the MEP-016E, it is a MEP-016B that has been retrofitted with the Yanmar L100 engine in place of the Onan unit.
Many changes get made, including adding an electric lift pump. The Onan engine has an engine-driven mechanical lift pump.

The current status of these units.

#1 MEP-016E -- running, making good power, failed VR2 (28V battery charging regulator-rectifier).
#2 MEP-016E -- seized, will not rotate, many things disassembled -- using as a parts unit.
MEP-701A -- Engine Control Board, aka Assembly 3/A3 pn 84-13178, not powering the fuel cutoff solenoid

I swapped the VR2 from the #2 unit into #1. Now instead of no DC power to charge the battery, the voltage is too high. I turned the unit off as it approached 32V. I have decided to just mount a 120VAC powered 28V charger instead, as these VRRs cost $315.

Back to the 84-13178 board.

Relay K4 on this board powers the fuel-cutoff solenoid.

I followed the test procedure for K4 in the TM-062759, starting on page 4-109.

It passes the relay K2 tests. It fails the K4 tests. Knowing that the K2 relay is good, I swapped K4 and K2. The board still passes K2 test, but, fails K4 test. The problem isn't the relay. This is a very simple board, terminal blocks, diodes and relays, that is it.

The problem must be one or more of the diodes in the circuit that powers terminal 2 of TB2. I will investigate next time I have time to get to it, maybe later today.

My question for this group is, has anyone replaced diodes on these boards before? If so, what part number diode should be used?
 

jas671

New member
14
15
3
Location
Pennsylvania, USA
Upon further investigation, the boards are fine. It turns out that the schematic on in the TM has the wrong pinout for the connection to the float switches on the fuel tank, which I verified by ringing out the wiring on my good running unit. The float switch on my MEP-701A is faulty. I bypassed it and am able to run the engine.


The schematic shows E1SW2 being pins A & B on the connector on the fuel tank. That is false. It is pins D&E.
A&B are the the high fuel switch that controls the auxiliary fuel pump.
 
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