Loss of throttle

[leon]

Yesterday I was coming home from a trip to the hunting property.  Truck was running fine and then I hit a railroad track at 60 mph, when all of a sudden the engine got loud (valves seemed to clanked louder than norma) and I lost some throttle power.  I never lost total power, just the majority.  I could press the pedal 2/3 of the way down but didn't have much power.  If I floored it, it downshifted hard and threw the rams up, but I didn't want to run it like that so I didn't do it but once.  Other than hitting the rr track pretty hard, the only thing out of the ordinary was I filled up with fuel a few hours prior.  I had a quarter tank prior to refueling (water in fuel possibly??).  I limped her the rest for the 45 miles home and made these observations:

1.  90% of the time if I let off the throttle, the depressed the throttle I would regain full power, sometimes for a short period, sometimes for several miles.

2.  Oil pressure and temp were normal.

3.  Auto trans was half a quart low so I topped it off.

4.  No leaks or loss of fluids.

Starts with no issue, however since I bought this truck in December it takes a while for the wait to start to come on.  Another member here said that is indicative of the ECM going bad (could this be related??).

I still don't know why it won't appear in my sig, but this is a 1999 3500 QC 4x4 CTD with 337,000 on the clock.

 

[Mopar1973Man]

Need to read error codes and report back your error codes. Then also check fuel pressure and report back both idle and WOT fuel pressure.

[leon]

Check engine light never came on. Will there still be error codes?

[dripley]

There can be. Not all codes will trigger the CEL.

[leon]

Ok, I'll either run it by Advanced Auto parts or see if I can borrow one. 

[leon]

P1693 is the only code that comes up. 

Now we have P0216, P1693, P1698 coming up. 

[Me78569]

 p0216 is almost always the vp44.  Do you have good lift pump pressure?  

 

Sorry to say dead pedal plus p0216 means a vp though

[dripley]

Not good at all.

[leon]

What's the best reliable and economical replacement for the vp44? Truck is bone stock. 

[Me78569]

DAP sells a good vp44.  

 

There are only a handfull of test stands out there to actually rebuild them so the likeliness is most pumps out there came from the same place.

 

Get one for under $1050 that has a good warranty and beat on it HARD for a month.  If it is gonna fail, as a result of a bad rebuild, it will do so in that timeframe.

[leon]

Wanted to add the truck starts with no problem. I thought I read somewhere a sign of a bad vp44 was hard to start. It's certainly weird the problem started as soon as o hit that bad/bumpy rr crossing at 65mph. 

[Me78569]

Try going over all the wiring to the ecm and vp44.  Use dielectric grease on ALL plugs

 

The p0216 literally means the ecm asked for xx.xx* of timing, but the VP44 could only give yy.yy* of timing.   Since this happened when you hit a bump my guess would be that there was some crud in the fuel system that got dislodged when you hit the railroad tracks.  This got into the timing piston and caused the issues.

 

 

there is not sure fire bad vp44 only happens with x y and z.  Rather you pick out common issues, if you have enough of them then the vp44 is the likely source.  

 

Do you have white smoke when you have low power?  

 

 

Another concerning thing is the WTS light not coming on as soon as you key on.  The WTS light coming on is the ECM "booting up" .  if that doesn't happen right away the ecm is on the way out.

[dripley]

There is some good diagnostic info on Blue Chip Diesel's web site if you to go a little further with diagnostics before buying a VP. It is worth a look.if you are interested.

 

When my OEM failed it failed different than most all of the failures I have read about. Did not know much about them back then and it was still under warranty and Dodge got to buy that one.

Edited August 30, 2017 by dripley

[leon]

Got a buddy bringing a fuel pressure gauge tonight and we're gonna see what we get. What would normal pressures be?

 

[dripley]

We here pretty say a minimum of 14psi at WOT. That allows the overflow to open fully and circulate the most fuel for cooling the VP computer. I believe if you go by the book you should see 10 psi at idle and maybe 5 at WOT. There have been a lot failures due to low pressure and that is where 14psi at WOT comes from. Hard to say what you will see on yours, depends on the fuel pump. The block mounted OEM pump and the in tank pump are both know to be crappy. I personally have an ADII165 on mine and run it at 18.5 psi at idle and sometimes I can pull down to 14. A lot us also run 2 stroke oil in the fuel at 1oz per gallon to help lubricate the VP. Fuel is the only lubricant that he VP internals see. Here is some further info.

 

[leon]

Yeah, I've been running TCW3 2 cycle in just about every fill up since reading that was best for lubricity.  However I bought the truck with 300k on her so I know the previous owner wasn't doing the same.

My lift pump is on the frame.  I may pick up another one, switch it out, and blow out the lines depending on what the fuel pressure gauge says.  It's a hell of a lot cheaper than the vp44.  I called a local diesel shop to see if they sell rebuilt vp44's but they haven't called back.  Is that a bad idea?

[Mopar1973Man]

15 minutes ago, leon said:

 I called a local diesel shop to see if they sell rebuilt vp44's but they haven't called back.  Is that a bad idea?

 

First off if you do get ahold of them find out the source of where they get them at. Then check my list in the article section to see if they are certified Bosch rebuilder of VP44s. Too many people claim to be rebuilders but don't carry the Baosch 815 Test stand for calibration of the PSG unit on the VP44. It takes about 3 hours of run time on the Bosch 815 test stand to get the PSG flashed. Yes you could rebuild pumps without flashing which a lot of shops sell rebuilt VP44's with used PSG's which is a gamble.

[leon]

At idle under a load fuel pressure is about 11 lbs.  At 60 mph/2000 rpms fuel pressure was about 2-3 lbs. When it acted up and I got dead peddle fuel pressure went up to 4-5 lbs.

The 2000 rpms is strange.  That seems a little high for that mph. 

[dripley]

 No need to be under a load at idle, just crank and see what you have. The bad one is 2 to 3 while cruising. Probably near 0 at WOT. Have you changed the filters? The pump could be shot also. Do you know what brand of pump it is? Is this pump using the factory fuel lines? If you are going to replace it also DAP usually has some good combo deals on VP's and lift pumps.

 The pump pressure you are seeing while cruising is low, very low. Mine will run at about 17 psi cruising, but stomp on it and its only down to 14.5. You get down to less than 14 and your getting less and less fuel for cooling the VP. The lower it gets the bigger the strain on the VP.  

 I have to agree with @Mopar1973Man on the pump. Get a VP from a reputable dealer. It  is expensive enough doing it once.

[leon]

Am I missing something, but if the VP is getting less fuel, would that not be a lift pump failure?  Meaning a bad supply to the VP?