Power loss

[Bernie]

I have a 202k mile 2003 Dodge Ram 2500 CTD HO 48RE Auto, stock except for a few transmission durability mods. Original injectors, lift pump, and a new turbo before I bought it around 90k.



This winter I started having cold start problems. The general consensus is it needs injectors. As it is now warm, it is still getting good mileage, and it is starting fine, I decided to delay that job until October when I have the time and the funds.



Thursday I started noticing an odd power loss. When driving (steady throttle) the poser seems to drop in and out, kind of like it is running out of fuel. RPMs stay about the same or drop (so it is not a trans problem). It got worse today.



As it is a stock lift pump with 202k, I replaced that tonight. I figured it had symptoms like running out of fuel, it must be running out of fuel because of a lift pump problem.



The new lift pump did not resolve the problem. I have no codes (that my generic obd reader can read).



What is my next step? Could be as simple as the throttle position sensor? Crank sensor? Is there a good procedure to test those sensors?

 

[Bernie]

A friend connected his smartphone OBD reader, and I am fairly confident the throttle position sensor is good.

We tracked data we thought was most likely to be the problem, and when the power loss occurred the engine load and fuel flow both dropped to zero.

Then, a new problem occurred. The fuel gauge dropped to zero (with the accompanying low fuel tone and light).

Any thoughts? Thanks!

 

[cerberusiam]

With an 03 and where you live, ECU connectors are a known problem corroding and causing major weird issues with just about any portion of the system. Place to start.



What did you replace LP with? Did you pull the fuel cannister and verify it is not plugged, corroded, or otherwise comrpomised?



Are you monitoring fuel pressure at the CP-3 to rule out delivery problems in the low pressure side?

 

[Bernie]

-I replaced the lift pump with another stock unit from Genos. I figured the original lasted 202k, I should get some good use out of another.
-I replaced the fuel filter when I did that. Fleetguard (as always)
-I did not pull the fuel filter canister at that time, as I didn't see a reason too.
-I have a slight drip from my new lift pump install. Probably not seated 100%. That is not causing the problems (as the old one did exactly the same thing), but I will be pulling the canister to correct that. Do you know of any directions to help with that task?

-I looked over the ECU, and I didn't see any issues that were immediately visible.
-They look quite clean (no corrosion I can see). Where do they typically corrode?

-No way to monitor fuel rail pressure (that I can find) on an 03 through the OBD system.
-I was trying to rule out low pressure side problem with the new lift pump.
-Any other suggestions to make sure the low pressure side is good?

-I read for any codes (there wasn't any). I disconnected the batteries for an hour to reset everything (just in case). No change.

 

[cerberusiam]

I am referring to the tank cannister where the sending unit and fuel pickup is. Its possible there is a problem there if the fuel gauge is wonky and you can trace a low supply side pressure problem.



Easiest way to access it will be pulling the bed. If you have things in the bed that will interfere then dropping the tank is the next step.



Geno's carries an assortement of tapped banjo bolts that will allow monitoring fuel pressure right at the CP-3 hihg pressure pump. Easisest way is get one of those, an 18" grease gun hose. Hook you gauge to the end of the hose as an isolator with the other threade dinto the tapped banjo bolt.



Externally, the ECU connectors will show no problem. The issue is almost always inside the connector block where the pins from the ECU contact the connector fittings. Extremely tough to see if if apart.

 

[Bernie]

Easiest way to access it will be pulling the bed.

You have a promising career in comedy

 

[cerberusiam]

You have a promising career in comedy

Six bolts, a couple wiring connections, a 6 pack of beer, and a friend or 2. Easy breezy.

 

[Mark31]

-I replaced the lift pump with another stock unit from Genos. I figured the original lasted 202k, I should get some good use out of another



My buddy Chris got about 250k out of the original on his 03 and about 10k out of the stock replacement. He now has a Fass "indirect" replacement. Mark

 

[Bernie]

Six bolts, a couple wiring connections, a 6 pack of beer, and a friend or 2. Easy breezy.

Leer cap, bedrug, wiring for in cap lights, warning light wiring, fifth wheel wiring harness (previous owner), all the stuff needs to come out of the bed, etc, etc, etc.



Then, adjusting the leer cap back on correctly, adjusting the door.



The only thing that has me thinking about it is my tank is about 1/3 to 3/4 full right now.

 

[AEdelheit]

I know when the FCA went out in my truck it made my truck
Sluggish , longer cranks and would stumble when driving, died on me 4 times, I don't know an accurate way to diagnose it but at that mileage would probably be a good thing to replace anyways

 

[Bernie]

I know when the FCA went out in my truck it made my truck

Sluggish , longer cranks and would stumble when driving, died on me 4 times, I don't know an accurate way to diagnose it but at that mileage would probably be a good thing to replace anyways

I have no smoke, so I haven't focused on the high pressure side of the fuel system. Did you have smoke with your bad FCA?

 

[AEdelheit]

No more smoke then normal

 

[Bernie]

I just got a check engine light, and I read the codes. I had four codes, all throttle position related.

That covers my acceleration problem. However, that doesn't really address the odd fuel gauge problem the other day.

One poster suggested checking the ECM connections. Any advice on what I might be looking for?

 

[Bernie]

Replace the TPS with one from Timbo. Problem solved. Thanks for the input guys.