Greetings. I have a 1993 Honda del Sol S with a D15B7 paired with an automatic transmission. I first became aware of the issue on Friday when I wanted to move the car out of my garage to make room for another del Sol to work on. I turned the key to the II position and found out that the fuel pump no longer primes and the CEL just stays on. The SRS comes on but goes away after roughly ten seconds (the oil pressure and battery lights stay on as well but this is normal). I tried to start it but the car just cranks, which is likely because no fuel is being pumped. I tested for spark by attaching a timing light to cylinder 1's spark plug wire while cranking and no light was being emitted.

> I checked and cleaned all of the obvious engine bay grounds (the thermostat ground has some exposed wire due to old, cracked insulation but no disconnections).
> I swapped the main relay with a working one from a running car (the original one works too as it's in the running car).
> I checked all of the fuses and even swapped them all with fuses from a running car (the original fuses work too as it's in the running car).
> I jumped the fuel pump directly to 12V and it turns on and functions.
> I tested the thick Black/Yellow distributor wire and it's getting 12V at II ignition position.
> I jumped the service connector to obtain codes but the CEL remained constant.

At the main relay (plugged in and back-probed):
> Yellow/White wire has ~12V all the time.
> Yellow/Black wires has ~12V at II position.
> Black/Yellow wire has ~12V at II position.
> Green/Yellow wire has ~12V at II position.
> Yellow/Green wire has 0V all the time.
> Blue/White wire has ~8V when cranking.

At the fuel pump connector, where the Yellow/Green wire leads to, I am not getting any power when the ignition is at the II position. This is what's causing the fuel pump not to prime, but why isn't any power getting to the pump? Also, how do I test for continuity with the Black ground wires at the main relay? I had my multimeter set to 200ohms, back-probed the Black wires using the red probe, grounded the black probe to the chassis, and got a fluctuating number no where near 0.

All of this is leading me to believe the ECU or the ignition switch is the culprit. But I am absolutely inexperienced when it comes to diagnosing electrical issues and don't really know what to look for. I would like to swap in a working ECU to see if it works but both of my other del Sols are manuals (manual D15B7 ECU, and chipped automatic D16Z6 ECU). Can I try the manual D15B7 ECU? Is there a risk of frying it too if the problem is indeed a bad ECU (the ECU worked perfectly fine before)?

I should add that the car was sitting for several weeks (as it's not driven during the winter) and sometime during those several weeks, I messed with the fuses (I don't remember if I disconnected the battery or not) because I was trying to satisfy my OCD by making two of my Sols have all OEM fuses while the one in question have Littlefuse brand fuses, rather than having them mixed up between all three cars. I'm hoping that I did not fry the ECU by doing this. I showed my father the circuitry of the ECU as he is an electrician who does a lot of soldering and he said there were no visible signs of components burning. Prior to any of this, the car ran absolutely fine.

So what do you suspect? Could it be the ECU? What do you suggest I test next? Thank you for your time.

 

So I decided to unplug and plug back in the ECU (re-bending some of the harness wires) and now the main relay makes a horrendous grinding noise, with the CEL now acting in unison instead of staying on constantly. Is this a ground issue??

 

Well, I unplugged and plugged the ECU connectors and repositioned the thermostat housing ground and when I turned the key to the II position, the main relay had a slight buzzing episode, stopped, and then acted normal allowing the fuel pump to prime. Tried starting it but it sounded like it wasn't getting spark (just cranked). Took out the key and tried it again and the main relay no longer responded, and thus no fuel pump prime (plus the solid CEL came back). I put the thermostat housing ground back to it's original position and redid the ECU connectors and now I'm back to square one--no fuel, no spark, and solid CEL.

 

https://www.team-integra.net/threads...eaning.193084/

they don't last forever, if you replace get the honda part.

ecu could have fried capacitors, just sent one of mine to the chipping service guy in nc on ebay with good reviews.

 

It turns out that the ECU is malfunctioning. I went ahead and tossed my manual del Sol ECU (P06 A01) into the automatic del Sol and turned the key to the II position and everything worked as it should. The fuel pump primed like normal and the CEL went off after the two second illumination. I put the automatic ECU (P06 A50) into my manual del Sol and it did the same thing where the main relay would not send power to the fuel pump and the CEL would just stay on.

Now I'm wondering how the ECU went bad all of a sudden. It had no problems prior to it sitting over the winter. Could it be that me pulling all the fuses (possibly while the battery was still connected (which I don't think it was)) somehow fried something in the ECU? Also, can the ECU be repaired in a DIY fashion or do I need to get another one? Do you recommend a junk yard ECU? There's one on eBay for ~$200, but that's kind of spendy.

 

there's lots of diy videos:

https://www.youtube.com/results?sear...ecu+capacitors

there are parts kits on ebay and here's the guy i sent mine to:

https://www.ebay.com/itm/HONDA-ECU-C...sAAOSwceNZWpwu

a new ecu from the dealer is like $700 lol, check car-part:

https://car-part.com/

looks like there's one for $65 plus shipping.