1991 Ram 50 intermittent hard start condition

[Recon1342]

Hello all!

My '91 2.4L is having an occasional hard/no start issue. CEL comes on, but usually clears after I've turned off the truck. I've pulled code 15 and code 21 from the ecu, so I have a general direction to look in, but I cannot for the life of me figure out what Mitsubishi is talking about when they say "Motor Position Sensor". The TPS and Coolant temp sensor I can find, but nothing for an MPS.

My dad bought this truck new in 91 and it's been passed on to me, so getting it fixed up will mean a lot to me.


Thanks for any help or advice you can give!

[Fingers]

Us 'mericans call it a crankshaft position sensor...

[Recon1342]

Us 'mericans call it a crankshaft position sensor...

Do you happen to know if the 2.4L has one? I cannot find such a critter in any of the usual parts houses.

Perhaps it's in the distributor?

[claych]

^^
Yes, both the "cam and crank position sensors are in the distributor.
i will see if i can get a pic to upload...
https://i.postimg.cc/qRCH06xv/IMG-0258-1.jpg

the plastic disc contains the two optical sensors- silver disc is trigger wheel-.

[Recon1342]

Claych- do you know if anyone makes a rebuild kit for the distributors, or is it a replace-the-whole-thing kinda deal?

[Law Dog]

I have a 2.4 distributor out of a 92 2.4 that had head issues to get it going. I’d need to look it over to make sure it’s worth your time.

[SubGothius]

Claych- do you know if anyone makes a rebuild kit for the distributors, or is it a replace-the-whole-thing kinda deal?

Shouldn't need either unless major components are physically damaged/broken/corroded beyond repair. Just disassemble, clean/lubricate, reassemble, and maybe replace that sensor module.

Speaking of clean/lubricate, if those sensors are optical I wonder if it might suffice to just clean up the sensor eyes and trigger wheel? Maybe someone sprayed lubricant in there that gunked those up, attracted dust, etc.

[claych]

Recon,

I have been unable to locate individual parts for 4g64 2gen distributor.

After tearing down a couple of these, the screws that hold the harness plug
to the dist body are installed with RED loctite so heat & care must be used on teardown.

I personally would recommend a " rebuilt " unit complete as the optical sensors could be dirty
but the sensors are so robust that the dist bowl would have to be wet with oil/contaminant
for a no-sync condition to exist ( which could cause your issue).

These optical sensors are VERY stout and seldom fail.

So the % are with you to get a good sensor with a reman dist.

~claych

[Law Dog]

Sold the used one I had

[Recon1342]

I pulled the dizzy cap and cleaned up the corrosion on the terminals, as well as the rotor. Fixed the problem, so I have new ones on order.