I think some were it has a opening in the fuel system that dosent leak fuel but lets air in when it shut off. I had seen this before. One time it does one thing and the next it does something diffrent. I thought it was sucking air in the return but from were some one has taped a hole in the suck side of the lift pump inlet fitting and run the line to that? The new hole isnt that great or strait so i replaced the fitting and used alot of sealer on it but that didnt help. Why can i put a 3 foot hose on the return and it will work? We have thought about runing the return back to the tank like factory but it was working the way it was. Why did some one reroute the return ? It was done when it was 2 years old before the now owner bought it. This thing has me stumped.One resone i am replaceing the filter is a good pump guy told me he had problems with them sealing.That's not a variable you described when swapping lines from bucket to tank. Don't know how a part that had no impact, will help.
Its has a flat bed so the pickup can be pulled. I ordered a filter yesterday from OR parts he said he could get a luberfiner filter and i would have it today.I went there early no filter they cant get luberfiner stuff? I went to the shop and blocked of the line from the tank to the engine at the engine and blowed air in the tank end. It had a break were the rubber clamps to the steel line. I replaced line bleed air out started it left for a hour it wouldnt start. I pumped it up tryed to start it in 10 minites no start. I pumped it up started it then clamped off return line started up ok. I pulled new overflow valve i could blow throw it and it wouldnt hold fuel on top of the ballbearing. Tomorrow i am going to the place were i got the valve and get a filter and valve. We fixed the grid heaters they work but its been in a heat building all but for one time when we had it outside a short time.The only variable seems to be your tank. Is it difficult to get the sender out. Perhaps you have some junk stacking up in the stand pipe or debris plugging the inlet strainer. That doesn't explain the night time bleed off though.
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I got it from a local cummins dealer i dont know what brand it is. They are very good to deal with if they say they have had a problem before i may drive to the nearest pump shop it will be a 3hour trip.Dam.. that's some bad luck.. did u buy the part # I had given?? Did it come in a Bosch bag??