...No more boost....

Porabowl

Registered User
Alright....i just got over my "bucking under boost" problem, i changed the wires and moved to autolite platinum plugs. Now i have another problem: no boost at all! I noticed a problem a week after i changed the plugs/wires. At idle, i used to read 20 on the vacuum side and i got about 8-10 psi boost at WOT. Then one day i saw that at idle it was reading 10 Vac and i would get no more than six boost. The next day i was getting even less of both....untill the gauge just went to ZERO and stopped moving. I'm not gonna lie....that makes me pretty sad. Before, i was getting a high-pitched noise from the supercharger. Now i don't get that noise, so i know it's not the guage that's broken, plus i get a lot less performance. Has anyone experienced this problem before? if so, what should i check first?
Thank you in advance, Tom - '93 red SC.
 
Check the sensing line for the boost guage. It is a thin black (maybe 1/16" diameter) plastic line that runs from a fitting on the Inlet Adaptor (connection from lower IC Tube into the intake manifold) to over near the driver's side fire wall area and then runs into the passenger compartment. Probably cracked or broken...possibley at or near the connector into the inlet adaptor.
 
One day I was getting 11-12psi and the next day I was getting zero. I looked at my belt and it was replaced. Haven't had a problem since then.
 
Make sure the bypass valve linkage isn't bound up against the back of the supercharger. Sounds like it's not closing all the way.

David
 
Check your collar nut on the sc top. Mine came loose one time and I thought the sc went south. In fact, it was just the nut. It was completely loose and was allowing the boost to escape there rather than going into the engine. Start simple with these engines...
 
Save yourself time and get a can of brake cleaner,spray the brake cleaner on your blower and hoses.Listen to your idle at the same time ,if you find a leak your engine will rev.It might help to isolate your problem.
 
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