Odd no start

[cummins2k]

About a week ago my wife went to drive my truck and it wouldn't start. It cranked but didn't even try to fire. Oddly the lift pump (airdog 150) ran when the key was first switched on but not after cranking like it always has. Also weird wad the lack of any attempt to fire. A few minutes later I tried again and it fired right up. Today after getting tires it did it again the techs had to push it out of the shop. Once again after about 15 mins of messing around it fired. Same symptoms. Now's its fine again. The truck runs fine once started, no codes, and its runs 14-15psi of fuel pressure. Reading about the internet I see the asd relay being a potential issue. I hear this supplies power to not only the lift pump but also the injection pump. Does any one have any information about this relay? I am baffled as to why the airdog turns on when the key is first switched on but not after it has been cranked.

[Mopar1973Man]

Lift pump is directly controlled by the ECM. (No relay)

The injection pump (VP44) is controlled by the fuel pump relay in the PDC.

As for the ASD relay I'm not exactly sure what that controls since it hooked up on the PCM and not the ECM. ASD as far as I can see in all the wiring diagrams has no connection to the ECM and should not effect it.

http://mopar.mopar1973man.com/cummins/2ndgen24v/wiring/wiring.htm

[cummins2k]

Thank you for that Mopar1973Man. That clears a few things up. Hopefully it is not my ECM. It is odd how when it decides to do this the pump primes when the key is turned on but afterwards the pump fails to run. My truck has always been finicky on hills but after cranking you can hear the AirDog run. Usually the second try and it fires. My AirDog 150 does have a relay but I doubt it's involvement due to the fact it primes on key on. However I could be wrong.Mind you when parked on level ground it fires on the first turn of the key so I have no doubt my engine is in good shape.

[Mopar1973Man]

Well I've seen several truck this year lose the lift pump part of the ECM where it randomily trips the lift pump and randomly shuts it down too...

[cummins2k]

Well I've seen several truck this year lose the lift pump part of the ECM where it randomily trips the lift pump and randomly shuts it down too...

Oddly the problem hasn't happened since. I am sure it will show it's head again just can't say when. If I continue to have problems I may just create a work around system.

[jlwelding]

Put a switch in it.

[cummins2k]

Well I was thinking that very same thing till today when the plot thickened.The OBDII connector was destroyed at Autozone while getting it scanned some time ago, so shooting in the dark here till I get it re-pinned.We drove about 15 miles into town and stopped at the store. When we left the store and fired it up it was fine. I drove to the end of the parking lot and started pulling out on the road and it didn't feel right. The Edge showed everything was ok. Good oil pressure, good fuel pressure, etc. So I pulled over and noticed the check engine light was on. While sitting there with the truck idling I observed the tachometer falling to 0 then rising back up, the engine would miss when it did it. All then sudden the engine went into a lope and it just kept doing it.I turned the truck on and tried the key trick. All it show was P1693 and P DONE. This was oddly similar to a previous experience I had before.About a year ago now when the OBDII port was broken, I had went in because a check engine light that showed up. It was P0336 then, the crankshaft position sensor. However the truck had no signs or symptoms so I thought it may had been just an erratic code. It was cleared and never reappeared.I have a feeling if I re-pin the connector and have it scanned it is going to show the P0336 code again.Makes me wonder if these problems are related in anyway.

[MnTom]

If your CPS is failing the ECM may not know what the engine is doing.

[cummins2k]

Well the plot thickens even further. I went to the auto parts store today and picked up the CKP sensor they ordered for me. I got home and pulled the starter. Mind you the light has come and gone a few times. After the starter came out I could get a clear view of the CKP sensor in the side of the block and noticed my first issue. This wasn't the first time this sensor has been serviced. Someone had broken the clip on the harness plug and used a zip tie in an attempt to hold it together. There was also some nearly disintegrated electrical tape. I am surprised this repair held together as long as it did. Since there was little I could do at this point I went ahead and pulled the sensor out. I put the new on in and re-wrapped it tightly with electrical tape. I am searching for a 3-prong weather tight connector for it as we speak.Either way with the new sensor in, harness cleaned, and it secured tightly temporarily the truck did seem to start with a more consistent length of time. Hasn't had the tach drop out yet, or started missing at idle.I guess time will tell if the gremlin has left. I don't have anyway to clear the check engine light at the moment so I guess we will see if the computer clears it after a few run cycles.

[MarbleCrusher]

Sounds like it could have just been that broken connector not always making a good connection, only time will tell!-Jordan-

[cummins2k]

Sounds like it could have just been that broken connector not always making a good connection, only time will tell!

-Jordan-

I think the new sensor is definitely giving a stronger signal. I am willing to bet the signal was weak to begin with. The truck sounds different from cranking to idling. On the highway it seems like it picked up power. Although I never would have assumed it lost power because obviously it lost it slowly overtime.

However if anyone is ever in the market to replace this sensor pigtail you can find it at:

Napa - ECH EC10

Rockauto - AIRTEX / WELLS Part # 1P1020