That wouldn't make the pump run when it shouldn't.

The relay is just a switch that gets flipped by an electromagnet. The electromagnet is a just a coil of wire. When the coil has electricity flowing through it you get a magnetic field that physically moves an electrical contact mounted on an arm.

Wht/blu in the diagram is the 12+ feed for the coil and for the actual power feed to the fuel pump. We have power on this wire only when the key is on.

The LT GRN wire is the ground for the coil supplied by the ECU. So the pump will only run when there is power on wht/blu and ground on lt grn.

We know wht/blu is doing it's job. Since the pump is running when it's shouldn't it means LT GRN is being grounded when it shouldn't. Either the MS3 is grounding the wire when we don't want it to or that wire is making contact with ground somewhere along the wiring run.

The same LT GRN wire is also split and runs to the diagnostic connector underhood. This means we have easy access to the wire underhood for troubleshooting.

The original testing I told you to do would rule out a bad relay. Since we now know it's not the relay we need to figure out if it's a megasquirt issue or a vehicle wiring issue. Easiest way to do that would be to unplug the ecu with the key on engine off when the pump seems to be continuously running.


https://cimg2.ibsrv.net/gimg/www.mia...322b8eff2d.png

No. I've never messed with an NB but there's nothing in the diagram to support that. How long the pump primes for looks to be entirely controlled by the ECU and has to be time based.

My Hardwire Relay sits right next to the fuel pump harness grommet. No wires go up to the dash. Get's signaled from the OEM relay and draws direct from the battery. All wiring is within the parcel shelf area tied up to the factory harness. 2004 MSM

Which is connected to the LT GRN fuel pump output off the ecu. Which is triggered for a set time to prime the system.


Highlighted is your regulator. When pressure reaches the point the regulator is set for the extra fuel is dumped back in to the tank while the pump continues to run.



https://cimg3.ibsrv.net/gimg/www.mia...92b9b40e29.png

its time based. so either the relay or the ecu.
by that logic, he shouldn't be having this problem, at all, but here we are, so......




in typical fashion, this is being over-theorized and will go on for many pages lol
if you pull relay and it dies then problem is either relay or ecu. or you can pull relay and check if trigger voltage is being supplied continuously.

or just not care and hardwire it bypassing all of this

I has hardwire kit I'll sell you. :naughty:

Tell me how this fixes his problem? See my reply to brainzata. See the diagram I posted.

When you HW the pump you're still using the same LT GRN wire from the ecu and the same output from the ecu. This is where we already know he has a problem.

Just to clarify how simple this is to test. Turn the key on. If the pump continues to run with the engine off, unplug the ecu. Tell us if the pump stops when you unplug it.

That's too easy. Way too easy. We need to discuss this for a few more pages before he tries that

how should he feel when doing it? what emotions should he expect and how will the car feel?

:likecat: for you.

I'm going with timid and apprehensive for $300, Alex.

I was actually responding to midtenn but forgot to quote. I understand the pump is turned off after a few seconds of priming. Thanks for the info though

Oh crap that was my bad. I thought you were boileralum.

Pump does absolutely nothing when the ECU is unplugged. No priming, period.

Plugged everything back in and it decided to act normal... for now. I'm sure it'll start sticking again the next time I turn it on.