1985 Ram 50 won't start-I'm throwing down a challenge to all mechanics out there

Sorry if this is a repeat post but I couldn't find it after posting the first time. Here's the set-up and troubleshooting I've done so far. My 1985, 2.0L, Ram 50 got harder to start over time and finally left me stranded. The last 10 times it started it didn't fire until I released the key and then it would start right up and run fine. Spark test with the coil wire only gets a spark when the wire is about 1/8 inch from a ground and spark is very weak. It won't spark at all if more than 1/8 inch away while cranking but will jump up to 3/8 inch for a few sparks when the key is released. It has a new distributor including pick up coil, and all internal electronics. Also, new (rebuilt) starter, dist cap, rotor. Swapped out the coil with a spare that checked out to spec. Ballast resistor is 1.6 ohms (per spec) and has continuity. Checked resistance on coil wire and it's well within spec. Cleaned and checked all wire connections. Disasembled the ignition switch including separating the plastic case and checking the contacts and found no obvious issues. I checked voltage on the black and white wire that goes from the ignition switch to the ballast resistor and it gets no voltage during cranking and jumps to 12 volts when key is released but still on. To add to the fun, after I installed the new distributor it started immediately and I left it warming up for about 10 minutes. When I shut it down and tried to start again, it was exactly the same as above i.e no sparky. I've checked continuity on every wire I can think to check and all passed. I dissassembled the start relay (on the firewall) and verified that both contacts activate when I put power to them directly from the battery but I haven't done any test on it while installed. I don't like the shotgun approach (replacing stuff till the problem goes away) and I replaced the distributor and starter for other reasons. I took a shot with a new cap and rotor just to eliminate them. Any one out there who can solve this mystery wins the coveted "genius mechanic of the year" award. Let the competition begin! Thanks, for any help anyone can provide. Scott

It has to be the start relay not closing when cranking - check the wires that go to the relay coil when the key is in the start position - you could jump from the black wire on the starter solenoid to the positive side of the relay to see if it starts that way. If it does, then there is a break in the harness to the start relay.

I second the repair.

Thanks Pennyman, I haven't been able to locate the start relay but I jumped a wire from the black starter solenoid wire to the positive side of the ignition coil and got good spark. I connected the coil wire and the truck started rignt up so I know you've honed in on the problem. I have a official dodge ram 50 shop manual and a haynes manual but neither wiring diagram shows a start relay (that I can find). Do you know if it's under the dash or in the engine compartment? By the way the relay I tested before (on the fender above the coil) was actually the one for the headlights and parking lights. Thanks for the diagnosis. Any help finding that relay (or a description of what it looks like) would be appreciated. Thanks, Scott

If you fallow the harness back you should run into it some where. i want to say it's just to the left of your foot when sitting in the drivers seat.

It should be above the fuse block on the drivers side kick plate. It is a rectangular box with a tab to bolt it down - look at this link for an exact pic of it - http://www.ebay.com/itm/300057568490...84.m1423.l2649

Thanks Pennyman, Unfortunately, that relay is for a 2.6L truck. By tracing all wires from the ignigion switch, starter, coil, and ballast resistor (and a lot of web based research) I've finally figured out that the 85 2.0L doesn't use a start relay. I has a wire directly from the ignition switch that goes to one end of the resistor and another wire on the same resistor post goes on to the starter solenoid. The 83 thru 85 2.0L trucks are bastardized from any other engine size and year with regards to wiring, carb, and ignition due to some temporary fixes to meet the new US emission standards. They incorporated better permanent fixes in 1986. The wiring diagram in the 1985 Ram 50 chrysler shop manual (which I have) doesn't even exactly match my truck. The Haynes manual I have is even more worthless. I'm still having the same problem but there are even more mysteries now. I used a jumper from the starter to the top post of the resistor (which is then jumped directly to the + side of the coil and, just like last time I got good spark and then reconnected the coil wire and it cranked right up. After warm up I shut it down and it wouldn't restart. I checked the coil and no spark. Back to ground zero. It's back to no spark until I release the key (from start to on) and then I get a really good spark for a couple of pops until the engine stops turning. I disconnected the jumper and it started just as I released the key (just like it was doing before if left me stranded). No matter how long I cranked it, it wouldn't start until I released the key. While it was running I tried to connect the jumper it would begin to die and when I pulled the jumper back it kept running. Clearly, the jumper was shorting out the current to the coil even though using the same jumper connected was the only way it would start when I tried it 30 minutes earlier. I ordered a new ignition switch because that's just about the only thing I haven't replaced but I don't have much hope that it will fix it. Any suggestions while I wait for the switch? Thanks, Scott

ignition problem is solved! I installed the switch and still no spark but it was for several model years so it came with an extra wire that didn't have a corresponding wire in my connector so I used it to add a circuit that supplied current directly to the coil during cranking only. I've got sparky coming off the coil now that'll jump 3/4 of an inch. My problem now is getting it back in tune because of all the adjustments I did on it trying to get it started before I figured out what was wrong with it. It starts up but dies as soon as I open the throttle any at all. I've tried opening up and closing the mixture screw as much as 1-1/2 turns in each direction (i.e too lean to too rich) but it still dies when I throttle up. If I let it idle long enough to warm up it will accelerate without dying if I retard the timing and adjust the idle to about 950 rpms. Any suggestions here are appreciated.

That sounds like a vacuum leek or the choke is not closing or the accelerator pump is not working.

Thanks for the response. The choke is closed and I can see gas in the throttle body when I pump the gas pedal so I'm pretty sure the accel pump is working. I also sprayed some starter fluid in the carb while cranking and it still wouldn't start but it would fire and stumble a little bit before going back to just cranking. It sounds almost like a fuel issue but the starter fluid test will usually eliminate that. Vacuum leak is a possibility but there aren't that many vac hoses (as I'm sure you're aware) and I haven't seen any obvious leaks. Also, I would expect the starter fluid test would identify any leaks that were present. I rechecked the spark and it's still strong as ever. I'm focusing on timing right now but the distributor is set in the same place that it started in earlier. It's got to be something simple but when you have fuel and spark and still won't start it gets trickier. Any more suggestions are welcome. Thanks, Scott

If you have a timing belt check to see if it's in time, or loosing teeth.

Can you link the switch you got? I can’t fine one. Everything says 87-90 and I have an 85

Ham (without reading everything in this thread A.K.A I dunno what switch you mean..?)

Switch Link: http://www.mightyram50.net/vbulletin...hp?albumid=569

Also, C.R.C. carburetor/fuel injector cleaner sprayed into the carburetor to clean the choke plate & everything it can reach REALLY helps...

I am not a mechanic but I have a friend :fred: who is a mechanic :wrench1:

That's the one, ignition switch. Thank you! Just needed that part number. I think I might have fried mine while doing a test (poorly).

Nice..! MistsubishiPartsCentral is the place that had the OEM ignition switch (they really had to hunt to find it; hope you get it N/P...)

The new switch fixed a slow cranking problem when starting the truck & I feel as though the dash red warning lights burn brighter now too...

Might you know the difference between ignition switch MB414579 and Mb031704? They seem to have the same fitment on MistsubishiPartsCentral.
I have a 1985 Dodge Ram 50 2.0 liter 2 wheel drive, not diesel

Also, MistsubishiPartsNow looks identical but is a little cheaper. Any thoughts?

geezer (?) or another member, pennyman (?) I forgot -- well, someone posted a photo of an ignition switch from another Mitsubishi vehicle (a car) that looked the same in the photos -- it was being sold online (I think) this one here: https://www.lelong.com.my/kx/mitsubishi+switch.htm