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artr1955's avatar
artr1955
Explorer
Dec 02, 2019

My generac diesel generator only runs with prime button

Diesel generator only runs with prime button held down model 004270-3. Oil level and coolant are fine as the breaker and 14 amp fuse. The thing that perplexed me is why it runs about 30 second after ...
wa8yxm's avatar
wa8yxm
Explorer III
Dec 03, 2019
The PRIME button also operates a fuel pump. Now one of two ways

one: A separate pump (often in-tank) that lifts fuel to the main pump on the generator.

2 The main pump but bypassing a relay on the Generator's control board.

Now with in-tank electric (or even in line electric) pumps becoming more and more popular over cam-operated pumps of old. The control board, sensors and that relay are all suspects.

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