Lost ECM output to lift pump

[WiscoRedkneck]

Changed fuel filter cracked line bled system tightened line started truck fuel pressure came up then 3 seconds later it went to zero shut truck off.  Checked for air lock then voltage and founds 2 volts output from ECM called air dog they instructed me to wire to 12v switched and this is common.  Tried that all issues resolved for now....  Had to leave for a trip so I decided to run it hooked as such truck performed as expected that was a week ago.

My issue is this does that mean the ECM is failing is there a way to find out I have never had one sign of ECM issues until now

Second is I often use the trucks radio when parked in ACC. and the fuel pump continues to run any suggestions on where to wire the pump to?

[TFaoro]

13 minutes ago, WiscoRedkneck said:

Changed fuel filter cracked line bled system tightened line started truck fuel pressure came up then 3 seconds later it went to zero shut truck off.  Checked for air lock then voltage and founds 2 volts output from ECM called air dog they instructed me to wire to 12v switched and this is common.  Tried that all issues resolved for now....  Had to leave for a trip so I decided to run it hooked as such truck performed as expected that was a week ago.

My issue is this does that mean the ECM is failing is there a way to find out I have never had one sign of ECM issues until now

Second is I often use the trucks radio when parked in ACC. and the fuel pump continues to run any suggestions on where to wire the pump to?

Does your lift pump circuitry have a relay?

You've got two options - 1 put the pump on a switch or - 2 find a fuse that isn't hot when you're in ACC and run a fuse tap.

[WiscoRedkneck]

I believe so, so this is common then?

Is ECM failing or does that large aftermarket pump cause an overdraw on the factory ECM output causing the failure?

[Me78569]

Semi common.  

 

Some light pump sdon't use a relay so all the power is drawn through the ecm, which is tough on them.

[Dieselfuture]

Like said above, ether use ecm power to power a relay, not sure if 2v is enough though. Or wire one up from 12v key on.

[IBMobile]

44 minutes ago, WiscoRedkneck said:

does that large aftermarket pump cause an overdraw on the factory ECM output causing the failure?

Yes it can that's why you would want to do this.

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/59_fuel/installing-protective-lift-pump-relay-r501/

 

2 volts wont run anything.

 

If you want 12 volts with key on  tap the red/light green (rd/lg) wire at terminal 87 of the fuel pump relay in the PDC and use it as the triggering power at terminal 86 of a relay, you install, for just the lift pump.  This will turn on the lift pump anytime the pv44 is energized.

[Alexio Auditore]

What type of lift pump is it? My raptor 100 did that in town, only noticed when my truck started running really rough, looked down at fuel pressure gauge, 0, but Everytime I shut truck off and turned back on, it ran for a few seconds at normal pressure then dropped back to zero. Literally got it home by turning the truck off and on, not recommended but what do you do. The stupid pump went bad and when they put the new one in, problem solved. They said it damaged the ecm by doing what I was doing to get it home and they installed a relay of some sort that ran the pump once the key was in on position, but I plugged it back into the ecm and no problems.(((well until now, pump is acting up again.)

[WiscoRedkneck]

41 minutes ago, Alexio Auditore said:

What type of lift pump is it? My raptor 100 did that in town, only noticed when my truck started running really rough, looked down at fuel pressure gauge, 0, but Everytime I shut truck off and turned back on, it ran for a few seconds at normal pressure then dropped back to zero. Literally got it home by turning the truck off and on, not recommended but what do you do. The stupid pump went bad and when they put the new one in, problem solved. They said it damaged the ecm by doing what I was doing to get it home and they installed a relay of some sort that ran the pump once the key was in on position, but I plugged it back into the ecm and no problems.(((well until now, pump is acting up again.)

Airdog FRRP 100 thanks IB I will wire it up that way.  It's getting a mechanical lift pump this winter because I absolutely hate these electric lift pumps

[Mopar1973Man]

AirDog 150 and now heading to 12 years old. Still going strong. Power relay and fuse.

[99dodge_pos]

I realize this thread is a year old, but having just gone through the same issue on my stock 99 Dodge 2500, I would like to add that IBMOBILE is 100% correct.  My lift pump power had also reduced to 2 or 3 volts while probing the connector. Also lost my ECM  wait to start light and truck would crank with a race car cam lope then die.  Ruled out VP44 failure by hot-wiring it with help from Doug at Blue Chip Diesel. Had my ECM repaired at AutoComputerSpecialist out of Florida.  I did the relay mod from IBMOBILE article, also did the VP44 ground wire mod, as the ECM repair company  listed low cranking voltage as part of the original ECM failure.  Great company highly recommended.  While doing the relay mod, after ECM repair, I found that the lift pump connector was faulty.  It still had only 2-3 volts coming through, but when probing the yellow w/white stripe power wire itself, it had 12.5 volts.  Would not have found it otherwise.  If you continue to use the electric lift pump, DO THE RELAY MOD, and ground wire mod, and help preserve your ECM.

 

[Dieselfuture]

Yeap, most of us did this, and it's not easy to explain sometimes until you do it yourself then you start to realize. I've been there. 

[99dodge_pos]

I didn't stop to think that most owners probably have already been there and done that given the age of these trucks.  My truck is a new to me truck with 155,500 miles on it, and the previous 2 owners obviously had not incurred this problem yet.  Lucky me.  Seriously, lucky me that others had been there and done that, and had a nature caring enough to pass it on for other newbies such as myself.  I just wanted to give a little back and post my problem and outcome on this thread as sometimes problem, and problem solved can be difficult to locate within the same thread.  I know it took me quite a bit of reading and research.  Everything costs so much these days and I can"t afford to do parts replacement in hopes of finding the problem.  Thanks to all the members and administrators for their caring and taking the time share.

[Dieselfuture]

8 hours ago, 99dodge_pos said:

I didn't stop to think that most owners probably have already been there

I was mainly speaking off members that are active on this form, and in no way I wanted to be a smart  with my comment. Sometimes people interpret wrong meanings with text messages I wanted to make sure I didn't make it sound like anyone is better than anyone else. We're still all learning, it amazes me after all these threads and forms we're still finding new discoveries and things to talk about. Either way I'm glad your truck is running better, now on to the next thing...

@Mopar1973Man Mike you need a new smiley for v2 tuning, so we're not blowing black smoke but rather living tire marks. 

[dripley]

It seems that we are gaining a lot of new members lately that are buying their first diesel in the 2nd gens. It seems the 2nd gens are starting g a new life cycle.

[99dodge_pos]

No offense taken Dieselfuture.  God is great and life is good!

[Mopar1973Man]

@99dodge_pos you find out we've got our own family of   guys here. Typically they throw in the comic relief to the thread keeping the tension down. Seriously though these guys typically have there head screwed on tight and have a wealth of knowledge to share.Just relax and enjoy the comments and they will get you past you hurdles.

[JAG1]

3 hours ago, dripley said:

It seems that we are gaining a lot of new members lately that are buying their first diesel in the 2nd gens. It seems the 2nd gens are starting g a new life cycle.

And the kelly blue book prices have had to be raised twice now on these trucks, from what I understand. A lot of it is because guys are finding a whole lot less problems with these trucks if set up properly.

[Mopar1973Man]

1 hour ago, JAG1 said:

A lot of it is because guys are finding a whole lot less problems with these trucks if set up properly.

 

Website like this, and the knowledge of fixing up an 2nd gen to be more reliable than a new 4th gen. 2nd gen truck and becoming highly sought after and the collector's item. 

Edited July 27, 2018 by Mopar1973Man

[JAG1]

It takes years of knowledgable folks posting on a good site like this to compile what to do for reliability and longevity. I thank even the newbie folks as well for contributing.