Just finished an 8 hour drive and I'm noticing my truck is lacking power at operating temperature, used to have no issues with taking off in 2nd when I had a FASS DDRP and stock injectors but now it struggles taking off in first while at operating temps.  *My fuel pressure at idle used to be around 9-10 at WOT it would drop to 0. This was when I first got the truck and knew nothing about it a few years ago now I have a FASS 150 with a sump and the gauge sits at 15psi and 14psi under WOT*. But I ran it like that for a couple of months just thinking above 0 was good enough. Fast forward to knowing what I know now, I'm pretty certain that I've damaged it and now I've got a weak VP44 but I don't have any codes or a CEL. All mods are in my signature, my iQuad shows my timing is moving properly as far as I know, it doesn't seem stuck or anything, no hard start issues. Thoughts? Replace it or just send it? 

On another note, the sluggish take offs could be map sensor related, but I see full sweep of 0 to 57 on the iquad while getting up to operating temps with plenty of power and my ISSPRO gauge can verify but when it's fully warmed up I get about 0 to 45 on the map sensor while the ISSPRO will still read 50+

Edited October 10, 20177 yr by Cronus577

31 minutes ago, Cronus577 said:

my iQuad shows my timing is moving properly as far as I know, it doesn't seem stuck or anything

 

Remember that is commanded timing, not actual timing. So if the VP44 is slow to get there or not quite all the way there you'll never know. When my VP44 failed it was stuck in full advance and iQuad still showed the standard timing number even though the pump was stuck in full advancement and running in limp mode and P0216 code.

3 minutes ago, Mopar1973Man said:

 

Remember that is commanded timing, not actual timing. So if the VP44 is slow to get there or not quite all the way there you'll never know. When my VP44 failed it was stuck in full advance and iQuad still showed the standard timing number even though the pump was stuck in full advancement and running in limp mode and P0216 code.

I'm thinking it's right about time to replace it, I don't know if it's the stock VP with now 357k miles on it or if it's a reman. Just seems like for my setup I should feel more power and not be so laggy, im only pushing 5-10 lbs of boost below 2k rpm and then it shoots up to 50+ but anything on the low end is laggggggy I doubt I have a boost leak, all boots and clamps have been replaced, and everything in the engine bay has been double checked for tightness

If you pull vp, At 355k it wouldn't hurt to check compression, and I still think checking for boost leaks is a good idea especially with tweens. 

Edited October 10, 20177 yr by Dieselfuture

25 minutes ago, Dieselfuture said:

If you pulm vp, At 355k it wouldn'thurt to check compression, and I still think checking for boost leaks is a good idea especially with tweens.

Pulm VP? I can check compression once I'm done moving but that will be a week or more from now and after I buy a compression checker which isn't readily available unfortunately

Yeah auto spell check, just fixed it. Maybe up your canbus fueling a bit to help spool on take off. And pull more timing down low to help spool  

43 minutes ago, Dieselfuture said:

Yeah auto spell check, just fixed it. Maybe up your canbus fueling a bit to help spool on take off. And pull more timing down low to help spool  

It's just on stock standard_fuel right now, so can't do that

1st gear take offs on hills sucks lol. Traveling half way across the country 3 times this week 

Have you changed filters including air filter? See if your turbo spins smooth, no excessive play.

 

Possible clogged tank vent, see if she runs better with the cap loose.

 

'Im curious... what size fuel lines are you running?

 

 

 

1 hour ago, JAG1 said:

Have you changed filters including air filter? See if your turbo spins smooth, no excessive play.

 

Possible clogged tank vent, see if she runs better with the cap loose.

 

'Im curious... what size fuel lines are you running?

 

 

 

New S475, New hx35 core. Both spins freely. Crazy Carl's twin turbo piping with new filter, everything is nice and tight, could be the tank vent, it gasps for air when I take off the cap to fill up. Fuel lines are the (half inch I believe) from the Fass 150 kit

2 hours ago, Cronus577 said:

it gasps for air when I take off the cap to fill up

 

Tank vent is plugged...

24 minutes ago, Mopar1973Man said:

 

Tank vent is plugged...

Could that be why the truck feels weak? And is it an easy fix it does the bed need to come off?

I could do that fix by removing the drive shaft and sitting under the truck. Little piece of wire and a bit of compressed air to clean out the vent. 

 You could just drive it with the fuel cap loose and see if it helps. Still needs to be cleared but that would give you some instant feed back.

I don't rely on the factory vent. It might damage the flapper poking around in there and then fuel squirts out whenever you top it off. I like a vented cap or make your own hole in the cap.

11 minutes ago, JAG1 said:

I don't rely on the factory vent. It might damage the flapper poking around in there and then fuel squirts out whenever you top it off. I like a vented cap or make your own hole in the cap.

 

Just be aware if you drill a hole in the cap it just means a better chance of getting water in your fuel. The tank is a spring loads check ball so it typically held shut so chances of water entering is rare. So using soft wire and compressed air you should be able to free the dirt and blow it out.

1 hour ago, dripley said:

 You could just drive it with the fuel cap loose and see if it helps. Still needs to be cleared but that would give you some instant feed back.

Currently driving from West Texas to Seattle Washington, well res test out as soon as I fill up for the 8th time

 

41 minutes ago, JAG1 said:

I don't rely on the factory vent. It might damage the flapper poking around in there and then fuel squirts out whenever you top it off. I like a vented cap or make your own hole in the cap.

Just drill my own hole or buy a vented cap?

27 minutes ago, Mopar1973Man said:

 

Just be aware if you drill a hole in the cap it just means a better chance of getting water in your fuel. The tank is a spring loads check ball so it typically held shut so chances of water entering is rare. So using soft wire and compressed air you should be able to free the dirt and blow it out.

I'll unscrew the cap for now and see if there is any difference. I'll look at the vent tomorrow after I get to Washington at around 5 am. This 32 hour drive non stop is for the birds, can't complain though I made myself a good setup

Edited October 14, 20177 yr by Cronus577

Are you moving to Seattle? 

 

Hows the mpg's cruising around at 60mph and 2400rpm??

1 hour ago, notlimah said:

Are you moving to Seattle? 

 

Hows the mpg's cruising around at 60mph and 2400rpm??

Yes sir, well Puyallup, haven't been calculating MPG right now but not good having to fill up every 2 hours. Was going to add up all the receipts and calculate MPG that way using our route. But I actually feel a HUGE difference in not only power & torque, lower EGTs, quicker turbo spooling, and lower canbus fueling numbers after I unscrewed the fuel cap. I was using 5th until I hit California and they have a 55mph max towing speed, plus their highways are bumpy and destroyed. So I think the issue has been resolved. First idle torque taking off went from having to run 1500 rpm and slowly engage The clutch to being able to start to pull this trailer up a hill from a stop without touching the throttle, thanks a ton @Mopar1973Man@dripley and @JAG1 been dealing with this issue for around 2 years thinking it was the VP. Kind of mind boggling something like a tank vent come cause such significant issues to performance., 

 

Iwould have never thought about the tank vent ever causing this big an issue but thank you guys so much! Now I can teach my wife how to drive a manual and this dual disk clutch thanks y'all as well!

Best to find a vented cap so it has the one way check valve built in for safety.

 

My redneck way of drilling the cap is you only drill a 1/8 inch hole thru the first layer on the underside of the cap. Sort of between the 'wagon wheel' spokes profile on the underside. Not all the way thru the cap Mike That way the outer shell/, top of the cap protects from water. Problem is no safety check ball in a roll over wreck.

 

finding a cap that has it's own one way vent, you'll need to go to auto parts and keep trying till you find one that fits. I got lucky and found mine laying on the ground at a filling station, so I don't have a part number.

 

Drive safe and glad we helped. It was the first time I ever got something right around here lol.

 

BTW, I never poked around inside the factory vent when I had about 40,000 original miles, topped off the tank completely full and the vent was squirting out 1/4 inch stream of fuel right after fill up. had to clamp with a piece of hose and bolt stuck in the end. I said so much for trusting those things, but who knows if or what PO did to it.

 

Never want to contradict Michael Nelson around here. He is the best of folks you'll ever meet so I'm just sayin what happened in my experience is all.

Edited October 14, 20177 yr by JAG1

Always good to hear of a problem solved. Simple or not so simple.