I went to the dyno last night and when they were strapping the car down, apparently they pulled a wire loose for the fuel pump and the car wouldn't run. After about an hour, we realized it wasn't getting fuel and found the problem. Now the engine runs, but runs poor. I got a MAF sensor low input history code and it sounds like a damn rice burner . The engine idles rough while the MAF is connected, idles better when disconnected, but still runs poor. AutoXray says that the o2's are well under 100mV on each side while running over 30 seconds, but starts off idling with o2's around 600mV. Both o2's are recently replaced bosch's. The car smells rich as hell and gots poor city mileage. Has a serious lack of power and stalls constantly. Anybody have any ideas what could be the problem? The plugs dont look bad and disconnecting the FPR didn't make a difference. The car ran perfect before loosing it's fuel pressure on the dyno.

 

Sounds like you may have issues with the fuel pump. What is sthe fuel pressure now?

 

This sucks. Sucks more because I'm standing right next to you working on it and we dunno what's wrong with it

 

Dont know what the fuel pressure is. My fuel pressure tool is at home in FL. The pump sounds just as strong as it did before, but I can tell you that when I pulled the filter off to check it and to drain the system for another regulator 5 minutes later, it had NO pressure in the lines. Just a few drops of fuel instead of pressure when I removed the filter.

The pump has 20k miles on it, it's a walbro. Has never given me a problem up to this point.

Getting ready to put a fresh filter and an new afpr on it now to see it that helps. I'm also going to check those wires that got pulled out to see if they got damaged. Maybe I'm loosing voltage to the pump...?

 

Update: put new autolite 106's in it and it still acts up. Swapped with a good known maf, still nothing. Unplugged the o2's and still nothing. I'm wondering if the opti may have some issues or maybe I have low fuel pressure...any ideas? The pump and opti both have 20k miles on them.

 

OK, gave it some thought. My fuel pump has always worked fine, and it still sounds the same, but the checkvalve in the pump has never retained any pressure in the lines when the engine was shut off. When installing the pump, I put it in the stock bucket, but I seriously doubt it's sealing to the bottom of the pump 100%. I'm wondering if maybe the pump is having issues now with pumping adequate fuel to the engine. I dont see how the engine could be having a problem since it ran fine up until the fuel pump wires were disturbed. The filter is new and the AFPR is a new accel unit. I'm getting a gauge tomorrow to check the fuel pressure while running. Anyone else have a similar problem?

 

Do you have any datalogs?