Fuel Pump Randomly Won't Prime
10-26-2006 | 05:55 PM
#11
I don't hear the fuel pump only when I get a no start. The truck runs fine once started. Looking at schematics last night, there is a Fuel pressure sensor on top of the fuel pump, it gets a signal from the PCM, then relays info back to the PCM, the info goes to the pump, that's why I'm theorizing the sensor is getting stuck, telling the PCM that the fuel line is primed and the pump isn't running
10-26-2006 | 09:31 PM
#16
Just trying to help a brother out man.......like I said. Pump. could be a sticky relay, but you said you switched relays and same problem, and the chance of 2 shitty relays is slim to none.....Or, its a poor connection somewhere that, when like you get in the truck, gets knocked loose. but it doesnt stop runnning when you go over a bump or anything, so I would rule that out too.
10-26-2006 | 10:00 PM
#17
Originally Posted by bigredexpress99
Just trying to help a brother out man.......like I said. Pump. could be a sticky relay, but you said you switched relays and same problem, and the chance of 2 shitty relays is slim to none.....Or, its a poor connection somewhere that, when like you get in the truck, gets knocked loose. but it doesnt stop runnning when you go over a bump or anything, so I would rule that out too.
when a fuel pressure regulator goes out, does it stop fuel flow and prevent the pump from coming on, or does it just let the fuel bypass and return to the tank?
10-26-2006 | 10:17 PM
#18
TECH Junkie
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From: Spring, TX
Originally Posted by Nickvrebel
yeah, I hear what you are saying, but what really leads me away from that is when I commanded the pump on with HP Tuners it came on. This tells me that for some reason the pump isn't getting the command to turn on, like a sensor or a maybe even a PCM that's having issues... I don't know.
when a fuel pressure regulator goes out, does it stop fuel flow and prevent the pump from coming on, or does it just let the fuel bypass and return to the tank?
when a fuel pressure regulator goes out, does it stop fuel flow and prevent the pump from coming on, or does it just let the fuel bypass and return to the tank?
This could be your problem. There are ways to tell if the regulator is bad.
Someone here may chime in to tell how. I think you will see fuel in the regulator.
Jim
10-26-2006 | 11:11 PM
#19
well, to tell if the reg. is bad, pull the vacuum line off of it. it will have a little gas in it of the diaphram is bad. Also, if it has been recently replaced, if it is not seated right, the oring inside binds up and causes a leak down. This only applies to 99-03 trucks though, 04+ they went returnless.....that is unless you have a flex fuel motor, then those are still return up to 07 I believe....
