Boost gauge dead, stuck on 30 in vacuum

89SCfan

Registered User
It seems every time I drive my car, something breaks :mad:

I was driving home last night and passed a slow car on a two-lane road (in a passing zone). Floored it, car boosted to 12 psi and I flew around grandpa and down the road I went. When I backed out of the throttle and slowed down to normal speeds, boost gauge came back down into normal range. Then about two miles later as I came into town, I looked down at the cluster and see the boost gauge all the way left showing 30 in vacuum. I stepped into the throttle a few times and it didn't move. Got home, revved the engine and still no movement. I checked the vacuum line connection at the plenum in the engine bay and all is good.

So what might be wrong? Bad gauge? Needle loose? If the line came off the back in the cluster the gauge should settle at 0 just like when the engine is off right? Any suggestions?
 
Last edited:
The spring that zeros the needle probably broke. Its pretty common and I don't think easily fixable without replacing the whole boost gauge.
 
ive had 2 stock boost gauges do that...i wasnt exactly shur the cause but id flick the dash to "unstick" it and sometimes it would release but then it was never accurate..
a,they are easy to swap in and out.but i never found just the boost gauge for sale,always had to buy the whole cluster just for the part.
b,good excuse to put in a stock voltmeter (well,one from another Tbird or cougar) in the slot and hook up an aftermarket boost gauge
 
gauge started working- sort of

ive had 2 stock boost gauges do that...i wasnt exactly shur the cause but id flick the dash to "unstick" it and sometimes it would release but then it was never accurate..
a,they are easy to swap in and out.but i never found just the boost gauge for sale,always had to buy the whole cluster just for the part.
b,good excuse to put in a stock voltmeter (well,one from another Tbird or cougar) in the slot and hook up an aftermarket boost gauge

Funny you mention yours started working after 'flicking' the dash. I tried using my palm on top of the dash a few times to try and jar it loose, but nothing happened. Then last night driving home it just slowly started working again. But now the range is way off. It reads from 28in vacuum to about 7psi under boost. I don't know if the needle came loose and slipped on the shaft or if the gauge is just defective. I may open up the cluster this weekend and play around with it to see if I can notice anything wrong.
 
i never found just the boost gauge for sale,always had to buy the whole cluster just for the part.
b,good excuse to put in a stock voltmeter (well,one from another Tbird or cougar) in the slot and hook up an aftermarket boost gauge

I have a couple stock boost/vacuum gauges if you need one.

I changed my '94 SC boost/vacuum gauge over to the LX volt gauge a few years back along with an aftermarket boost/vacuum gauge in the pillar pod. You'll need the LX gauge surround also.
 

Attachments

  • gauge and car pics 016.JPG
    gauge and car pics 016.JPG
    123.6 KB · Views: 468
  • gauge pics 2 007.JPG
    gauge pics 2 007.JPG
    148.2 KB · Views: 464
I have a couple stock boost/vacuum gauges if you need one.

I changed my '94 SC boost/vacuum gauge over to the LX volt gauge a few years back along with an aftermarket boost/vacuum gauge in the pillar pod. You'll need the LX gauge surround also.

you are correct about the bezzel,i completly forgot. BUUUT my 2nd one i did i just bought a used lx cluster and dropped in my 140mph speedo and tach(for premium fuel label purpose) and routed a aftermarket boostgauge and that was the cheapest/easiest route ive taken so far on this fix..
and i was wrong,ive done it 3 times now..once in my 4.6swaped sc and now twice in this current sc
ya,dont bother taking it apaprt hoping you can fix it, im 99% shur either the needle slips or the spring is shot..make shur you ahve the parts beofr you take upon the task..its not hard just tedious..if i remebr correctly ulle need a t12,13mm and a 10mm maby something else im forgetting but thats the jist of it..just getting lots of fun positioned bolts out.
 
Last edited:
I had one that failed and stayed stuck in vacuum and I'm pretty sure it was because of the Heet & washer fluid mix I was using on my meth injection system. When I removed the gauge, I saw some blue crusty residue on the vacuum hose nipple. I'm now using methanol & distilled water 50/50 and haven't had any more issues with the gauge.

David
 
Back
Top