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Parkerco · 10-27-2015, 06:43 PM

Need a little advice as to how the lift pump is supposed to operate on a 2000 Cummins 5.9 w/vp44 injector pump. Have had 2 occasions recently when I start the engine that it starts and then immediately dies but starts right back up and runs fine. The last incident was when it started and ran for maybe 5 seconds and then died and would not start again. After reading numerous posts on the subject here, I have concluded that I may have either a weak lift pump and/or a weak fuel shut off solenoid. Also, there was a suggestion that possibly the ECM locked up and that the batteries should be disconnected temporarily and then reconnected. I did this and it started but I don't feel comfortable that that was the whole problem. I checked the lift pump and found that it ran for a few seconds when the key was turned on and then it stopped. Question is: is the pump supposed to run continuously or only until the system is pressurized? Also, if anyone has had similar problems I would appreciate any advice. I do plan to replace the OEM lift pump with an aftermarket FASS or similar brand and possibly a fuel pressure gauge. Thanks in advance for any help.

Skip426 · 10-27-2015, 10:35 PM

The lift pump on the 5.9 Cummins, with VP-44 and HPCR. will run for 12>15 seconds from key on, then stop until the engine is cranked over and started , at that time it runs continuously until the key is turned off.

The shut off of fuel to stop the engine is internal in the VP-44, not an external solenoid.

ladagobago · 10-28-2015, 05:28 AM

I have also experienced this problem. With the top off the pump filter, watched as the DW turned the key on. the fuel only entered the filter (after the pump) for a few seconds. to fill the bowl we did this several times.

I finally found that the main filter was not tight enough and air was seeping past the o ring. after a harder twist on the filter I did not experience a back flow of fuel. any air leak in the fuel line from the tank to the lift pump may allow air into system. this will allow fuel to back flow in the line. when this occurs you will not have a continuous delivery of fuel to the lift pump and subsequent injector pump. Hence the engine will stop. when you have it fully primed this go normally.

I also read that there was a check valve but never found it. If it has material holding it open then the fuel could drain back toward the tank. Remember that the fuel is sucked through the main water separator filter first before it gets to the lift pump.

ladagobago · 10-28-2015, 05:32 AM

one other thought. you did not mention how long the MH sat idle before you were experiencing this condition. If it was a very long time link 30 days or more a good practice would be to turn the on and off several times to be sure the fuel is filled in the final filter fuel bowl. Like three times - on and off - leave it on for say 20 seconds each time.

Parkerco · 10-28-2015, 08:57 PM

Thanks for the advice and tips. Further research has shown that the VP44 is very sensitive as to how much pressure the lift pump provides, so I will replace the Carter pump with a Raptor pump which supplies much higher volume and pressure. Hopefully this will alleviate associated problems with the VP44 starvation and damage as well as solving the no start problem. BTW, the coach had not been sitting when the problem arose but rather happened on our way home as we were leaving the campground. Will let you know if these repairs do not fix the problem. Thanks again.

Smitty77 · 10-28-2015, 10:22 PM

Raptor, FASS (Note: Does not need to be the full FASS duel filter and air separation module, they offer a quality stand alone fuel pump too.), and other fuel pumps. In a bypass mode feeding the VP44 (Or in my case, a ISL CAPS era engine.) can be a win/win on two fronts:
1) Bypasses the potentially problematic lift pumps, with a solution that should be good for many years of service.
2) Does not shut off after the short start up period. Providing positive fuel pressure to the injector pump system. This, as mentioned, eliminates fuel starvations issues. And at the same time, helps both in cooling the injector pump while keeping it well lubricated via fuel. Both, should add life to any injection pump.

Best of luck to you on your mod,
Smitty

Parkerco · 10-29-2015, 05:57 AM

Thanks Smitty. I'm thinking the Raptor FRRP as a replacement. I like the write-up from the guys at Blue Chip as they seem to know what they are talking about and this is the pump they prefer even though they do sell other brands as well. Haven't decided wither or not to add a pressure gauge as well. Like the idea of knowing the pressure at all times but at my age

I'm not sure I want to be rolling around under the coach running wire etc.

noserider · 10-31-2015, 01:42 PM

Quote:

Originally Posted by Parkerco

Thanks Smitty. I'm thinking the Raptor FRRP as a replacement. I like the write-up from the guys at Blue Chip as they seem to know what they are talking about and this is the pump they prefer even though they do sell other brands as well. Haven't decided wither or not to add a pressure gauge as well. Like the idea of knowing the pressure at all times but at my age

I'm not sure I want to be rolling around under the coach running wire etc.

I bought the Raptor for my 5.9 Isb but have not installed it yet. The first thing I did was install the fuel pressure gauge. I was curios to see how my Carter was performing before I changed it. Turns out it was doing good. I know it's a PITA to roll around under the coach and have debris fall in your eyes and on your face ( happened to me) but in the end I think the pressure gauge is important if you have a VP-44. Even a Raptor or Fass can malfunction or totally quit on you without you knowing. Maybe you can get someone to help with the gauge install. If not, I agree to change out the Carter and maybe add the gauge later if you can.

Parkerco · 11-01-2015, 07:31 AM

Noserider - Just a note before your install. Talked with the guys down at Blue Chip just to make sure that the raptor would fit my application. They assured me it would but very strongly suggested that I add a relay in the wiring. Said they have had reports that the load the pump puts on the EMC, overloads it and damages it. To be safe, run the existing wires from the Carter to the relay and run new wire from battery to relay to pump. Relay tricks EMC into thinking it is still running the pump so it will operate the same as before. Hope this helps.

noserider · 11-01-2015, 07:39 AM

Very interesting information. Thanks!

Parkerco · 11-10-2015, 07:08 PM

Well, I got the Raptor pump installed and added the pressure indicator kit. It required a little modification of the existing mounting bracket but that was simple enough. Am pleased with the pump and mounting kit from Blue Chip and everything seems to work as advertised. However, this morning I went to start the coach and it once again started and then immediately stopped as if something had shut down the fuel. Hit the starter again and it started right up and kept running just fine. Every time after that it started and ran perfect. Am curious as to whether anyone else has ever had this problem and what was the cause. Because there is no external fuel shut off solenoid with the VP44 injector pump I am a little concerned that it may be an EMC problem. Any thoughts?

noserider · 11-10-2015, 09:07 PM

Quote:

Originally Posted by Parkerco

Well, I got the Raptor pump installed and added the pressure indicator kit. It required a little modification of the existing mounting bracket but that was simple enough. Am pleased with the pump and mounting kit from Blue Chip and everything seems to work as advertised. However, this morning I went to start the coach and it once again started and then immediately stopped as if something had shut down the fuel. Hit the starter again and it started right up and kept running just fine. Every time after that it started and ran perfect. Am curious as to whether anyone else has ever had this problem and what was the cause. Because there is no external fuel shut off solenoid with the VP44 injector pump I am a little concerned that it may be an EMC problem. Any thoughts?

Did you add a relay to the Raptor? I spoke to Airdog tech support about the relay. They agreed there are some reports of ECM failures but would not confirm or deny it was caused by the bigger amp draw put on the ECM by the Raptor.

Smitty77 · 11-10-2015, 11:26 PM

For sure not Apple to Oranges here - but a post i will follow and appreciate.

We have a CAPS era ISL370, for sure non VP-44 era. But, with a history of Lift Pump failures. The CAPS, if well fed with fuel, and lubricated well with either Ethanol fuel, or normal ULSD with Supplemental Additives (I run with Optilube in each tank.), is able to take over quite well once the Lift Pump had done it's job.

I went with a FASS independent fuel pump, that splices in and bypasses the standard Oem Lift Pump. But, if the FASS goes out, and fuel is not 'lifted' to the CAPS - I'm dead in the water

!. So, to keep it KISS, we'll look for the same pump at a bargain, the FASS, and carry it as a spare

!

Best to all, and good luck feeding the ISB!!
Smitty

Parkerco · 11-11-2015, 08:34 AM

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.