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My truck never gave me a problem up until about a year ago (99 diesel) and then it became hard to start. I should say it always started, but not until I'd cranked it a while. Took it to a diesel mechanic and all he could do was put a light on the dash to indicate to me if there was any fuel in the system. Said it was what cummins recommended. It gets better when it's warm. But 5 minutes in the parking lot it starts again. Any ideas?
 

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ive got a 99 also that wont start after its warm. truck runs great. 156,000 miles. people on here tell me its the injection pump but i dont think so. been doing this for about a year and a half. still running strong just wont start after i shut it off when warm. starts just fine when its cold. i think it is somethin electrical
 

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Hard to start when it's cold.

ive got a 99 also that wont start after its warm. truck runs great. 156,000 miles. people on here tell me its the injection pump but i dont think so. been doing this for about a year and a half. still running strong just wont start after i shut it off when warm. starts just fine when its cold. i think it is somethin electrical
Well mine is just the opposite: won't start when it's cold. It cranks fast and finally starts then it runs fine. I park it long enough for it to get a little cold, and it's hard to start again. The longer I park it, the harder it is to start.
 

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grid heater

Does it take a while for the fuel sensor that the mechanic put in to come on?

If it comes on right away i would check to make sure your grid heater is working
 

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mine does the same thing, it start wicked hard after sitting for 6 hours or more. Once its running its fine i can shut it off and restart.
 

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have you guys thought about the fuel sending unit ? may be working slow .
 

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Check your fuel filters. Look at the one in the frame rail. If they are clear I would say that it is either the lift pump or injection pump.
 

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longshot7- Verify that your lift pump is turning on when the key is clicked to "on" Mine was doing that, and I think it was a loose connector at the lift pump. It only did the hard start when the lift pump didn't kick on. I caught it doing it. Lift pump is only a couple months old, and I had just done a fuel filter.
 

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im goin threw the SAME problem the i found out my lift pump is leaking down its prime and that means there is air in the fuel so in looking in the market to get a airdog 150
 

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There is a diaphragm inside the VP-44 injection pump that tears and causes hard starting after the engine has been warmed up. In other words, when you first start the truck for the day it will start easily, but then you park it and try to re-start it a half-hour later and find that it won't start at all or it will take 5+ seconds of cranking to start.

If you are having that problem, your VP-44 is most likely on the way out.

To keep from getting stranded just remember this: If you are unable to get the truck started at all, open the hood and open the water separator and drain fuel from the water separator for about 5 seconds. Close the water separator and go start the truck. You will find that the truck starts right up. Take it home ASAP and replace the injector pump.

I have been through this whole process myself last August. I lived with the problem for as long as I could (4 months) until it got so bad that I had to open the water separator for every warm-start, so I replaced the VP-44 and it has run like new ever since. At the same time I also replaced my aging lift pump with a new "improved" stock pump and a Vulcan lift pump relocation kit, and added fuel pressure, boost, and exhaust temp gauges. Everything is still working great 10 months and 25k miles later.
 

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My truck never gave me a problem up until about a year ago (99 diesel) and then it became hard to start. I should say it always started, but not until I'd cranked it a while. Took it to a diesel mechanic and all he could do was put a light on the dash to indicate to me if there was any fuel in the system. Said it was what cummins recommended. It gets better when it's warm. But 5 minutes in the parking lot it starts again. Any ideas?
Baically what Spacehiker said is true... But the cause of it exactly is the lack of fuel pressure. :w:



MINIMUM FUEL PRESSURE AT WOT IS 10 PSI...

Now for you that have just a low pressure light. It is set for 5 PSI which is too late and you doing damage to your VP44 with knowing... I highly suggest you get a fuel pressure gauge and install it... Like shown below...



But Spacehiker is also right about the hard starting too. Once that diaphram is ripped you'll continue to have hard starting till you replace your VP44 pump... Here is how to replace it...

VP44 Replacment

So now that is siad I would suggest a good solid fuel pump like FASS 150 or AirDog 150. Because they have better filters than stock, pump more volume, and both have a lifetime warranty...

AirDog Fuel Pump
 

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There is a diaphragm inside the VP-44 injection pump that tears and causes hard starting after the engine has been warmed up. In other words, when you first start the truck for the day it will start easily, but then you park it and try to re-start it a half-hour later and find that it won't start at all or it will take 5+ seconds of cranking to start.

If you are having that problem, your VP-44 is most likely on the way out.

To keep from getting stranded just remember this: If you are unable to get the truck started at all, open the hood and open the water separator and drain fuel from the water separator for about 5 seconds. Close the water separator and go start the truck. You will find that the truck starts right up. Take it home ASAP and replace the injector pump.

I have been through this whole process myself last August. I lived with the problem for as long as I could (4 months) until it got so bad that I had to open the water separator for every warm-start, so I replaced the VP-44 and it has run like new ever since. At the same time I also replaced my aging lift pump with a new "improved" stock pump and a Vulcan lift pump relocation kit, and added fuel pressure, boost, and exhaust temp gauges. Everything is still working great 10 months and 25k miles later.
Exactly what is happening to mine right now. Put in a new fuel pump in the tank on Sunday. Drove it Tuesday and it quit. I jumped from the fuel relay to the pump. It started and ran until I got it home. Shut it off and went to start it again it wouldn’t start. Let it set overnight it started right up. Drove it shut it off at the store. Came back out and it was hard to start
 

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It's no biggie! Welcome to the forums! 😁
 
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