350 TBI needs starting fluid

[JM in KY]

My ‘87 V1500 with a 350 needs a spray of starting fluid to get going after sitting overnight. It just started acting this way last week. Runs like a top once it’s started and injectors appear to spray a nice cone of fuel when the engine is revved. I don’t see any leaks along the fuel lines and there’s nothing dripping on the ground or smells of gasoline.

Where do I start? What is the common failure point in this situation?

 

[vr1967]

I just worked on an 88 that was the same, crank with starting fluid and run fine afterwards. On it, it turned out to be a faulty MAP sensor, but I checked all the other systems to make sure none of them had an issue either.
To check a MAP sensor -

There are 3 wires going to the sensor. 5v hot, a feed back, and a ground. The feed back is the middle wire.
With a multi meter, check that you have 5v going to the sensor. Plug it in, and tap into your feed back wire. I used a straightened paperclip.
Turn the key on, and you should have right at 5v on the center wire. Connect a vacuum pump to the port, and for every 5in of vacuum, you should lose app 1v (with no vacuum, should be 5v, with 5” of vacuum, should read 4v, 10” of vacuum, should read 3v, etc)

That will let you know if your map sensor is good.

 

[fast 99]

Or fuel pressure check valve is bad with low fuel pressure. Fuel pressure should hold for a time after shut down, pressure should be 11+. Know specs say 9-13 but have seen several that wouldn't run at 9.

 

[Galane]

One problem the GM TBI has is the fuel pressure regulator spring breaking. TBI rebuild kits usually don't include that spring.

It's not difficult to check. Take the top off the TBI and the regulator is on the underside at the back. There's a hole in the bottom of the regulator where moisture (usually from condensation or washing the engine) can get in and rust the spring. Can't plug it or the regulator won't work. Replace the diaphragm and other parts in the regulator even if the spring isn't rusty or broken.

I've seen them looking like they somehow got submerged in mud. Must have been used in an environment with a lot of dust and humidity.

Does anyone make stainless steel springs for these? If not, some company ought to.