How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Cat Man Your Own Question
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8412
Experience:  I am ASE Master Truck Certified.
30708357
Type Your Medium and Heavy Trucks Question Here...
Cat Man is online now
A new question is answered every 9 seconds

To ya. I am working with a 3406 in a 96 FL truck. The serial

Customer Question

Good morning to ya. I'm Ray, I am working with a 3406 in a 96 FL truck. The serial number is ***** I'm haveing trouble with its running just shortly after a cold start. I starts right up but misses and dies in a minute or so. It is loosing fuel pressure. After it starts the pressure will be about 75 pis with a 10 psi pulse. As it dies, the pressure drops to 10-20. If I pump up the new hand primer to 40 I it will start and the miss clears out. The pressure comes back to the 75 psi and still has a pulse to it. If I speed the engine up to 1500 the pulse is about 30 psi. The filters are new and I have no air in the supply line to the head. Any ideas where to go on this?
Submitted: 12 months ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 12 months ago.

Thanks for asking your question. I will try and help you out.

There are several things I have seen cause this.

The first is the relief valve in the fuel pump is faulty and opening and closing.

Second is a restricted fuel return line or the fuel Inlet line. This can cause the fuel pump relief valve to open.

Third is a faulty hand priming pump.

And lastly is a faulty fuel pressure regulator.

Please reply back if you need more help or have more questions. I am happy to assist.

Expert:  Cat Man replied 11 months ago.

Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.