Diagnosing a VP44 Injector Pump Unit – Good or Bad? - Dodge Cummins Diesel Forum
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post #1 of 4 (permalink) Old 07-24-2011, 08:16 PM Thread Starter
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Cool Diagnosing a VP44 Injector Pump Unit – Good or Bad?

Trying to confirm I have a bad pump before unloading $1,000 for another unit.

Pulled off from a stop light, got up to 50 mph for a ¼ mile distance and the motor died. No fire, dead. Pulled OBD II codes and got P1689, P1688, P1689, P1688. Towed the truck home, changed the fuel filter (purchased the truck a years or so ago and unsure of previous service work), bleed fuel at banjo fitting. No fire, dead.

Followed “Blue Chip Diesel” VP44 diagnose procedure;
Full tank of fuel
Lift pump had 11 psi
Removed VP44 electrical plug, 12v across pin #7 and #6. No voltage across pin #5 during “run” and “Start” key positions.

Pulled all injector line off VP44, bleed lift pump a VP44 banjo fitting, connected VP44 electrical plug.
Turn key to run position, lift pump ran, small amount of fuel dribbled out of VP44 injector/port fittings

Turn motor over and fuel a small stream of fuel fired out of each fitting, appears rotor is working as each each fitting/port fired independently in a circular pattern.
The fuel streams shot-out about 4” and fell down. Pushed a gloved finger over fitting/port and easily shut-off or stop fuel discharge from VP44. Is this the Lift Pump 11 psi I am seeing through the VP44?

Any comment or suggestion would be appreciated, trying to avoid a $1,000 misdiagnosed repair, the fuel firing out of the VP44 in a circular firing pattern is puzzling me as the VP44 may not be the problem.

Truck is 1999 2500, all stock, 110,000 miles, past service history is unknown.

Only previous problem that may relate to what I have today is occasionally (maybe 10 times in the last year) the truck felt like the motor died for split second and then recovered while cursing down the road.

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post #2 of 4 (permalink) Old 07-24-2011, 10:51 PM
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1689 is a death code. Be smart and do a P pump conversion.


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Early 04, 6 speed, power everything. Stock. so far.
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post #3 of 4 (permalink) Old 07-25-2011, 10:12 AM
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P1688 is the electronic death code...

P1689 could be just the fuel pump relay being bad or actually a communication problem between the ECM and VP44...

Fuel pressure is too low so more than likely the VP44 over heated and killed itself... Remember the overflow valve STARTS closing at 14 PSI and is completely closed by 10 PSI. So if you had only 11 PSI I bet money the VP44 failed from lack of fuel flow.

As for the output pressure it should of been about 4,500+ PSI if the VP44 was working. But since the pump is brain dead it not pumping.

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post #4 of 4 (permalink) Old 07-25-2011, 01:07 PM
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Not knowing the previous history of your truck means you've done just about all you can to determine if the VP is working or not. It sounds to me like its not. As Mopar1973Man mentioned, your fuel pressure is/was to low. Call Chip at Blue Chip Diesel. His pumps are more expensive but he has a wealth of knowledge about them, he will stand behind his product, and if his replacement pump doesn't fix your problem then he'll take it back. A Blue Chip Diesel VP combined with a fuel pump that can supply 100 GPH of fuel at 20 psi idle / 15 psi WOT through 1/2" fuel lines will keep that VP running for many many miles.

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