Just moved my lift pump via the Vulcan kit less then a week ago.

The fuel pressure readings are funky. I am using the electric gauge on my Juice.

This will sound weird, but it runs higher pressure under load then when letting off or idling.

It first starts up, then runs 14-15 PSI. Then when you get going it holds 13-15 PSI going down the road. Then, when you let off and your coasting, it will drop to between 6-8 PSI. This is bizarre to me. Also, when it is that low and you stab it, the pressure goes right up. Say, 12-14 PSI. I am yet to pull it below 8 PSI, wide open throttle.

This lift pump is a little over a year old. The old one idled at 10 and could be pulled to 0 PSI easily when it went south.

I'm almost thinking the sender maybe? Or I have air in the system. It did struggle to start and required bumping the starter(to prime the pump) about 5or 6 times.

The sender is on the end of a hose right off the schraeder valve. This way I could zip tie the sender off to the side and don't get the vibration right off the engine.

Everything was fine until I relocated the lift pump.

What do you guys think?

Should I just order up a new lift pump? I was thinkin about having a spare anyways.

 

I had a simular problem. 10 month old relocated lp started dropping fp. It almost always dropped when I let off- like when I crested a hill, but when I gunned it the fp went back up. I replaced the lp and the problem is gone.

I have yet to discover the source of the problem, but I have a couple suspects. I'm wondering if it could be the pick up. Vulcan recently started offering a draw straw to replace the pick up and I'm considering giving one a go. The second suspect is an electrical gremlin- either an underperforming alternator or the longer wiring causes a voltage drop.

I am very possible way off but would like to hear some ideas for troubleshooting this. How old is that fuel filter?

 

Brand new fuel filter. Old one didn't look bad either. Only about 7 or 8k on it and about 9 months old. I can get them for $11 so I have been changing every 6-8k.

Well, I will probably order up a new lift pump and see if it changes. If not, I guess the old one becomes a spare.