I have A 2018 Frontier SE 6x6 with A Kohler Command Pro engine . seems to have A fuel delivery problem . I took the fuel line off the pump on the valve overturned the engine over and A little gas came out -- not as much as I would think--Then I find out that there is A second pump electric very hard to get to and lots of bucks----how do I determine which one is bad-----When I squirt gas in the intake the engine runs--- Thank you'll for any input--Gunner11--side note I ordered the valve cover pump figured the cheaper one and simpler to put in to start with.