jschunke Posted July 31, 2009 Report Share Posted July 31, 2009 Hi, It's a 1994 Seville SLS, Northstar 130k. It starts right up when cold. But difficult to start within an hour or so after running it. The message "Disabled Switch" has occasionally shown up. Doesn't the neutral safety switch prevent the engine from turning over? In my case the engine turns over, but it doesn't start right up as it has reliably done for years. Thanks Link to comment Share on other sites More sharing options...
MrEldo97 Posted July 31, 2009 Report Share Posted July 31, 2009 Try replacing the Fuel Pressure regulator. This is symptomatic of a leaky FPR. Link to comment Share on other sites More sharing options...
RalPh Posted July 31, 2009 Report Share Posted July 31, 2009 Sounds like you could have a problem with your FUEL PRESSURE REGULATOR (FPR) What happens is gas leaks past it into the intake and causes a Rich condition that the hot engine has problems starting with. When cold, some of that gas evaporates before you start and what doesn't causes little problem because you need the extra fuel anyway (choked) The quick & dirty test for it is to pull the vacuum line off the top and suck on it a little (yea, I know...) There should be NO GAS in the line, if there is, the FPR needs replacing. Lots of posts here about this Link to comment Share on other sites More sharing options...
jschunke Posted September 17, 2009 Author Report Share Posted September 17, 2009 Thanks for the replies. Unfortunately, the problem still exists even after replacing the fuel pressure regulator on the 1994 Seville. I used an OEM part. It starts right up when cold, but difficult to start after sitting for an hour or so after running. Any other suggestions? Thanks. Link to comment Share on other sites More sharing options...
jackc Posted September 17, 2009 Report Share Posted September 17, 2009 I went through this with my 93 after replacing the injectors with a reman set, and replacing the FPR. In the end, there were 2 problems that I found: 1. The new OEM FPR was bad. 2. One of the injectors was dripping fuel. In your case, I'd probably start by putting a fuel pressure gauge on it and seeing how long it holds pressure after a hot shut-down. If it drops quickly, something is leaking. There are also some OBD diagnostics you can run to try to isolate a leaking injector. Diagnosing a fuel drip on the 93-94's is harder than later models because the fuel rail and everything fuel related is inside the manifold. It may take alot of patience to sort it out. Link to comment Share on other sites More sharing options...
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