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Dr. Hamman
Dr. Hamman, Dodge Technician
Category: Dodge
Satisfied Customers: 6286
Experience:  I have 30 years of Dodge Technician experience. I know these cars in great detail.
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My 99 Dogde 3500 with a Cummins will start and idle, but

Customer Question

My 99 Dogde 3500 with a Cummins will start and idle, but when you press the accelerator pedal it start running very rough. I replaced the fuel filter and can here the lift pump running in the tank. Any thoughts. Thanks.
Submitted: 6 months ago.
Category: Dodge
Expert:  Dr. Hamman replied 6 months ago.

I would check the fuel pressure to make sure the lift pump is delivering fuel at an adequate rate. The pump can be running and still be a problem. The best setup for these is a pump that is external to the tank. The dealerships want to use the much weaker in tank pump. Your truck originally had the external fuel pump, Dodge quit making the pump, and created an in tank replacement. I have worked on a lot of these trucks, and the external pumps are a lot stronger, and last longer in my opinion. So a pressure test will tell you if the pressure is too low, the pressure should drop as you rev the engine if the lift pump is bad.

The original pump bolts to the drivers side rear of the block down low. You should see an aluminum block there bolted to the original bracket, Dodge made these bypass blocks. If the lift pump is failing, I would recommend installing a good quality original style pump. Oreilly auto parts has a Precision brand E16018, it is a great pump, and the cost is about $159. When you test it if the pump checks out good get back with me and I will help you figure out what the problem is, most of the time these symptoms point right at the lift pump. If you have any more questions feel free to ask, good luck with it and thanks for using just answer.

Expert:  Dr. Hamman replied 6 months ago.

Did you get a chance to check it out, and did you find a problem.