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-   -   Fuel pump shuts off at low RPM (https://www.miataturbo.net/megasquirt-18/fuel-pump-shuts-off-low-rpm-86843/)

ryansmoneypit 11-30-2015 01:47 PM

Fuel pump shuts off at low RPM
 
New to MS3X, here is the problem I have:

When trying to set the idle (tried with AFR from 11-15, on ID1000's) it sounds really good until I get to 850 RPM, then I can hear what I believe is the fuel pump relay, click, then instantly the engine dies. Its not like the idle is too low, and it stumbled to dead, but it is actually idling very steady, and if I go 1 RPM below 850, I hear the click and it dies.

This happens on both open and closed loop idle.
Any Ideas?

sixshooter 12-01-2015 10:52 AM

Just thrusting in the dark here but the ecu cuts the fuel pump if the engine isn't running (in case of accident). Perhaps your setting rpm for changing from "crank" to "run" is at 850rpm? Just a guess of where to start since no one else if jumping in. Check your cranking settings.

ryansmoneypit 12-01-2015 11:24 AM


Originally Posted by sixshooter (Post 1288158)
Just thrusting in the dark here but the ecu cuts the fuel pump if the engine isn't running (in case of accident). Perhaps your setting rpm for changing from "crank" to "run" is at 850rpm? Just a guess of where to start since no one else if jumping in. Check your cranking settings.

Great thrust. I'll check that tonight!

ryansmoneypit 12-02-2015 08:15 AM

Nope. Was set to 300 rpm crank to run.

Savington 12-02-2015 10:45 AM

Does it instantly die, or does it cough and stumble?

ryansmoneypit 12-02-2015 10:47 AM


Originally Posted by Savington (Post 1288437)
Does it instantly die, or does it cough and stumble?

Dies instantly.

Low idle, low idle, click, dead. Low like 850, which doesn't seem that low to me.

Matt Cramer 12-02-2015 11:21 AM

Can you post an MSQ and a data log of the problem?

ryansmoneypit 12-02-2015 11:26 AM

I will tonight.

patsmx5 12-02-2015 02:18 PM

The last time you sent me a log, I told you YOU HAVE A SYNC ISSUE.

If you still have a sync issue, then you still have to fix that.

ryansmoneypit 12-02-2015 02:29 PM

Crap, you're right. I thought it was just related to my wrong ignition setting. I will try and figure out this sync issue tonight.

Savington 12-02-2015 02:36 PM

If it dies instantly, it's not the fuel pump.

patsmx5 12-02-2015 04:04 PM


Originally Posted by ryansmoneypit (Post 1288540)
Crap, you're right. I thought it was just related to my wrong ignition setting. I will try and figure out this sync issue tonight.

Try what I already told you. Or try adjusting the pots on the MS3X. There is a method to adjusting them, and it may be the cause of your problem.

ryansmoneypit 12-02-2015 07:35 PM

4 Attachment(s)
I captured a tooth log, but without understanding what I am looking at or for, I am sure not going to start tuning knobs inside the ms. can someone help me decipher? this is a 32-2 wheel

One tooth log and one big LOG.

I accidentally ate my bridge last year and had a toothy log. Hurts.

[ATTACH]Attachment 156509[/ATTACH]

Braineack 12-02-2015 08:04 PM

I think it was the fuel map and injector settings.

ryansmoneypit 12-02-2015 08:06 PM

So what about the tooth log? Normal, abnormal?

patsmx5 12-02-2015 08:19 PM

1 Attachment(s)

Originally Posted by ryansmoneypit (Post 1288669)
So what about the tooth log? Normal, abnormal?

You need to do a composite lot, not just a tooth log.

But the last composite log you sent me showed the cam sensor dropping out as per the picture/description I gave you, and it reported lost sync reason 2. Will post picture here too.

The .msl log you just posted shows you lost sync EIGHT TIMES and each time was reason 2.

Still the same.

Previous pic I sent you, same issue then as you have now.
https://www.miataturbo.net/attachmen...ine=1449105555

ryansmoneypit 12-02-2015 08:27 PM

Heah, it happens under 1000 rpm.

ryansmoneypit 12-02-2015 08:28 PM

New stuff coming soon.

Matt Cramer 12-03-2015 09:51 AM

You are sometimes getting a noise pulse in the gap on the crank trigger. I see one such event in frame 12 of the tooth log. If this were a VR sensor, I'd say try running a 10K resistor inline with the crank sensor.

ryansmoneypit 12-03-2015 03:44 PM

When viewed with the composite log, using this 36-2 wheel, should I be seeing TWO long lines, representing the two missing teeth? I'm wondering if maybe the signal voltage is justadjusted too low?
I ask because I see 1 long one, 1 that is much shorter right next to it, then the bar.


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