Hey guys I am having issues with my Cummins I purchased almost two months ago. I am really confused with this thing. It is the long bed, extended cab, so it should have the 35 gallon tank. At a half tank I am at 300 miles. Over the next 80 miles I am down to a 1/8-1/4tank. I was driving highway and should be looking at 18-20 mpg. Last night I parked at a friends house on a slight incline not thinking anything of it because I still had a 1/4 tank, no low fuel lights or anything. When I went to leave the truck fired right up but died seconds later. I went to the gas station and picked up 5 gallons and dumped it in. Still wouldn't start.

Over the past two months I've been filling up roughly at a half tank and only getting 18-22 gallons so I assumed the gauge was mainly accurate. What issues am I having? Its very frusrating?

1. Why is my fuel gauge so wrong? I should have more fuel than what it reads.

 

Do you have an aftermarket lift pump on it?

 

I'm sorry I forgot to clarify, the truck is completely stock as far as I know.

 

In these trucks the fuel level sender is notorious for failing. You may need to replace it.

But it also sounds like the 1/4 tank issue that so many people had with aftermarket LPs a few years ago. That is why I asked if you have an aftermarket LP.

In google type in "1/4 tank issues" and a bunch of stuff will come up about it.

 

I've been reading up on it, a draw straw should alleviate this right?

 

Actually the fuel sender is replaceable.
Mopar1973Man's Dodge Cummins Articles - Fuel Gauge Replacement Sender

As for 1/4 tank issues even with the old school Drawstraw I I don't have any issues. As a Matter of fact I ran into town and just got back home from getting fuel. I was below the 1/8 tank and had the fuel light on.

Drawstraw I and how my is setup.


Zero Problems with 1/8 of tank to near empty.


Also running a AirDog 150.

 

Has the lift pump been replaced before by a Dodge dealer? They come with the lift pump mounted up on the side of the block but the replacement places it in the tank. I have also seen the fuel pick up no longer hold fuel and run out when on an incline or going around turns. It is either that or your sending unit is not acurate. It may be empty and reading 1/4 tank.

 

Thanks for the replies guys, I put 5 gallons in and bumped the starter let the fuel pump run and on the second cycle it started up. Ran to the gas station and filled her up and it took 20 gallons. So all together I put in 25. I still had 10 gallons?

 

Have you hit anything on the road recently that may have smacked the fuel tank causing damage to the fuel pick up? Either way It looks like you are going to be dropping the tank to replace or repair a fuel pick up.