belairbrian

This is the 93 del sol SI

Been having an itnremittent start. Typical no fuel pump turn on type.

At first was onec a bout every 2 months. Now I can duplicate it every hour.

I pulled the main relay and reflowed solder joints. No help. But the relay may be after market as it is the right shape but no markings at all except AJ 05/09 printed on end.

When it happens it goes like this. Turn keyto II check engine light on no fuel pump prime. Cycle switch several times and fuel pump primes and car starts and runs. Shut off and will restart. Wait an hour and same problem.

If I'm reading the factory manual diagram correctly, in position I the first relay should energize. Position II second relay energizes, MIL goes out.

I ran the relay on the bench using my 12v power supply and it passed all three parts of the test procedure. So I held the relay and turned the key, nothing happened. slightly turned key back from II to I and I could feel relays click and pump primed. So far I can repaeat this sequence fairly consistently. But once I get the first prime it works until I let the car sit a while (30-60 minutes).

So I'm thinking failing contact in the ignition switch. If so is it really a 1993 specific part like the part lookup sights say. Or is their a interchangeable alternative. Do I have to change the entire lock asssembly or can I just change the switch. keeping in mind that it is an auto trans not a 5 speed. The 5 speed shows 93-95 as the same part on Del sol and civic. Guessing this has to do with the start interlock maybe.

But leary of the Main Relay being aftermarket so I may change that regardless. Has anyone ever seen an OEM main relay with no part number or manufacturer markings?

On the main relay, should I just buy new or get a parts yard one for $6 and check the solder joints.

Heck maybe I should just build a toggle switch and push button start panel to replace the switch.

TomCat39

I can't speak about the del sol per say, but there is a difference between the ignition electrical between the manual and the automatic.

There is two connectors on the automatic while the manual only has one.

And you won't have to replace the lock cylinder/assembly just for the electrical.

I have to replace the electrical part of the ignition on my wife's 93 automatic civic.

I can only find a new electrical part on ebay for 92-95 civic manual. I have been thinking about getting that, and going to the salvage yard and pulling the same part from an automatic civic.

Then I can rip apart the used part and see where the extra wiring goes and solder it to the new ignition.

I think this maybe the most cost effective method. Not sure if any of this will be suitable for your situation.

Former User

When the engine won't start and the pump won't prime, does the CEL turn on and stay on when the key is in ON(II)?

92ehatch

He said it does come on.

I'm in same boat myself. Every time i go to put a meter on it it primes. So I've just let it ride so far

Former User

I missed that. Thanks. This information effectively rules out an ignition switch problem.

The problem is most likely the ECU, but there are a few more tests that can done to confirm.

belairbrian

The reason I'm concerned about the ignition switch is that I can use it to clear the malfunction.

By slightly moving the key torwards poistion I it primes the fuel pump.

Any suggestions are welcome. Can any one answer this? With the ignition switch in position I should relay one in the main relay be energized? It appears by the schematic it should. That is not happening.

I have also verified the battery voltage was good and G101 is clean and tight.

Former User

Again, if the CEL turns on when the pump won't prime, the ignition switch is fine.

belairbrian

Ron,
I went back and looked at the function cahrt for the switch and the schematic for the main relay circuit. Figured out why I was getting confused.

I figured out that the "switch positions" are 0, I, II, III, but position I does not line up with the IGN 1 connection. Rather IGN 1 and IGN 2 are both connected in position II. I was thinking IGN 1 was connected in position I which it is not.

But I am consistently finding that the main relay does not respond to position II but cycling the key will cause it to work. Based on the schematic the first coil of the main relay should energize as soon as the switch is in position II regardless of the ECU response. In fact relay 1 should energize with the ECU removed and the switch in position 2 as it will have 12v from the battery thru IGN1 then the ACG fuse (15A) at pin 5 and a chassis ground at pin 2.

So I think I need to figure out why I have to wiggle the switch to get the relay to respond.

Probably will replace the main relay first and see if that solves the problem.

Former User

In ON(II), does the CEL turn on when the pump won't prime?

belairbrian

yes it is on and remains on

92ehatch

If that is the case then wiggling the key is coincidental. Ignition is fine

Former User

Discard bad ignition switch idea.

belairbrian

Been busy with some other stuff and finally got a chance to get back to this. I get why it's not the ignition switch.

So I've done some additional testing to narrow this down.

1) Swapped in a new Main relay. No change.

Did some checks to clearly define what is going on.

The following Sequence is repeatable

Turned key to ON, CEL illuminates
after 25 seconds pump engages, primes and CEL goes out

Turn Key to Off

Turned key to ON, CEL illuminates
after 7 seconds pump engages, primes and CEL goes out

Turn Key to Off

Turned key to ON, CEL illuminates
after 5 seconds pump engages, primes and CEL goes out

Turn Key to Off

Turned key to ON, CEL illuminates
after 2 seconds pump engages, primes and CEL goes out

at this point the time from key ON to pump start is consistent.

Allow car to sit for 30 minutes and time from key ON to pump start goes back to 25 seconds.

I also conducted these tests at different ambient temps. 32F, 45F and 59F with no effect on results.

Thinking next step is to remove battery power and allow ECU to reset. Don't think this will solve anything but it eliminates a reset as a fix.

Really thinking it is an ECU (maybe capcitor charging/discharging somewhere). Would like to find a schematic of the entire ECU internals but haven't come across one.

belairbrian

One other thought, Since I have a 12v bench power supply (supports up to 65 amps) should I apply power directly to fuel pump just long enough to confirm the delay is not in the pump motor?

Thinking I can remove the Main relay and apply power from that connector.

Former User

The ECU is almost surely bad.

I've never seen one.

Former User

A better test is to unplug ECU connector A. With the key in ON(II), does the fuel pump always run immediately and stay running as long as the A7 pin in the ECU connector is grounded?

belairbrian

Well I guess this is pretty much settled. I grounded A7 and pump ran instantly and continuously. Looks like I'll be swapping the ECU. I ordered one to have as a spare anyway so I'll stick it in when it gets here.

Unfortunately a p28 at the local pull a part last about an hour. About the same as an Accord HVAC panel. So getting either there is nearly impossible. There was one they left behind but it was rusted beyond belief.

On the up side I finally had a use for my magnetic meter leads. Worked perfect for grounding.

Former User

I love your electrical savvy and enthusiasm -- not gonna lie.

belairbrian

I fixed aircraft computers for over 20 years. As your sig says troubleshoot.

Too many people use swaptronics to solve problems.

Former User

belairbrian

Just wanted to close this out. The replacement ECU arrived today and as Ron suggested it was the fix.