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Discussion Starter #1
i have a 99 which the lift pump was going bad it went out so i replaced it now i have trouble starting it when it is cold it will start right up sometime sometimes u have to crank it sometimes when it is up to temp it wont start at all..... i think i just have air in the system i hope.....
 

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TDG Mafia Member #21
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1,345 Posts
Any codes? Sounds like maybe a VP going south.
 

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I had the same problem when I switched to a FASS. My guess would be that your metering diaphram in you VP is cracked. The metering diaphram seperates out a lower pressure for start up, but when cracked, the higher pressure of the new lift pump keeps it from actually metering the fuel, and especially when warm, it needs the low pressure to start. here is how to check, when the truck is warm and not running, unplug the lift pump pig tail (I'll post a pic tomorrow). If the truck starts right up, without much cranking,
SHUT IT OFF IMMEDIATELY, but now you know you have a cracked diaphram.

You can easily fix this with an oil pressure switch, to turn the pump on after the engine cranks over. I've been running this way for 8 months now without any issues. If this is your problem, let me know, and I'll tell you how to set it up.
Sean
 
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