Sometimes when I try to start my car (93 del sol,d16z6) the fuel pump doesn't prime and the car wont start. This only happens sometimes. I've tested the wires at the main relay with a test light. The YEL/WHT, YEL/BLK, and BLK/YEL wires all have power with the key in the "run" position. The BLK, BLU/WHT, and YEL/GRN wires don't have any power with the key in the "run" position. What gets me is the last wire GRN/YEL. When I test it, the fuel pump comes on and the test light lights up dimly. Is this a ground issue? The thermostat ground point is clean. Or is it a signal wire to the relay issue? Not sure which wire that one is.

Any ideas anyone?

 

there is a thread that you might want to read, someone had the same problem you are having i think it was posted in nov or early dec of 2011 try looking for it, you might find your answer.

 

Resolder the main relay.

This is normal and should have happened. The Grn/Yel wire gives the ECU control of the fuel pump. When the ECU grounds this wire, the fuel pump will run.

 

Check the transmission ground sand down the surface and bolt the ground back on see if this helps

 

Yeah that old thread was mine. I have the same car 93 del sol si D16Z6.
I chased that problem for a year. I had changed fuel pumps, ignition switch, main relay, cleaned grounds etc. Turned out it was the ECU. Water/ condensation damage. It would start intermittently especially after a overnight rain. Eventually it wouldn't start at all. I got a junkyard P28 ECU for about $130. Fixed it been good for the last 6 months.
The Ecu was 18 years old. Car had 190K miles.

 

So could be the ecu?
As for main relay, this is the second replacement I've gotten. When the car first started doing this I immediately thought it was the main relay. So I warranted it and it still had the same problem.
I haven't sanded the ground point, but it's already shiny so I didn't think it would help.

 

Any more ideas?
Isn't there some wiring I can check?

 

I forgot to mention that the check engine light stays on when the fuel pump doesn't prime (code 43, fuel supply system).

 

That's my main relay all shiny and new with no cracks in the solder. So my problem is elsewhere right??

 

Then start looking at the ignition switch.

 

I've tested that with my test light as well. It works fine every time, even when the fuel pump doesn't run.

 

Doesn't look like the main relay to me, unless the Del Sol uses a different one than the Civic.

 

God it straight from o reilly's. There's do seem to be bigger than the stock one.

 

Give it a try.