Engine/Transmission (1998.5 - 2002) pusher pump realy switch

[PHellen]

I installed a bd drag comp box on my 00 dodge awhile ago and also installed a carter inline pusher pump at the same time. I set the pump to turn on with the fuel pump wire with a relay. I noticed at the time the truck would crank over and over like it was out of fuel. SO i had to install a switch to turn off the pusher on start up the turn the swicth back on once the cummins was running. It works great but a hasle to turn the switch on and off all the time. Does anyone know what causes this? My buddy did the same setup on his 01 and he doesnt need a switch. Got me?





Pat

 

[Gary - K7GLD]

IF the installed relay actually DOES shut off the added pusher the same as the stock LP does, WHY would you NEED yet another switch to shut it off AGAIN?



Sounds to me like your relay is miswired...

 

[PHellen]

i need to shut it off the start only. otherwise when cranking over it runs the pusher with the pump so it doesnt start. I dont need to shut it off twice. I just havethe switch to kill the pusher on start otherwise the pusher somehow starves the engine and it just cranks likes its out of fuel. the pushers postive is taped into the postive wire on the pump so when the pump turns on so does the pusher. I have noticed if start the truck real fast after the ignition is on it will work but if i wait i have to turn off the pusher

 

[OPoole]

sounds like you could have to much fuel psi. at start up? do you have a gauge.

 

[PHellen]

no fuel pressure guage yet soon

 

[Gary - K7GLD]

I still don't get it = ONE place you say:



"I set the pump to turn on with the fuel pump wire with a relay. "



And NOW you say:



"the pushers postive is taped into the postive wire on the pump so when the pump turns on so does the pusher. "



SO, which IS it - do you have an EXTRA relay controlling the added pusher - or did you just wire into the power wires to the stock LP?



The power fed to the stock LP MIGHT not be sufficient to power *2* pumps - you might overload the circuit - that's why most of us DO use a separate relay and power lead for the added pusher...

 

[Big White Beast]

My relay is in the cab.......

And while cranking I can hear it chatter from the lower voltage supplied by the stock LP. Never had a starting problem.



My relay could be considered a higher draw one as I opted for one that could handle 20 amps. If you have one of the micro relays the lowered voltage from the stock lift pump could still be enough to keep it activated.



Another possibility is if you did use one of the smaller relays you could have welded the contacts shut on start up draw to the pusher. Check and make sure it's still working properly.



Garrett

 

[isb360]

In the next couple of weeks, I am going to install the Carter inline pusher to augment the OEM lift pump. I own a shop manual and it prescribes what the different duty cycles are that the OEM LP goes through, one duty cycle on start up and one while vehicle is running.



My thought pattern is this: why fool with the ECM-controlled start sequence by having too much pressure during cranking? There is such a thing. I am going to hook the pump up directly to a keyed 12v source, but I am also going to put an on/off switch on it. I will start the truck on the OEM system only, then when it fires, flip the switch and run the pusher pump. Then, because it'll be connected to a keyed 12v source, if I turn the truck off and forget to turn the pusher "off", it will not keep running.

Besides, I think it's cool to have an extra switch in the cab that can impress passengers



I just replaced my LP and am showing 12. 5psi at idle and I can pull it down to 7psi with the PM3 box on setting #5, so I definitely need extra fuel capacity. I will install my MaxFlow system this spring.



Hope you find these thoughts useful.



Tim

 

[Gary - K7GLD]

Some have tried the "extra switch" method, but few seem to stick with it very long - YMMV...

 

[PRout]

I had considered firing the LP relay from a same circuit that temporarily shuts off when the starter is cranking, and then comes back on when the key is in the run position only. I think some accessory circuits (like for the radio) do this.



Seems like that should get you pretty close to having the pump running & off when you want it. . Havent really thought it through yet.



One thing that wouldnt be good is if the motor isnt turning, but the key is still on. That would mean the pump is running while the motor is off. . Not sure how bad that would be, but at least you wouldnt have a load on the ecm that way.

 

[Gary - K7GLD]

It's really not that big a deal - you simply run an added relay that receives it's operating power from the same source as the stock LP - very low added current draw, Radio Shack sells one with a pair of 20 amp contacts for somewhere well under $10 - then you run a separate 12 volt line thru that relay and on to the added pusher pump - all this in my case runs off a spare keyed point in my fuse panel... Thus, the added pump runs/shuts off exactly the same as the stock LP...

 

[Sixpack]

Originally posted by Gary - KJ6Q

It's really not that big a deal - you simply run an added relay that receives it's operating power from the same source as the stock LP - very low added current draw, Radio Shack sells one with a pair of 20 amp contacts for somewhere well under $10 - then you run a separate 12 volt line thru that relay and on to the added pusher pump - all this in my case runs off a spare keyed point in my fuse panel... Thus, the added pump runs/shuts off exactly the same as the stock LP...

Gary if I read your post correctly your pusher pump relay is triggered by a keyed on power source instead of the lift pump?

 

[PHellen]

gary the relay postive runs straight off the batt. , the stock pump wire goes to a toggle swith then back to the relay. I wired it like this so i can turn off the pusher pump to start.

 

[Big White Beast]

PHellen

I think what Gary is trying to say is that there is no need to shut off the pump for starting if it follows the stock lift pump. The stock pump lowers voltage during start-up. This in turn, at least for me, toggles the relay and does not allow the pusher to pump full pressure till it's started. No need for a separate switch.



The actual power for the pusher can come from any of the keyed power sources. That way when the key is off there is no power at all to the relay.



As I said earlier if your relay is following the stock pump it may be that the reduced voltage is enough to still engage your relay and that's why the hard start. If I remember right it drops to 7 volts during starting.



Garrett

 

[Gary - K7GLD]

"Gary if I read your post correctly your pusher pump relay is triggered by a keyed on power source instead of the lift pump?"



NO, what I said was THIS:





"you simply run an added relay that receives it's operating power from the same source as the stock LP"



Plainly put, the SAME power leads that power the stock LP are spliced into and used to power the coil on the added relay - it is the SEPARATE 12 volt lead from a separate source that powers the added pusher thru contacts inside the added relay... THIS way, the pusher is CONTROLLED by the same circuit that controls the LP, but runs off it's own separate isolated power source...



Clearer?

 

[Steve St.Laurent]

The ECM doesn't reduce the voltage to the pump, it pulses the power to the pump to reduce the pressure during cranking - like turning a switch on and off rapidly. Problem is that it's so fast that the relay doesn't have time to turn on and off. What I do is turn the key to the on position and then wait for the pumps to stop before cranking and it lights right off. If I turn the key on and immediately crank (while the pumps are running) then the starter cranks the engine several revolutions before starting (probably 1 second or so).

 

[crawler]

What Year Truck?

If your truck is a 98 or 99 you need to go get the ECM reflashed for a "hard start condition". I have the same problem on a lot of the 98. 5 and 99 model trucks . The best solution is to have the truck reflashed. After the reflash the pumps will only run for a short period when you turn the key on then turn off when you are cranking (eliminating high FP during cranking) then come back on after you quit cranking.



Hope it helps.



Wes

 

[Big White Beast]

Steve is probably right.....

As I said earlier my relay is located in the cab. I hear it chatter during starting. When I measured the voltage it seemed to drop. Probably due to the speed of the digital MM.



I'm notorious for just jumping in and turning the key, never a hard start yet.



Garrett

 

[Sixpack]

Originally posted by Gary - KJ6Q

"Gary if I read your post correctly your pusher pump relay is triggered by a keyed on power source instead of the lift pump?"



NO, what I said was THIS:





"you simply run an added relay that receives it's operating power from the same source as the stock LP"



Plainly put, the SAME power leads that power the stock LP are spliced into and used to power the coil on the added relay - it is the SEPARATE 12 volt lead from a separate source that powers the added pusher thru contacts inside the added relay... THIS way, the pusher is CONTROLLED by the same circuit that controls the LP, but runs off it's own separate isolated power source...



Clearer?

So plainly put you are using the lift pump power to trigger the relay that powers the pusher pump..... I can see how this would work after reading Steves post.

Clearer, somewhat!