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My nightmare trip and now a problem.


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Hi all,

I need some guidance, but first my story how the problem came to be.

The first part of September we went to the midwest (Iowa) from Utah with a 2700lb camper in the back. Truck was running fine.  First stop in Sidney, Neraska I noticed what looked like a large wet spot on the drivers side rear wheel well cover.  Looked like I ran through a puddle, but no rain or puddles insight.

Checked under the hood and did not see any problem.  Checked under the truck in the morning and no leaks or spots on the ground.  Ok so far so good.

Next stop in Lincoln, Nebraska and the wet spot had just about disappeared.  Got to Altoona, Ia. and still ok.  The weather all the way there was good..

Left Iowa on the 3rd and the wind was very bad.  Truck was bucking a head wind all the way to Kearney, Nebraska.  Stopped for the night and looked at the rear wheel area again.  Major wetness there and front wheel well also.  More checking and discovered diesel fuel had been spraying all over.  Drips on the ground from the fuel under the frame and engine.  Looked under the hood, started the engine, had the wife rev the engine while I looked for the leak.  Nothing!!!  Still 700 miles to go to home. Now what?  I guess find a trusted shop in Kearney to look at it. 

Friday the 4th.  Mechanic took over an hour and a half trying to find the blasted leak.  Finally found it.  I was coming from the middle of the back of the VP44 where the little button or electrical connector is located. You could see it just barely blowing bubbles.  I guess the added workload from the headwind made it leak that much better.  VP44 bad, one available in the area.  He started taking the old one off to get ready for the replacement.  Got a call from his supplier, the employee he talked to was wrong as he sold the last one and just shipped it out. Should have one in by the 9th.

Great, labor day weekend, stranded, no place to go, no VP44!  Got towed to a campground to spend the weekend. The old VP44 had 1 month left on the warranty and only 4000 miles on it, but I had no way to get a replacement for the defective one and no way to replace it myself.  Ate that one.

Fast forward to the 9th.  Got a new one (rebuilt of course) and we were on our way ( A lot poorer though).  Started great, ran fine at freeway speeds, but I noticed a little miss at idle when we stopped for the night.  Started fine the next morning, but still had an occasional miss at idle.

Made it home ok.  Still had the miss at idle.  Been busy with doctor appointments and such so the truck just sat in the garage.  Went out yesterday,  started the truck, still had the miss at idle.  Not normal so I checked for codes and the P1690 showed up.

I just know enough to be dangerous without a little (a lot) of help. 

What could it possibly be and what is the best way to fix it?

 

 

99 SLT 2500 Ram, 71676 original miles, fuel boss, 4 gauges, all the rest stock.

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DTC P1690: FUEL INJECTION PUMP CKP SENSOR DOES NOT AGREE WITH ECM CKP SENSOR

 

Monitor & Set Conditions

Fuel Injection Pump Crankshaft Position (CKP) circuit is monitored when ignition is on and engine is running. DTC may be stored when no signal exists within specified window parameters with no Camshaft Position (CMP) sensor or CKP DTCs present.

 

Possible Causes

  • AC Noise Across Fuel Transfer Pump
  • Other DTCs Present
  • Wiring & Connectors
  • Fuel Injection Pump Static Timing
  • Fuel Sync Signal Circuit Open
  • Fuel Sync Signal Circuit Short To Ground
  • ECM

Testing

1. Measure AC noise to ECM by connecting DVOM between ground and terminals No. 48 and 50 (Red/White wires) at ECM harness connector. If AC voltage is 25 mV rms or less, go to next step. If AC voltage is greater than 25 mV rms, replace fuel transfer pump. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.

 

2. Turn ignition on with engine off. Using DRBIII® scan tool, check for DTCs. If no additional DTCs exist, go to next step. If any additional DTCs exist, repair other DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .

 

3. Using scan tool, check Good Trip Counter for DTC P1690. If Good Trip Counter for DTC P1690 is displayed and equal to zero, go to next step. If Good Trip Counter for DTC P1690 is displayed and not equal to zero, go to step 5 .

 

4. Turn ignition off. Disconnect FPCM harness connector. FPCM harness connector is located on end of fuel injection pump. Check for poor connection/terminal contact at FPCM harness connector. Repair as necessary. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for poor connection/terminal contact at ECM harness connector. Repair as necessary. Using DVOM, measure resistance of Dark Green wire between terminal No. 8 on FPCM harness connector and terminal No. 18 on ECM harness connector. If resistance is less than 5 ohms, go to step 7 . If resistance is 5 ohms or greater, repair open in Dark Green wire
between FPCM and ECM.

 

5. Turn ignition off. At this time, conditions required for DTC to be stored are not present. Inspect wiring and connectors between FPCM and ECM. FPCM is located on top of fuel injection pump. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. If no problems exist, go to next step. If any problems exist, repair wiring or connectors as necessary.

 

6. Check fuel injection pump timing. See CHECKING FUEL INJECTION PUMP TIMING under FUEL INJECTION PUMP TIMING in ON-VEHICLE ADJUSTMENTS - RAM PICKUP - DIESEL article. If fuel injection pump timing is okay, go to next step. If fuel injection pump timing requires adjustment,
adjust fuel injection pump timing as necessary.

 

7. Ensure ignition is off. Disconnect FPCM harness connector. FPCM harness connector is located on end of fuel injection pump. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Using DVOM, measure resistance between ground and terminal No. 8 (Dark Green wire) on FPCM harness connector. If resistance is 5 ohms or greater, replace and program ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If resistance is less than 5 ohms, repair short to ground in Dark Green wire between FPCM and ECM.

Copied one of mopar1973mans responses to another member. Couldn’t find out how to just copy link. 

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  • Board Of Directors

You should be keeping good fuel pressure between 15 and 19 psi to keep the VP44 healthy and not cause slow death or premature wear. Also be running some 2 stroke oil in the fuel, around 1 ounce to the gallon, to reduce the scoring caused by the ULSD fuel we have these days. The VP44 injection pump was designed around the higher lubricity fuel we had back when they were being installed on the 24 valve Cummins. 

 

A couple questions;

Is the old lift pump or the in tank fuel pump still in the tank?

 

Do you have a fuel pressure gauge?

 

Have you ever removed the fuel module in the tank to see if the screens are clogged?

 

Did you try clearing the codes?

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Sorry, I know the post was a little long, but my question was in the last part of the post.

Truck ran fine until the new VP44 was installed.  I didn't notice the slight miss until I stopped for the night 350 miles away.

Not sure which part of the testing I should start with.

I have a fuel boss mechanical fuel pump, I use 2 stroke oil, I have all the gauges. Fuel pressure 17 psi.

Had no codes until new VP44.

Haven't cleared codes yet.

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Remove the breather on the front of the engine. The pump gear is behind it. With a mirror look and see if the key is engage with the notch in the gear and the pump shaft. Also the key is directional. If put in backwards it can throw the timing off. You would have to pull the pump to check that one.

Edited by dripley
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  • 4 weeks later...

Had to give up and take it to a trusted mechanic.  He found that the new VP44 was bad.  Ohm reading from the electrical on the pump was open thus the P1690 code.  Timing wire bad.

Waiting for a replacement or repair from the place in Nebraska.

3 weeks later and I still have no truck.  :cry:

  • Sad 2
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