I have an '89 CSX that doesn't have the VNT turbo. I have an SBEC FWDP modified, and that works fine and was running that for awhile. Have another SBEC that is socketed and changed the chip to run a boost button cal, in preparation for changing over to E85. The car ran with that cal for about a week. I put the FWDP modified SBEC back in to go to the SoCal meeting, because I don't have a wideband and figured the FWDP cal wouldn't lean out near 16 psi or so. That Friday evening, I noticed that the engine stumbled and the lights dimmed, for a second or so when taking a bumpy corner fast. Didn't think much about it until that Saturday, when the fuel pump didn't prime with the key in the on position. I checked all connections under the hood and put dielectric grease where I thought it would be needed. No change. Looked in the '90 FSM and it said if the HEP was bad, the ASD would kick in and not initialize the pump. Changed the HEP and the car started, but died when the rpms dropped close to idle.

That Sunday, was able to goose the throttle and get the car to idle at 1900 rpms or so, but it wouldn't drop to normal idle speed. Left it alone for a couple of days while looking at posts and saw that shadowjake was having a similar problem, but in my case, the car ran with either SBEC. Tried the other SBEC I have and got the same result. Put in another HEP and it would idle and then die. I was able to check the fuel pressure and noticed that when the idle was high, the fuel pressue would start to drop and then the engine died.

When the car was running at a high idle, the fuel pressure was around 55. I also noticed that at night, it was around 45* or less, that the pump wouldn't prime when it would prime during the day. Don't know what would cause this problem, just by changing out SBECs. Help. Thanks.