1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Hope someone can help... I have a 1993 Honda Civic EX, 1.5 L.
It has a 1/2 a tank of gas in it. After driving it and parking when I went back an hour later to start it, it would not start.

It is not getting fuelto the fuel filter and to the engine.

I took out the electric fuel pump. It works fine. Problem is there's no power to the fuel pump.

I checked all fusses are okay.

Is there any other relay that may signal power to be sent to the fuel pump?

Since there is power to the fuel gauge connection at the tank can I splice into that power to power up the pump? Is that a bad idea safety wise ?


Any ideas?

Thanks,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Check fuses 31, 24, and 18. If those are fine, resolder the main relay:

http://techauto.awardspace.com/mainrelay.html


Attachment 460039

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Holly crap Ron J Awesome! Thank you so much taking the time to respond and for all the information.

I think it's the relay, as there's no power to the fuel pump and as I noted I did check all the fuses. I also checked to see if it was getting a spark pulled a plug but didn't see a spark. I didn't ground it first though. So I'll make sure that's okay too. But I think she'll start if she gets fuel. I did try starting fluid to see if it would start she almost did. That's what got me checking the fuel. But since it's fuel injected I didn't know if starting fluid in the air intake would even work.

Again thanks so much for you help. It's my Marine son's girlfriends car and he's just back from Afghanistan and back at base in NC. He called me here in NVA to see if I could help. This cars on it's last legs but I'm helping them keep it going. I just changed the left CVC joint with the tips from this great web site and folks like you. Doing the ball joint is the tricky part but all went well.

Thanks again,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

A bad main relay can cause a no-fuel and no-spark problem because the main relay directs power to the ECU. Resoldering the main relay should do the trick, but if it does not, let us know.

Hats off to your Marine son. I hope he stays safe.

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Thank you RonJ. I guess I was heading in the right direction with what i was checking. I'll check the relay and if need be try to get a new one.

My son turned 21 over there he's an in the infantry and saw combat. He like so many other young men and women are willing and want to do service. He wants to go back. I wish we'd get out of that mess as I don't think the people want us there and you can trust no one.

Thanks again,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Hey Ron,

Well I went and picked up a new Main Relay ( didn't think I could do the fix on the existing one) it's made by Standard the RZ number is different than the RZ-0132 Mitsuba one I took out but all the plugs matched so I bought it and installed it. :( Bummer it still would not start the car still has no fuel or spark.

Do you think there's a difference even though the plugs and numbers on the plugs matched on the new Main Relay?

Is there another relay that might be the problem? Maybe the starter cut relay? (I looked for this one but couldn't see it as noted in the drawing)

All fuses look good the ones in the fuse box under the dash and the ones in the engine compartment. I'm also not sure which fuses are #'s 31, 24 or 18 but I have as I said checked them all visually. Are there any other fuses?

Thanks again,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Too bad. The starter cranks the engine but it won't start, and still the fuel pump does not prime and there's no spark at the plugs, right? If so, here's what to do next:

1) Test the three main relay fuses with a test light. Click the Test Fuses link in my signature. The diagrams below show the location of the fuses. Some blown fuses will be missed by visual inspection.

2) Make sure the G101 ground wire attached to the thermostat housing (see diagram) is clean and tight. This grounds the ECU and distributor.

3) Unplug the MAP sensor connector, turn the key to ON(II), and measure voltage to body ground at terminals for the Yel/Red wire and Wht wire individually in the connector (see diagram). Do you measure 5V?

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Attachment 459994

Attachment 459995
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Attachment 459996

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Attachment 459997

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Hey Ron,

THANK YOU Ron for hanging inthere with me on this. So you don't think there's a problem witht the different Main Relay as I noted?

Yes, the engine turns over.

I'll check this tomorrow on the fuses, are C904, C905 and C906 the 3 main relays I should be checking? Good idea on checking the G101 ground. I think that was messy.

On the voltage check, is 5Volts what's required? What should it be and what if it's not?

Thank you again,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Let's assume at this point that your new main relay is fine.

The first (main relay) fuse (#31) is in the hood fuse box and the other two (main relay) fuses (#24 and #18) are in the dash fuse box. I posted the fuse box diagrams so that you can find them easily.

No. Those are unrelated relays plugged into the hood fuse box. You want to test the three fuses I listed above.

If it is heavily corroded, then take a wire brush or sand paper to it to expose clean metal. There must be good metal-metal contact between it and the thermostat housing.

Yes, those two MAP sensor connector terminals should have 5V with the key in ON(II). (The third terminal is a ground wire). If there's no voltage on either of the two connector terminals, you have a bad wire or bad ECU.

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Thanks Ron. I checked those fuses they are all okay.

I cleaned the ground connection and it's on tight.

The Map sensor check on the White and Yellow/Red had no voltage.

If there's no voltage on either of the two connector terminals, you have a bad wire or bad ECU.

I checked the voltage at the MAP Sensor by hooking the red (Volt meter wire) to the White wire and the Black (volt meter wire) to the car to a good ground. I had no voltage.

When you wrote I may have a bad wire do you know what one it may be?
The ECU is that the Electronic Control Unit? Sorry for the dumb questions.

Thanks, I do feel we are honing in on this problem but without your help, I'd be lost.

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Did you measure battery voltage at both top test tabs of each installed fuse, as described at the link?

This is definitely a problem. The expected 5V at both MAP sensor terminals comes from the ECU (the car's computer). It seems unlikely that both wires would be bad, so we'll first consider the other possibilities:

(1) Bad ECU
(2) ECU is not getting proper power or ground.

In general, you rule everything else out before considering that the ECU is bad. Therefore, you should first focus on (2).

Do the electrical tests in the diagrams below. You don't need the test harness. You just need to backprobe the connectors with your multimeter probes. There's also a mistake in diagram 2. The location of ECU terminal A25 is wrong. I am happy to answer any questions you may have about these tests.

Attachment 459969


Attachment 459970

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

These diagrams and pin outs of the ECU connectors should also help:

http://www.phearable.net/tech/wiring...schematics.gif

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Thanks Ron,
This is starting to get above my head. Not sure I can effectively do the tests.

I'll give it a shot.

Do you think there would be any visable damage to the ECU that I may be able to see?

Thanks,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

None of the tests are much more difficult than testing fuses or the MAP sensor connector with a multimeter. Again, I can help walk you through the tests.

What kind of multimeter do you have. Can you post a picture?

Referring back to my last post, did you test for voltage at both top test tabs of the three fuses (31, 24, 18)?

In most cases, no tests or inspection will identify a bad ECU. If you do see any signs of burning or damaged of components, it may be bad. The ECU is behind the passenger kick panel:

Attachment 459967

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Hey Ron,

Sorry to say, I did not check those 3 with a meter. I did a visual and changed each to be sure. So, no I didn't check it with a light (don't have a light) or my volt meter. I'm sorry I'm somewhat of a dummy on the electrical stuff. That's why I wrote you how I checked the MAP sensor. Pretty sure I did that right. I could not get any solid voltage the meter digetal numbers kept changing and reading less than a volt.

I'll go home at luch and get a picture of my volt meter and try to post it.

Thanks,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

I am pressing you to do the tests because you need to be sure it's not a simple fuse problem or that the fuse does not get power before moving forward with the diagram tests. By the way, fuse 24 is the ACG fuse mentioned in the first step in the diagram.

Not many people are comfortable with electrical testing, so don't worry about it. You may want to repeat the MAP sensor connector voltage tests using the negative battery post as ground. If you read 5V, then you can repeat the same tests using your original ground source. What was this ground source?

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Ron,



My ground source was metal in the engine area.

After I re-check the MAP sensor and the 3 fuses again and I start to try to do the other tests. I'm not sure which sensor or where the EGR valve lift sensor or Throttle Angle sensor is to start things off.

I'm going to run home for lunch and see what kind of meter I have.

Thanks,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Sounds good.

A stock 93 EX should have the D16Z6 engine. Ignore any EGR sensor tests -- your engine does not have this sensor.

The throttle angle sensor (aka TPS) is on the throttle body:

Attachment 459965

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Okay thanks. Here's my meter is a Radio Shack digital readout.

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

^Looks good, but the red wire probe must be plugged into the far left unoccupied (red + symbol) port for the tests you need to do.

When the probes are in their proper slots, turn the dial to the DC V setting for voltage measurements or to the K(omega symbol) setting for resistance (Ohm) or continuity measurements. (Edit: Actually, it looks like the red probe is already in the correct slot for voltage measures, but you do need to move it for the resistance measurements.)

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Ron,

I rechecked the MAP sensor plugs voltage using the battery negative as ground. Here's what I got: On the White wire I had .339 volts and on the Yellow/Red I had .330 volts less than a volt on each.

I used my meter on all fuses including #31 under the hood with the key in the on position and all were good a tad over 12 volts.

On the recheck of underdash fuse #18 I only got 2.4 volts again the key was in the on position. I forgot to try #24. :( This car is a few miles from where I live, I keep making trips out to it to try and solve this problem. So close and yet so far.

I did not try any of the other tests yet.

Thanks,

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Just to verify, you did these tests with the key in ON(II), right? If so, this confirms the problem and tells you that the low voltage does not result from a bad ground.

Fuse 18 should only read battery voltage in ON(III), but there's no need to redo the test. Next time you go out there, test fuse 24.

Assuming fuse 24 (ACG) is fine, then next do the tests in the diagrams. If you have any questions, just post them. In ECU connector A, pin A25 is directly above pin A26, despite the error in the diagram.

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Yes, I had the key in the on (II) position when testing. Not sure what problem it confirms, do you mean it's more likely looking like the ECU?

I'll re-check fuse #24 and start the other checks next trip out.

Thanks

Pete

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

It confirms that the ECU is not supplying the expected 5 reference volts to the MAP sensor and also shows that this problem is not due to a bad engine ground. The tests in the two diagrams should tell you why the ECU is not supplying voltage to the MAP sensor. This could be due to a bad ECU or a bad power or ground wire for the ECU. You need to do the tests to pinpoint the specific problem.

Re: 1993 Honda Civic EX 1.5 L, electrical /fuel pump issue
 

Crap I forgot to recheck fuse #24 I'll do that after work today.

I did check the first two steps the MAP & Throttle sensors the engine light did not go off. So next after I check fuse #24 I'll start the other resistance tests.

Pete