Bought a 99 gmc rcsb 5.3 4x4 last week, my fuel pressure is dropping over night so i figure i need a new pump. I work at a chrysler dealer and all our new cars a returnless systems (which makes more sence to me) i was thiking about converting my truck to a returnless system. I plan to go the F/I route later this year, so im going to get the feul system done now. Has anyone converted theres to returnless? or is it a bad idea? please post your input thanks.

 

If you plan to go FI then keep your current fuel system. The returnless system is not worth converting to anyway IMO. The FPR in your current system is vacuum/boost sensitive and will give you more fuel pressure as the boost goes up ensuring that you have a good supply of fuel when you need it most. The system you have now gives you a lot more options for tuning the fuel system when the time comes.

 

If you are dropping some fuel pressure at night its OK. The returnless system does that. I am willing to bet (depending on mileage) that your Fuel Pressure Regulator needs to be replaced. If you plan on going with a FI system you will need to make sure your fuel system is 100% up to the task. Keep the return system, it is better all around. Congrats on the new truck!

 

ok thanks guys thinking it was going to be to much work anyway. well the truck is hard starting in the morning so i thought the check valve on the pump might be leaking back alil. so im going to replace the pump, i might as well get a better pump well im at it too so i think im going to go with a 255 pump, it seem to be a pretty common pump. did a search and found some helpfull info but anyway think im going to go that route.

 

This sounds like a Bad Fuel Pressure Regulator. If you change the pump, be sure to change the FPR.