[tklefler]

OK, I have read alot of threads on here and to get to the point my truck just won't start. Cranks forever, but won't start. Looking for suggestions. So heres the story....
Thought the VP44 Pump finally died, when changing fuel filter, i always just fill the canister with fuel after replacing it and it always starts right up. This time it did not. but just as it fired once i turned off the key and has never fired again.

It is a 99' 2500, 4x4, Cummins, Manual Transmission.

So i replaced the VP44 with a new Integrity Pump from Thoroughbred Deisel and while at it i installed a new Air Dog FP100 Lift Pump.

Still will not start.

Here is what i have checked and can say...

1) The Lift pump works fine, getting 15psi (have guage on it) and it is cycling correctly.
2) I have power at pin 7 of the VP44 (12.23V)
3) I have ground at pin 6 of the VP44
4) Pin 5 does not have power during run or start position of key, but doesn't have power for the 3 seconds it should when the key is turned off either.
5) I have switched the fuel pump relay with the horn relay
6) Bigggy,,, I have NO codes.
7) I have cracked 3 of the injectors (1, 3, 4) and I get no fuel out of any of them
8) I have completely removed the old filter/seperator canister, since put in the Air Dog.
9) I have a new Overflow Valve on the return line that came with the new pump.
10) i have the Super Chip Mileage XP program in it, so i cleared the program and reloaded it.
11) I have fuel at the VP44 from the pump, i pulled the quick disconnect from the Liftpump and it filled a canister before the pump stopped cycling.


Only thing i have not tried is to power pins 6 & 7 of te VP44 with the connector removed and see if it would start and idle and have not tried shooting ether down the intake. I will try this tomorrow.

Thanks for reading and hope you know something i don't

 

[Off-road]

try hot wiring the vp, if it will not start then, the vp is junk.....

btw, i wish you the best of luck with that airdog, search on here about them, they arent having too good of luck lately..... mine went out once already, and has only been on the truck about 1.5 years and 15k miles.....

 

[thumper 549]

Bleed your fuel filter, (crack the fitting at the top of it and run the lift pump until bubbles are gone)
loosen up the injectors and crank it for 30 sec .
Do that a couple times. (let starter cool off )
You should see fuel leaking at the injectors.
As soon as you do, slightly snug the injectors .It will fire off. Tighten things up.

 

[tklefler]

Sorry for late follow up guys. Thanks for the advice on the issue.

I went out this morning and had to hook up another truck for power as the batteries are now dead due to the amount of cranking and discharging them.
But once that was done, I cracked open all the injectors but 2 & 6 as they are very hard to get to. After 3 cycles of cranking for 30 seconds then waiting 2 min. For starter to cool, finally injector 5 spurted fuel, then 1 the 2 & 3. Before I got 2 & 3 locked the truck was running.

Thanks again for the advice!!

 

[thumper 549]

Generally just open the ones most EZ to get to .
Generally - you have to do that every time you change a Fuel filter.

 

[Off-road]

thankfully i havent had to do that every time i change mt=y filters, but, VERY IMPORTANT BUT TOO, i have canister filters, not a cartridge filter. i prefill them and then have no issues with air in lines.....

 

[island8]

Try Hotwireing the vp, directions are on blue chips website.

 

[bigfish95971]

Do a full bleed through injectors as thumper said above. Charge batteries first.

 

[thumper 549]

Always take the time to purge the air from your new F.filter, Or it becomes a bigger fight.
I have a manual over ride switch to the lift pump. I run it it as long as i want.
I open the top vent in filter and weight till i get fuel. Then weight a couple min also screw the vent in a couple turns.
Run the pump till bubbles quit or mostly quit..close it
The crack the injectors.Etc

 

[tklefler]

Thumper529, the manual override switch is a great idea, but why break the fittings. Wouldn't air be returned to the tank through the return line from the VP44? I would think the VP44 and the lines between pump and injectors would never lose prime.
Thus you could use the manual switch to purge all air before starting. Does this make sense?

 

[thumper 549]

IDK - air rises to the top? I have a stock fuel filter so it is quite EZ.
If i do not crack the top i notices the air just gets compressed ..Because if i wait whilest lift pump runs then open I get a Hissssss.
Works for me.

(Mine always looses the prime on fuel filter change out) I do not see how it could not.

 

[Off-road]

ive always had good luck changing the filters and refilling the canister/filter with fresh fuel, then starting and let idle. the air will usually work itself out.

 

[tklefler]

Off-Road, had same success in past, until This last change, it fired and died on first start, then never fired again. Fried rthe VP44.

Thumper 549, it is possible the return line only returns fuel when engine is running or only at a preset pressure. I know there is a "overflow valve" at the return line banjo.

Well, it is running and the issue was air in the lines between the pump and injector. Bleeding them fixed it, lesson learned

 

[Off-road]

what lift pump are you running? both tk and thumper

 

[thumper 549]

I have a genuine cummins Lift Pump still on the side of the block. 175K on it and 9 pounds of thrust . it used to be at 16 lbs! LOL
Time for a new one.......and so the money continually flows out my walllet past this trk.
I think Cummins is about 10 grades above the Dodge POS.

 

[tylerallout]

When I change mine I normally just put new filters on the Airdog and then bump the starter to get the lift pump to run twice and it is good to go. So far I haven't had a problem with it, same when I drain the water separator.

 

[Off-road]

thumper if your below the 10 psi threshold you should seriously seriously consider a new lift pump. the common thought is anything less then 10 at WOT full load is hard at the minimum on the vp44. and anything less then 14 psi is thought to contribute to the early failure of the vp44, as the electronics are not receiving adequate cooling.....

 

[thumper 549]

Basically you can up and up the pressure but at some point there is no more volume.
The electric board on top needs to have a continuous flow across it to cool the one transistor that blows.
If the pressure never drops to zero then there is excess flow, or at least enough to return to tank.
A VP will run with out a lift pump, but it kills the transistor on the board.
I have 270000 miles on a stock VP ....its hard to argue with success .
There is do it right , Kill, and over kill.
Yes i will replace the Lift pump...next summer. In the warmth

 

[Off-road]

Basically you can up and up the pressure but at some point there is no more volume.
The electric board on top needs to have a continuous flow across it to cool the one transistor that blows.
If the pressure never drops to zero then there is excess flow, or at least enough to return to tank.
A VP will run with out a lift pump, but it kills the transistor on the board.
I have 270000 miles on a stock VP ....its hard to argue with success .
There is do it right , Kill, and over kill.
Yes i will replace the Lift pump...next summer. In the warmth

true it is hard to argue with success... but, thats where the big line kits come into play. they flow the volume of fuel to the vp44, thereby allowing it to actually return fuel to the tank from the vp44 before the injection cycle. this extra flow is what is actually cooling the vp44, as the returned fuel is cooling in the "heat sink" of the fuel tank. therefore you may actually get even more mileage out of the old vp without killing it.

 

[thumper 549]

Is the fuel line 1/4 inch? (ID)
What ever it is - pressure and volume do not equal linear results.
Volume is necessary commodity to carry the heat away from that pesky transistor.
The whole problem is is the residual after shut dwn.
No matter what the volume is, it becomes a "was" as soon as the key is turned off.
Even with a lift pump running as in "hot wired " the way a VP is built, fuel will not enter there and go back tot he tank according to "blue chip" as they have tried.