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

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

Hey Ron,

I was able to get back to the Honda on Sunday. I pulled out the ECU and opened it up to see if there was any visable damage.

Man it looked like it flamed a little there was a burn mark on the cover and a hole melted in the unit. I should have taken a picture to show you.

It requires a 37820P28A51 ECU (Verified by the number on the existing one)so we're going order it.

Any good sources you could recommend?

Thanks again for all your help.

Pete

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

One concern is that a short in a ECU wire or sensor destroyed the ECU. If so, this potential short could also destroy your replacement ECU. Post several clear front/back pictures of your bad ECU. If you are lucky, someone may be able to look at the burned areas and tell you specific ECU wires to test for a short.

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

Ron,
Thanks. Here's the pictures I took. It's that brownish round capacitor that fried.

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

Wow. That's the worst ECU blow out that I've seen.

Bump for anyone who may be able to identify a possible source for this ECU failure.

Pete, you may want to PM member 94EG8. He may be able to give you some input.

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

This is a rare and interesting, thanks for the images, Pete. This looks like a ground fault, or a ground short, not actually a problem with the ECU, I believe. Some wire, somewhere in the car had decided to grab a hold of 12V and then rush the 12V+ of pure power, with no fuse protection, into what we call the ECU ground. Another words, if you put the wrong polarity to the ECU something's going to fry.

The solution to this problem is first check the harness while the harness is still connected to the ECU (check pin B1 yellow/black) and make sure it's ground, If not, cut that wire and then run a separate ground wire there - eventually going into into the ECU. Second, check the harness one at a time (pins A23, A24, A25 this is all based on the link http://www.phearable.net/tech/wiring...schematics.gif Ron J posted) and make sure it is ground, If not, cut those wires and run another ground wire there. This is because the ECU typically has many grounds. Do that before you plug in your new ECU, otherwise you'll fry your new ECU. Also, it would be wise to check all the inputs pins into the ECU and make sure it isn't 12V+ where it isn't suppose to be, or ground where it isn't suppose to. If you are unfamiliar with this, alternatively, you might want to try tear the car apart and find that short and yank it out. This will leave no possibility that the short could do more damage.

Secondly, the ECU looks like it's salvageable because none of the other components are affected, except for the traces. The giant diode (the fat black grenade looking thingy) had protected the ECU. In some other cars, other than Honda, you could be facing all sorts of damage and expenses. This is one reason I stay with Honda or Toyota.

That's all the advice I give at this point, they may or may not be accurate because I'm not there to probe around. Other than that, if you really want to help you could report back what voltages you did find on pins B1, A23, A24, A25 to ground, as mentioned above. They should be zero Volts. If they are not zero Volts, use your handy skills to turn them zero Volts. Probing these pins is part of the process of hooking up a new ECU and will also help others solve the puzzle.

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

Thanks Ron and HondaWrench,

I will try to check all this out and will do so before I plug in the new ECU.

I did notice that a battery sized cable that grounds the engine to the frame looked like it was some what burned almost as if it was smoked also had sort of a green build up on it. I took it off and cleaned it up but the wires just don't look good. Not sure if that was and issue.

I have a meter as I wrote Ron but I'm still not sure on how to check these ground issues or from the pins on the plugs If you or Ron can show me a picture then I can get it (Sorry for being so stupid on this guys) and I do really want to again thank everyone for helping out.

Pete

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

Usually, people would complain that acid spills (which eventually leads to shorts) will fry all kinds of components on the car. After the cleaning, you may have eliminated the shorts, which is great, but might be confusing when your probe results say that there are no shorts.

You might want to put the red probe of the multimeter and put it in the cigarette lighter socket, (see image) the center part that's deep inside that hole. Turn on the ignition so you have power to the lighter. Second put the black probe to a metal ground part of the car, a bolt or something, or the metal outside ring on the cigarette lighter. It should read about 12V. Make sure the harness is connected to the ECU. Next, while keeping the red probe steady and firm on the cigarette lighter socket, put the black probe on the metal strip (pins) part I've pointed on with the arrows (for example B1, etc.) These are the ECU ground. Looks like there are lots of them I've missed earlier. It should read about 12V. If not then you've found the problem.

Next, while continuing to keep the red probe steady and firm on the cigarette lighter socket, probe B2. It should read 12V. Lift up the black probe and then put it on A25. Write down the voltage down. This will be useful for others who understand what the voltages mean. Keep on probing all the other pins (A26, A24, A23) that I've pointed on with the arrow until all of them are probed. What you are looking for is one that did not read 12V. If it doesn't read about 12V then the wiring that leads to that pin is damage. To fix it, you might need to cut that wire and bolt it to the frame of the car or where it normally bolts to.

A word of caution: When probing the metal pins, don't allow the probe to touch other pins next to it. Just touch the pins you want. Hold your breath, to keep your hands from shaking. A slip up could mean a frying death to other components.

http://i38.tinypic.com/jhaqf7.jpg

All the pins I mention here are ground, are reference to the diagram Ron Posted. It's only accurate as the diagram. So, please double check my work.

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

Thanks HondaWrench,

Great pic's that really helps me. Love how you drew the meter wires in too. Is it possible to check these same plugs without the ECU? It may have already been sent off to IL for repair.

Thanks,

Pete

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

Yes, that's fine. From the visual appearance of the burnt board it looks like the only short is the yellow/black wire (pin B1.) I wanted you plug it into the ECU because that tells a lot more. But that isn't necessary.

For your reference there may be 13 ground pins altogether, you might want to check them all, if you get the chance. Here are the pins.

A23 power ground
A24 power ground
A25 power ground
A26 sensor ground

B1 power ground
B2 sensor ground
B12 sensor ground
B13 sensor ground
B14 sensor ground
B15 sensor ground
B16 sensor ground

D21 sensor ground
D22 sensor ground

Beware that when the ECU is disconnected, some pins (such as the sensor ground) may no longer be ground. That is when an ammeter comes in to play. Your meter can measure amps but they're kinda too low for this.

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

Well, I checked all like RonJ@HT and HondaWrench suggested and ordered the ECU from a source suggested here on this site by another guy.

When I was checking ground as Ron and HondaWrench wrote don't cross touch any other pins or other crap could short:o

So I put the new ECU in and had my fingers crossed as I turned the key to start. Nothing! man I was bummed... I'd worked on this thing for so long and I felt defeated...:cry:

Then I remembered what you guy wrote and thought I should check the fuses again since I had that slight spark when checking the pins...
Sure enough, the ECU 15 Amp fuse had blown! I changed it said a prayer and turned the starter key and BAMB! It started on the first turn of the key:thumbup:

I owe it all to you guys... Thank you Ron for guiding me through this and thank you HondaWrench for helping me with this as well you and others who also offered suggestions were great. It sort of restores my faith in humanity that so many folks were willing to take the time and help. Thank you all.

Pete

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

Well, here I am again. It's only been a few weeks of ok running with the new ECU.

The car just stoped running. ECU still looks good, it's getting fuel but NO Spark....:cry: Not sure what to check now all fuses are ok.

Any ideas where to start:scared:

Thank you,

Pete

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

Any CEL codes?

Remove the distributor cap and the 15A hood fuse 31 (ECU/PGMFI). Have a buddy crank the engine while you check whether the rotor turns. If so, the timing belt did not snap.

Now also remove the rotor and inner cover. Check whether there is battery voltage on the Blk/Yel wire attached to the igniter unit. If so, remove the coil and resistance test it and take the igniter unit for testing at an auto parts store.

Attachment 458978

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

Thanks Ron.

No CEL codes that I noticed after I turn the key on the CEL goes out.

One thing I didn't wriet is that a 15 amp fuse to I think the lights was blown,
I replaced it but that didn't help. All others are good.

Also the car had overheated some that my sons girlfriend stopped let it cool down and then put antifreez in it then it ran okay until it just stopped.

The rotor is turning as I took the cap off to clean inside and had to crank it to align the screw that holds the rotor. The 15Amp ECU hood fuse is okay too.

I'll check those wires for voltage. Are the coil and igniter separate parts that just come out?

Thanks Ron,

Pete

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

Does your distributor have an inner cover?

Yes, they are separate and just come out:

Attachment 458977

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

Got it thank Ron.

Pete