I have 97 psd that is running around 85psi of fuel pressure at the schrader valve. I used an actual fuel pressure gauge to check it, although the package did say not to use on diesel, but as far a I can tell fuel pressure is fuel pressure. When I rev it a little it pegs out the gauge. I am thinking my fpr may be bad, but not sure. Any suggestions are appreciated. Also a step by step on checking fuel pressure with a gauge. I just hooked up the hose to the schrader and started the truck, gauge bounced back and forth between 80 and 90 psi. I have a wvo conversion, but I don't think that should affect anything to do with fuel pressure.

Mike

 

Okay guys, after doing some more reading I checked the fuel pressure again at the schrader valve when I got home. this time I checked it with a tire gauge that goes up to 120psi. It is a stick type, so I got a max. reading. At idle it is 100psi. Apparently I have some problem, so help me out on this one. I do have the wvo conversion, so a blockage in the return line could be possible, or just crap in the fpr itself. My truck also has a tw chip and it is cali emissions if that matters. How far out of range is 100psi and how much should it be while running down the highway? What kind of damage is this doing?

Mike

 

im runnin 75psi. i think thats a good number. idk though. if you dont mind me askin. what the wvo conversion

 

Your first reading with the gauge is the most accurate....80-90 psi and may be OK. It
depends on the gauge accuracy. You should always go by the highest
reading...not the average. This is what the fuel system sees even though it's
for a short time.

90 psi spikes are a tad too high IMO. Look at the top of the filter housing to
see if it's flexing up and down. I did a FPR shim (95psi peak) and saw the
top doing this. I ground off the shim (80psi) a bit and now the flexing is
gone.

BTW: You may have trashed the FP gauge. The rubber, o'rings & internal workings
may not be compatible with diesel...not sure about WVO (Waste Vegetable
Oil) though. The tire gauge is not reliable at all. Those are for people that do
not have a FP gauge.
When an FPR goes bad it usually shows lower pressure due to the internal
spring loosing tension..although you may have a blockage the. Clean the
FPR screen.... might help??

Have you done the FPR shim? If so, remove it and put in a smaller shim (BB, Ball bearing ect)

 

This is going to be a liitle long, so get a cold one. The wvo kit is from greasecar.com. It has worked good for about 50k, but now I am having trouble sucking diesel past the "in" valve. The valves a are 12v solenoid valves rated to 75psi. There is basically a "in" valve and a return valve. You warm up your truck and then switch to wvo. That opens the in valve and the return valve, so you burn wvo from auxillery tank and return back to the wvo system. A couple miles before shutdown you switch to purge and that burns diesel and returns diesel thru the wvo lines to flush them out. All of the wvo in lines run thru heater hose that heats it thereby thinning it also. It is basically a simple idea, but if I am running 90psi fuel pressure at idle how high might it be at 2600rpm when I am running 70 on the highway, that is when it sucks almost all diesel. It is a california truck, so I have not done the fpr shim, I read once on here cali trucks run higher pressure anyway. Bottom line is I don't want to damage anything and I need to know how high my pressure gets top end so I can buy the appropriate valve. thanks for the resopnses!!!

Mike

 

I did have some build-up on the "in" side of the wvo valve, so If I had build-up on the return, could this cause the high pressure?

mike

 

Yes, the way the fuel system on our trucks works is " fuel is sucked from the tanks (via selector valve) through the low pressure side of the fuel pump; then pushed under low pressure through the fuel filter and housing and back to the high pressure side of the fuel pump; and then pumped under high pressure (70-80 psi is ideal) through (cali only: fuel pulse dampener) the metal lines at the rear of the pump into the fuel passages in the heads, through the injectors and then to the FPR (which regulates the pressure by bleeding off excess pressure) and then back to the tank.

So a blockage in the return line could cause high pressure.

 

Unfortunately I have developed a great understanding of how the fule system, at least on my truck works. When I installed my greasecar.com wvo kit I kept on hand tightening the fuel bowl lid and trying to get my truck to run, because it had always worked before. Now, with the kit on it works a little different. Basically you hook the high pressure side to the in valve of the kit (common side of valve) and hook the other two together. The end result is it no longer pumps into the fuel bowl but rather sucks thru it. If your seal on the top of the bowl or the water drain is leaking, you run out of fuel. kind of a pita, but it saves me thousands in fuel cost. I am going to bypass my wvo return valve and then check my pressure, my thought is that vavle is probably gummed up. I will let you know how it goes. If anyone would like pics of the wvo kit or info let me know.

mike

 

I am trying to do a similar WVO conversion to my 97 PSD but stuck trying to figure out how to tie into the return side. Could you tell me how/where you put your solenoid for the return line?
Also did you have to block the air bleeder orifice between the filter and return line? I was told that if left open, it would cause fuel contamination.

 

We have a forum that's dedicated just for WVO systems, you may get a response there too.
WVO forum CLICK ME

 

Oh hey, thanks!!!!