Scratching our heads a little. Fuel pressure is bleeding down from 65psi after turning burb off. Down to 40psi in 5 min. Down to below 20psi overnight. Have put a check valve in the feed line (i suspected the check in the pump was bad), and have replaced the pressure regulator. Truck is hard to start if the pressure drops too low, however there has been a few times in this mystery that it wont start with 60psi. Ether shot starts right up. Once it is running, there are no problems, even at a load and at WOT doing 80mph. Where do I go next?

 

details
1999 K1500 4x4
196,000 trouble free
new plugs, wires, cap, rotor
fuel pressure regulator
aftermarket fuel check valve installed just in front of tank on the rail
fuel pump is 4 years old

 

I had about the same problem as you. I had to "prime" the fuel pump quite a few times to get it started. I read 55psi on my guage and found that 75 was needed to at start up. I changed my fuel pump and havent had a problem since. Hopefully this may help ya

 

Pretty common problem on the 99 model it is your fuel pressure regulator fuel pump would have nothing to do with bleed down only pressure. It take 60 to 66 PSI to start if you have 75 PSI is way to high. Anything less than 60 PSI and you will be craanking for quite a while to get it to start. Fuel pressure regulator is inder the upper intake manifold. Its kinda a pain to change but it can be easily done.

 

Thanks, but we changed that already. I just put a guage on the same year truck that is running fine, and the pressures read the same as mine, with the exception of the bleeddown after shutdown. Since we installed the oneway check valve in the line, and put a new regulator in, I am thinking that my pressure is bleeding down through the injector. I might need a new spyder assembly. That is more than the pump!

Does anyone know how to test the injector assembly? One injector firing eight cylinders for 196,000 miles seems like a good possibility....

 

Even though you just changed it it may still be bad but it could also be spider assembly or a bad Injector. check and see if you have any fuel in your Vaccuum lines if you do then the new regulator is also bad if not then I would look at leaking injectors and then move to the spider assembly. Just trying to help out.