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EA81: Distributor?

Ea81 Brat Distributor POS

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3 replies to this topic

#1 ajslacker

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Posted 17 October 2017 - 01:34 PM

I have an 85 Brat that isn't getting spark. New plugs, new plug wires, new ignition coil, new disty cap and rotor. I pulled out the distributor and noticed the distributor shaft has about 1/8 inch vertical play and 1/16 horizontal play. Is that too much on both sides? Do I need to replace the whole distributor? Could that be why it doesn't start? Any info is appreciated.

#2 mhisstc

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Posted 25 October 2017 - 01:33 AM

I am having what may be a similar problem with a 100% stock '85 BRAT.

 

Here's a few things you might want to check in addition to what I have going on that may provide some kind of insight into your issue.

 

Have you verified there is absolutely no spark and it's not just a timing issue? One way to verify you have no spark is if your fuel pump doesn't do it's short little run to ensure the carb is primed as you rotate the ignition key from Off to On positions.  The fuel pump should also run continuously in the Start position, which you can hear a little more faintly as you crank the vehicle and briefly again as you return to the On position back from Start.

 

If you replaced all of those ignition parts at once, you should triple check you have the plug wires leading to the correct plugs since it's easy to mess up.  A timing issue could have also been created if you pulled the distributor and didn't index the distributor body and shaft/rotor before you pulled it.  You also have to make sure you don't rotate the engine and then get everything lined back up when you put the distributor back in. 

 

My BRAT sat for about 15 years, so I completely cleaned out the fuel system including rust and varnish removal in the tank, installed a new fuel pump filter and hoses out back, and dismantled, cleaned and checked the Hitachi carb.  I also went completely through the vacuum and ignition system diagrams to verify hose and wire routing, replaced a couple of hoses, and checked all of the specs of all the electrical components. This included verifying the Ohm value of the coil primary and secondary and the Ohm value of the ignition control module (a.k.a. trigger coil or signal generator).  According to the Chilton's manual, the coil primary should be 0.84-1.02 Ohms and the secondary should be 8.5-1.02 kilo-Ohms.  It also indicates the reluctor gap should be 0.012-0.016" or 0.3-0.4mm with a resistance value of 130-190 Ohms on the signal generator (ignition control module).  If you check the ignition control module and don't get a reading the first time, swap where you have the leads on your multimeter connected. I don't understand why, but I found one way it would give me a valid reading, and the other way it wouldn't and would read infinity like an open circuit instead.

 

Anyway, I was happy it ran, but it was still just a little bit "sputtery".  As I drove it for a couple of days like that, I thought maybe the fuel system wasn't as clean as it could have been and the carb needed cleaned again.  But as luck would have it, it failed to start at all one day in a store parking lot. There was no sound from the fuel pump, so I was worried the fuel pump control unit may have gone bad.  I towed it back home to trouble shoot it and figured out by going through all the same things I went through previously that the ignition control module (trigger coil/signal generator) was showing a resistance value of infinity.  It looked like that module went bad.  As I inspected it, I also saw wear marks on the module from the reluctor rubbing on it and it also looked like the reluctor may have been hitting the stator.  That's when I took a closer look at the distributor shaft play.  It was bad, and the general condition of the distributor internals was sketchy looking.  When I looked up those components on Rock Auto, I found the module was $93 while the entire distributor was $116.  It was a no-brainer to take care of it all with a new distributor.

 

When the new distributor arrived, I indexed everything on the old one, pulled it out, popped the new one in, and it ran like a champ.  Shortly after I installed the new distributor, I noticed my voltage gauge was showing swings in the voltage with values that were too high at higher RPM and too low at lower RPM.  It appeared the voltage regulator was bad in the alternator.  Once I replaced the alternator, my voltage was rock solid where it should be.  It ran great for about another week, then it failed to start on me again just like it had done previously.  There was no sound from the fuel pump. Again I feared it was the fuel pump control unit, but when I checked the ignition control module, I got infinity resistance again, so it appeared the module went bad in the new distributor.  I never verified the initial Ohm value of the ignition control module was within tolerance according to the Chilton's manual when I first installed the new distributor because it ran great when it ran.

 

So figuring I got a new distributor with a bad module, I warrantied it back to Rock Auto and ordered a new distributor. I also wondered if maybe the bad voltage regulator had something to do with the original and new ignition module failing. I still had the old, but verified good coil installed, but to rid that as any possible failure point, I installed a new coil, which I verified did meet the specs on the primary and secondary before I installed it.  So when the new distributor arrived, I installed it, but nothing changed.  I got no sound from the fuel pump, and the engine didn't run.  Figuring there was no way the module was bad in my second new distributor, I poured a little fuel in the carb and it still didn't run.  So then I checked the Ohm value on the module.  It was NOT in spec with the 130-190 Ohm value the Chilton's manual says it should have.  It was more like 820 Ohms.  Crap, does this mean I got a new distributor with another bad module?  I really didn't want to have to try and warranty a second new distributor.  That's when I found I could order an ignition module from OReiley's for $20.  They also had one for $92, but I went ahead and got the $20 one as they both appeared to be the same one I had and were both listed for use in the BRATs Hitachi distributor.  There was no difference stated between the two on the web site, and the store personnel couldn't tell me what the difference was either.

 

I got the new ignition module from OReily's today.  Before I installed it, I checked the Ohms value.  It was around 830.  Uh Oh.  That's NOT in the range Chilton's says it should be and it's nearly the same as the one I'm going to be replacing.  So I went ahead and replaced it.  Same problem.  No fuel pump noise, and no run.  Crap.

 

The only thing I can think of is that there is some kind of difference between ignition modules that otherwise appear identical that is causing the resistance within the module to be out of tolerance for the system, and the fuel pump control module that verifies spark before running the fuel pump can actually distinguish the difference between modules based on it's resistance, and it refuses to run the fuel pump.  The reason I say this is because if I remove either or both of the positive or negative power leads from the coil, my fuel pump will run as it should to prime the carb when I run the key from Off to On, but it won't run when in the Start position because there is actually no spark happening.  If I leave the key in the On position and remove one of the power wires to the coil, or I pull the fuse to the coil, or I unplug/replug in the Fuel Pump Control Module, the fuel pump runs briefly to prime the carb, but will not run when cranking the engine and the engine will not fire.  To me that says my issue is the ignition control module sending an incorrect Ohm value to the fuel pump control unit, and the fuel pump control unit refuses to run the pump, except when transitioning through the correct resistance value as the power to the coil is connected/disconnected at the various locations I indicated.

 

I need to repost my specific issue in another thread to see if I can get any help myself, but I thought my issues may help you trouble shoot yours.


Edited by mhisstc, 25 October 2017 - 01:42 AM.


#3 ajslacker

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Posted 25 October 2017 - 08:36 AM

I installed the new distributor and after a little coaxing it started up but promptly died. It will start without me having to hit the gas pedal or anything and will idle smoothly for about 8 seconds then it starts backfiring and it dies. What exactly is the sound the fuel pump makes? Mine is a Spectre replacement i got off of parts geek.

#4 mhisstc

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Posted 25 October 2017 - 10:00 AM

What exactly do you mean by "coaxing"?

Idling smoothly for a few seconds and then dieing sounds like fuel starvation.  Does your carb need cleaned?

Backfiring sounds more like a timing issue.

 

You might be able to hear the fuel pump better if you open the door and lean out while strarting.  It makes a pulsating little "brrrrr" sound.  If you're pump is especially quiet, you can have a helper either lay under the pump, or put their hand on it and feel if it is running as you start the vehicle.

 

Triple check the plug wires are going from the cap to the correct plugs, and that the timing is set correctly.  Did you properly index the old distributor before you removed it and replace the new one in the same manner? If you can't get it to run long enough to check the timing, or you didn't manage to index the distributor properly, you can set the overall timing "back to zero" by doing the following:

* Remove the distributor.

* Remove the #1 spark plug wire and plug.

* Put your finger over the plug hole while turning the engine with a wrench on the crankshaft bolt.  When air pushes out, you are on the compression stroke.  Keep a close eye on the timing mark on the flywheel. The air should stop pushing out just about the time the "0" degree timing mark comes up.  Set the flywheel at "0".  The engine is now at top dead center.

* Align the little dimple stamped in the timing gear at the base of the distributor with the straight edge of the notch at the base of the flywheel housing just above the timing gear and while keeping it aligned, put the distributor back in.  That sets up the distributor to align with the #1 cylinder electrode on the distributor cap while the engine is at top dead center.

* Replace the spark plug and wire.

* Start the car and check/reset the timing.

 

If everything else is OK, the engine should run well enough with the spark at 0 deg (top dead center) for you to now set the timing correctly at 8 deg. before top dead center, or whatever you particular vehicle should be set for.







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