Community Forums

greystroke · 08-11-2012, 12:12 PM

Quote:

Originally Posted by Steve Ownby

If you don't mind, give us a run down on your gauge install. Sounds like a smart thing to do. I think I remember Spike45 posting about this at one time.

The install was quite easy. There are two 1/8 npt plugs on top of the fuel filter. I installed my sensor in the plug that is the fuel inlet. I run a wire to the front and put the guage on the lower half of the dash. Connect the 12v to a convenient ignition source so the guage comes on with the first turn of the key. Worst part of install is running the wire.

It is a Westec 0-15 guage. Other ranges and mfgrs are available. Purchased from Geno's Garage. My nominal pressure is 9 psi. A new cummins pump should run 12-15 psi for this ISB. You can get after market pumps with higher pressures so if you do you will have to get a 0-30 guage. Stock is fine with me. I plan on ordering a stock cummins pump from ebay soon for a spare.

greystroke · 08-11-2012, 12:27 PM

Quote:

Originally Posted by EngineerMike

Most diesel injection pumps will draw fuel unimpeded under most conditions. However, most rigs will encounter conditions at times where the IP can't pull enough fuel to avoid internal starvation, which leads to remarkably fast internal wear in the IP. Keeping positive pressure on the IP's input is important on all diesel IP's imo. Rebuilding an IP is expensive, not to mention being sidelined w/your rig wherever the breakdown happens to occur.

Good point Mike. My VP44 gets it's lubrication from the fuel so if you don't have a minimum pressure the VP44 injection pump may fail. From my 9 psi input the VP44 ups to pressure to about 15000. The danger on mine is that if the lift pump fails the mechanical pump inside the VP44 will keep the engine running. So it will just destroy itself. That is why I installed the guage. My pressure is acceptable now but I will need a new lift pump soon.

EngineerMike · 08-11-2012, 12:45 PM

I burned up the IP on a GM diesel when the cheap oil pressure cutoff relay (pressure operated switch in which the cheap contacts burned) left the LP w/out signal, and not running. This type of pressure relay is an SEA safety that cuts off fuel feed if the engine stops, in case it stopped due to accident in which a fuel line was severed. I believe later model designs now use the ECM to provide the safety.

I learned to listen for the LP cycle every time I turned the key to ON before Start. Sound = LP working. However, once the engine starts the circuit reverted to thru the cheap pressure relay, so if that failed there was no warning the IP would be starving. I was going to install a bosch type relay & warning light, but traded the coach before I got to that. Cummins LP failures on ISL's are most likely to be leakage, but they do happen. I should probably install that warning LED on this rig.

Steve Ownby · 08-11-2012, 01:09 PM

Quote:

Originally Posted by greystroke

The install was quite easy. There are two 1/8 npt plugs on top of the fuel filter. I installed my sensor in the plug that is the fuel inlet. I run a wire to the front and put the guage on the lower half of the dash. Connect the 12v to a convenient ignition source so the guage comes on with the first turn of the key. Worst part of install is running the wire.

It is a Westec 0-15 guage. Other ranges and mfgrs are available. Purchased from Geno's Garage. My nominal pressure is 9 psi. A new cummins pump should run 12-15 psi for this ISB. You can get after market pumps with higher pressures so if you do you will have to get a 0-30 guage. Stock is fine with me. I plan on ordering a stock cummins pump from ebay soon for a spare.

Thanks for the info. One more thing for the to do list.

greystroke · 08-11-2012, 02:09 PM

Steve,

Very cheap insurance to know the LP is working. That IP is super expensive.

jlfbatonrg · 08-11-2012, 05:19 PM

You can also purchase a 5 psi warning sender for the Dodge Cummins engines, they will work on any diesel if you can install them on the output side of the final fuel filter. That's what I used on my older Cummins, and have it set up on my current common rail Cummins. I think including a 12V LED that is mounted on the dash, some 14 guge wire, and the sender made the total cost was about $25.00. As has been said, it's cheap insurance.

smiller · 08-11-2012, 05:27 PM

Quote:

Originally Posted by jlfbatonrg

I'm a bit confused here. Cummins converted the ISB fuel system to a common rail injection system in 2003 where, according to Cummins technical support, the system only uses the lift pump to provide an initial "spurt of fuel" to the high pressure gear driven pump. According to Cummins the newer high pressure pump will "draw" fuel to the common rail at almost no pressure after the initial start. It will run on as little as 1 psi. On our ISB, before I was aware of this, I installed a low pressure fuel sender unit and an auxilliary fuel pump based on my experience with the old VP44 injector pump system in our 98 Discovery. We've had no problems at all.

I think this is correct in that a weak/failed lift pump on a common rail system (2003 and later) may cause hard starting and perhaps some running problems but typically will not damage the high pressure pump used on the common rail engines. Details are available at the Geno's Garage and TDR sites in the tech notes section.