Engine Stutter's and won't accelerate

[moposcar]

My 03 suddenly started stuttering and wouldn't accelerate. It had been running fine, but when I went to take off from a stop sign, it wouldn't accelerate and would violently rev up to around 2000 rpms then drop to 1000. If I let off the throttle it would idle fine. I legged it 20 miles home doing 35 mph at the most and just barely giving it throttle. The engine basically surges up and down if you give it throttle. In park it will go ahead and rev up.

I think it is the throttle position sensor (not sure correct term), but there are no engine codes being tripped. I replaced the lift pump (behind the filters) a couple of years ago and it isn't acting anything like that. Truck has been harder to start as of late, but that seemed like a dragging starter.

I've read the other posts on this, but mine seems different. Am I correct to start at the sensor?

BTW the truck just rolled 300,000 this week.

Thanks,

 

[AH64ID]

With it not accelerating in conjunction with the rev to 2000 I suspect you have a transmission issue.

 

[moposcar]

I had a new transmission installed 2500 miles ago

 

[AH64ID]

Even more reason to suspect it.

If the engine rev's and doesn't accelerate that's not an issue with the engine.

 

[moposcar]

Went to my parents and checked my truck, it started and I drove it to my shop. Changed the fuel filter in it and I couldn't hear the lift pump coming on to fill up the fuel filter. It was bad, so I put a new lift pump in and everything seems to be ok now. I probably need to get the FAS pump and do away with the stock one.

MY throttle has slack in it, and I am wondering why. I can move it 1/2" (at pedal) before the it makes the throttle on engine move.

 

[AH64ID]

Went to my parents and checked my truck, it started and I drove it to my shop. Changed the fuel filter in it and I couldn't hear the lift pump coming on to fill up the fuel filter. It was bad, so I put a new lift pump in and everything seems to be ok now. I probably need to get the FAS pump and do away with the stock one.

The symptoms you described do not indicate a lack of fuel flow, so hopefully your issue is fixed and will not return.

Are you still running the engine mounted lift pump? If so I would upgrade to the OEM in-tank pump, it's the most reliable pump you can get.. much more so than AD, FASS, or the engine mounted pump.

 

[CharlesinGA]

Went to my parents and checked my truck, it started and I drove it to my shop. Changed the fuel filter in it and I couldn't hear the lift pump coming on to fill up the fuel filter. It was bad, so I put a new lift pump in and everything seems to be ok now. I probably need to get the FAS pump and do away with the stock one.

MY throttle has slack in it, and I am wondering why. I can move it 1/2" (at pedal) before the it makes the throttle on engine move.

This doesn't make sense. There is no throttle on the engine on an '03. The throttle cable passes thru a grommet in the firewall, is anchored with a push in anchor to the plastic wheel well shroud, and terminates at the throttle position sensor on the underside of the LH battery box forward of the temp sensor.

I installed the Mopar in tank fuel pump kit last year. It was a modest amount of work but not too bad. Removed the bed of the truck and changed out the pump, installed the relay kit on the back end of the LH battery box, and removed the LH wheel well shroud to get access to the wire connector to pin in the additional two wires. The harness on back under the floor to the tank has the additional wires already (same harness as a gas engine).

The instructions call for doing some programming with the DRBIII system at the dealer (I think it only changes the model specification of the engine) but I am yet to find a dealer with a working DRBIII in the Atlanta area. Either they do not have the system, or it does not work, that is the story I always get.

Fass pump is loud, (a friend had one), and I bought one, but on a 2wd it cannot be installed as per the instructions, so it sits on my workbench and I punted and got the Mopar in tank kit.

Charles

 

[moposcar]

I agree it didn't act like a low fuel issue. That is why I thought it might be a throttle sensor issue because it wouldn't respond to my throttle imput.

It is hard to describe it, but when I said it would rev up, it would rev a little, then quit and act like it was going to die, then pick back up. The last time the pump went out, it just died like the old gas engines with a carburetor. It stuttered once or twice, I gave it gas, it picked up for a short while and then died. This time it didn't do that and would actually start after sitting. But the pump wasn't working.

I just installed the pump on the back of the fuel filter bowl....I thought the FASS system was the way to go? My 05 has one on it, and it seems to do OK.

 

[AH64ID]

Lots more reported issues with aftermarket pumps than OEM in tank pumps. There isn’t a benefit for the aftermarket pumps unless you need the flow for power, but at that point your goal is power and not reliability.

Reving a little and quitting sounds like a fuel pump, but you said it would rev to 2000 and not move… that’s very different. One points to a fuel issue and the other to a transmission issue.

The CP3 can suck fuel on its own, but a fuel blocking failure can keep that from happening. That’s more common with the engine mounted pump than the intank, but it can happen to both.