The optical pick-up is a crank position sensor. It "reads" the tiny slots in the thin stainless plate located under the distributor rotor button. That info is sent to the ECU which triggers the power relay(located on the flat bracket beside the distributor) to energize the ignition coil.I hope this is correct , I'm open to correction if I'm wrong.

When acquired my Raider it had been setting for 6 yrs. After draining the gas & replacing it w/ fresh ;it would turn over hit once or twice & that was as far as it would go. I did a complete tune-up, same thing. Replaced the optical P/U ($109) - it ran..I believe there are troubleshooting instructions in the down-loadable manuals. I'll try to find some page #'s & get back to you.

You need a voltmeter to read the codes, and an ohmeter to see if the wires have continuity.

Download the factory shop manual for your truck, or the closest thing to it, like an 89. Look both at the wiring diagrams and the harness layout diagrams to trace your wiring from the control relay to the fuel pump. The wiring diagram will show wire sizes and colors, and connector numbers. The harness diagrams will show connector locations and harness routes. I'd start at the fuel pump and work back to the relay. Very easy to have a corroded connector or broken wire under the truck, or under the passenger carpet or back seats.

The intro to the electrical section will show you connector shape codes, wire color codes, how to find shorts and broken wires, and mucho other useful stuff, like how to read the diagrams, electrical gizmo symbols, and suchlike stuff.

If the pump runs when removed, it's a wiring or relay problem, or the pump ground wire. I'm suspecting the latter, but check it all.

Picked up a analog multimeter from radio shack for 15.00 (i'm weak when it comes to electronics). According to the FSM the diag port should be above the climate control gate..I only have 2 fuses up there ?? I found what looks to be the diag port screwed to the top of a shroud for the ECU. I connected it anyway and the needle only moved a little to the left. Sorry for the rookie ??'s but i've never used a multimeter and think i might be missing something. Thanks again for everyones input and paitience with my noobness. Chris

I'm not sure if the '91 is drastically different than the '89, but in my '89, the diagnostic connector is behind the glove box.



It's the white connector with 3 wires...

Hope this helps <img src="/forums/images/graemlins/kewl.gif" alt="" />

Eric W.

Look at that connector with the catch up. Connect the voltmeter leads to the upper right and lower left wire connectors and switch the ign to on. You should see a series of needle movements. Long time movements are the tens place in a two digit number, and short time movements are the ones place. For example two long pulses and three short pulses would be 23. A constant string of same length pulses means no error codes. If it swings over to about 12v and stays there, the ecu is bad.

You need to set the gauge on a range (like 0-20v DC) that puts your expected voltage near the middle of the scale. Your voltmeter will almost always be set on 20v DC for car work.

Still no start but she still turns over. Thanks for the replies. I think i did the diags correctly today because the analog needle did sweep to the far right continiously which means the ECU is ok (according to the FSM). Although i did have to ground it to the door hinge to get a reading. Had my friend test the spark with a plug out and he got a little jolt. Then loosened the fuel intake line at the rail and there was pressure. So it appears i have spark, fuel, and ecu cooperating........I may have to prowl the mitsu dealer at closing time and see if i can barter a tech's time. Work has been so slow and i am struggling to stay afloat. sob, fustration, sob, fustration...Chris

If you don't already have it go to www.mitsubishilinks.com and download the raider_fsm_1989_powertraindiagnostics-30l.pdf document. This contains Mitsubishi's own no-start and driveability test procedures. You might want to read through the no-start test procedures as it will help you focus and eliminate causes in a methodical manner <img src="/forums/images/graemlins/cheers.gif" alt="" />

Eric W.

You sure the pump from the junk yard is any good.

It appears to. Yesterday when after trying to start her...i loosened the screws that attached the fuel hose to the fuel rail. Did a little jiggling and gas started spraying out that appeared to be under pressure.

89ISMINE...i have the fsm on my desktop and i will review it again. I will probably tow it to the local mitsu dealer for a obd1 plug in and test. I just dont trust my multimeter readings....It swept to the right repeatedly stating everything is ok with ecu ? But then why wont it start <img src="/forums/images/graemlins/barf.gif" alt="" /> <img src="/forums/images/graemlins/barf.gif" alt="" />

The ECU doesn't always tell you the problem so if it does come up without any codes stored, then there can still be a problem and you likely read the codes properly.

Need to start checking the basics. Air, Spark & Fuel. I'm no expert at that so I'll leave it to someone else to chime in with more questions/symptom info request or suggestions.

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