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Been a while since I posted, so, I'm back lol.

I just put a Walbro 255 fuel pump in my '95 9C1 LT1. I finally fixed my fuel leak that I just encountered, but my main problem is, I'm experiencing longer crank times now. I put a fuel pressure gauge on it before I fixed the fuel leak (on Sunday), and when I would turn the key on, the fuel pressure would be at around 42psi, but after the pump cycled, the fuel pressure would drop down to 0. (This was before I fixed the leak, I will throw the fuel pressure gauge on again later after I get home from school.

Since then, I had to fix the sending unit so it would not leak anymore. What could possibly cause the drop in fuel pressure? Any ideas?

(Now also, let's keep in mind, I haven't changed anything in the fuel system other than the pump and the sending unit. Unless I need to revamp my tune for the bigger pump?)
 

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The tune won't affect anything, as the regulator will control the fuel pressure. Have you checked the pressure since fixing the leak?

If you're losing pressure, something is leaking. Could be an injector, the anti-drainback valve in the tank, or a line.
 

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I have the same issue with the Walbro pump that I purchased from Auto Performance Engineering. I drove to APE's owners house to pick-up the pump, he explained the installation process and mentioned that he thought he did not get the tube on properly when he installed one in his son's car, so he would turn the key on & off 2 or 3 times before starting the car. I have learned to do the same, I'll turn on the key, wait for the pump to stop, turn off then start the car, it works much better. From this, it seems the Walbro's don't hold the pressure when not pumping. I don't know if this a "feature" because it's a higher pressure pump than stock or what. I would also like to understand the answer to this problem.
 
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