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No LP prime but the truck runs like a top

608 Views 4 Replies 3 Participants Last post by  99coalroller24V
My truck stopped priming and/or bump start priming about a week ago. My fuel pressure is 15 psi at idle and 13 psi at WOT. My Raptor 150 LP is new and runs only once the truck is running. I've been through the LP harness and relay and all is good. I can bypass the relay and the pump runs fine. That said, I'm getting only 8.5 volts from the ECM with the key in the "ON" position. Once the truck is running I'm getting 12 volts from the ECM. Maybe a coincidence, but it just started getting cold (30 - 40 degrees) here in the last couple of weeks. I've been through similar threats that are resolved with a new ECM. They however, have other issues like wait to start light not working or not turning off, rough idle, codes, or no start. My grid heater is working fine, the wait to start light comes on as usual, no codes and the darn truck runs great. Any feedback as to what I'm missing here would be most appreciated.
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Side note: I also need to crank up my posts to 50 so I can get back in to the classifieds and look for a new ECM...
Maybe the grid heaters are pulling the batteries down too much? That wouldn't explain why the lp isn't running when you bump the starter though. Just a thought. If nothing else, you can reply and add to your post count.

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Good call on the grid heaters pulling down the voltage. That said, I installed two new batteries this week and also disconnected the grid heaters to see if they were the luck, still no prime. Thanks for another post.
fierjgwergewgweg edited
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