I have the CFM-tech adjustable style regulator, just wondering if anyone has had any issues with sudden lose (13 down 7) of fuel pressure and then it comes back with one of these. Truck will run fine for a while (days-weeks) then suddenly go to around 7-8psi. Typically it’s after it sat for about 2-3 hours after driving it. Very hard to diagnose because by the time I can work on it the pressure is back to 13 then it will not have an issue for a few days or even weeks. I have replaced the stock fuel pump with a good replacement; don’t remember the brand but it wasn’t the cheap one. Also replaced the fuel filter and problem has continued. The pre-filter on the original pump was falling apart so I was really thinking that was the problem. The only other thing I can think of is the fuel pump relay is going bad but I would think that it would happen more consistently if it was that.

Any ideas? Dose the computer control the voltage to the fuel pump in anyway?


1989 suburban 350 tbi, th400 trans.
New fuel pump and filter.