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Discussion Starter #1
Bought the truck in March or so and previous owner said the raptor pump has been on for 8+ years or so. I just put a fuel pressure gauge on this weekend, as well as pyrometer and boost gauge. Found out that not only did it make 10psi at idle, but it doesn't hold pressure like I would expect.

I'll turn the key on and the pump will kick on, now to 20psi, but once the pump kicks off the gauge drops to 0. Once I start the truck, it jumps back up to 20psi. I have looked all over and there are no leaks anywhere.

I'm hoping that there are some seals or something that I can replace. I also know there is a screen somewhere on the pump that occasionally clogs up, but I couldn't see that causing this issue.
 

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Discussion Starter #3
Alright, I was just expecting it to hold some pressure after it kicked off.

New problem, I guess related to after I cranked up the pressure. It now idles at 18-19 psi. First start up will be fine. But after I shut down and try to restart several hours later, it will crank for a good 5-6 seconds before it lights off.

So far it has not failed to start, but it has always fired right up before this. Just not sure whats going on.
 

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Correct. Turn it down to 12- 15 or 15-17 max..
 

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Discussion Starter #6
Alright, just took it down to 15. Well see what happens.

Now I just have to figure out what’s going on with my electrical situation and the darn ext voltage regulator. That threads over in the non power train but should probably be over here.

Dropped back to 12.4 volts on my way home from hauling hay the other night.


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Did it stay there or going up and down? Sounds like alt isnot charging at all adn you are barely still running on battery paower. Charge batteries now to keep it running for testing.
 

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Discussion Starter #8
I know it's not ideal, but I have ran it like this in the past without an alt and my voltage has dropped to 11.6 with no indications of any problems. After it got that low, I charged it and put on a new ext reg and it worked for a while, still with pulsing 14.5V to 15V.
 

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Discussion Starter #9
Charging issue solved for now. Again, thread is over in non-powertrain.

Adjusted fuel pressure again to 14psi at idle, drops to 10 at WOT. Still hesitates on a hot restart, but I don't think I want to go lower.

Any thoughts?
 
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