Hello wonderful world of H-T!! So I recently got my turboed 99 si out of storage (been in for 2 years, thanks kids & divorce!!), and when I turn the key to "on" the main relay does not click for upwards of 30 seconds. As soon as the main relay does click the fuel pump instantly turns on.

I took the main relay out of my parts 99 si and same problem. Any ideas on where to start lookjng would be greatly appreciated!!

 

This symptom is usually the sign of a bad ECU. Does the engine run fine after ther pump primes? If so, the common fix is to replace the inexpensive electrolytic capacitors on the ECU printed circuit board.

 

After the pump primes it starts right up. Seems to have a slight miss possibly but other than that seems to be ok.

It was stalling when I'd come to a stop with the clutch in, however changing the main relay seems to have fixed that problem?

 

If you have a known good ECU, swap it in. Then go from there.

 

I have the OEM ECU, I should be able to switch my chipped ECU just to see if the fuel pump primes correctly but not start correct?

 

Correct

 

I agree with muellersfan... bad capacitors in the chipped ECU. Have them replaced immediately or replace it with a known good socketed ECU... and make sure it has NEW capacitors since the original ones are now 25 to 28 years old.

 

Your symptoms match exactly to the problem with failing or failed (dried out or leaking) electrolytic capacitors!

Hope you follow up with your findings. Did swapping in the other ECU remedy your issue?

If you can do basic soldering you can repair your own ECU for just a few dollars in electrolytic capacitors!

 

I replaced the current chipped ECU with the stock ECU. Fuel pump instantly turns on. I took the cover off of the chipped ECU and it appears C15, and C19 have "burnt"? This make sense with my problem?


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Those capacitors are leaking not burned. When the capacitors burn, the ECU is generally trashed because the exploding capacitor burns a big hole in the PCB.

 

So do I spend the money / time to "fix" this one or just buy a new socketed ECU and switch the chip

 

It's your choice. The cost of the replacement capacitors can be paid for with a jar of pennies. The desoldering of old capacitors and soldering of new capacitors is very easy. Check out YouTube videos.

 

Guess that's what I'll try, your right doesn't cost that much. Can't hurt anything worse that it already is lol. I'll give it a try and if not I'll just order a new socketed ECU.

Thank you guys for your help!!

 

If you lack experience soldering, find an old printed circuit board with electrolytic capacitors and practice removing and installing them. If you do, you'll be more confident working on the ECU board.