Fuel Pressure Isolator blow-out

Hi Michael,

I have a question about your fuel pressure isolator. I've been running one of your mechanical fuel pressure gauges on my 01 Dodge Cummins for almost a year with no problems other than my own mistake of barely over tightening the nut at the connection to the fuel pressure tap right before the VP44. This resulted in a tiny leak of a few drops of diesel which I have been living with.

The gauge itself worked great until a recent trip to California when I tried adding XDP's fuel additive for the first time (I have always used Stanadyne lubricity additive in the past). After 2 tanks of fuel with that additive (about 1000 miles) I lost fuel pressure. When I looked under the hood the isolator (bolted to the firewall)was wet with diesel.

I have read on other forums about people having isolator failures due to fuel additives. Have you ever heard of this problem with XDP's product? Some folks suggest eliminating the isolator entirely and replacing with a needle valve, but I have also heard that the FP gauges are not designed to have diesel in them and doing so would void the warranty.

What do you suggest? Any chance you can help me out with a replacement isolator and braided line with fittings? I'm willing to pay, but didn't know if ISSPRO covered this sort of thing.

Thanks in advance for your input.

My isspro ev1 fp gauge has had diesel plumbed to it for over a year with no issue. My isolator finally quit to but it was a genos garage one.

Sent from my LG pad

I have a isspro isolator if your interested.

Our gauges are fine with diesel running into them, but we recommend the use of an isolator with cab mounted gauges to keep from running fuel into the cab.

Have you tried tightening the bolts that hold the isolator halves together? Can you post or send me a pic of the isolator?

Thanks,
Michael Pliska

Thanks for the input, guys!

Yes, Michael, I did try tightening the two sides together. I will take a photo tomorrow. Can you PM me an email address I can send it to? It's not a lot of fuel leaking but it is wet at the isolator.

I have a FASS DDRP lift pump that's over 5 years old so it may have given up as well, but I'd never seen any diesel leaking at the isolator before and I did just switch fuel additives. I will try to find another way to check VP supply fuel pressure to see if its the gauge or the LP. Either way, I'm in the market for an isolator and a braided line with fittings as both have very slight leaks - or maybe I'll just try the needle valve option and skip the isolator all together.

Thanks again.

Hi Michael,

I've sent you a few PM's and gotten no replies. I'd like to send you a photo if it's helpful. Could you pm me your email? I'm not sure how to post on the thread. It's been a week and I need to get my truck back on the road.

Thanks in advance.

I just wanted to see if you had sent the photos, I had PM'd you my work & personal email addresses but had not seen anything come in.

Michael,
I have had my isspro and isolater on my truck for
5 yrs. I installed a fuelab 200 about 6 months ago.
Last week pressure dropped 5 pounds. I filled
isolater with new antifreeze, didn't help. Can these
isolaters go bad ?

:lolly:I still have my isspro isolator if anyone wants it.

Blueboy said:

Michael,
I have had my isspro and isolater on my truck for
5 yrs. I installed a fuelab 200 about 6 months ago.
Last week pressure dropped 5 pounds. I filled
isolater with new antifreeze, didn't help. Can these
isolaters go bad ?

Click to expand...

Aside from rupturing the diaphragm and causing a leak, there isn't much else that can go bad on one. Did you push the diaphragm to the fuel side while filling the gauge side with antifreeze? Here are directions for that:

Remove the line and fitting from the "gauge" side of the isolator. Using a skinny but not sharp rod (like the eraser side of a wooden pencil, or a chopstick), push into the isolator from the now-open side, to push the piston completely to the other side. If the isolator is mounted such that the gauge side port is not pointing straight up, temporarily remove the mounting hardware and hold it with that port pointing up. In this orientation, fill the gauge side of the isolator with antifreeze (using a turkey baster or syringe), then replace the fitting and tube. Remove the other end of the tube from the back of the gauge, and fill it with antifreeze (using the turkey baster or syringe). If you have someone helping you, it helps to have them loosen the tube at the isolator (while still holding it with the fitting pointing up), to let air out of that end while you force the fluid in from the gauge end. Re-install the tube to the back of the gauge, tighten everything up, and check for leaks.