Archived Lift Pump Wired directly to fused Relay

[REdmon]

From my issue below, I had my mechanic install a fused relay connecting the lift pump to the battery. However, I called him today and he says he is getting an error code for the injector pump in which the ECM doesn't see any draw from the lift pump. Is there any specific wiring that needs to be done to make the ECM see a draw so it doesn't throw an injector pump error code?

Thanks,

Our 1999 Dodge Ram 2500 wouldn't start at the store for my wife (stuck). After calling me on my way home from work, she said it started and I told her to drive directly home. 1 minute later, she calls and the truck died in the street. I made it down (30 miles away) and had it towed to the closest reputable diesel shop. After checking it out the next day, the mechanic called and said the injector pump was bad. I told him to replace it. The next day he calls and says there is an additional problem with the lift pump acting sporadic. I tell him I have a new spare (problematic lift pumps I was aware of being a member) and I drop it off. He installs the lift pump and calls back stating the pressure is a little better (10 PSI down to 8 PSI on acceleration), but that there is an electrical intermittent occurring in which the lift pump doesn't always feed. If the truck is running and you turn it off, 1 out of 5 times it won't start back up and you have to turn the ignition back off. A second try will get the truck started. He doesn't know what the issue could be and couldn't get back onto the job for 2 weeks due to schedule being booked. I will pick the truck up tomorrow and take it to my local mechanic, but is there specifics that may be causing this issue?? Your help or suggestions are greatly appreciated.

Thanks

Ron

 

[p-Bar]

the ecm needs to show a load and since you are using a relay that doesn't load the circuit enough. I don't remember what value you will need .

 

[hcole]

I did what I told you I did with my lift pump and have NEVER heard of this setting a code. This is entirely new to me.

 

[SAndreasen]

sounds like reputable jumped shop the gun and replaced the injection pump when the problem was the lift pump

 

[Bob4x4]

The factory retrofit pump kit runs off a relay,IT does NOT trip a code

 

[REdmon]

The factory retrofit pump kit runs off a relay,IT does NOT trip a code

Bob, my understanding is the LP was wired direct to the batter to the LP, and the Relay wired from a terminal thats hot when the ignition key is turned on. The ECM has been taken out of the picture. Therefore, no current draw on the ECM which believes the LP is dead and therefore the injection pump throughs an error code.

I need someone that knows how you get around the ECM no longer seeing the current draw from the lift pump.

 

[hcole]

REdmon, could you tell me what code number is set? Does your check engine light come on? I'd like to know for my own reference.

 

[SnoKing]

Not letting the ECM control the relay may cause more issues than the code. Start issues may well be in your future also. Snoking

 

[cerberusiam]

I need someone that knows how you get around the ECM no longer seeing the current draw from the lift pump.

The simple way is just a fake relay that does nothing but provide a load to the ECM. Doesn't negate the issues that will ensue with the IP but it should stop the codes. The right way is replace the ECM and move the power supply for the LP to the relay.

 

[dknoch]

When I was trouble shooting a hard start with mine, I disconnected the lift pump and got a code for the lift pump. No codes set for the injection pump. What is the code so we can help?

 

[REdmon]

REdmon, could you tell me what code number is set? Does your check engine light come on? I'd like to know for my own reference.

I will call the mechanic tomorrow and ask and then post.

 

[REdmon]

Darn, I didn't think this would be such a major production. The mechanic set it back to factory with the ECM feeding the LP. The problem noted is that the truck won't start on the 5th or 6th try, You turn the key off and it will start. I am afraid of having an intermittent in which the LP doesn't feed the injector pump and I destroy the new one installed. This vehicle has been in the garage for 2 weeks, mechanic scratching his head and making calls. I need the TDR members with the knowledge speak up and tell me how to set it up so it runs correctly. If you can recommend anyone on the forum that a pro at this, provide me a name and I will email them.

Thanks

 

[hcole]

REdmon, I await the code. I have mine set up like this so I KNOW if it's not pressurized. I monitor the pressure at the fitting that looks like a tire valve on the VP. I then installed a pressure gauge in the truck on the 'A' pillar. I installed an isolator next to the fuse block under the hood. Then I tee'd into the line and installed a GM oil pressure sensor that was one of those idiot lights that was on when you had less that 5 pounds of oil pressure. This in turn turns on the light I have mounted inside at the lower dash around the emergency brake on low pressure. The light is wired hot so it's ground is passing through the oil sensor. I also have a buzzer wired in with the light to sound off if I have low pressure. I have ran this way for 3-4 years and 100,000+ miles. My running down the road pressure is about 15 lbs.

 

[p-Bar]

=I need someone that knows how you get around the ECM no longer seeing the current draw from the lift pump.

Don't you want to show a load on the ECM to fool it thinking there is a lift in the circuit?

 

[REdmon]

I called the mechanic today and asked him what the error code was. He stated that he didn't recall exact, but said it was the code for failed Lift Pump. He said he put the LP back into the circuit and it continued to have issues of starting 1 out of 5 times. He made some calls and said he was told that if the O-rings on the injector tubes were worn, it could cause the same issue. If he doesn't have a handle on this in the next day or two, I am going to have it towed back home in my local area to my mechanic. I don't want to end up having to shell out for an ECM as that would run another $1400. I will update as I get more information.

Ron

 

[dknoch]

The Orings will cause trouble. Park it nose down and it should start fine if it is a lose of prime issue. Nose up will be a hard start. Read through the diagnostics help here, call them if you need to http://www.bluechipdiesel.com/#.

Good luck!