The site will time you out if you take too long to write your post..I copy to clipboard when I post a long one just in case now...

Anyway, if you put the pressure switch on the VO side of the VO check valve you will not get that rapid on/off of the diesel pump when you loose VO pressure. However, when this happens you should not get any sputtering! When I accelerate hard in this condition the diesel pump just stays on. When was the last time you changed your diesel filter?

I don't see that there would be much of a functional difference if you moved the pressure switch to the other side but I ask you. What are you interested in?The pressure of the VO or the fuel pressure at the engine? I also want to know if the diesel system can maintain pressure....

O that explains why I got the error!

I agree with you leon. I dont really care who is giving me the pressure to run my truck, just as long as its running! so monitoring the pressure on the engine is really more important.

my diesel filters (yes I have 2 - did the itp prepump kit) were both changed about 2000 miles ago. I dont think my sputtering was from clogged filters, more like it trying to figure what pump to use and the moment it takes for the pump to build pressure. its not a big deal really. that should not happen if I keep my tank full! O and when I finally get a gauge to see the level in the tank from the truck! all I have is the gauge on the tank now.

I need a little help, it appears my system is trying to turn on before it is up to temp then it quickly turns off and kicks the bypass on. Just looking at the temp gauge when the system first tries to start, it appears it is not up to 160 degrees yet. When I wait a little longer and turn the system on manually (by turning the main switch on) when I know the truck is warm it comes on fine. Any idea what would cause it to try and turn on early? What it weird is that it started happening after I changed the filter last weekend. I looked around underneath last night, I couldn’t find any loose wires. What do you think? I have just over 5000 miles running this system, I followed Leon's design and it has been working great until the past weekend when I changed the filter. I had a wix on it, but the local store only had a fram, so that is what is on there now. Any suggestions?
Thanks.
David

I would pull the wire on the temp sensor and watch it with a meter or light bulb. that is what sends the signal to turn the system on. if that closes early, then your sensor is bad. if the system comes on before the sensor closes, you have a wireing issue somewhere.

David,

This is strange. I can't see how the filter could be related. I would also focus on the temperature switch before anything else. They are designed with a switching temperature differential to avoid this issue. ie it will turn on at 160F but not turn off until below 155.

What is the time between when it turns on and turns back off?
Which switch did you use? Where is it mounted?

It is possible "now with colder weather" that the temperature coming out of the radiator could be fluctuating this much as it is warming up.
You could also see if it does this if the truck is stationary (the radiator would be much less effective)

Thanks for the input, I will start looking at the switch this weekend. When it tries to come on it immediately shuts off and turns the bypass on, just looking at the temp gauge it does appear to not be at the normal temp it usually comes on (but it is close sometimes). If I wait a few more minutes for it to warm up, it does work. I actually moved the temp switch to the heat manifold on the wvo pump under the truck. When I had it on the water pump it would flicker a lot when it was cold trying to turn on, since I moved it back by the pump when it decides to turn on, it happens without the flickering. It does take longer for it to heat up back there, probably another mile or so. I wouldnt think it would be the filter either, especially the way it works fine when it is good and warm, but that is the only thing that has changed lately. Maybe I pulled a wire or something and I have a short. If the switch was bad, why would it even turn on then turn right back off?