Lift Pump at IDLE problem

Shilohsho · 05-11-2008, 08:06 PM

I've got the lift pump mounted at the tank on the frame. It's been that way for 70k miles. Also, I've got a low pressure light to monitor it.

Lately, it has randomly lost pressure at IDLE after 4-5-10 minutes. It does fine when under power going down the road. This only happens at idle.

What's the Problem here?

Also, I know it's time for FASS but that doesn't explain the current problem!

__________________
'99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

HARRISDIESEL · 05-11-2008, 08:14 PM

Im not trying to sound like a know-it-all but i think (or guess!!) what is happening is your lift pump is getting very weak and your injection pump is pulling the fuel just enough to cut the light off!! at idle your injection pump is not pulling enough but your lift pump isnt pumping enogh, while throttle is on the injection pump is pulling!! And that results in injection pump failure!! A fuel gauge my help you figure the amount of fuel your lift pump is pumping!!! I would try checking the pressure at idle and WOT!!

__________________
02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k

10/4/08 537hp 1050t

Shilohsho · 05-11-2008, 08:24 PM

I've got a pressure guage on the "dirty" side of the fuel filter housing. The pressure light is on the "clean" side of the filter housing. The other day the light came on at idle, I checked the guage and it was on 0 psi. so i shut the truck down. I gave it a second then cranked it up and the guage was at 12-13 psi at idle.

I'll check tommorrow what the pressure is at WOT.

__________________
'99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

NickBeek · 05-11-2008, 08:44 PM

Have you checked all the plumbing? Sounds like you may be pulling air instead of fuel from the tank sometimes. Just a guess.

__________________
2006 Dodge, 2500, CTD, 4x4, 6 Speed, SLT, Thunder Road Package, Mineral Grey, MBRP Muffler Replacement Kit, Fast Idle Enabled.

HARRISDIESEL · 05-11-2008, 09:38 PM

Either your getting air or your carter pump took a dump!!

__________________
02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k

10/4/08 537hp 1050t

$30 Cowboy · 05-11-2008, 09:53 PM

This might make me sound stupid, but what about your power source. At idle, you might be losing power, like a bad alternator or something. When you get on it, you regain power...but like i siad...maybe im slow...lol are your lights dimming at all?

__________________
Cowboy Cadillac 2007 Dodge 3500 DRW QC 4x4; 6-speed, RanchHands, 4" TBE w/ 6" Tip. AFE stage2, Silencer ring MIA

Shilohsho · 05-12-2008, 07:33 PM

Alright, today I watched the guage and the light and the guage was holding 12-14psi at idle and 11-13psi down the road. At WOT it was no less than 10 psi.

Maybe air but I don't see how. The power source is the original wires extended down to the frame at the tank.

__________________
'99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

HARRISDIESEL · 05-12-2008, 07:40 PM

It maybe you TPS too!! call me and I will run a diagnostics test for you!!

__________________
02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k

10/4/08 537hp 1050t

dieseldude5.9 · 05-12-2008, 07:47 PM

Quote:

Originally Posted by Punchy

This might make me sound stupid, but what about your power source. At idle, you might be losing power, like a bad alternator or something. When you get on it, you regain power...but like i siad...maybe im slow...lol are your lights dimming at all?

This is exactly what i was going to say also. If you have a bad connection on the power or ground source it will cause high resistance and seem that you motor is weak. It would do this at idle because your alternator is not at its full output and this would lower the amperage going to the pump even more. Then when your driving you alternator is putting out full volts and amps and would temporarly fix the problem until your return to idle. Hope this helps. if you understand what i'm trying to imply.

__________________
08' QC, H&S 5" DPF delete, EGR delete, Edge juice w/attitude

Shilohsho · 05-12-2008, 07:52 PM

Tommorrow I'll check the voltage output at idle.

Will, I'll give you a hollar in the next day or so.

__________________
'99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

HARRISDIESEL · 05-12-2008, 08:36 PM

10 4 shosho!!

__________________
02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k

10/4/08 537hp 1050t

KATOOM · 07-06-2008, 11:47 PM

I've been checking posts because I had the same problem today. My FP dropped to 8 psi at idle for no apparent reason and after a few minutes it came back up to the normal 14-15 psi. Everything was fine there after but I did throw the P 1693 code. I no wonder were the real problem came from and was wondering if you solved your problem. I never bothered to look at my alternator output so I cant speak for that.

__________________
'01 2500 Sport 4x4 5spd, EZ, straight piped, no sillencer ring, aFe, 2 lo kit, Dakota FP/Isspro Boost and EGT all on pillar, Pac Brake, 285's

05-11-2008, 08:06 PM	#1 (permalink)
Shilohsho Cummins Fan Join Date: Oct 2007 Location: Seneca, SC Posts: 50 Shilohsho's Truck Pics	Lift Pump at IDLE problem I've got the lift pump mounted at the tank on the frame. It's been that way for 70k miles. Also, I've got a low pressure light to monitor it. Lately, it has randomly lost pressure at IDLE after 4-5-10 minutes. It does fine when under power going down the road. This only happens at idle. What's the Problem here? Also, I know it's time for FASS but that doesn't explain the current problem! __________________ '99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

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05-11-2008, 08:14 PM	#2 (permalink)
HARRISDIESEL Cummins Enthusiast Join Date: Oct 2007 Location: Fair Play SC Posts: 267 HARRISDIESEL's Truck Pics	Im not trying to sound like a know-it-all but i think (or guess!!) what is happening is your lift pump is getting very weak and your injection pump is pulling the fuel just enough to cut the light off!! at idle your injection pump is not pulling enough but your lift pump isnt pumping enogh, while throttle is on the injection pump is pulling!! And that results in injection pump failure!! A fuel gauge my help you figure the amount of fuel your lift pump is pumping!!! I would try checking the pressure at idle and WOT!! __________________ 02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k 10/4/08 537hp 1050t

05-11-2008, 08:24 PM	#3 (permalink)
Shilohsho Cummins Fan Join Date: Oct 2007 Location: Seneca, SC Posts: 50 Shilohsho's Truck Pics	I've got a pressure guage on the "dirty" side of the fuel filter housing. The pressure light is on the "clean" side of the filter housing. The other day the light came on at idle, I checked the guage and it was on 0 psi. so i shut the truck down. I gave it a second then cranked it up and the guage was at 12-13 psi at idle. I'll check tommorrow what the pressure is at WOT. __________________ '99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

05-11-2008, 08:44 PM	#4 (permalink)
NickBeek Cummins Nut Join Date: Jan 2007 Location: Upstate, SC Posts: 478 NickBeek's Truck Pics	Have you checked all the plumbing? Sounds like you may be pulling air instead of fuel from the tank sometimes. Just a guess. __________________ 2006 Dodge, 2500, CTD, 4x4, 6 Speed, SLT, Thunder Road Package, Mineral Grey, MBRP Muffler Replacement Kit, Fast Idle Enabled.

05-11-2008, 09:38 PM	#5 (permalink)
HARRISDIESEL Cummins Enthusiast Join Date: Oct 2007 Location: Fair Play SC Posts: 267 HARRISDIESEL's Truck Pics	Either your getting air or your carter pump took a dump!! __________________ 02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k 10/4/08 537hp 1050t

05-11-2008, 09:53 PM	#6 (permalink)
$30 Cowboy Cummins Nut Join Date: May 2008 Posts: 458 $30 Cowboy's Truck Pics	This might make me sound stupid, but what about your power source. At idle, you might be losing power, like a bad alternator or something. When you get on it, you regain power...but like i siad...maybe im slow...lol are your lights dimming at all? __________________ *Cowboy Cadillac* 2007 Dodge 3500 DRW QC 4x4; 6-speed, RanchHands, 4" TBE w/ 6" Tip. AFE stage2, Silencer ring MIA

05-12-2008, 07:33 PM	#7 (permalink)
Shilohsho Cummins Fan Join Date: Oct 2007 Location: Seneca, SC Posts: 50 Shilohsho's Truck Pics	Alright, today I watched the guage and the light and the guage was holding 12-14psi at idle and 11-13psi down the road. At WOT it was no less than 10 psi. Maybe air but I don't see how. The power source is the original wires extended down to the frame at the tank. __________________ '99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

05-12-2008, 07:40 PM	#8 (permalink)
HARRISDIESEL Cummins Enthusiast Join Date: Oct 2007 Location: Fair Play SC Posts: 267 HARRISDIESEL's Truck Pics	It maybe you TPS too!! call me and I will run a diagnostics test for you!! __________________ 02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k 10/4/08 537hp 1050t

05-12-2008, 07:52 PM	#10 (permalink)
Shilohsho Cummins Fan Join Date: Oct 2007 Location: Seneca, SC Posts: 50 Shilohsho's Truck Pics	Tommorrow I'll check the voltage output at idle. Will, I'll give you a hollar in the next day or so. __________________ '99 3500 Slvr drw quad cab 4x4 5spd 4.10s, Van Aaken box, Banks Brake, 4" exhaust, K&N Cone, SouthBend Con OFE,KDP-killed!, Frame Mounted Carter Pump, Boost/Pyro Guages, Leveling Bags on rear, Onboard Air , Welded 5th gear nut 234hp/579tq 2/2/08

05-12-2008, 08:36 PM	#11 (permalink)
HARRISDIESEL Cummins Enthusiast Join Date: Oct 2007 Location: Fair Play SC Posts: 267 HARRISDIESEL's Truck Pics	10 4 shosho!! __________________ 02 2500 4x4 6spd 4.10 tst comp t-bars ddp240s FBDs2monster44 scottyair .093 lines bored tubes IIsilverbullet66/74/14 htt manifold fass150 6in miters watermeth oringed studs spearco sbc dd 20s 35in mudgrapplers 240k 10/4/08 537hp 1050t

07-06-2008, 11:47 PM	#12 (permalink)
KATOOM Cummins Nut Join Date: Jan 2006 Posts: 418 KATOOM's Truck Pics	I've been checking posts because I had the same problem today. My FP dropped to 8 psi at idle for no apparent reason and after a few minutes it came back up to the normal 14-15 psi. Everything was fine there after but I did throw the P 1693 code. I no wonder were the real problem came from and was wondering if you solved your problem. I never bothered to look at my alternator output so I cant speak for that. __________________ '01 2500 Sport 4x4 5spd, EZ, straight piped, no sillencer ring, aFe, 2 lo kit, Dakota FP/Isspro Boost and EGT all on pillar, Pac Brake, 285's