Fuel Press gauge install

[SMOKNZ]

I finally got around to hooking up my Diprocol Fuel Pressure gauge this morning. I installed it with the supplied Isolator and filled the cavity with antifreeze after I gently pushed down the diaphram in the isolator. I am only getting a little over 20 psi of fuel pressure. Is there a special bleed procedure I need to do with the antifreeze in the isolator to get an accurate reading, or is my pump just shot. Truck seems to be running OK.

Bill

 

[uloadit]

have to bleed out the fuel line to the isolater then fill up the antifreeze in the other side and make sure everything tight

 

[BIG JOE]

have to bleed out the fuel line to the isolater then fill up the antifreeze in the other side and make sure everything tight

X2 Bill.

 

[SMOKNZ]

With the fuel pump running crack the fitting at the isolator until only fuel comes out? Is this what your saying?

 

[BIG JOE]

With the fuel pump running crack the fitting at the isolator until only fuel comes out? Is this what your saying?

Yes.. With the fuel line connected from the tap point, to the isolator.. crack the fitting At the isolator and bleed ALL the air out with the fuel pump.

(I held a rag over the connection and had the wife cycle the key on 'til the line was purged with fuel and tightened the fitting with the pump running. No start)

After say 3-4 start/shut downs, I was able to get a little more coolant into the the isolator and line to the gauge. Been in service for 7-8 years now.. no issues. Diprocol too.

Joe

 

[DaveBen]

After say 3-4 start/shut downs, I was able to get a little more coolant into the the isolator and line to the gauge. Been in service for 7-8 years now.. no issues. Diprocol too.

Joe

Joe, I am confused, again... What coolant are you referring to??

Dave

 

[SMOKNZ]

I bled the fuel line to the point where I had straight fuel in the line and when the fuel pump shuts off I don't have any bubbles going back toward the fuel filter. Pressure on the gauge still reads 23psi or so. The only way to add coolant is to remove the fitting on the isolator, correct? Does the gauge side with the coolant in it have to be bled as well? I see the large screw on the isolator on the fuel side can I remove this and crack the fitting on the gauge and push the diaphram to get coolant right up to the gauge then tighten it up and re-bleed the fuel side? I think I will try this and see how it goes.

Bill

 

[BIG JOE]

Joe, I am confused, again... What coolant are you referring to??

Dave

From the isolator, to the gauge, coolant/anti-freeze is used to transmit the actual pressure readings Dave. I've also seen a light oil used.

That way, should the gauge fail.. or the longest run of tubing.. only a very small amount of basically inert, non-flammable liquid is lost (like, in the cab?)

This "Isolator" method gets used in many remote monitoring applications where hazardous liquids or gasses are monitored.

Good Insurance.

Joe

 

[BIG JOE]

I bled the fuel line to the point where I had straight fuel in the line and when the fuel pump shuts off I don't have any bubbles going back toward the fuel filter.

* Yer good to go.

Pressure on the gauge still reads 23psi or so. The only way to add coolant is to remove the fitting on the isolator, correct?

*Correct

Does the gauge side with the coolant in it have to be bled as well?

*No. At least I didn't.

I see the large screw on the isolator on the fuel side can I remove this and crack the fitting on the gauge and push the diaphram to get coolant right up to the gauge then tighten it up and re-bleed the fuel side?

*The large screw should be on the GAUGE SIDE... Mine is... Might be yer psi reading problem ????

I think I will try this and see how it goes.
Bill

How'd it go Bill ????

As I said earlier, after a couple Starts, and the coolant had gone into the tubing, I put more coolant in the isolator.. seemed to purge more air out.. still has a few bubbles but I'm think'n it has to do with the viscosity of "Coolant".

I get true and correct readings, with no bounce.

Joe

 

[SMOKNZ]

Joe,

The isolator has a sticker on it indicating "Gauge Side" and it is the side without the Screw. According to the install directions, the isolator is held screw side up and then that screw is supposed to be loosened and the fuel pump cycled until fuel starts coming out and then retighten it.

I pulled the isolator and the popped the screw from the fuel side and pushed the diaphram to get the coolant right up to the gauge. The wife then tightened the fitting. I then took off the gauge fitting with the line full and topped off the gauge side which wasn't very empty, I got only a few mL's of coolant back in. I then bled the fuel side again to get all the air out. Still only seeing 20 psi, and when I go WOT it goes down to about 7psi. I guess next step is to hook a known good gauge to the port off the bowl and see what it reads. Maybe I do have a bad pump?

Bill