Is my boost guage stuck?

when i bought my '94 sc the guage was fine. 15-20 back pressure. 10-12 psi max positive boost.
put in a k+n air filter: the back pressure then hovered around 8-10 while the boost decreased to about 10.
however, after i got my car back from having my tranny rebuilt (w/ a stage 1 trans go shift kit added) the guage no longer shows any back pressure. it stays at 0. and i'm only showing 5 psi boost. the performance doesn't feel any different. it still takes the same amount of gas/acceleration before the sc starts making boost. all my hoses are attached tightly and nothing looks decayed. could the tranny rebuild done something? or is that just an amazing coincidence? ????

Tube to the gauge is crappy

Ford used a small diameter, hard plastic tube for this so it would fit into a wiring harness and go through the firewall. Unfortunately, it can become clogged with oil brought in by the EGR valve.

If you look at the connection to the intake (located after the intercooler on the driver's side near fire wall), they have an "fitting" on the end of the plastic tube so it will connect. I had the same problem with mine "sticking" so I just replaced that whole run from the intake all the way to the gauge with either 1/8" or 3/16" (can't remember) fuel/vaccum hose and have had no problems.

Of course, the guys at the shop may have taken it loose for some reason and forgot to reinstall it.

Good luck.

as it turns out. . .

the plastic tube had gotten brittle from age and/or engine heat. it had a noticible crack in it and when i touched it, a chunk of it came off in my hand. i found some rubber vaccume tubing and made a patch, after cutting off the rest of it that was brittle. my boost is now showing 12 psi full throttle. thanks for the help.

vivisex666 said:

the plastic tube had gotten brittle from age and/or engine heat. it had a noticible crack in it and when i touched it, a chunk of it came off in my hand. i found some rubber vaccume tubing and made a patch, after cutting off the rest of it that was brittle. my boost is now showing 12 psi full throttle. thanks for the help.

Click to expand...

I had this exact problem with mine.. glad you were able to solve it. In my case, I couldn't find any tube right away to replace it so I used electrical tape to patch it.. lol.

You might also check the connections of the other small hoses near the area where the boost line sources its vacuum, as all these can leak with time.