Hi there (me again),
my 1990 na ran great for about a week, no issues at all. Then I changed the CAS o-ring and it still ran great, no startup problems at all.

then, today, I drove it about 10mi without issue. Went to get back in and start it, no start. Car cranks over just fine but doesn't run.

fuel pump does not prime when key is switched to on, or when I jump the diagnostic pins. the previous owner replaced the fuel pump not too long ago so I believe it's good. All of the fuses check out and I made sure the fuel rail hoses are in the correct order.

any suggestions?
- david

 

Main ECU relay.

 

that's my thought too, I've been running around trying to find one today. Is the "upgraded" main relay from FM any good?

 

I didn't know that was a thing, so I can't attest to it. I just removed wired in a separate fuel pump relay fed directly from the body to remove the current draw though the main ECU relay.

 

I purchased 2 main relays off amazon picking whatever generic brand that costed ~20. One to install in the car, one to throw in the glove box for a rainy day. No issues running the original replacement for ~1.5 year. I would like to include, im running 2 SPAL fans that are fed through the main relay as well.

 

Do you have a DMM and are you willing to do further troubleshooting or are you content with the diagnosis?

 

Is this a Megasquirt? If not, it won't prime. And just for clarification, the key must be in "run" position to jump fp/gnd.

Check for voltage at an injector with the key on, or the purge solenoid. Or if it's a MS, if you can't connect any more, that'll be a red flag for the main relay too.

You can always pull the main relay out and jump the two terminals together with a piece of wire with two spade connectors crimped onto it as a temporary fix/test.

 

The diagnosis was correct, I was able to jump the main relay spades and it primed/ran. Also when I replaced the relay the CEL came on so I am positive it's the relay.

 

not running megasquirt *yet*. But I tried the jumper wire and it worked so it is the main relay.

 

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