I purchased a 91 Dakota 5.2L that had only 89,000 miles on it. It has minimal wear and tear on the interior, no rust, and has evidently been stored inside a lot of the time. I think it has had ongoing unfindable problems which led to years of nonuse. The problem I was having originally was no cabin heat. I changed the heater core, flushed, etc. and finally changed the water pump. The impeller had severed off. After what I thought was a very good changeout, the truck will crank but not start. I found this site and read every post I could find relating to it, and since the water pump changeout, I have replaced spark plugs, wires, distributor, rotor, water temperature sensor, serpentine belt, fan clutch, hall effect sensor, fuel filter, have been through every splice in the whips, checked functionality of the relays, redone all grounds, replaced battery terminals, new battery, ohmed out all fuses, and she still will only crank. Can this be caused by a part of the ignition switch? I am going to look down the throttle with it open to look for evidence of a throttle leak next, but I am running out of ideas. It looks like it might be the SMEC (computer), and I am reading at Mopar that a new computer would have to be programmed according to the VIN. Dodge dealer here says its obsolete with no substitutes, so they wouldn't be able to program a new one anyway. Cardone looks like they have one but I know they just "rebuild" old cores. The morning that I did the water pump, I drove it across the lot to where I worked on it. It never had starting issues until the changeout. I have checked, rechecked, and double checked everything I did. I would appreciate anybody having experience on the 91 5.2 helping out. I am getting no power to coil, no power to fuel pump, but jumping out ASD makes the fuel pump run.

 

You probably did something to cause the timing chain to move off a tooth or so and that will cause the problem you have. I don't have the instructions in my head but there is a manual method to set the Cam and Crank to get the timing chain set correctly. These motors do not time via the Distributor the computer sets timing. The distributor will only change when the injector fires. You can get computers for this motor. The VIN helps them get the right computer but the computer is not tuned to the VIN that would be crazy to do since they make so many.

 

I've checked that the pistons are fully extended towards the spark plug hole for each position of the rotor. I never cranked the engine while installing the pump, never manually rotated it. And it was starting just fine before, so I don't see how I could have caused the timing chain to jump.

 

I gather it cranks, but does not catch?

If so, I'd also check the ground wires ... on my 1988 LA motor (NOT the same as a Magnum!), the ground wire is to the timing chain cover bolt; with it loose, I can get a crank on the starter due to the other ground bolt, but it won't start due to no fire.

(I'd also check the ground wire up at the battery; and the splice the later Gen1's have there between the battery tray and the firewall end of the windshield washer reservoir. That seems to be a common failure point.)

Also, the ignition switch may have failed coincidentally; it would be worth it to grab the FSM and prod the back side of the switch connector and make sure that it's doing what it's supposed to.

RwP

 

I have completely gone through the splices, they look new even. Completely redid all grounds. No resistance is evident from one end to the other when checking at any point in the wiring. I am going to have to order a new SMEC controller. I will ohm out the start switch at some point while waiting for the computer. I am hoping to restore this old girl and to keep it for a long time, so I am glad to be replacing important parts.

One thing is sticking out in my mind from when I did the water pump. The water temperature sensor, which is conveniently located under the a/c pump, had become brittle, and I noticed that the insulation had broken off on both wires where they enter the sensor. I don't think they touched each other or ground, but who knows. I am wondering, if they did short, if that could have toasted my smec. I did replace it, but it was a substitute part, a borg-warner. I was just glad to get a substitute part at the time, I may have added another problem. I am looking for the correct resistances across the sensor for various temps. If anybody has a chart or can direct me that'd be great.

 

Also would like a link to a downloadable service manual other than Haynes

 

Not sure about for free.

However, the 1991 is available on Ebay for under $25 shipped as I type this in paper.

RwP

 

Can the coolant temperature sensor cause a no-start?

 

I don't know about for 1991. For the LA motors, nope.

RwP

 

I found this today; http://troubleshootmyvehicle.com/chr...t-a-no-start-2 I found this about the ASD; http://www.allpar.com/fix/codes/sens...-shutdown.html