Luckytrucker66
Recruit
- Joined
- Aug 16, 2022
- Messages
- 5
Hello.
I am working on a 2004 Johnson 50 hp 4 stroke. It starts no problem and idles great. It will accelerate perfectly and runs great for about 30 seconds then dies out. If you re prime the primer bulb, it will fire right up and do the same thing again. If you keep priming the bulb while driving, it will run all day.
I checked the high pressure side of the VST and it holds steady at 40 psi. The low side builds up to 15 psi and holds there. I took the intake plenum off and took apart the VST tank. There was little debris in the fuel pump filter screen but nothing bad. I blew all lines and filters out with compressed air. There was some debris come out of what I believe to be a pressure regulator in the bottom of the VST. It also takes a fair bit of pressure to open said regulator. I unfortunately do not have a pop off guage to see how much pressure it takes to open it. Cleaned out the needle and seat at the top of the VST and blew it all out as well. Took apart the low pressure fuel pump and found nothing of any concern. Diaphragm was not dried up. Put it all back together and still same problem. I did try a different gas tank and fuel hose as well without any luck. Any ideas? I did read on another post on this site about checking the high side pressure on acceleration. I have not done that yet but will.
I am working on a 2004 Johnson 50 hp 4 stroke. It starts no problem and idles great. It will accelerate perfectly and runs great for about 30 seconds then dies out. If you re prime the primer bulb, it will fire right up and do the same thing again. If you keep priming the bulb while driving, it will run all day.
I checked the high pressure side of the VST and it holds steady at 40 psi. The low side builds up to 15 psi and holds there. I took the intake plenum off and took apart the VST tank. There was little debris in the fuel pump filter screen but nothing bad. I blew all lines and filters out with compressed air. There was some debris come out of what I believe to be a pressure regulator in the bottom of the VST. It also takes a fair bit of pressure to open said regulator. I unfortunately do not have a pop off guage to see how much pressure it takes to open it. Cleaned out the needle and seat at the top of the VST and blew it all out as well. Took apart the low pressure fuel pump and found nothing of any concern. Diaphragm was not dried up. Put it all back together and still same problem. I did try a different gas tank and fuel hose as well without any luck. Any ideas? I did read on another post on this site about checking the high side pressure on acceleration. I have not done that yet but will.