[HELP] New MS3 huge fuel leak
 

I'm new to tuning and need some help. I was searching around for an answer to this and couldn't find one anywhere. Today I installed a new MS3 pro into my 1990 miata with a BPZ3 engine and a turbocharger, it previously had an AEM 1070 tuned by somebody else. I installed the new MS3 pro and began setting it up in tunerstudio, I had the car turned on to accessory and I noticed that fuel was leaking out of my intake. I had my car on accessory for about 15 minutes before this happened. My intercooler, all my intercooler piping, my intake manifold, and my turbocharger had all been filled with fuel. I drained my oil and am currently getting all the fuel out of my intake and engine. I am hesitant to try and set this up again before figuring out what happened. Can anybody help?

This sounds very similar to what happened to my car: https://www.miataturbo.net/engine-pe...hooting-99512/ and ended up being a busted diaphragm in my fuel pressure regulator. It'd be worth checking that, there aren't a whole lot of explanations for that much fuel that far outside of the cylinders. If you pull a spark plug are all 4 cylinders full as well? I guess it's possible you have a wiring issue with the megasquirt, but that seems unlikely.

post up your tune file. something is holding the injectors open. wait, his idea is better ^^^^

I didn't pull my spark plugs but I drained my oil and there was fuel in my oil so I assume that the pistons had filled with gas as well.

Aren't injectors good for something like 100PSI of holding power? I would think even with a busted FPR, it shouldn't flood unless the injectors are hanging open.

With a vacuum referenced FPR you have a vacuum line running from the intake manifold to the fpr. Manifold vacuum moves a diaphragm to change the fuel pressure. The suggestion is that the diaphragm is torn which would allow fuel to run into the intake manifold through the vacuum line.

Ahhh, OK, I was thinking the implication was that it was still feeding through the injectors. Makes sense.

Whether gas is getting into the engine via the FPR hose or by injectors being held open, the fuel pump is also staying on and not just priming. No way you are going to get that much fuel with a 2 second prime.

You are going to have to do some diagnosing. Hook the MS back up but first disconnect all the injectors and the FPR vacuum line. Then turn key on like you had before and listen for fuel pump prime. If it primes, great. If it stays on without an RPM signal, you have one issue.

If you are getting fuel coming out of the FPR, then that solves that. If not (and might as well double check) get a noid light for the injector connector and see if the light is on steady. If not, and FPR is not leaking, I don't know what else it could be other than an intermittent issue.

My guess is that there is some "jumper" somewhere in the harness for the AEM to control fuel pump and somehow that is affecting the MS. Or as pdexta mentioned a wiring issue within the MS. Maybe it's wired for seq injection and your harness is still batch?

Yeah the fpr is what I would look at 1st. Had a similar experience on an older car I had a few years ago, and that vacuum line was like a fire hose dumping fuel into the intake. Simply pull the vacuum line off and look for fuel. Other than that, it would have to be an injector stuck open, or something in the MS holding it open.

What's the back story on this? Was it running on the AEM yesterday, and today with the MS it filled the engine with fuel, or is it a situation where the engine/injectors/fpr have been sitting for a long time?

Disconnect the FP relay and run the MS in IO test mode. Test each injector. Report back.

Edit: Measure the voltage across the injector while testing. The injector voltage should measure roughly 12V x the DC. So with an output interval of 200ms and a PW of 20ms you should get ~1.2V.

It was running on the AEM yesterday with no problems.

I believe that whenever I've had my car on accessory my fuel pump would be constantly running. It's never been an issue in the past for me.

1.6 cars had some fuel pump wiring routed through the air flow meter. I'm sure someone just jumped it so it's always on instead of having the ecu control it.

It's one of those "in case of" things. In case of an accident and severing of a fuel line, a stalled engine won't keep the fuel pump running.

In this case, it may have been a good thing. Exposing a problem before it lead to a bigger problem.