RV Repair: onan emerald series twin cylinder, jumper wire, magnolia texas

Question
Bill,  
this unit will only run as long as you hold the start button. as soon as you release the start button the engine dies. I cant find a wiring diagram or troubleshooting chart. could you help?  the unit is in a 1990 motor home. my customer just bought this rv so i dont have any history.          
                                greg mobley

                              auto repair specialists
                               magnolia, texas
                               281-356-7840
                              gregmobley@charter.net

Answer
Hi Greg:
When you push the start button there are a couple of things bypassed. One of them is the oil pressure cutout. It is a sender just like most other oil safety switches. It is accesible under the cover near the oil filter. Also make sure the oil level is correct. Unfortunately you have to take the oil filter out to get access to the sender and then you can't run the genset. But you can take the sender out and bench-check it. The control board voltage to the coil is also bypassed when you start the generator. As soon as you let go of the start button the voltage comes from the control board. The coil is located in the right rear of the unit. I usually run a jumper wire to the hot side of the coil and if it runs then the board is bad. The other thing I have also seen is the the throttle closes when you let go of the button. Look at the the throttle rod as you try and start it. The throttle is wide open when the unit starts and then the governor takes over when you let go of the start button If the throttle closes then the governor is bad. Good luck.
Bill