Hello everyone, this is my first ever post, as I ashamed to say I tend to read and enjoy but never find the time to share! but this was such a long and challenging problem (Great end!) that I felt I must share and hopefully help someone else! I recently purchased a 2008 290 Sundancer which came with a non functional Kohler 5 ECD generator. The mechanics report was "High pressure fuel pump failure" I research high pressure fuel pumps and they ran for around $600. So before I made that purchase I thought I would trouble shoot it myself. So I tried to start the generator: To my surprise it started but within 2 seconds stopped giving error AF. After reading several manuals it turns out AF is a fault from outside the system. In my case it was the CO2 detectors. The previous owner had disconnected them. My system has the remote control module at the breaker panel which includes that interlock. You will find the remote connection at the rear of the generator which you can unplug to remove any issues with the remote system. (Its a white connect directly behind the LED panel on the rear case. I think its 9 pins but I may be mistaken) So with the remote disconnected I tried again! It started but stumbled and stopped, the 2nd attempt same thing, 3rd and final it stopped with a UU error. (Under voltage) After asking around everyone said "Change the plugs! that's what I always do". So I listened a got new plugs. (BPR4ES $3!!! at Autozone gap .024 to .028") Installed no difference. Strangely the old plugs were clean (No oxide) and "Wet" very strange. I checked both for spark and it was blue and strong? Still the same problem, it starts but stumbles and stops (Giving several errors) So maybe the mechanic was correct. High pressure fuel pump. Unfortunately the Kohler fuel pressure gauge was very expensive so I went in with my trusty harbor freight unit. (Just for reference the generator has 2 fuel pumps in series, a small primer pump that runs after the fuel filter that feeds the high pressure (50 psi) fuel pump that is water cooled). I connected my fuel pressure connection to the schrader value on top of the high pressure fuel pump to get a reading. 0 psi? very strange? I removed the Schrader value to see if it was blocked? Nothing? After much head scratching and research it turns out the value isn't connected to the system and should read 0. OMG!. If you follow the output pipe from the high pressure fuel pump it leads to the fuel injector and there is another Schrader value that is used for purging after fuel filter replacement. I was definitely getting pressure there but it was impossible to connect too, to get a reading. With a little creativity I disconnected and reconnected only the fuel pump end off the fuel line and connected my inline pressure gauge to the end of the pipe. (Hope that makes sense I'm connected to the fuel pump but disconnected from the injector) Magically I have 50 psi of pressure!!! Glad I didn't purchase the $600 fuel pump! Confused? I have a spark and Fuel pressure? The plugs are wet? Not sure why but I sprayed a little starter fluid on the spark plug and magically the generator started up very strong? (Don't recommend start fluid in the cylinder etc. it can cause over pressure situations! But a little on a spark plug may give you a change in behavior. Which happened for me) It had to be the fuel injector! It must be dripping out gas not spraying gas as it should. The injector sits on the top of the engine and is attached to the output pipe of the high pressure fuel pump. There is only one and it has a single electrical connector. So I went on the hunt for a new injector. This turned out a little more tricky that I expected as they wanted to sell me the injector assembly (Including the head casting). Finally I was able to get the injector alone GM62619. It was $127. The replacement is easy but you may want a chapman set to help you with the 2 cap head screws (little tricky for fat fingers!) Just unclip the old injector and install the new one to the fuel line assembly. Replacing the injector took 10 mins and the generators has run perfectly ever since!!!