Onan Diesel Gen set wont prime.

[Rkesselus]

Looking for advise on a problem with my 7.5 Onan Quite Diesel generator. Did service on the unit including replacing flexible fuel supply lines to the fuel filter. Now when trying to restart I can not get the unit to prime. The pump is working and fuel is circulating from one line to the other. Thinking I had reversed the lines I made several swaps with no change. My new lines are clear and I can see the fuel moving in the lines along with a lot of air bubbles. Any suggestion as to what I have done wrong or what the problem my be?

[WILDEBILL308]

Originally Posted by Rkesselus

Looking for advise on a problem with my 7.5 Onan Quite Diesel generator. Did service on the unit including replacing flexible fuel supply lines to the fuel filter. Now when trying to restart I can not get the unit to prime. The pump is working and fuel is circulating from one line to the other. Thinking I had reversed the lines I made several swaps with no change. My new lines are clear and I can see the fuel moving in the lines along with a lot of air bubbles. Any suggestion as to what I have done wrong or what the problem my be?

Did you change the filter? Something is leaking because I don't think you should see any air. I would call Cummins and ask how to purge the air. You may have air in the injectors. Let us know what you find.
Bill

[twinboat]

If you see air bubbles moving towards the generator, from the tank, you need to find where the air is entering the line.
You need clean, clear fuel going into the injection pump.

[Rkesselus]

Originally Posted by Rkesselus

Looking for advise on a problem with my 7.5 Onan Quite Diesel generator. Did service on the unit including replacing flexible fuel supply lines to the fuel filter. Now when trying to restart I can not get the unit to prime. The pump is working and fuel is circulating from one line to the other. Thinking I had reversed the lines I made several swaps with no change. My new lines are clear and I can see the fuel moving in the lines along with a lot of air bubbles. Any suggestion as to what I have done wrong or what the problem my be?

Thanks for the reply's. problem solved. Everyone was correct I was sucking air but could not figure out where. All I had done was install new lines form the metal lines to the filter. The lines were new and the clamps were tight but I still was sucking air. The supply line from the tank was working prior so I would not think there was problem with them. Finally removed the lines and found a very small pin hole in the supply line. It was only noticed with a vacuum or pressure place on the line. I found it by removing the line and putting pressure on it. Took the line back to the Auto Parts store and showed it to the manage. Not sure what he did other than to get me another line. i think he has a rat in his employ.

[Mekanic]

Originally Posted by WILDEBILL308

Did you change the filter? Something is leaking because I don't think you should see any air. I would call Cummins and ask how to purge the air. You may have air in the injectors. Let us know what you find.
Bill

100% agree.

[WILDEBILL308]

I would also make shure the clear line is rated as a fuel line. It could degrade quickly and cause more problems.
Bill

[Rkesselus]

Originally Posted by WILDEBILL308

I would also make shure the clear line is rated as a fuel line. It could degrade quickly and cause more problems.
Bill

They are high dollar racing lines I am not concerned except for the AH that poked the pin hole.