Low boost! Please help!

[zray]

The gauges are from Paxton, so maybe the isolator and the FMU are too. I'll have to double check that though.

the isolator is made by Mallory. they will sell you a new diaphragm for it if you contact them directly. If it has leaked, or if the diaphragm is old (and not pliable) your gauge will not work properly.

Z.

[Gemelli]

That must be what the M stands for on the isolator. I took this picture yesterday.



Thank you very much for the info about Mallory. I will email them today. I'll look for instructions on rebuilding the isolator, but any advice or instruction from you would be very much appreciated.

[zray]

".........Thank you very much for the info about Mallory. I will email them today. I'll look for instructions on rebuilding the isolator, but any advice or instruction from you would be very much appreciated.

there's not much to it.

1) don't overtighten the screws that hold it together.

2) make sure the case halves are very clean.

3) smear a bit a vasoline on the perimeter of the diaphram (both sides) where it seals against the case.

4) the most most important factor is to fill up the hose leading to the gauge with 50% solution of antifreeze completely up to the threads of the fastener. And fill up that half of the isolator with 50% antifreeze also. Very quickly join the two pieces, keeping any spillage to the basrest minimum. Very much air in the line makes the gauge not as effective.

If you spill any be sure to wipe it up so no animals get poisoned. Actually I use pet safe "Low Tox" antifreeze (by Prestone) in all my vehicles, and in the isolatoir. Something to consider.

the mallory is for your fuel pressure gauge, not a boost gauge, right ?

Z.

[Gemelli]

I guess emailing them is out. I didn't look terribly hard, but I didn't find an email address for customer service. I did find a phone number, which I'll call tomorrow. The isolator is for the fuel pressure gauge, which is not working at all. It's an original Paxton gauge, so I'm sure the whole setup has been around for a while. I'll rebuild the isolator and refill the tubing as soon as I can get the parts.

This thread was started because of a low boost condition, which I thought was resolved. Unfortunately, the increase to 5.5 pounds was apparently a one time deal. I haven't rebuilt the intake side of the setup yet, but I have tried taking the intake tube off the air box a couple more times with no increase in boost. If the gauge is inaccurate, it still definitely made more boost when it showed more boost on the gauge. Any other input on this would be great!