Who's good with regulators in TBI units? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chevy3+3 · 10-02-2016, 09:12 PM

I have felt like I've had a vacuum leak for a while now. Not a bad one but definitely causes my acceleration to come in & out while trying to accelerate. I started spraying down my vacuum lines and around the TBI unit with carb cleaner.

When I spray carb cleaner directly beneath the fuel pressure regulator at the back of the TBI unit the engine stumbles and tries to stall. I did it several times and had the same results. I thought if a regulator diaphragm was cracked or leaking that it would be leaking fuel. Problem is I am not leaking any fuel I can see but instead it appears that there is a vacuum in the little hole on the bottom of the regulator cup. Is this possible?

Anybody have any thoughts?

kelsfine69 · 10-03-2016, 05:34 PM

The TBI base gaskets are famous for sucking in.

Mr.Chevy4x4 · 10-03-2016, 10:40 PM

Yes, exactly what I was thinking. Probably the base gasket. Seen it several times. In fact I got a SMOKING deal on a 454ss that ran like crap when I bought it. $8 TBI base gasket later it ran like new again.

Mike

Chevy3+3 · 10-03-2016, 10:43 PM

Its not the gasket. I tried to locate it again tonight but was unsuccessful. I will get it figured out eventually.

When I bought the truck it had a leaky base plate gasket. I replaced it so this one is in good shape.

10-02-2016, 09:12 PM	#1
Chevy3+3 Registered User Join Date: Oct 2013 Location: Winfield KS Posts: 489	Who's good with regulators in TBI units? I have felt like I've had a vacuum leak for a while now. Not a bad one but definitely causes my acceleration to come in & out while trying to accelerate. I started spraying down my vacuum lines and around the TBI unit with carb cleaner. When I spray carb cleaner directly beneath the fuel pressure regulator at the back of the TBI unit the engine stumbles and tries to stall. I did it several times and had the same results. I thought if a regulator diaphragm was cracked or leaking that it would be leaking fuel. Problem is I am not leaking any fuel I can see but instead it appears that there is a vacuum in the little hole on the bottom of the regulator cup. Is this possible? Anybody have any thoughts? __________________ 88' Chevy V30 3+3 4x4 Dually 454 TBI/NV4500/NP205

10-03-2016, 05:34 PM	#2
kelsfine69 18 Till I Die Join Date: Mar 2005 Location: Alberta, Canada Posts: 1,522	Re: Who's good with regulators in TBI units? The TBI base gaskets are famous for sucking in. __________________ 2011 GMC Acadia 1969 GMC BBC LS7 2007 GMC Crew Duramax 1987 Camaro Iroc 350 Tuned Port Injection 42000Km 1987 Chevrolet Silverado 350 TBI 1987 Chevrolet Silverado 350 TBI(yes 2) Take me drunk, I'm too home...

10-03-2016, 10:40 PM	#3
Mr.Chevy4x4 Registered User Join Date: Jul 2007 Location: Sims, NC Posts: 531	Re: Who's good with regulators in TBI units? Yes, exactly what I was thinking. Probably the base gasket. Seen it several times. In fact I got a SMOKING deal on a 454ss that ran like crap when I bought it. $8 TBI base gasket later it ran like new again. Mike __________________ All things Chevy truck: 1986 SWB "Jolene" boosted 5.3/4l80e project

10-03-2016, 10:43 PM	#4
Chevy3+3 Registered User Join Date: Oct 2013 Location: Winfield KS Posts: 489	Re: Who's good with regulators in TBI units? Its not the gasket. I tried to locate it again tonight but was unsuccessful. I will get it figured out eventually. When I bought the truck it had a leaky base plate gasket. I replaced it so this one is in good shape. __________________ 88' Chevy V30 3+3 4x4 Dually 454 TBI/NV4500/NP205

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