80 sc starting issues

[toothache]

I have a 1980 sc which is giving me a fit with starting issues. When I try to start the engine sometimes it starts fine, other times it runs for a short time and then shuts off. It acts like the cold start valve works but the fuel pump does not kick in. It has plenty of fuel in the tank. I did what Bently said and jumped the fuel pump relay at #30 and 87a. with switch on I had 12 volts. I ran a wire to the black wire at the fuel pump and then touched the other end to 12 volts. The pump came on instantly. I turned the key on and lifted the sensor plate. I could not her the fuel pump. Any suggestions would be helpful. Thanks

[ossiblue]

First try a new relay, or swap out to a known good black one just to test. A sticking relay could account for the problem and it's an easy check. The test you ran by lifting the sensor plate points toward a relay failing to switch over to power the pump through the ignition terminal (87a).

[snbush67]

This sounds like you have an intermittent connectivity issue. Clean the pins on the relay, make sure they are making good contact. Check the wires and make sure they aren't cracked and corroded.

And what L.J. Said.

[gazzerr]

The pins on the red relay can get a little loose in the relay socket. You can get a small screwdriver or razor blade and spread them to make the pins a bit wider. The relay will fit much more snugly in the socket. Could be as simple as that.

[emac]

All of the above or your CDI box could be going. Mine did the same

Ernie

[boyt911sc]

If you want to know and learn about your starting problem, start with the basic tests. Since this subject has been well discussed in this forum, search for DKLever48's post about FP relay and socket testing. Everything you need to know is well covered in the thread. And if you have any question, just ask.

You also need a pressure gauge to do a meaningful evaluation. A running FP without knowing the delivery pressures is next to nothing. It is imperative that you use a fuel pressure gauge for troubleshooting any fuel injection system regarding fuel pressures.

Tony

[Joe Bob]

Relay and/or fuel pressure. Gauges are a must on CIS diagnosis. Borrow or rent a set.