Hard Start after FASS - Should I repair VP44???
09-17-2006, 07:13 AM
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Hard Start after FASS - Should I repair VP44???
I installed a FASS 95 GPH HPFP and within 3 days, I was experiencing the hard start symptoms discussed in the FASS installation manual. I am currently NOT experiencing any VP44 symptoms like sputering, surging, etc. The truck has 114k on it and the FASS is the third "lift pump" for it, after two factory LPs. In the FASS manual, it states that the hard start issue is related to a diaphragm, which was too thin on the 98.5-2002 VP44s" and when exposed to less than 5 PSI FP for a period of time, would wear excessively. Is this worth repairing??? If so, how much will it cost? And who can do it? Local dealer??? Or should I just drive it now until the VP44 buys the farm? 
Thanks
Thanks
09-18-2006, 03:19 AM
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It sounds like the VP is Terminal; If this is the case, you will need $1.2K + to replace it - and there is no way of knowing when it will finally fail! You might want to make a preemptive strike and swap it before it leaves you stranded.....
I read a post recently where someone had another source for hard starting that WASN'T the VP, you might search for it...
Good luck!
I read a post recently where someone had another source for hard starting that WASN'T the VP, you might search for it...
Good luck!
09-18-2006, 05:36 PM
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I installed a FASS 95 GPH HPFP and within 3 days, I was experiencing the hard start symptoms discussed in the FASS installation manual. I am currently NOT experiencing any VP44 symptoms like sputering, surging, etc. The truck has 114k on it and the FASS is the third "lift pump" for it, after two factory LPs. In the FASS manual, it states that the hard start issue is related to a diaphragm, which was too thin on the 98.5-2002 VP44s" and when exposed to less than 5 PSI FP for a period of time, would wear excessively. Is this worth repairing??? If so, how much will it cost? And who can do it? Local dealer??? Or should I just drive it now until the VP44 buys the farm?
Thanks
Thanks
We see this issue more and more with fresh Reman VP's. Its not high pressure really, as the ability to make pressure quickly is the issue here. The ECM hobbles the stock LP by using pulse width modulation. This just pulses the pump to slow the shaft, and lowering pressure. This is fine for the stock vein style pump. The Gerotor will make pressure as soon as you spin the gears. SO pulsing the FASS/HPFP may not work very well to reduce pressure for starting. In that link i covered a good way to hobble the FASS when cranking. Simple and shouldn’t take 10 mins to do. Let me know if you need any more help!
09-18-2006, 08:26 PM
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I too have the hard start problem with a fass, but it only occurs when the engine is hot, starts fine when cold...My truck has 80k & I replaced the LP 8 months ago when the FP dropped tp the 8-10psi range, steady 15psi since..I just returned from a long trip hauling a camper and had a hard time restarting when the engine was hot...After it had sits overnight, it starts normally...What is a "smarty" as referred to in the solution for this problem???...thanks....
09-19-2006, 08:32 AM
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I discovered a little trick that you can do to make it start normally every time without a smarty or a reflash. When its cold it starts normally every time. But when its fully warmed up, it will want to act up and and start hard. What I do is don't wait for the "Wait to Start" light to go off before I start it. When I turn the key and the FASS kicks on, I give it about 2 seconds after it kicks off and then start it. Starts like it should. This has been working well for me.
09-20-2006, 12:19 AM
#7
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The ECM is designed to pulse the current to the lift pump during engine cranking, to lower fuel pressure to the injection pump. This cures a hard starting problem caused from too high fuel pressure. Not all engines suffer from this problem. The newest Smarty has helped address this by shortening the first power pulse to the lift pump.
The FASS is probably creating too much pressure, which is causing hard, hot start problems. Waiting a couple of seconds after the lift pump truns off allows the fuel pressure to drop down to a lower level and allows for an easier start.
The FASS is probably creating too much pressure, which is causing hard, hot start problems. Waiting a couple of seconds after the lift pump truns off allows the fuel pressure to drop down to a lower level and allows for an easier start.
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10-02-2006, 10:55 AM
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02-10-2019, 06:02 PM
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Won't start when hot cummins 275 with 11,000 miles
I have recently had this problem with my 1999 Holiday Rambler, with cummins 275. The injector pump seems to be weak, and to check that, I momentarily unplugged the lift pump upon starting. It started right up. The injector pump is letting to much fuel through when hot. Each time I tried with the lift pump active on start up, the engine would just spin over like it was starving for fuel. Apparently it is just the opposite. When I unplug it, the engine cranks right up. Of course I had help with this operation, as it started and I immediately plugged the lift pump back in. Now.... I picked up a normally closed relay and installed it at the lift pump to shut it off during the cranking process. I hooked it up to the starter solenoid for the temporary power to shut off the lift pump with the solenoid. So far works fine.
Now I don't know how long this will keep me going, but it is a cheap fix instead of replacing my vp44.
The relay is just a generic one I picked up at the local napa store. It is a kit with the relay, and the receptical with shot wires to solder to.
Hope this helps, I know it did me!
Now I don't know how long this will keep me going, but it is a cheap fix instead of replacing my vp44.
The relay is just a generic one I picked up at the local napa store. It is a kit with the relay, and the receptical with shot wires to solder to.
Hope this helps, I know it did me!
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