Need some collective wisdom suggestions on a problem
05-11-2019, 12:02 PM
#21
Burning Brakes
Thread Starter
I thought I would post an update to this as I learned something (I think), I finally got some time to work on it, and I did actually find a problem. I replaced the FPR and it did not change anything about the way the fuel pressure acted. Except that the new shiny one sure looks purty now. 
I pulled the fuel filter and found it nearly impossible to blow through. I replaced it with a new one and it has definitely changed the behavior of the fuel pressure gauge. Although the base pressure is the same, when I hit the throttle the pressure now jumps higher immediately rather than dropping as it did before. In addition the car feels "lighter" on its feet when I drive it. I cannot say 100% that this was the issue that stopped me in my tracks but it certainly needed done. What is interesting is that this fuel filter only has about 5K miles on it, but at the same time it is 5 years old, as I only drive about 1000 miles a year on this car. I cut the filter apart and can find no visible accumulation of dirt on the paper folds. Unless someone can tell me differently I assume that from sitting for long periods, the fuel itself partially dried or gelled and clogged up all the small pores in the paper.
Anyone know if the Walbro has a safety feature to it that shuts it down if if overheats from working too hard? That would be one thing that could explain my sudden shutdown and later restart.
CTM Chris, I didnt see your response before. Lots of good info there. I have had my car on the dyno a few times and to the dragstrip multiple times. I also have a G-tech, and a wide band monitor. I have used all these things to get it tuned to where it is. Thanks for the response.
Roy
I pulled the fuel filter and found it nearly impossible to blow through. I replaced it with a new one and it has definitely changed the behavior of the fuel pressure gauge. Although the base pressure is the same, when I hit the throttle the pressure now jumps higher immediately rather than dropping as it did before. In addition the car feels "lighter" on its feet when I drive it. I cannot say 100% that this was the issue that stopped me in my tracks but it certainly needed done. What is interesting is that this fuel filter only has about 5K miles on it, but at the same time it is 5 years old, as I only drive about 1000 miles a year on this car. I cut the filter apart and can find no visible accumulation of dirt on the paper folds. Unless someone can tell me differently I assume that from sitting for long periods, the fuel itself partially dried or gelled and clogged up all the small pores in the paper.Anyone know if the Walbro has a safety feature to it that shuts it down if if overheats from working too hard? That would be one thing that could explain my sudden shutdown and later restart.
CTM Chris, I didnt see your response before. Lots of good info there. I have had my car on the dyno a few times and to the dragstrip multiple times. I also have a G-tech, and a wide band monitor. I have used all these things to get it tuned to where it is. Thanks for the response.
Roy
05-12-2019, 12:08 PM
#22
Tech Contributor
CTM, I know it isnt a relay issue, I could hear the pump running and I still had no fuel pressure. I put the snow system on because when I put the motor together things were a little tighter than I anticipated and I was having to use either octane booster or mix in a little race gas to stave off detonation and spark retard. To get it to run properly I had to pull so much timing it made a big difference in how the car ran, turning it from beast to blah. With the Snow system it runs great on pump premium. I dont know how it will hold up long term, but at this point it performs as intended. It was not easy getting everything to fit in the C4, there aint much room left here GM didnt use!
Roy
Roy
05-12-2019, 01:16 PM
#23
Burning Brakes
Thread Starter
It was a bear to get in. The pump is in the right front wheel well. The controller is behind the same wheel well inside the engine compartment. The reservoir is in the back in the compartment behind the seat, and there is a 3/4 inch plastic hose run from there to the front so that the pump always has plenty of juice to draw from. There is literally no spare room in these cars to work with.
Roy
Roy