vp 44 loosing prime while running
04-01-2018, 09:46 PM
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vp 44 loosing prime while running
ok background: new VP44 sent back tested good reinstalled. new ecm. new battery cables and batteries. fass booster no problems in flow to VP44. new rely for fuel system. Vp44 is beginning to loose prime after a drive period of at least 45 min to an hour. it starts jumping then when rpm get around 1000 it shuts down. Pump is completely dry. the pump will reprime and truck will fire after bleeding fuel system of air and run fine untill it decides to lose prime again. after installing the new pump and having the dealership install new ecm. dealership found no problems with truck when they had it.
04-02-2018, 04:45 AM
#2
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This can be caused by an injector not sealing against the combustion chamber.
The return flow from the injectors is fed back to the pump, and if an injector washer does not seal some exhaust gas enters the return fuel.
I'd start by pulling the injectors, installing new washers and o-rings. (And checking the hold down bolts for proper adjustment)
The return flow from the injectors is fed back to the pump, and if an injector washer does not seal some exhaust gas enters the return fuel.
I'd start by pulling the injectors, installing new washers and o-rings. (And checking the hold down bolts for proper adjustment)
04-02-2018, 01:01 PM
#4
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The only other thing I can think that would cause this is if you have a hole in a fuel line somewhere in the suction area- meaning between tank and lift pump.
Easy to check if you have the stock fuel filter- just take a transparent hose and connect your fuel filter water drain to the fuel filler neck- open the water drain and bump the starter. No bubbles allowed!
About torque values- I'd strongly suggest that you get a factory service manual , eg from genosgarage-
https://www.genosgarage.com/category...service+manual
CDs are only 35 $, the best money you can spend on these vehicles.
Easy to check if you have the stock fuel filter- just take a transparent hose and connect your fuel filter water drain to the fuel filler neck- open the water drain and bump the starter. No bubbles allowed!
About torque values- I'd strongly suggest that you get a factory service manual , eg from genosgarage-
https://www.genosgarage.com/category...service+manual
CDs are only 35 $, the best money you can spend on these vehicles.
04-03-2018, 07:51 AM
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no had a fuel pressure gauge hooked to it one time while it was doing it pressure never changed. thats how i know there are no problems whatsoever in the fuel getting to the pump.
04-03-2018, 04:44 PM
#7
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Well, a fuel pressure gauge will not tell you anything about what is in there that has the pressure.
Imagine a garden hose with a pressure gauge- let's say 15 psi of water pressure.
Now we empty the hose and use an air compressor to apply 15 psi of air pressure- you will read the same on your gauge.
Yep, doing the valves is a good idea.
But... I'd do the test with the fuel filter first, costs you less than 15ft of transparent hose (you can re-use that too), and check the injector sealing washers.
Imagine a garden hose with a pressure gauge- let's say 15 psi of water pressure.
Now we empty the hose and use an air compressor to apply 15 psi of air pressure- you will read the same on your gauge.
Yep, doing the valves is a good idea.
But... I'd do the test with the fuel filter first, costs you less than 15ft of transparent hose (you can re-use that too), and check the injector sealing washers.
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