hi. I'm a newby here though I have guest visited a number of times. I'm stuck on this no start problem. My 5.2L just quit while idling at a light. Towed it home. Found there was no compression to speak of...figured it was a timing chain jumped. I pulled the cover and found the chain was real loose (240,000km=140k miles). changed it. Still no start...rechecked the compression...none. Long story short: my gauge is broken. Bought a new one and surprise 125-135psi! Soooo, checked for fuel pressure: 40psi. Checked for spark: good spark at (new) coil, but irrattic at #1. Checked cap + rotor...not great. So replaced that too. Spark is good, but still no start. WT_ ?Brain is tired! Any input would be appreciated.

 

One of the gears may have jumped the chain when it was running and that's why the engine quit. If so, the timing will be off and the truck might not run if you didn't correct it when you initially fixed it. Only way to fix this is to open it back up and ensure everything is at top dead center.

Another way to tell is the computer will set a code for the timing chain jumping a tooth. Cycle the ignition on and off three times and check for codes. (On(not start), off, on, off, on. On the final turn to on, leave it on and watch the check engine light. If you've done it correctly, it will flash out the code. Flash pause flash flash represents code 12 for example.) I don't remember what code is for the timing chain jumping a tooth, but you can find that info in the FAQ.

 

thanks for the response. I was very careful installing the new gear set (mark on cam gear at 6, crank mark at 12 with #6 at TDC- as per my haynes manual) The compression #s seem to indicate all is well there. Spark seems good with the new cap & rotor. Recent coil replacement too. I can hear the fuel pump run and the pressure is good. I saw on a similar thread that the ASD relay could be at fault, so I switched it with a known good one - no change. They also spoke of a faulty splice in the harness below the fuse/relay box - checked them (there is 3- 1 ground and 2 positive); all good too! There was a rusty ground point there, so I cleaned it up. Still no go.... I am thinking maybe the injectors (MPFI) are not getting a signal to fire...? I am not quite sure how to check that. Any input? I think some models use a cam and/or crank sensor to trigger the injectors. I don't think mine has those...do you know? '93 5.2L magnum V8, multipoint EFI.

 

Cam sensor is in the distributor under the rotor. There's another name for it but I can't remember. Crank sensor is on the bell housing of the transmission I believe. If not, it's at the back of the motor really close to the transmission. But yes, it has those. It is possible that one of those sensors went and is causing a timing issue. Did it stumble or anything before it died? Does it put or sputter when trying to start it? Any attempt to run at all?

As for testing an injector, no clue. The way I would do it is pull an injector and see if it fires as someone tries starting the truck, but I wouldn't recommend doing that lol

 

ok, I guess I'll brave the cold in the morning (-24 C) and see if I can find those sensors. It doesn't sputter or anything. Same when it quit...just stopped. Just from listening, it seems to crank a bit fast...I don't know though, because it always started instantly before. When I worked for Toyota, I used to loosen the cold start injector and try to crank it...it sprayed real good if it worked! Don"t be smoking anything to close! I guess on these you would have to remove the whole fuel rail to see them fire. In one of the other threads I read, someone suggested listening to the injectors with a stethoscope (while it's running) to hear a clicking noise as each one fires...mine won't run....Arrgh!

 

If it stopped suddenly while running, that might point to the ignition coil. Do you have a known good ignition coil around that you could test?

 

It's called a pickup or hall effect or something along those lines

You should be able to hear the injectors run as the fuel pump primes.

At least I can with my 94 motor

 

I can hear mine clicking when it primes with the '93 v6. Tested it as soon as I read this.

DukeDomB, he said in his first post that he has good spark right through to the number 1 plug once he replaced a few things (including the coil).

Professor sir, can you get the truck to run if you hit the gas while trying to start it? Don't floor it, but hold the gas pedal slightly and see if that helps the no start condition. It may be starving itself for air?

Also, -24? Whereabouts are you if you don't mind me asking

 

I haven't tried holding the throttle open while cranking it. I will give it a try. I thought the injectors would only "click" while cranking...otherwise wouldn't it flood the engine? I wasn't brave enough to try looking at it in this cold. I'm in Belleville Ontario, by the way...on the NE end of Lake Ontario....it's -29C now (feels like -39 with the wind chill factor. It's a new record low.... old record was -28. For our American friends 0C=32F, -40C=-40F) I don't think I will be looking at it again until it warms up a bit! Thank God I have a stable full of old trucks to drive in the mean time...the Dakota is really my "summer" vehicle. Anyways, I was thinking that maybe there is a ground point for the PCM or a connector to the distributor/cam sensor/crank sensor that might be bad. Any ideas where they might be? Has anyone had to change the crank sensor? It looks, in the Haynes manual, to be a bitch.... I guess the easiest way to change the cam sensor is to pull the distributor and do it on the bench. I must admit I am getting gun shy of pulling more stuff apart, since I may have to take it into a "real" mechanic to have it diagnosed. I hate replacing parts without testing them to see if they are truly defective. Is there a good service manual available for this truck? The Haynes manual just isn't complete enough for this level of diagnosis... again, I appreciate your time & help.

 

It is possible it has a bad ground somewhere, but from what I understand about these computer controlled things is you would either have no spark, or no fuel, or both no spark or fuel if the computer isn't running as it should. Based on what you've told me, I'm really leaning towards the truck starving itself for air. It's possible the IAC is bad, or even just the passage is blocked. That's why I say to try opening the throttle a little bit while you try turning it over to see if that helps.

I've personally never had to replace a crank or cam sensor. I've heard the crank sensor is somewhat easy, but I know the cam sensor sucks. I would probably pull the distributor to do that job as well.

As we speak right this second, it's -28C, -39C with the windchill here in Winnipeg. Brutal winter we've been getting here in Canada this year. Brutal cold and tons of snow. I know how you feel about not wanting to diagnose in this cold lol.

As for a better manual than the Haynes manual, there isn't one really. However you can go into the FAQ and somewhere in there there's a factory service manual for the 1995 Dakota that translates back to earlier years somewhat too