Help!! 1990 CB7 turning off when at a stop!

[Frosty_CB7]

Hey everyone, so to make this as simple as possible im having issues when braking to a stop my car shuts off, it will only stay on if when I am almost to a stop I let go of the brake then finish. But if I simply press on the brake until the stop my RPMs will significantly drop to zero. Help CB Family please! Thanks in advance. I'm thinking I have a vacuum leak, because if I brake it with the niche(tap off then finish braking) right before the engine is about to die off the RPMs KICK! Back up to normal. It's a stock f22 '90 Coupe with A/T

[lbus9168]

does it do it any other time? does it shut off when Parked if you apply the brakes quickly?

[nexuslite]

I would check the transmission fluid if that looks good try checking all the fuses, then if you are still having the problem pull the belts and check that everything is turning freely, Alternator, Power Steering Pump, A/C Pump and anything else that should be turning. If all of that look okay then get a vacuum gauge and check your vacuum.

Start with the easiest and cheapest solutions first then work up to buying tools to diagnose it.

[Fleetw00d]

From your description, it is shutting off as if it is starved or air or fuel, not that it is electrically shutting down, correct (dash warning lights come on as if you just turned the key to "ON")? If you had a vacuum leak, it would likely idle high. Does it set any codes ("CHECK ENGINE" light stay on?)? According to the OEM manual, the idle air control valve (IAC) is the primary thing to look at with idle issues. Your's may have trouble reacting to dumping the throttle for a stop. Engine "braking" through the transmission may help it keep turning until you get close to a stop (no more engine braking trying to turn the engine) and the IAC may not be able to open enough/quick enough to make up for it. By letting off the brake briefly (still with engine braking helping to turn the engine), it may give it time to catch up. There are threads on here on how to remove and clean the IAC valve. I suggest having a new gasket available for reinstallation.

Check your fuel pressure as well, should be 40 - 47 psi with the fuel pressure regulator vacuum hose disconnected and pinched. If pressure is low, first thing to try would be a new fuel filter.