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Discussion Starter #1
Looks like I mat have spoke to soon about my truck running fine with the new Fass fuel pump. I have had it in for about 3 weeks now and I am now having trouble getting the engine to start. The truck seems to start up fine on the first try then right after it starts it lobes a couple of times then shuts off. After that I just hit the starter for a while then stop hit the starter for a while the stop and so on until it starts, 3 time now this has worked. I just tried taking the inline fuse out of the fuel pump thinking this would relieve the high pressure at start-up and the truck would fire right up. But that was not the case so I put the fuse back in and just kept trying the starter til it finally starts. Once it starts the truck runs fine.Is this a for sure sign that my injection pump is bad? Also is there any reparing the pump or is my only option a new one.
 

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Not sure I know exactly what your saying so bear with me while I attempt:

Is there a possiblity you have air in your lines or somehow you have are letting air bleed in from somewhere.

Your fuel pump has a 50% duty cycle on start up. And even when the pumps go bad I'm not sure they do what your saying. I could be wrong.
 

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Just a quick thought. as said in the above post check all fittings for snugness. so as to eliminate all possibility of air in the system. do any codes appear on the odometer when you check it? check for water in your fuel. also check for fuel gelling in the new pump filters. try a additive I like two cycle oil and sometimes a little powerserve or FPPF winter blend. are you using a bio blend of fuel? it gells alot sooner than reg #2 diesel. just something to ponder. Tod
 

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If the VP44 pump is bad you should replace it. i have never read or heard of anyone other than a bosch shop rebuilding one . But stranger things have happened.:Thumbup:
 

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Murray689 said:
Looks like I mat have spoke to soon about my truck running fine with the new Fass fuel pump. I have had it in for about 3 weeks now and I am now having trouble getting the engine to start. The truck seems to start up fine on the first try then right after it starts it lobes a couple of times then shuts off. After that I just hit the starter for a while then stop hit the starter for a while the stop and so on until it starts, 3 time now this has worked. I just tried taking the inline fuse out of the fuel pump thinking this would relieve the high pressure at start-up and the truck would fire right up. But that was not the case so I put the fuse back in and just kept trying the starter til it finally starts. Once it starts the truck runs fine.Is this a for sure sign that my injection pump is bad? Also is there any reparing the pump or is my only option a new one.
Any updates?

As hard as he's saying it's starting. And not doing anything I can't see it being the VP44. It seems when the VP44's are going out they do mildy hard starts, low power, dead throttle, idle power at start up, misfire, etc.
 

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Discussion Starter #7
Hard start- More info

Ok, sorry for the delay. I do have some more info. Checked to see if any codes were showing and there are none. I noticed that this issue started when the truck was at 1/4 tank of fuel and seem to get harded to start everytime I shut it off, but like I said it ran fine once it starts. So I went to the gas station and filled the truck up and it is starting fine now. So the only thing I can think of now is that maybe it is a problem in mounting the pump to high or to low causing the intake line on the pump to drain back down into the tank when the fuel gets to a certian level creating an air pocket in the line.I mounted the pump on the underside of the bed frame like the instructions showed. I installed the larger pick-up tube in the tank, but I am positive that it was low enough (about an 1/8 to 3/16 from the bottom). So now I am just wait to run the fuel level down again ad see if the problem starts again, and then maybe call fass and see what they say.
 

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Discussion Starter #9
Yes I do believe that it is an air issue from the inside of the tank but I just dont understand how its getting in the line. All the fuel lines are new and the new pick-up tube I installed in the tank is new from fass. The pick-up is a steel pipe about 3/8 in size with a thick wall. And like I said the tube is about 1/8 to 3/16 from the bottom. The tanks hold I believe 32 gallons so at a 1/4 tank when the hard starts begin there should still be plenty of fuel in the tank tube keep the pick-up submerged. That why I was leaning to the idea that maybe my fuel pump was mounted possible to high causing the fuel to drain out of the intake side of the pump causing air air pocket in the line once the tank gets to a certian level. If that is even possible?
 

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I doubt it...

You setup is like taking a straw in a drinking glass and filling the straw with water and capping the end with you finger... The water will stay in the straw as long as there is no air leak around.

So it means there is a drain back issue or a air leak...

I would pressurize the fuel tank with 2-3 psi at the most and start looking for leaks...
 

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Discussion Starter #11
Thanks for the advise. I will start looking for air leaks once the tank get low enough for the truck to begin with the hard starts again.
 
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