93EXCivic
93EXCivic MegaDork
7/24/21 8:27 a.m.

Trying to get my sadly neglected 93 Civic going again. It had no spark and I replaced the distributor which seems to have fixed that but now the fuel pump doesn't come on when I turn the key on. Is it likely then fuel pump or a relay? I forget symptoms of the main relay. It isnt the cap on the ECU cause I replaced that not too long ago and it looks in good shape. 

bobzilla
bobzilla MegaDork
7/24/21 8:28 a.m.

Main relay.

LopRacer
LopRacer Dork
7/24/21 12:14 p.m.

I was going to say main relay, to test if you can get to the wires easily, do you have  power to the pump , at the pump? Then likely the relay.

solfly
solfly Dork
7/26/21 4:35 a.m.

Usually main relay but I had one that was a bad ignition switch not grounding the pcm

93EXCivic
93EXCivic MegaDork
7/31/21 7:12 a.m.

Ok replaced main relay. Still no power at pump. Any ideas?

logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
7/31/21 7:36 a.m.

I would check the wiring.  Here are some pages from the factory service manual that should help.  

 

 

 

 

logdog (Forum Supporter)
logdog (Forum Supporter) GRM+ Memberand UberDork
7/31/21 7:40 a.m.

Sorry some of the images are sideways.  I posted them from my phone.

 

I have the ETM as well if you end up needing schematics

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/1/21 4:21 p.m.

Follow the wiring diagram.

Don't just check power and ground at the fuel pump connector, check power vs. battery ground too.  (isolate where the issue is)  The way you are checking it, you are verifying that the pump is not getting both, but don't yet know what is missing.

Type Q
Type Q SuperDork
8/1/21 9:49 p.m.

Doe it crank over? I had a problem in my '93 Si where it would not crank. The problem turned out to be the clutch switch that keeps you from starting with with out the pedal pushed down. There's a little $3 plastic button in the mechanism that dry out and fell off. So when you push the peddle in, it ws not contacting the switch. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/2/21 7:34 a.m.

Backing up, do you have a check engine light when key on/engine off?

eastsideTim
eastsideTim PowerDork
8/2/21 8:42 a.m.

Does the 93 model Civic have that wiring connection under the distributor that is easy to miss, but keeps the car from running, like the old 1st gen Integra?

einy (Forum Supporter)
einy (Forum Supporter) Dork
8/2/21 8:54 a.m.

Go back to the relay, and dig into what is going on there.  Do you have power being output to the fuel pump from the relay?  If yes, then the problem lies in the wiring from there to the fuel pump.  If no, is the power to the command side of the relay present (when the car is in a state where it should be)?  If no, it is a control side issue that you'll need to use the wiring diagram to dig into.  Etc., etc. 

93EXCivic
93EXCivic MegaDork
8/6/21 9:47 a.m.

In reply to Pete. (l33t FS) :

No I don't believe so but I can't remember off the top of the head. I'll check when I mess with it this weekend.

93EXCivic
93EXCivic MegaDork
8/6/21 9:48 a.m.
Type Q said:

Doe it crank over? I had a problem in my '93 Si where it would not crank. The problem turned out to be the clutch switch that keeps you from starting with with out the pedal pushed down. There's a little $3 plastic button in the mechanism that dry out and fell off. So when you push the peddle in, it ws not contacting the switch. 

Yes it cranks no problem.

93EXCivic
93EXCivic MegaDork
8/6/21 9:48 a.m.

I'll dig into it these ideas a little more this weekend.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
8/6/21 12:12 p.m.

If the Check Engine light does not come on when you turn the key on, the computer is not getting powered up.

The usual cause of this is the main relay.  Sometimes you can leave the key on, wait a while, then hear it click. The check engine light comes on with the click...

 

If it sat for a while and stuff isn't getting powered up properly, I'd start chasing powers and grounds with an eye towards critter-related damage.

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