Engine/Transmission (1998.5 - 2002) Fass lift pump, hot start issue

[CGPike]

I recently installed a FASS lift pump system. So far I love it, but it seems I now have a hot/warm start issue. It seems to start normal when cold, or normal after driving and shutting down for at least an hour, but when I shut it off and restart anywhere from 10 minutes to 45 minutes later it cranks quite a lot before it starts. It never did this before I installed the pump. I didn't install a gage or light when I put in the pump. Gage seemed a little pricy so I put off purchase and installation until another day. It seems when I researched before going for the FASS system, something along this line was mentioned, but I can't be sure. Any ideas out there? Sure appreciate any suggestions. I'm an old school kinda guy and hate to hear an engine crank. Thanx in advance for any thoughts!

 

[clw1100]

Mine does this too.

First off Welcome to the TDR. I noticed your #1 post. My truck has been doing the same thing for years (after I put the FASS on of course). I talked to Brad (DPP owner) and he told me that my VP44 pump's return valve or something could not handle the higher pressure and volume of the FASS. Basically a bad valve in the pump that only shows itself in this situation. TO test this he had me remove the fuse going to the FASS and try starting the truck. (But immediately turn it off after starting. ) It should start normal with the FASS unplugged.



I put a in-cab switch to turn off the FASS when needed. I wish I new a better fix, maybe somebody "in the know" will respond also.

 

[LowFly]

Here are some past threads:



https://www.turbodieselregister.com/forums/showthread.php?t=157182&highlight=FASS



Copied from another site.....



"1. The Pressure switch works well. All you need is the Hobbs switch (78143 -- HOBBS number) and plumb it into the extra oil port on your filter head. Cut the Green wire, going into the (FASS) Relay, back far enough to splice on an extra length of wire. Take that wire you spliced to the (FASS) relay plug and attach it to the Hobbs switch.



2. You can also so the same with the "relay trigger Hot wire". Just cut the red wire (In the FASS harness) between the Stock engine harness and FASS relay. Splice an extra length of wire on the section going into the relay. Then tap that wire to a fuse that is hot only in the "Run" Position (EX: Power window fuse) Just make sure the fuse is 15A or higher.



3. You can also get your ECM reflashed as well with the latest from DC. The can be done one of 2 ways: Go to the dealer and have them do it, or find a buddy with a Smarty and try it out. Once you flash your truck Smarty (EVEN when going back to stock) it will update the ECM with the latest and greatest from DC.



4. Hate to say this one at all... ... but VP might be giving you fits. BUT working one these things has showed me that VP's only get worse when you start seeing symptoms. SO its worth waiting it out before sinking TONS of cash into a new one.



Hope this helps!"



Those are the some fixes we have found.



I believe the main reason that some trucks have starting issues is that the FASS makes pressure a lot faster than the stock LP. The computer tries to reduce pressure when cranking by cutting back the duty cycle of the pump. In other words, pulsating the pump rather than just running it 100%. This is fine with the stock pump, but the FASS can make pressure faster, so the short pulses don’t do much for dropping the pressure at cranking with the FASS. SO some trucks have issue with this.



I also want to toss a guess that the VP-44 probably does something different with timing if the engine is already warm. AND at this state... . the high pressure affects it more than when cold. I could be way off... ... and is just a guess. BUT i wonder if this is why the reflash is helping with the hard starts? OR does the reflash lengthen the time on the pulses? I need to do some more digging.

 

[clw1100]

Anybody know where I can get a Hobbs oil pressure switch? Any of our sponsors carry this? I can rerun my manual switch to this and save me a little headache.

 

[LowFly]

Anybody know where I can get a Hobbs oil pressure switch? Any of our sponsors carry this? I can rerun my manual switch to this and save me a little headache.

In your situation, i would suggest the fuse tap... . easier for how you got it run and you don’t have to spend money on a Hobbs pressure switch.



SO i assume you have you relay signal wire run into a switch in the cab? Just take that signal wire and tap it into a wire/fuse that is hot only in run.



I updated the fist post i made with the Hobbs Oil Pressure switch part number... ... .

 

[clw1100]

You hit the nail on the head, so to speak. I will try the fuse trick.

 

[CGPike]

thanx

You guys are awsome! These discussion make perfect sense to me! I've been reading TDR for a few years now... ..... but have never tapped all your "brain power". Thanx a lot, I will be addressing this later in the week before my next trip. Gary

 

[LowFly]

Let me know how it works out... ... for my feed back at least! Thanks!

 

[AJ]

Fass

I look at the gauge, after turning the "ignition" on and the initial pulse occurs,as soon as the pressure drops to zero. . crank

AJ

 

[RTillery]

AJ has my method nailed. Key on, pump whines and pressure hops to 17lb. 2 seconds later and pump stops, pressure starts falling. Hit the starter and she fires right up, cold, warm, in between.



If I miss it(rare), I can hit the starter again immediately and it will start right up even though the pump is now running.

 

[CGPike]

wow........

Hi all,

Sure glad I made that post a couple of days ago. I have been busy and not addressed my problem as you all suggested. I am planning on trip on Thursday... ..... so I was putting it off until Wed... ... ... (ya, I know). Had the dump trailer on today, stopped for lunch, went back out and it wouldn't start. Had I not listened to you all I would have been dead! Armed with all my new found knowledge, I cut the red wire to my FASS system, put a jumper wire on one end tightly, and taped it. (Remember I was out to lunch), then I had my son hold the other end of the jumper wire until I cranked it... ... ... ... . bango... ... ..... instant start, he then hooked up the jumper wire and we taped it and finished the day! Wow, you guys saved my day! Does this mean I am more likely to have a serious problem with the VP44, or does it mean you have a good fix, (until I hook it up to a fuse circuit such as the pwr windows you suggested? Thanx again... ... ... ... Gary

 

[clw1100]

No serious problems with the VP. Like I posted, mine has been doing it for over 2 years and 80K miles.

 

[JohnnieWinona]

FASS spring

hola, i have not been on the forum for a few years. I was driving up to ATS a few weeks ago to have a new transmission and all the trimin's installed. As i crossed into Colorado, (pulling a trailer), me rig missed for the first time in it's 160k life, and the 'check engine light' went on. By the time i got to Denver, it was running sort of ok. I had ATS check it out and -yes the LP wasn't, and the VP gone. :-https://www.turbodieselregister.com/forums/newreply.php?do=newreply&noquote=1&p=1524443#-)

I had them install a VP slightly modified, and a FASS w/o filters. Upon return to newMexico, i had the hard starting issue. i got into the FASS website, 'Trouble Shooting' hardstarting. They stated that they changed the spring a while ago. i called ATS and they said yes, it is the spring causing too much prestart pressure, pull the spring out of the FASS, cut 1/2 coil.

i did.

Immediately, all was well, the pump was quieter, never a problem starting. i'm ordering the slightly weaker spring to replace my cut coil, and a fuel pressure warning light, just plugs in and only goes on under 7lbs.