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Hard to Start When Hot


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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.


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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 ;)

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  • 1 month later...

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.

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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.

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