Random Momentarily loss of power

[Vinster_Beta]

I have a 2001 Dodge 2500 5.9l that is stock other than a Predator mechanical fuel pump that I have recently put on. I have had the issue even before I've done any work to the truck of there being brief second of no power and then returning like nothing happened. I will be driving normal (Smooth accelerations) and every once in a while the truck will loose power and go back to normal in a matter of a second. I've always thought it was a problem with the stock lift pump on the side of the motor so i recently replaced it with a predator lift pump and haven't seen it run below 14psi. But even after I did so it still does this intermittent loss of power issue. It can vary from every other ride to weeks between cycles. I have no codes or lights on the dash and am starting to think it might be the VP disagreeing with me and wanting to quit. I have no tunes or anything going on with it and I tried resetting the APPS and nothing has changed it. Only other thing I could think of is air or suds making its way to the Injection pump every so often. Anyone have any thoughts?

[Haggar]

Vinster,

 

It will drive you nuts.   There are so many things it could be.   ECM, VP, or it could be like you said, slugs of air, or random limp mode from the map....

 

My brother's truck did this.  Eventually it got worse and eventually cold start/cold driveablilty issues.  All without a single code.  The VP was the culprit, but extremely hard to diagnose and I don't suggest you just replace yours until you have exhausted other means of diagnosis.  

 

GL

Hag

[Vinster_Beta]

I haven't had very many starting issues or cold start issues yet, other than the very occasional ( One every month) where I will have to hold the Ignition longer or hit it twice. Which I always thought it was fuel slowly draining back to the tank. Hasn't prevented daily driving or anything so I haven't bothered with that. Figured it was an old diesel truck thing. Wondering if its something simple like the check valve or something

[Haggar]

Vinster,

That sounds like what you suspect.  Slow drain back.   For long sits, I bump the starter just enough to energize the pump for the 30 seconds or so.  shut it back off and wait 30 seconds or so and start normally.

 

For my brother's truck there were many years(3-5) between the random power losses and the final poor cold start/driveablilty problem.   After the poor cold performance (some see it as a poor hot start/hot driveability) we checked closer and swapped ECM PCM (from my truck to his) etc and the problem stayed with his truck.  So we shotgunned and changed VP.

 

GL

Hag

[dripley]

I have experienced this bucking along with some dead pedal issues many years back on mine. The only issue that could found was low fuel pressure from the in tank pump that Dodge put on mine. I fixed that issue and the problem went away. I dirty fuel can cause it also. If yours is old replace and see what happens. 

 

Like @Haggar says above above there is no fun chasing some of these issues that present no codes. Work the easy stuff before thinking about the expensive stuff.  

[Vinster_Beta]

2 minutes ago, dripley said:

I have experienced this bucking along with some dead pedal issues many years back on mine. The only issue that could found was low fuel pressure from the in tank pump that Dodge put on mine. I fixed that issue and the problem went away. I dirty fuel can cause it also. If yours is old replace and see what happens. 

 

Like @Haggar says above above there is no fun chasing some of these issues that present no codes. Work the easy stuff before thinking about the expensive stuff.  

Agreed, when I put the new lift pump system I did verify that mine didn't have the in-tank pump on it but I haven't bothered to drop the tank and check screens if the pickup unit has any. Tempted on maybe adding a Fuel sump or see if I can find an aftermarket filter setup to rid any air that could be getting into the system. Was trying to avoid using a sump in fear of it either leaking or getting knocked. I figured the stock filter system would had done a decent job of riding the system of air but i could be wrong. 

[dripley]

6 minutes ago, Vinster_Beta said:

Agreed, when I put the new lift pump system I did verify that mine didn't have the in-tank pump on it but I haven't bothered to drop the tank and check screens if the pickup unit has any. Tempted on maybe adding a Fuel sump or see if I can find an aftermarket filter setup to rid any air that could be getting into the system. Was trying to avoid using a sump in fear of it either leaking or getting knocked. I figured the stock filter system would had done a decent job of riding the system of air but i could be wrong. 

It would drop the tank and see what those screens look like. If its the oe fuel basket that could the be issue. It would be a not so difficult thing to check. I would even consider taking those screen out and just put an inline filter before the lift pump that is easily changeable. The filter was speaking of was the one on the engine block. 

[Vinster_Beta]

27 minutes ago, dripley said:

It would drop the tank and see what those screens look like. If its the oe fuel basket that could the be issue. It would be a not so difficult thing to check. I would even consider taking those screen out and just put an inline filter before the lift pump that is easily changeable. The filter was speaking of was the one on the engine block. 

I guess I'll start with that this weekend and see what Horror stories if any surface from it, and yea, the filter on the side of the block is what I was referring to as well

[wil440]

I have an Assassin mechanical pump with a drawsraw in the fuel basket for supply, easy to do with the tank dropped

[Vinster_Beta]

So I checked the screens and to my surprise the had hardly any particulates on it, at least not enough to cause any issues. I guess next cheaper solution would be is to swap out the drawstraw for the bigger aftermarket version. The truck still uses stock fuel lines back to the tank. I guess I'll plan on swapping those out for bigger lines and see if the extra volume could help.