I own a 1989 YJ and the previous owner put a fuel injection conversion on it. I have a couple of questions about this:
Is it possible that it still has the original MCU under the dash and a new model computer and ECM mounted to the firewall on the driver's side?
I am having trouble with the fuel pump and spark. I re-did the ground to fuel pump and that seemed to help but now I am having issues where the fuel pump won't turn on and there is no spark. Then sometimes the pump will pump and the car will be flooded and I hold down the pedal and I will get a rough start and after that clears up it will start as many times as I want but if I let it sit for a while I am back to no fuel pump engaging?
I would appreciate some input into this situation.
What timatoe said! The old ECU was mainly a control for emissions stuff and timing (IIRC). Once you change from the stepper motor controlled carb, or switch the ignition, the ecu and everything connected to it are just excess weight in your vehicle. If you tell us what sort of EFI system you have there is probably some advice available.
Not sure how to identify what kind of fuel injection system it is? With the old ignition on I was still getting signals to the MCU? All the videos I watched on doing the conversions showed removing the harness from inside the vehicle.
If it's the Howell conversion ( injectors at the old carb location as opposedto the Mopar which has injectors by each cylinder), the ECU does not control the spark at all,however if your spark module is bad, it can confuse the injector control and may cause flooding when starting. Normally the fuel pump shoud run for 2 seconds at startup, but even if it does run longer it should notflood unless you have some leakage at the injectors.
'89 Wrangler YJ
97 Grand Cherokee (ZJ)
87 MB 560SL roadster
There is the original computer in behind the glovebox and there is a computer on the firewall. It was running great one week ago. Now have no spark or fuel. I replaced the Crankshaft Position Sensor and the distributor. The wiring is a mess. I wish I had someone in my area that I could pay to take a look.
I have a meter...the computer on the firewall is from a 1992...If I ground terminal 85 on the fuel pump relay the fuel pump comes on but still no spark? I do have 12v to the green/red wire at the coil and 12V at the grey wire on the coil....but no spark our of the coil. I am starting to suspect the computer, because I am running out of other things to test.