Engine/Transmission (1994 - 1998) Fuel leak/lack of power/black smoke. Related? What is the major malfunction??

[SPearson]

Hi, I am having a few issues with my truck. 96 12v, auto. I just replaced the serp belt , water pump and thermostat. My issue is I don't know that much about the fuel system.

1. the truck will die if left in (automatic) drive when coming to a stop/ idle really rough and rpm drop.

2. Lack of power/black smoke(small puff) at lower rpm most visibly, high rpm too.

3. Rpm/shifting gears the truck loses lots of power and the rpm drop.

4. Fuel leaking right above the starter out of a knuckle looking part. (About 4" above the starter, not the fuel filter) about a drop every second in park/idle. If in park and I raise the idle to 2500 rpm, the dripping stops.

5. I replaced the fuel filter and no difference.

6. When I towed a 10,000 lb. load for 250 miles and disconnected the trailer, the truck ran A LOT better for 5 miles... almost like the weight load cleaned something out. i. e injector. Then it went back to running like crap.



If anyone has a repair idea for me, please let me know. Thanks!!

 

[SPearson]

Joe George thinks it's the fuel heater. It seems he may be right since the truck does not like to start if it's really cold outside, parked uphill, or if it sits for 2 days.
Ideas?

 

[GOlsen]

Could be the lines going to the lift pump? Although, you usually can't see a leak because it will start sucking air in. Usually you end up with lack of power and white smoke though. It could also be the fuel heater, it's in a similar area, a little more towards the front of the truck. Is there any way you can take a picture and post it up?

 

[Flying_gage]

Just posted about this. A lot of the same issues as I was experiencing. My truck had 5-6 leaks from the top of the tank to the back of the lift pump. I would also recommend buying a Vulcan draw straw if you are gonna replace the lines. All told it was a little over $70 to do everything.

The truck runs better in general. But I noticed a huge difference loaded. With a jeep on a trailer and a full bed of junk, (prolly about 6500 pounds). It ran significantly better!

 

[SPearson]

Could be the lines going to the lift pump? Although, you usually can't see a leak because it will start sucking air in. Usually you end up with lack of power and white smoke though. It could also be the fuel heater, it's in a similar area, a little more towards the front of the truck. Is there any way you can take a picture and post it up?

I can't get a good pic, I tried. It's leaking about a drop per 1-2 seconds at idle a few inches directly above the starter.

Any ideas? Thanks in advance.

 

[GAmes]

Read Joe G's fuel system write-up. I'm sure you will find the answer there.



Joe G's fuel system writeup - Dodge Cummins Diesel Forum