red97tib

So my Tib has sat for years because I didn't not want to mess with it until other projects were finished. Well I started working on it again today. Here is a baseline of what has been done since the car last ran correctly.



I've installed a Megasquirt plug and play from KFX. The Innovative Wideband O2 Sensor with gauge. Walbro 255 in tank fuel pump. Socks fuel rail with pressure regulator. 440 injectors. Supercharger and some other things I can't remember.



My issues are these. The fuel pump no longer primes or runs. But if it is provided power through the test lead in the engine bay it turns on. I have swapped out the fuel pump relay with the window relay (since they are the same) and the windows work with either.



Also my idle air control valve can be heard making noise as soon as the key is put into "on" position.



After switching back to the OEM ECU all of these problems continue. But after an hour or more of testing the IAC valve stops making noise and the A/F gauge stops coming on. I'm sure the IAC and Fuel Pump are related wiring issues. If I can solve one I think the other will go away.



Does anybody have any ideas?

Stocker

My IAC will also chatter quietly to itself with the key on; I do not consider this to be a huge problem. The fuel pump is rather worse. If the fuel pump is not getting power wih regular relay activation, and you have a good relay and should-be-good ECM telling the relay to come on, it seems it should be either wires, fuses or the relay socket. If this is a car you can live without it running, I think it should be called more a hassle than a nightmare, because this is a pretty simple fuel system.

XGODZX

came across this, don't know if you've seen it before or can help ???



http://www.newtonnet.co.uk/coupe/service/electrical.htm

wheel_of_steel

Well you can check that the fuel pump relay is getting a signal with a multimeter for starters. To me, it sounds like the megasquirt is a bit unhappy and not sending the 'alright you may start' signal. What sort of diagnostics can you pull on the megasquirt?

JonGTR

Like above, you need to refer to the MS wiring diagram and locate the fuel pump relay wire. Make sure a signal is being sent. When the ignitionis turned on, the fuel pump should get a 3 second signal to prime.

red97tib

I have driven the car on the Megasquirt prior to the supercharger install. I have removed that from the system and went back to the OEM ECU and the problem persists. All testing at this point will be done on the OEM ECU.



I have ran a power probe across the wiring of the fuel pump. In the "on" mode one wire goes to something like 14 volts and another goes to like 8 volts. I don't remember the colors at the moment and I'm not checking due the to the temperature being, fingers go numb in two seconds in my garage, cold. The yellow wire only provides an out put when power is supplied from the engine bay jumper connection.



When I energize the fuel pump using the engine bay testing point the fuel pump turns on just fine. I've swapped the fuel pump with my other Tib and it worked there.



The service manual sucks because it just says "test voltage" and doesn't really point you in a good direction.



How do I test the relay socket? I have placed a power probe there and found connection 1 at 14 volts (IIRC) and 3 at ground the others always stayed grounded too (I think). I would assume this is not functioning properly. This was tested under key "off" and "on" positions yet no change was seen. Do I need to start tracing wires back to the ECU from the socket relay looking for a damaged one?

wheel_of_steel

Hmmm, maybe. Well just thinking aloud here:there are four pins on the relay

-signal input

-signal output

-big voltage input

-big voltage output



So you should be getting a constant battery voltage on your 'big voltage input' pin, and like jonGTR said, a short period of signal voltage at the 'signal input' pin. This is usually 5 volts but it could be 12. Maybe this is the 3 volt pin you were talking about? I'm pretty sure the signal voltage is regulated at 5v so you may have a damaged wire to trace. Can't hurt to check for earth leaks and the overall resistance of that wire.



I would also be checking for spark - if there is spark, that indicates that the ECU is probably trying to start the car but there is a problem with wiring or hardware somewhere. If there is no spark, the ECU is unhappy and isn't giving the all-clear for the car to start.

wheel_of_steel

Also I just remembered: sometimes Hyundai uses switched earths instead of switched supply voltages to run things - the thermo fans for example. The item receives constant power, and the ECU actually switches the earth on and off. I don't think this is the case with the fuel pump, but it would be worth checking if everything still seems fine.

red97tib

Checked the spark on all 4 cylinders with the OEM ECU and I had spark across the board. At this point I am assuming I will have to do some tracing of the wires leading to the relay socket and see where that goes. I might take apart my second tib just to match some wire voltages and wire colors and things.

Stocker

The voices tell me crank-but-no-start is often a dirty crank sensor hole or bad crank position sensor or its wires. It takes just a couple minutes to check and couldn't hurt, even if it doesn't help. Seems like you wouldn't get spark though so