Threaded Mode | Linear Mode

ktbtrucking · 10-12-2016, **(Subject: isx will not start cranking low fuel pressure )**

they has changed the lift pump but still no start, changed high pressure pump and runs great now, they advised me that lift pump was bad also and it might have caused high pressure pump to fail, thank all for the help

10-12-2016, **(Subject: isx will not start cranking low fuel pressure )**

(10-12-2016 )ktbtrucking Wrote: they has changed the lift pump but still no start, changed high pressure pump and runs great now, they advised me that lift pump was bad also and it might have caused high pressure pump to fail, thank all for the help

otherwise known as they fucked up and have to justify the lift pump.

Rawze · 10-12-2016, **(Subject: isx will not start cranking low fuel pressure )**

(10-12-2016 )Unilevers Wrote:
(10-12-2016 )ktbtrucking Wrote: they has changed the lift pump but still no start, changed high pressure pump and runs great now, they advised me that lift pump was bad also and it might have caused high pressure pump to fail, thank all for the help

otherwise known as they fucked up and have to justify the lift pump.

I agree -- mostly ...
Even if this guy would have called me in the middle of the night from the side of the road, I still would have recommended the gear pump first after knowing it only made 70 PSI. The lift pump is bypassed by a check valve as soon as the gear pump primes and makes pressure.

Even so,.. Bad guess-work aside -- A new lift pump and clean-out of the intake screen, check valve, dong a leak-down on the injectors, etc. and checking the actuators etc. is not a bad idea as an investment if those components were old and had a lot of miles and use on them. So, in the end,... you have really lost nothing unless those components that were replaced are new and not worn out yet.

Coco620 · 10-12-2016, **(Subject: isx will not start cranking low fuel pressure )**

(10-12-2016 )Unilevers Wrote:
(10-12-2016 )ktbtrucking Wrote: they has changed the lift pump but still no start, changed high pressure pump and runs great now, they advised me that lift pump was bad also and it might have caused high pressure pump to fail, thank all for the help

otherwise known as they fucked up and have to justify the lift pump.

Lol

preacherboy24 · 10-12-2016, **(Subject: isx will not start cranking low fuel pressure )**

Like Rawze said you can lead a guy to water.....

If you take a look at my previous replies you wouldnt have spent the money on the lift pump.

Geared_Cortex · 11-20-2019, **(Subject: isx will not start cranking low fuel pressure )**

Hi , I just wanna update this thread with my personal experience so it maybe helps someone having the same issue. So it happened the first cold day of the winter here in Canada. I tried starting the truck and it was cranking slowly with 4 brand new Cummins batteries I had put in like 1 week before , it ended up dying and giving me the low fuel pressure code 94/18 . So I tried starting it with booster packs and batterie charger but no luck. Drained the water in davco still nothing. So I started investigating and found the very well hidden lift pump fuse that was blown. After changing it the lift pump started working but was sounding funny and of course no start .So I changed the filters in case it was that but still no start . So I came here to read on the subject like I always do and ended up on this thread. So after reading this I hooked up insite to see what was the fuel pressure when the fault code came on and it was 64 psi so I assumed I had a bad gear pump especially after reading that they just go bad without any warning. But I still was hoping it was a stuck drain back valve. So I dismounted the Ifsm and the lift pump and the valve looked good , checked if fuel shut off valve
was working and it was fine, changed the seals on it just because I was there already and cleaned everything up . Powered the lift pump and it sounded like it was pumping but no start and insite telling me 43psi while cranking . So tried poking the compuchek fittings with a screwdriver I had nothing coming out . So I knew at that point that my problem looked like a gear pump but it was just the lift pump not providing fuel to the gear pump to build any pressure especially after I had the system unprimed by changing the filters . So after I put on the new lift pump I still couldn't start the engine even with insite telling me that the pressure at key on was now 30 psi and while cranking it was 150 psi . I was really confused. Started looking for electrical problems and ecm related stuff but couldn't find anything . Cranked the truck maybe 30 times. Ended up calling a mobile mecanique to come fix it . While waiting for the guy chilling with my dad , I said to him come crank the truck for me I wanna try one last time but with ether this time. To my surprise the truck started. It was rough at first but after a few minutes it was back to normal and been starting like a charm now. So my reason for writing a novel about this is just to give someone else that could have the same issue a chance to maybe see something similar there experiencing and not end up spending on unnecessary parts and labor that could have been as simple as just some air in the system that is stubborn to come out.
Correct me if I'm wrong please. I wanna learn as much as possible.

Chamberpains · 11-20-2019, **(Subject: isx will not start cranking low fuel pressure )**

Your problem sounds like you had a bad lift pump and a fuse blown. Had you changed that then primed the system properly, your truck would've probably fired off. But, you changed the fuel filters after the lift pump dumped out a bunch of fuel, then the fuel filters being changed probably drained out the rest of the fuel. They become a real bear to start once fully drained.

What leads me to this, is you made no mention to the low fuel pressure code coming back after the lift pump replacement and Insite showed the gear pump working then. As it was making 150 psi (normal cranking psi) during cranking. Which lands the next reasoning of trapped air from when you drained the filters.

Thanks for the update. These surely help people.

Rawze · 11-20-2019, **(Subject: isx will not start cranking low fuel pressure )**

On a completely dry fuel system, it takes up to 4 or 5 cycles of letting the lift pump run for 2 minutes intervals at a time, cycling the key to get it to come back on each time. It can take another 4 or 5 cycles of 30 seconds each of cranking it to get it to fire off.

=============

-- I reduce this torture to the starter and batteries greatly by pressurizing the fuel tanks to 10 psi or so and bleeding the lines, compu-check ports on the gear pump, etc. really well. I will then cycle the key in the dash and let the lift pump run about 3 times. ... then, here is the typical result...

Here is how long it took to crank and run Waterloo's truck the very first crank up after doing this ...

http://rawze.com/forums/showthread.php?t...1#pid27361

I.E.> It took a total of about 40 seconds of cranking time to get the fuel all the way to the injectors, even with all of the lines, filters, and the pump purged of air.

Evotrucker · 11-20-2019, **(Subject: isx will not start cranking low fuel pressure )**

(11-20-2019 )Geared_Cortex Wrote: Hi , I just wanna update this thread with my personal experience so it maybe helps someone having the same issue. So it happened the first cold day of the winter here in Canada. I tried starting the truck and it was cranking slowly with 4 brand new Cummins batteries I had put in like 1 week before , it ended up dying and giving me the low fuel pressure code 94/18 . So I tried starting it with booster packs and batterie charger but no luck. Drained the water in davco still nothing. So I started investigating and found the very well hidden lift pump fuse that was blown. After changing it the lift pump started working but was sounding funny and of course no start .So I changed the filters in case it was that but still no start . So I came here to read on the subject like I always do and ended up on this thread. So after reading this I hooked up insite to see what was the fuel pressure when the fault code came on and it was 64 psi so I assumed I had a bad gear pump especially after reading that they just go bad without any warning. But I still was hoping it was a stuck drain back valve. So I dismounted the Ifsm and the lift pump and the valve looked good , checked if fuel shut off valve
was working and it was fine, changed the seals on it just because I was there already and cleaned everything up . Powered the lift pump and it sounded like it was pumping but no start and insite telling me 43psi while cranking . So tried poking the compuchek fittings with a screwdriver I had nothing coming out . So I knew at that point that my problem looked like a gear pump but it was just the lift pump not providing fuel to the gear pump to build any pressure especially after I had the system unprimed by changing the filters . So after I put on the new lift pump I still couldn't start the engine even with insite telling me that the pressure at key on was now 30 psi and while cranking it was 150 psi . I was really confused. Started looking for electrical problems and ecm related stuff but couldn't find anything . Cranked the truck maybe 30 times. Ended up calling a mobile mecanique to come fix it . While waiting for the guy chilling with my dad , I said to him come crank the truck for me I wanna try one last time but with ether this time. To my surprise the truck started. It was rough at first but after a few minutes it was back to normal and been starting like a charm now. So my reason for writing a novel about this is just to give someone else that could have the same issue a chance to maybe see something similar there experiencing and not end up spending on unnecessary parts and labor that could have been as simple as just some air in the system that is stubborn to come out.
Correct me if I'm wrong please. I wanna learn as much as possible.

I believe when i just got my truck, the gear pump was going out. shi#t at least you knew what you were looking for. I was blind as a bat in dark and worse.... i found this forum and all the great ppl in here to baby walk me down all those steps lol.

yesterday i was working on changing out the guts in fuel dampners behind the IFSM, right after taking them both off. I released one thing, i didnt change the small little gaskets on the back side of the dampners the first time around.... after that i made a 3rd trip to cummins to do it right this time. I believe that is why it was leaking again because of those two small gaskets. Anyways, i had to purge the air out of the IFSM maybe for 1-2 hrs before i saw no more small or tiny air bubbles. Today i tried cranking the truck over and nope! i was like f$%k! come on lol.... then it hit me, like a semi with no brakes down mount eagle. I didnt cycle the system, so after cycling it 10-15 times just because. she turned right over, just a little ruff but smoothed out shortly right after.

One thing ive noticed, im not braking or stripping as many clips,bolts,wires and etc while fixing the truck LOL!. guess that means im starting to get a little better at this.