Diesel-Dan

I just got a truck in for repair and found the lift pump to be bad. The owner wanted to go with aftermarket means of ridding the lift pump prob so I went with a FASS. We got the pump blead and finaly started. I drove the truck and brought it back to the shop. Let idle for a few mins. We had some diesel drips but left overs from the bleading. Then we ate.....came time to move the truck in the shop for close and it would not start. We had to blead the system and finaly cranked and ran. I let run for several mins and then let sit for about 15mins. Then went to crank up for a test.....nothing....just cranked and cranked!!! SO i got a prob with this truck loosing prime to the injectors. What would be a good reason for this? Posable VP bleed sticking open? I know we got good pressure to the pump from the FASS...we checked several time.....i just want to know if this has been a prob in the past because i dont think i am the only poor sap in this world that its happening too!!! At least I take care of my rig!!!!!!! Thanks!

Dan

O yeah....no codes....'99 3500 Quad. We are starting to lean twards a VP...........if so...this guy will be starting out on the right foot.....thanks......

Stamey

Mine has been doing some weird starting things since I installed my FASS. I found it would turn over more than usual, and I have had instances when it would not start if I kept turning it over, but if I stopped, waited 3 seconds or so, and turned it over again, it would start. In my situation, the truck has to sit for a long time, like overnight or all day while I am at work.
I am suspecting air, and have just found that when Cummins rebuilt my engine (cracked block), they pinched the o-rings on one of the connector tubes in the head. This may be my air/leak-down problem, but I haven't finished putting the truck back together so I don't know if fixing that O-ring will fix my starting problems. It will be done tomorrow night.

Chris

Shortshift

Had the same thing after installing the Fass. Ran great, but wouldnt start 15 minutes later.

Im not sure exactly what the problem was, but I ended up re-inserting the OEM filter back inline, and plumbing the Fass to the back of the filter. It got better, but was not solved.

I replaced the fitting supplied w/ the Fass (that is supposed to go to the VP44) to one that I got from Rip Rook's fuel line kit. Also re-tightened the filters on the Fass.

Problem is gone. Starts like it used to which was always impressive.

The only thing common to the original problem, and removed when the fix happened was replaced the fitting from the install kit to another kind without the rubber o-ring, and tightened the filters on the Fass.

Might be a problem w/ the o-ring on the supplied fitting letting air in the system, not sure.

Diesel-Dan

OK....rebuttal....if air was to get in the system under low pressure, would it be safe to say that under 17 PSI of pressure it would leak? I am not getting any leaks of any kind. I have been over the lines fnt to rear. I contacted the owner and he disclosed (this morning) that the truck was getting harder and harder to start and then one day it just quit. Enter us. We get the truck DOA from 2 hired hands with just enough info to tell us "this dang truck don’t run or start! Can you fix it? *SPIT* *DING*" We do some diagnosis and find the lift pumpy is no worky! SO, looking at the previous history of the truck (150k mi) I am not leaning towards the FASS. AND we let it sit overnight, came in and primed the pump. Tried to start it and BOOM! Fired up! We drove it about 15 miles and then let it sit for 15 mins......NO BUENO! No Start.....soooooo.......im pulling my hair......with a big cross eyed grin on my face

Dan

Diesel-Dan

ok...here is what i am going to try. I am going to get the truck running and kill it. Pinch off the FASS hose to the pump at the VP. Let sit for a while. Then try to start it (After takeing the pinch off.....apparently you cant apply back pressure to the FASS set up!) Hopefully this will let me see if its the FASS or the pump/motor. got to try something....

Dan

ALSO just thought of this. When bleeding the lines on the head, we don’t get any pulse until LOTS of cranking. BUT on #4, it just flows like a water faucet all the time. No pulses.

AlpineRAM

Hmm- does the fass pump run while cranking? Maybe just unplug some electrical connector to the fass to make it stop while cranking would be a good idea? The stock fuel system is designed to lower pressure while cranking and Cummins says that too high pressure while cranking can lead to hard-no start conditions.

Just my 2c

AlpineRAM

Diesel-Dan

The FASS system uses the same plug that you unplug from the LP. It just runs an extention back to the pump. SO it should do exactaly what the LP does when cranking and bumping the motor. And from what i can tell....it is. No run during cranking. Runs for like 25-30 seconds after cranking.

AlpineRAM

Hmm- did you try to unplug it? This seems to be the "test" for bad timing solenoid on the vp44 some dealers do. I heard that if it starts good with the plug off and bad to not with the plug on chances are good that the vp44 will throw codes and go to heaven soon.

AlpineRAM

Palmetto_kid

have you tried replacing the fitting like ShortShift did?

Diesel-Dan

If i had one lying around i would. I just don’t see the FASS being the issue. This was a progressive problem before the FASS was even installed. I have talked to SEVERAL people that know these 24V engines like the back of their hands (along with yall) and they seem to point towards an internal bleed off in the VP (Its the original by the way, and that is probably why i am not getting any codes with no drivability probs other than the hard start). They don’t see it happing in the high pressure lines due to the, well....the high pressure, and would be very visible. AND second, we do way to may of these FASS's to not see this problem more often. That is why I am double and triple and quadruple checking my connections to rule out installer's goof. I see that we revived a dead truck with a new heart and still nee to fix the aneurism in the brain.....

Dan

SBishop

QUOTE
"ALSO just thought of this. When bleeding the lines on the head, we don’t get any pulse until LOTS of cranking. BUT on #4, it just flows like a water faucet all the time. No pulses."

With those indications..... You have a Bad VP44.

Diesel-Dan

OOOOOOOOKKKKKKKK! Got it figured out. I did some reading and calling and this is what i found. I tried what AlpineRam suggest and about 3 others i talked too. I unpluged the FASS and about 20 seconds in......Fired right up! SO i think we are talking about a VP now.......going to go pricing......thanks for all the help.....

Shortshift

Ok, not arguing here, but just to be accurate, and you may be correct as I'm not nearly qualified to be a mechanic. Maybe my VP44 is on its last leg as well.

But I had the exact symptoms you described in the original post:

-Cold: Boom, fired right up. Every time.

-Hot after sitting 15 minutes: Hard start. Maybe 2 or 3 times of going through the cycle. I found that if you dont wait for the pump to stop, and start immediately, it would start most of the time, but if you wait for the pump to stop, it would not start without a fight.

The only difference that I see, is you stated that in your case, the truck would not start hot without bleeding lines. Maybe that is the major difference.

Your rebuttal was that wouldnt you see a leak inder 17psi? That is what I thought too when I was told I had air entering the system. I had doubts, because I rechecked the connections already.

Turns out that there was not enough air entering to cause an obvious leak while running. I changed the fitting at the back of the oem filter because it was a possible suspect. When I went to try it out, I took one last look at the fass, and I did notice some dirt from slightly weeping fuel at the fass filter (the large one). I grabbed the filter wrench, and cranked it down a little more & wiped it off.

It fired right up, and has ever since. Cold, or hot. Seems to be fixed...

My mistake was, I changed 2 things at a time. Now cant be sure what it was. Dang Rookie.

Diesel-Dan

Well...hot or cold it didn’t start. It was a fluke that it just crack right off after sitting the night. We let it sit all day here after is did its temperamental thing again...and it was VERY cold when it didn’t start the last time. I tried SEVERAL time to crank....dang near 30 without any luck at all. I talked a guy and he told me to disconnect the FASS (3rd person to tell me that) and try to start it. SO i did for a last ditch effort. 15-20 seconds of cranking and BOOM! Crack right off! I didn’t let it run more than a min and then shut it off. (To test my theory) Let it sit for about an hour and a half and tried again. BOOM! No probs! Turned off. Let sit for 45 mins. BOOM! The cust came and picked up the truck (Going to see how it does and see if the pump gets worse....better then just tossing the $1100 at it! And yes, reman 027! Not new…it’s a farm truck!) and BOOM! They drove it home...after the last time the truck seemed quieter.....like the FASS was working better....like my bosses truck got lots quieter after the FASS and injectors...almost like that....so who knows...i talked to the gent again that helped me out most of the day and he said that some pump place told him that it was some fueling diode that was sticking (Didn’t know diodes could stick...) that was causing the bled off......weird...as long as it starts and runs.......fine with me....and if the pump is needed.....im here....but many points taken....and many thanks given to all that helped! This is how we all learn......i am a gas mechanic by trade....and this diesel thing is new...but not soo bad once you get the basics down.....and know the quarks....everything with a pinch of salt....and i bet we have enough salt in here to keep the Titanic afloat! Love all the diferant ideas and suggestions....it all good diagnosis stuff to remember for the next time......*shudder*...........the next time........

Dan

Shortshift

Hey, nice job Dan. Sounds like these guys got some great service...

Was thinking, maybe they could tap into the pump ckt and run it through a momentary push button switch, so when they turn the key and push the button in, it removes power from the pump while they are cranking.

Maybe a temp solution you can help them out with until they can come up with some bucks and have you change their VP44 later. I bet a Fass install, diagnostics, and a VP all in one bill, has got to be brutal.