weird/intermitent problem - Miata Turbo Forum -Boost cars, acquire cats.

Welcome to   Members

General Miata Chat A place to talk about anything Miata

LinkBack Thread Tools
Old 08-08-2013, 10:34 PM   #1
Junior Member
Thread Starter
iTrader: (15)
Join Date: Apr 2010
Location: quebec,canada
Posts: 403
Total Cats: 1
Default weird/intermitent problem

i have a weird/intermitent problem wich i think is related to a MS,i would just like to confirm my fears.

i have a 1990 miata with a built 1.6 running a custom gt2560rs/MSPNP ms1v3.

i recently sold the car to one of my good friend and he forgot the key on ``on``position for a long time(couple of hours)and the next morning, the fuel pump wasent priming when the key was on the ``on`` position.

since that day a couple of problem happened,wich are probably all related i guess.

the fuelpump is normally activated by the MS to prime for 3 second. now it`s not turning on at all. we installed a new relay,so the the pump is ``on`` in all time when the car is on the on position. it `solved` the problem and now it`s working great again.

on the first road test, the oilpressure and water temperature needles start freaking and bouncing(a lot, not like a little milimeter) and when the needles freak like this, the alternator stop charging.when the car runs, my multimeter indicate 12.2 volt, while the car runs.

details-alternator is new, not rebuilt, battery is new, and no parasitic lost anywhere,,.

it`s really, really weird, and if i`m not mistaken, the 1990 alternator is regulated via the compurer, right?

so i fear something happened to my mspnp, because not the fans wont come on, the alternator wont charge,and the pump wont prime as it should.

i know it`s a long message, but i tried my best with my broken french accent to explain what`s happening.

if you have some spare time, i would greatly appreciate,since i dont want to let him drive the car as is

thanks a ton for youre time.

kaboshe is offline   Reply With Quote
Old 08-09-2013, 12:06 AM   #2
I'm a terrible person
iTrader: (19)
FRT_Fun's Avatar
Join Date: Apr 2009
Location: Arizona
Posts: 7,292
Total Cats: 178

The regulator in a 90' alternator is part of the alternator... it's not charging if you only have 12.2 when it's running. Leaving the key "on" shouldn't do anything other than drain your battery.
FRT_Fun is offline   Reply With Quote
Old 09-16-2013, 01:06 PM   #3
Senior Member
iTrader: (8)
Join Date: Oct 2006
Location: Lexington SC
Posts: 950
Total Cats: 12

I am having similar problems on my 91 with 96 engine and alternator using MS. I have had several instances where the engine stalls when I come to a stop with the AC running. It then refuses to start for 5-10 minutes and then magically starts. During this time there is no fuel relay clicking or pump priming sounds. It happened to me this past Friday while logging and I noticed that tunerstudio was showing the fuel pump being on during the priming pulse, so the MS is sending the signal, but the relay is not getting energized.

I have also noted the coolant temp and oil pressure needles moving, especially at higher rpm. I also had to replace my second alternator in 2 years this past weekend (I know rebuilt alternators arn't the best).

I tried installing a new Bosh 40A relay directly controlled by the MS to bypass the circuit opening relay (fuel pump relay in the 91) and ran a seperate circuit for the relay control both while using the Bosh relay and the OEM relay. Still had the random cutouts.

It only does it when warm. I know the battery voltage is OK because I am always able to turn the engine over just fine, just no fuel pump.

I now have a jumper permanently located in my diagnostic box so that I can at least install a jumper between TEN and F/P to force the fuel pump to run. This will usually get me going. Once I get it started with the jumper I can remove it and the normal fuel pump control will work fine. I can even restart it without issue.

I even thought it was a bad MS, but I had just swapped to my old MS1 box 30 min before it stalled on me this past Friday. I don't think it is MS related, thats why I cose to post it here.
Rallas is offline   Reply With Quote
Old 09-18-2013, 03:18 AM   #4
Elite Member
iTrader: (24)
Join Date: Jun 2007
Location: Sherman Oaks, CA
Posts: 4,472
Total Cats: 3

Have you tried changing main relay?
UrbanSoot is offline   Reply With Quote
Old 09-18-2013, 03:18 AM   #5
Elite Member
iTrader: (24)
Join Date: Jun 2007
Location: Sherman Oaks, CA
Posts: 4,472
Total Cats: 3

Have you tried changing main relay?
UrbanSoot is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 12:25 PM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 12:45 AM
Odd Steering issue interestedofold Suspension, Brakes, Drivetrain 5 09-29-2015 01:42 PM
Annoying little leaks AlwaysBroken Engine Performance 5 09-06-2015 12:53 AM

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 01:00 AM.