Cummins 5.9 lift pump operation

[noserider]

Originally Posted by Parkerco

Yes, I did install a relay for the Raptor. Involves some cutting and splicing but overall not too difficult and insures peace of mind. Still have this concern about the engine shutting down immediately after start but at least I know it isn't because of no fuel from the lift pump.

Great. Can you describe the process for wiring the relay. You mentioned running a wire to the battery in a previous post and I was under the impression I could use the power from the ECM to open the circuit on the relay. Also some info on the relay itself and if you had to buy a special plug for the relay or was it the old style that you can attach wires without a plug.

[Parkerco]

I bought my relay from Del City.(actually you can probably get one at any auto parts store) It is a standard NO/NC continuous duty relay and comes with a plug connector with pigtails that need to be butt connected to your other wires. You will have to cut the male and female ends off the chassis pump plug and the Raptor plug and butt connect extension wires to them. Then run two wires (20 or 22 ga) from the chassis wiring that formerly plugged into the OEM pump and connect to the relay power supply terminals. (These will now activate the relay instead of running the pump) Next, run a wire (12 or 14 ga) from the battery + to the relay. (good idea to install an inline fuse in this wire) Now run a wire (12 or 14 ga) from the relay to the + wire coming from the Raptor and butt connect. Lastly, connect a wire from the - wire coming from the Raptor and connect to a good ground on the engine. Now when you go to start the engine you will activate the relay instead of the pump which will in turn provide power to the new pump. Hope this is clearer than mud. Most likely the relay will come with a wiring diagram as well. Hope this helps.

[noserider]

Originally Posted by Parkerco

I bought my relay from Del City.(actually you can probably get one at any auto parts store) It is a standard NO/NC continuous duty relay and comes with a plug connector with pigtails that need to be butt connected to your other wires. You will have to cut the male and female ends off the chassis pump plug and the Raptor plug and butt connect extension wires to them. Then run two wires (20 or 22 ga) from the chassis wiring that formerly plugged into the OEM pump and connect to the relay power supply terminals. (These will now activate the relay instead of running the pump) Next, run a wire (12 or 14 ga) from the battery + to the relay. (good idea to install an inline fuse in this wire) Now run a wire (12 or 14 ga) from the relay to the + wire coming from the Raptor and butt connect. Lastly, connect a wire from the - wire coming from the Raptor and connect to a good ground on the engine. Now when you go to start the engine you will activate the relay instead of the pump which will in turn provide power to the new pump. Hope this is clearer than mud. Most likely the relay will come with a wiring diagram as well. Hope this helps.

Thanks for the explanation.

[jporietis]

Just to add to this post. The lift pump runs about 10 to 15 seconds as soon as the key is turned on. If you "bump" the starter the lift pump will run about 30 sec.
I also have the 5.9 and am in the process of installing the Fass pump and a pressure gauge. After doing some research and talking to "experts", I am going to install the Fass near the tank and use it to push the fuel 20 feet instead if sucking as the original pump does.
I have all the wiring harnesses done, holes drilled and just need some cooperation from the weather and I will get it done.

John

[ladagobago]

Originally Posted by jporietis

Just to add to this post. The lift pump runs about 10 to 15 seconds as soon as the key is turned on. If you "bump" the starter the lift pump will run about 30 sec.
I also have the 5.9 and am in the process of installing the Fass pump and a pressure gauge. After doing some research and talking to "experts", I am going to install the Fass near the tank and use it to push the fuel 20 feet instead if sucking as the original pump does.
I have all the wiring harnesses done, holes drilled and just need some cooperation from the weather and I will get it done.

John

I am not certain that running a pump with out a filter is a good idea. you may be pulling debris from tank and messing up the pump. see the diagram. The pump should be sucking fuel through a filter first. Just my thoughts on this matter.

On our boat we always had several filters before the fuel pumps. reason was to separate any water and filter any crap that might mess up the pump

[jporietis]

Originally Posted by ladagobago

I am not certain that running a pump with out a filter is a good idea. you may be pulling debris from tank and messing up the pump. see the diagram. The pump should be sucking fuel through a filter first. Just my thoughts on this matter.

On our boat we always had several filters before the fuel pumps. reason was to separate any water and filter any crap that might mess up the pump

Hi

Thanks. I forgot to mention that yes I am including a small filter between the pump and tank.

[noserider]

Originally Posted by ladagobago

I am not certain that running a pump with out a filter is a good idea. you may be pulling debris from tank and messing up the pump. see the diagram. The pump should be sucking fuel through a filter first. Just my thoughts on this matter.

On our boat we always had several filters before the fuel pumps. reason was to separate any water and filter any crap that might mess up the pump

Where did you get your diagram? Not sure how other coaches are setup but on mine the lift pump is before the fuel filter. But I agree with you in theory. I think the Raptor being a gerotor pump is suppose to be less prone to failure from dirty fuel.

[Parkerco]

Guess different coaches have different fuel line setups but on my 2000 Discovery the lift pump is after the water separator filter and before the secondary filter. Then from secondary filter to the VP44 injector pump. Put the new Raptor in the same location.

[noserider]

Originally Posted by Parkerco

Guess different coaches have different fuel line setups but on my 2000 Discovery the lift pump is after the water separator filter and before the secondary filter. Then from secondary filter to the VP44 injector pump. Put the new Raptor in the same location.

Agreed. Just one combo water separator fuel filter on mine. Never understood why but seems to work fine.

[ladagobago]

my diagram is mine own made for the discussion. my chassis is FL with ISB and on a Winnebago body. I would not care which MH I had, it would be set up that way. no point in putting a lot of crap and water into a pump. That is why God help us make filters.

[noserider]

Originally Posted by ladagobago

my diagram is mine own made for the discussion. my chassis is FL with ISB and on a Winnebago body. I would not care which MH I had, it would be set up that way. no point in putting a lot of crap and water into a pump. That is why God help us make filters.

Best answer I have seen this year for anything

[RichKimball]

Originally Posted by Parkerco

Yes, I did install a relay for the Raptor. Involves some cutting and splicing but overall not too difficult and insures peace of mind. Still have this concern about the engine shutting down immediately after start but at least I know it isn't because of no fuel from the lift pump.

I installed the Raptor lift pump recently too. Had not heard about excess current draw possibly to damage ECM. Thank you for this note.

Great...now to go out and wire in a relay to the new pump.

[onechaddude]

Originally Posted by mevman

I installed the Raptor lift pump recently too. Had not heard about excess current draw possibly to damage ECM. Thank you for this note.

Great...now to go out and wire in a relay to the new pump.

I installed a relay on mine when I added a raptor pump. Cheap insurance.

Chad

[Triker56]

No one suggested to replace the hose from the W/S filter to the Lift pump.
Sometimes after a hose gets old it can get a pinhole that sucks air in it when Lift pump is running. But not leak fuel out when engine is off.