I was wondering if somebody here could tell me how and where to hook a test gauge to check fuel pressure. The truck is a 2001 and only has 59000 miles. The check engine light is on, and reading with a scanner I'm getting a code of P1688. If I turn the key on and off, I get P1693 on the dashboard. Truck seems to be running ok. My father bought this truck new, so the mileage is correct. Any help or suggestions are appreciated.

 

vp44 is toast!

 

Hopefully, the fuel pressure supply from the lift pump to the injection pump has remained above 5psi. Before running it any further, I would put a test gauge on it, or better yet, install A-pillar gauges for fuel pressure, EGT and boost pressure.

Also, before replacing the pump, I would pull the electrical connector off the aft end of the VP44 fuel injection pump, spray both sides with electrical contact cleaner, blow it out dry with an air hose, apply dielectric grease, reconnect and hope for the best. This eliminated VP44 failure codes on my truck due to dirty contacts.

 

You might read thru here or use the search function:

https://www.dieseltruckresource.com/...dation-316280/

 

1st clear all codes. There is a Schrader valve on the driver side of the VP-44 pump, hook up a fuel pressure gage to that, cycle the ignition (bumping starter over with out starting engine) to get the Lift Pump running, if it is still OEM the lift pump is on the driver side lower rear of the engine, bolted to the block! You need at minimum 5psi, preferably 10+psi to the VP-44, if you have the 5+psi start the engine, take another reading, it should maintain 8+psi, (for OEM crap) if it drops below 5psi and stays there STOP engine, you can also replace the fuel filter, when these clog up it blocks ALOT of fuel flow to the VP-44. With a new fuel filter try all the above again, if you still have low pressure replace the OEM/stock lift pump. There many aftermarket lift pumps to choose from most are frame rail mount and not cheap but much better than the stock lift pump. Try all the above before condemning the VP-44. Good Luck!

 

On a 2001 24valve the lift pump is on the block and not in the tank?

 

Yes

 

Unless the poor owner was convinced to "upgrade" to the in tank pump by a dealership............

 

Yeah, that.

 

Thanks guys! I hope it hasn't been converted, I've owned it since it had 4,000 miles on it.