New VP44, new FASS 95 hard starts when hot?

LKuilder

LKuilder

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Jul 10, 2008
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I lost my original VP44 about a month ago after 208,000 miles. I installed a new Scheid VP44 from Haisley and got the truck going again. I ran the truck for a few days to get it going again and then installed a brand new FASS 95 system which I had sitting here for a few years. The FASS has been on for a week now and I have had no problems. The past 3 days or so the truck has been getting harder and harder to start when its hot / warmed up to operating temperature. When the truck has sat overnight or all day without running it turns over and starts right up. When the truck has been up to operating temperature it cranks a LONG time before it will start. Sometimes, quitting cranking and trying a second time gets it to start. I tried both immediately cranking as soon as I turned the key on and waiting until the FASS pump cycled off to crank and neither helped when the motor is warmed up. I'm trying to figure out what I can do before I get stranded somewhere. Any advice / help would be greatly appreciated.
 
dieselbeef said:
fp guage? says what when
Click to expand...

When I was on the stock lift pump I was at 12-13 psi at idle and 10psi under acceleration at the outlet of the stock fuel filter.

On the FASS now I'm at 18psi at idle and no lower than 15psi under acceleration at the VP44.
 
usually the hard start after it is warm is a sign of a bad injection pump. might want to give Scheid a call and see what they say.
 
Go figure, I go to fix it this morning and its working flawlessly! I'm going to keep running it until it starts again. I drove it over to my shop (about 8 miles) and having been starting and stopping it here with no problems. I've tried sitting uphill, downhill, and level in case it was leaking down somewhere and that makes no difference. Engine is plenty warm already and it is starting perfectly everytime. Hopefully its figured itself out but if not I'm going to try pulling the relay next time it does it.
 
I bet its from too much fuel pressure. Next time it does the hard start thing, get out and pull the fass fuse and try to start it again.
 
Put the fass on an oil pressure switch. Should solve the problem. If not then its possibly a bad VP. If it was connector tube o-rings it should give it a hard start hot or cold.
 
when i put my fuel system on we found out that the factory wiring for the fuel pump was failing intermitenly. Put a new relay on and it did not solve the issue. eneded up buying a universal relay and hooked it to an ignition source and bypassed the whole factory crap. My fuel lab pump is set at 20 psi and never moves even at wot. never had an issue starting my truck hot or cold.
 
If it is something wrong with the VP would it cause hard starts all the time or just sporadically when its hot? Because there are times when the truck starts easy as can be and others when it cranks for a long time before it starts all when its hot. When it doesn't start I can quit cranking and start cranking again while the FASS is running for the 30 something seconds and it fires right off the majority of the time.
 
I installed a vp for a customer along with a Fass DDRP. Ran perfect when it left the shop. Now it's having a hard start. FP and wait to start doesn't affect it. Took it to pump shop, they plugged straight into VP44 with their box, cranked perfect every time. Still not sure what the issue is, but has something to do with ECM not giving vp44 power.
 
im having the same issue with my truck right now. if its been sitting all night long it will fire right up but if i get it up to operating temp and shut it off it does not re-start. i have to give it a small hit of ether and when i say small i mean small, all i do is give a short burst into the air filter. it will almost immediatley start.
 
I'm getting more and more frustrated. Anytime I go to try and get it to hard start so I can pull the fuse going to the FASS out and see if it helps the truck will fire right up. Could it be that the fuel system is losing prime somehow? When the truck won't start, I can quit cranking and the FASS continues running and then as soon as I turn the key again it barely turns over and fires right off almost every time. And the hard start doesn't occur every time either.
 
I had the same problem, and the oil pressure switch fixed it. But then when I went to twins I had to use the oil port the switch was in for a feed line. When I removed it, low and behold it worked fine again for a year and a half, no issues. Then the VP died. One thing I found was that if I unplugged the FASS relay, when experiencing these conditions the truck would always start fine. So I tried installing a relay in the battery power supply to the fass, to a keyed accessory such that I could manually kill power to the fass for starting. To my surprise that did nothing. I then put the relay in the ground line for the fass relay trigger (the one that plugs into the factory lift pump plug). The relay is going across the N/O circuit so the pump functions as usual, but can be shut down by switch or button if necessary. The curious thing to me, is after doing that the truck works fine. I never have to shut the pump down. It seems like it has to do with resistance in that line or something.
Sean
 
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