Yes, you have found the root cause. 9.8 volts is way too low when cranking.

You could have problems with the cables and connections on battery and starter. Any connection that smokes or is hot durring and shortly after cranking is a problem. Make sure those issues are addressed first. If it's all good then go after the starter.

 

Well I did a quick check of the cabling and connections to the starter and there doesn't seem to be a smoking gun to me. Cables aren't melted, connections are clean and tight. So the starter? I'm just hesitant to put another starter in it and I still have the problem - also if it is the starter would the issue be present when just cranking to turn the engine over? When I disconnected the fuel and ignition and just turned it over with the starter it seemed fine. But I can't think of anything else that would be causing the voltage to drop out like that.

Thanks for your help

 

There is more load on the starter when cranking to start when compared to cranking with no fuel or spark. The spark plugs fire before TDC and the starter needs to overcome that extra load.

You could have a bad solenoid that isn't consistently making good contact thus increasing the electrical resistance in the starting circuit. Very common failure for an older starter. I know you replaced it with "new" but it could be a rebuilt. Because of the intermittent nature of this problem, this is the most likely failed component in my mind.

Another possible issue could be that there is inadequate lubrication of the motor bushings. This would cause physical binding of the starter when cranking under load.

The final issue that I can think of is that the commutator and brushes are worn or damaged. This would be another potential electrical issue with the starter.

Like I stated before, if this were mine I would tear down the starter to check these items. I understand if you aren't comfortable with that.

The starter is the one new component in the starting system installed before this issue came about. It is an unknown variable and is the key component in the starting system. Don't trust as fact that since it was sold as new that means it is good. There are far too many bad new parts being sold these days.

It was common practice years ago to replace items like starters just because they were old and thought to fail soon. Now a days, it's far better to wait until the part fails before replacing it. Far too often new issues are introduced by installing new parts. New parts should never be shotguned, instead they should be installed one at a time and verified that they function.

You did a lot of work on this engine and have been pulling your hair out trying to figure out this issue. It seems complex because of all the work you have done. The root cause has been found, low voltage when cranking. You had the battery load tested and you found the cabling good to the starter. The two componens left are the starter and starter solenoid. Since these came together on your new starter, the starter appears be the source of the trouble.

If you don't want to tear into the starter for fear of voiding any warranty, you could get a junk yard starter for comparison.

 

This was very informative, thanks. Tried the local yards but no used starters so I got another one on order.

 

Timing is NOT advanced during start up, its retarded to allow for easier start up. The only thing the starter has to overcome is compression on the firing cylinders and mechanical friction.

Also, the brushes on these starters wear out and the commutator gets chowdered up with copper/graphite from the brush wear. Rebuilding the origial or junk yard starter is really easy and worth it if the planetary gear set, engagement gear set and solenoid is working.

Clean the commutator off and sand it with 800 grit, clean out the slots between the commutator bars, replace with whole brush assembly (84-2001) will work. Clean the trash out of the body, off the stator, regrease drive out slip ring, drive out gear, and engagement gear guide pin, back side of the stator bearing with normal wheel grease. Use moly grease for the planetary gear set and light machine oil on the solenoid plunger.

Super easy to rebuild and the OEM Mitsubishi starters are FAR superior

 

Welp, new starter, same problem. When installing the new starter I clean and sanded all terminal connections for good contact. I also disconnected the power cable at the passenger fuse box, cleaned it up. It had a little bit of green crusties but nothing concerning. I swapped the ASD and ignition relays with the fuel pump and AC relays just to rule them out. I pulled all the ignition related fuses in the block, cleaned them up and reinstalled. And it's still doing the clunky bog down on startup.

I just don't get what else it could be or where to go from here. The fuse block itself? Ignition switch not maintaining good contact?

I also have a perfectly fine extra starter if anyone needs it.

 

Have you tried jumpering positive on the starter motor lug (wire side into the starter motor body) directly to your battery with a set of jumper cables to see if it turns over nice and fast?

 

I laid a screwdriver across the terminals and the starter/engine turn over 'normally'. No bogging down.
I checked underneath the dash, ignition switch wiring looked ok, no damaged wires or anything.
Started it about half a dozen times this afternoon. Got two okayish starts and the rest were crappy. The last start was one of the rough ones, followed by the engine surging from about 250RPM to 1200 RPM three times, then it died.
And on the last two starts when I shut it down my temp, gas, oil pressure and voltage gages all stayed where they were.

 

bipassing the solenoid or triggering it? There's 3 terminals on it

 

Triggering it, although I’m starting to believe this isn’t anything to do with the starter. This is the second new starter, and if I take the ignition circuit out of the equation either directly triggering the starter or unplugging the coil and fuel pump relay the starter and engine both turn over normally

 

Will it crank right if you jumper the starter relay?

 

I jumpered between the 87 and 30 positions in the power distribution center and the starter/engine turn over like normal. Similar to how it cranks if I disconnect the ignition or jumper the starter at the solenoid.
I also replaced the crankshaft sensor for the hell of it. No difference.

 

Eliminated another theory. Hope you all are still along for the ride.
The alternator and AC compressor are grounded to the engine block via the mounting brackets (as I understand it). I did paint the engine block and brackets during this whole rebuilding process. I disconnected the AC compressor, and made a ground wire to run directly from the alternator chassis to the adjacent engine block grounding point. Still have the issue.

I tested the ignition switch by connecting a voltmeter to terminal 86 at the starter relay in the PDC, then turned the tumbler to START. I had a steady 12.5V, it wasn't fluctuating or anything like the ignition switch is making erratic contact or anything.

I pulled the distributor cap. Everything looked normal, distributor is tight.

Next - do you all think this could be caused by the idle air control valve? I believe it opens with the throttle valve shut on startup to admit starting air to the engine. Based on the erratic RPM and shutdown I saw after startup the other day, what are you thoughts the IAC is sticking shut and failing which is choking the engine out....

 

You mentioned in your first post it has good fuel pressure, does it hold fuel pressure after its shut off?

 

Yes, 35 psi was relatively stable after shutting off the fuel pump. At least it didn’t discernibly drop over about a minute.

i also pulled the IAC. I manually depressed it and reinstalled it to make sure it was “open” on start up and still got the hard start.