You might want to try changing the PCM if you have a spare, even if its from another model year, you might find that the engine will fire because of that alone, if that's the issue, just find yourself a suitable replacement and your on the road again.

 

I have a problem along the same lines. Here’s the description:
I just got a 99 Ram 1500 with a dead 5.2l. No CEL -- I hooked up an OBD scanner and there are not codes. It fires a little bit when just turning over and it fires a bit better with the gas pedal floored but never gets running on its own. I’ve done the following:
+ checked the distributor alignment – set the 1 cylinder at TDC on the compression stroke and the distributor rotor was pointed right at the #1 cylinder mark in the cam position sensor.
+ I had a low resistance on the coil so I swapped it with the coil from my running 99 Ram 1500 with a 5.9l. The 5.9l didn’t run with the other coil but the 5.2l still doesn’t run with the ‘new’ coil installed. Even switched the coil wires around and no difference.
+ I switched the PCMs around and there was no difference.
+ Checked the fuel pressure and it’s 48 psi at the rail.
Still no CEL or any codes at all and all it does is fire a little when I first turn it over and when I floor it, it ‘surges’ (almost runs) but doesn’t catch. I’m at a loss on what to do next. I have the 98 5.9l here so I can switch parts over but which ones?

 

Jerrod,

It could be a number of reasons. Cmckenna should be able to help you since it seems like something electrical (Fuses, injectors not firing).

--Dan

 

When you swapped the PCM, did you take the replacement PCM out of a running vehicle or from a shelf? I had a bad PCM so I swapped it with an extra I had off of another 1999 Ram. When I tried to run the engine, still nothing. Engine would kinda start for a second when engine was cranked but then nothing. Only way to get it to run was by dumping fuel into the throttle body. Eventually after checking everything I could think of, I tried another PCM out of a running vehicle. Truck fired right up. Only way I know how to tell that a PCM is working is by pulling it out of a running vehicle in the first place. Don't make the same mistake I did.

 

Yes, I swapped the PCM from my 98 which is running perfectly. I also swapped the crank and cam position sensors (one of the dist cap bolts broke off....so that's nice) and it still acts the same...nothing's ever changed with the exception of switching the coil (VERY slight improvement).

I hooked up the fuel pressure gauge to the test port on the rail and located the dial so I can read it while cranking. The gauge fluctuates about 5 psi as the engine cranks at idle and is rock solid at 49 when floored. I assume that the injectors are being turned off when the gas pedal is floored which is why the needle is solid at 49. I'm a bit concerned about the 5 psi fluctuation at idle but I'm not sure what's normal for our trucks (and my formerly running truck really isn't anymore due to the parts swapping). I also can figure out why it fires a little better when I floor it vs. idle (after a while of flooring it, it stops firing but fires a little bit when it goes back to idle and then nothing again).

I'm beginning to suspect the injection system but not sure where to start with this thing...it has me baffled (not saying that this is a major accomplishment but it's a mystery!).

Thanks.

 

Is there a list of things to try now that I've exhausted all of the obvious? It's like there's a switch on this thing that I just need to turn on (or switch over from my other truck).

 

Sounds like something could be triggering the Automatic shutdown relay. Either that or the relay has been shorted. Might want to try moving some relays around in the box near the battery. If for some reason the ASD relay was triggered, it would automatically kill your engine as soon as you start to crank the starter. If that's not it, you might need to find out what sensor is faulty enough to trigger the Automatic Shutdown Relay. Focus on the simple stuff. Coolant sensors aren't gonna stop your engine from starting, transmission sensors wont, rear axle, etc... Try going back to the stock coil, check all your grounds, throttle body sensors, other sensors on the block pertaining to maintaining air fuel ratios. Check to see if you are getting proper voltage to the sensors that are used for startup, that will help you find bad wires if you have them.If you have a scanner that can display engine parameters, this would be the time to use it. If not, Scanguage is a good one that is about $150-200 that can display all your engine parameters which will help you eliminate the possible sensor or sensors that are malfunctioning.

Also, tell us what you did to the truck or what happened suddenly to cause this. Try just retracing your steps.

 

I tried moving the relays around and there was no difference. I assumed, at the time, that an ASD relay trip would result in an OBD code...Do you know if this is true? The OBD scanner I used didn't have the sensor outputs (only fault codes and the sensor that led to the fault codes) so I don't know what the sensors are doing, just that the PCM thinks that they're all cool. You'd think that the PCM would sense that your cranking away, the engine's not starting and tell you why but I may be asking a bit much (in 1999, anyway...the engineers were too busy partying like it was 1999...because it was).

It does seem like the injectors are firing (since I see a fluctuation on the pressure gauge that goes away when I floor the gas)...some other sensor isn't jiving with the rest of the system enough to let it run but also not enough to throw a code....hmmm.

I think my next step is to somehow get a hold of a scanner or software+cable for my laptop (Scangauge?) that gives me sensor data. If anyone in Minneapolis/St. Paul who reads this has one they'll let me use, I'll buy the beer! After all, I now have two dead Dodges in my driveway now that half of the sensors from the running one are on the dead one!

Thanks for your input, Slomojo...I appreciate it!

 

Software. Free.....

Cable. 38 bucks.

 

awesome