Ok so since I'm on my second ISSPRO gauge in this truck, I've been paying extra attention to it and the FASS. Well I've noticed a couple things and just wanted to clear the air. I don't think anything a wrong but just wanted to get some extra input before I moved on to worrying about the next thing.

 

Currently have less then 1/4 tank so keep that in mind...

 

If/when I bump the starter, the FASS will run/prime but I don't see any fuel pressure build on my gauge. Once I finally start it takes 5+ seconds before it shows any readings which end up between 16-18 at any given point. 

- Anything to worry about here?

 

While driving I noticed recently that the needle would bounce around a couple psi with no relation to throttle input.

-Could this be because of low fuel?

 

Finally, my gauge is setup with just a tee into the fuel line, to a needle valve, then gauge. The needle valve is cracked literally as little as possible to get a reading on the gauge. The way it's setup now I can't see a cranking pressure (if it takes that long to start) since it takes a bit to build pressure. 

 

-Should I open it a little more to get a quicker response from the gauge? 

Too close to the VP44 is most likely what is wrong. Your at the strongest water hammer pulses from the VP44. So it would be best to move your tap point towards the stock filter or aftermarket pump.

So I was on the phone was FASS and I was sitting in my truck with it idling watching the gauge hop around and all the sudden it just stopped and didn't do it again. Drove all the way home, no issues. Parked for a bit up hill and when I went to start it even bumped the fuel pressure up to like 5psi. Started no problem and no pressure fluctuation.

 

The only thing I can think of that fixed this was tightening the return line on the FASS. That's the only thing I changed. I guess it was leaking a little air in the line and causing some fluctuation in my pressure. We'll see if that fixes my hard start when parked uphill.

6 hours ago, Dieselfuture said:

On fuel temp in vp, my guage says 130ish when driving down hwy. That's coming from my qwadzila. Tank full or empty. 

I didn't know the quad had a fuel temp?! That's cool man! I just figured the fuel is hotter on a low tank because one time since I had my fuel boss I ran the tank really low on a long trip. When I got off the highway to get fuel my pressure dropped from 17 at cruising speed to like 13-14 at idle. It scared me at first, but when I filled up with fuel, everything went back to normal so I assumed it was due to the fuel being heated up and getting a lot thinner. Maybe I was wrong? 

Issue is fixed! Also ended up fixing my hard start troubles HERE

20 hours ago, Dieselfuture said:

On fuel temp in vp, my guage says 130ish when driving down hwy. That's coming from my qwadzila. Tank full or empty. 

Did not know there was a fuel temp sensor on the engine or fuel system. Did you have to add a sensor?

I'm sure someone will correct me if I'm wrong, but I believe the vp44 has a temp sensor built in and can put the truck in limp mode if it gets too hot. 

Yes. But there is only one case in 11 years have I ever seen a P0168...

 

Interesting. With so many heat related failures from low fuel volume/pressure I would think the code would be more common. I wonder if that temp sensor is unreliable or the threshold for high fuel temperature is just too high. Does make me wonder with what Dieselfuture said about his temp being the same with fuel tank full or empty. I was pretty sure the fuel would be quite a bit warmer when the tank is on the low side. What do you think Mike?

Actually I think most failures are more AC noise related than actual heat related. All the people in southern states with unruly high temperatures in the desert and like I do here in the Riggins valley reaching over 110*F just about every year.

 

In that case I wonder why it is that the alternators in these trucks have so many issues with AC noise. Or is it just that the VP and other electronics in these trucks are uncommonly sensitive to AC? 

 

With regard to to the fuel temp, I just meant shouldn't the fuel be significantly hotter when the tank is at 1/8 vs 3/4? 

Both... As they increased the amperage of the alternator the wattage gets higher and heat becomes the issues on the diodes. As for the electronics they are just simple computers like your laptop or cellphone. Now try charging your cell phone with a bad charger and tell me what it does to the cell phone? So the ECM has everything just like a laptop. A CPU, (Hard drive) which is a PROM (Programmable Read Only Memory), then RAM to excute the software from once booted up and interfaces like MOSFET's turning power on and off to different things. VP44 is it own standalone computer with its own PROM, CPU, RAM, etc. Since you can do the BlueChip hot wire test this proves there is some logic there to control it as a standalone.

Thanks for the explanation! I always like learning more about the VP!

1 hour ago, dripley said:

Did not know there was a fuel temp sensor on the engine or fuel system. Did you have to add a sensor?

No, just part of qwadzilla options for one of the monitoring options. 

23 minutes ago, Dieselfuture said:

No, just part of qwadzilla options for one of the monitoring options. 

There is a sensor in the VP that monitors fuel temp? There has to be something the Quad reads it from.

Quadzilla and Edge Juice both can read the fuel temp.

Just now, dripley said:

There is a sensor in the VP that monitors fuel temp? There has to be something the Quad reads it from.

That would be my guess, man if only I could figure out why I'm not able to post pictures. Every time I click on reply button that attachment paper clip shows up for a quick second then disappears. 

Had that problem a while back but dont remember how it was solve. The solution came from the site. You must report the site. I dont remember how to do that either.