Hi

Car has had an intermittent miss for a while, and now is running really rich in open or closed loop. Finally managed to connect a laptop up to it last night (plug on the back of the aldl connector was loose..), but I think I wiped any codes in the process.

Looking at the datalog, most of it seems normal, but the fuel pump voltage is around 8.3V? Looking at some previous logs I'd taken, the voltage sat around 13V. I put a pressure gauge on it, it sits on 40PSI at ignition, and goes to 35PSI. After turning it off, it drops to 22PSI after about 7 minutes.

The wiring around the fuel pump relay is really bad, basically bare wires and dirt.

Is this pressure drop-off too fast? The pump voltage doesn't seem right, but I'm not sure what that would do if it seems to be able to get the pressure up to 40PSI.

thanks for any help, car is a stock 88 305 TPI, o2 sensor is new, plugs, leads, dizzy cap, rotor, maf, maf relays are a year old, TPS is .55v at idle.

 

Well, finally managed to sort it out. I replaced the injectors, which didn't fix the richness, but I think did get rid of the occasional miss as one of the injectors seemed to be leaking. So I changed the fuel filter last night and it's running (mostly) fine again. The idle seems a little high so I'll need to adjust the iac/tps. Taking the fuel filter off, it was a bit gunked, but I swear it was also on the wrong way round.. which couldn't have helped.

For anyone pulling their plenum off to get at the injectors, get a lot of sockets beforehand that will work with T-40 torx nuts. Preferably something with a long thin extension (to get the ones under the runners), something that will work in a small spot (I had a socket wrench that you can just twist the handle, for the one behind the EGR on top of the manifold), and maybe an allen-key type bar, in case any are really stuck.

For the fuel filter, had heard a lot of stories about pressurized fuel spraying everywhere, but if the car has sat for a few days, and you then empty the lines by disconnecting the pump and turning it over, some fuel dribbles out, but not much.