Hello,
I am new to this forum, so please bear with me if this topic has been covered many times before. I am pretty much inexperienced with the electrical side of the car's functionality, so I would greatly appreciate a simplified explanation, if possible. For instance, when advising me to test a relay or wiring, I need a 'dumbed-down' explanation, as in spell-it-out-for-me. Sorry, I just don't know much about the root causes of electrical problems that keeps a car from starting & running.

I have a 91 CRX (187K miles) that I drive infrequently. It's kept in my garage, and I would drive it around once a month for half an hour, start up the car every two weeks and let the engine run for 20 minutes, and then the rest of the time hook up the battery with a battery charger (in trickle mode) to keep it charged up. I'm wondering if the battery charger is screwing up the electrical function of the car's relays and fuses. I have no idea, really. I have the red clamp hooked up to the + battery post, and the black clamp hooked up to the car's frame. Hopefully this is the correct way to hook up the battery charger. I know there's a main ground connection from the negative (-) cable to the car frame, but not exactly sure where it's located, or whether it's clearly visible. Perhaps someone can point me to exactly where it's located, so I can check if the connection is in good order.

I thought I had a bad main relay that was the cause of my car not starting, but that doesn't appear to be the case. Back in mid-January '24, I had a problem with the car not starting. So I took out the main relay and resoldered all the joints, and the car started up and ran fine. (BTW, I had done this way back around 2012 to get the car to start up, which kept operating normally right up until Jan 2024) I started the car repeatedly each day for a few consecutive days to make sure the car would start, which it did.

​​​Fast forward to mid-February '24, and I was back to having the same issue. So I got a new OEM Honda main relay put in, but the car would no longer start. I noticed that in earlier times, when the car was working properly & normally, I would hear two clicks when turning the key to the ignition position. The first click was followed by another click a second or two later. But now, I am only hearing one click. The second click, which I have learned is the fuel pump being activated. So, would it be safe to say that the fuel pump is not engaging? And if so, for those of you experienced CRX guys, what steps would you take to diagnose the issue I am having?

So far, I have checked all the fuses under the driver's side dash. Also the main fuse box in the engine bay. Fuses all look normal. That's as far as I've gotten. I have not checked the wired connector unit, the section that fits into the main relay unit. It's very difficult to get access to it to inspect it, I have noticed.

I would be grateful for any and all relevant information provided, as simplified as possible. I'm in the class of CRX Repair for Dummies.

​​​​BTW, I reside in the Dallas, TX suburb. If any of you fellow CRX members are in the Dallas area, please send me a DM.

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Black clamp should be on the car battery negative post when charging.

Does the engine crank and not start? Or is the car a "no crank, no start" situation? Also in TX, but a lot closer to Houston.

 

Thanks for your response. I have the CenTech battery charger I got from Harbor Freight. The instruction says to put the red clamp on the battery positive (+) post, and the black clamp on the car body frame (-). It obviously charges the battery when I do this. But you are saying I should place the black clamp on the negative post? Not sure which is the correct way. I am inclined to believe what the CenTech manual tells me, because that's how a proper car jump start connection is done (car to car).

The car cranks, but does not start. Fortunately, I bought a Honda Service Manual years ago, which has been indispensable to owning a CRX. Following the troubleshooting instructions, I have initially diagnosed the issue as a bad fuel pump. There is voltage going to the fuel pump, but absolutely ZERO activity/reaction when the ignition is turned ON. All the fuses check out OK. Main Relay is brand new, so I am uncertain what other relay needs to be checked that prevents the fuel pump from engaging. The engine ground is okay, apparently because it is feeding voltage to the fuel pump. That got me wondering if a bad fuel pump can crap out like a bad light bulb. I always thought a bad fuel pump died out in stages, not cut out like a light bulb. This makes me suspect that the fuel pump might not be the sole culprit.

Anyway, I am trying to make absolute certain that the fuel pump IS the sole culprit (before I have to drop the tank).

There are a few Main Relay harness testing that have not passed, so I am uncertain if the results are correct, or I that I am doing it incorrectly.
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On page 11-110 I followed the steps and determined that voltage is available, which apparently means the fuel pump needs to be replaced.

​​​​​​On page 11-112 I am getting the following results:

Step 3: I am NOT getting continuity. Using the multimeter, I inserted the red probe into the BLK wire (2). Then I placed the black probe on the car body, but getting nothing showing on the multimeter. What am I doing wrong? Is there a setting I need to select in my multimeter to test continuity? Suggestions are welcome.

Step 4: I am able to get battery voltage (12.21 volts)

Step 5-6. I am able to get battery voltage (11.73 volts)

Step 7-8: I am not getting the approximate 10 volts. Only getting 0.02 volts. No. 2 (10A) fuse is good. Don't know what I need to do with the comment "If no voltage... check the wiring between the ignition switch and fuse box and from the fuse box to the main relay."

Step 9-10: No response, no noise from the fuel pump.
NOTE: I was able to establish (on page 11-110) that battery voltage is available going to the fuel pump.

So, the above is my current situation. Would anyone care to take a look at my diagnosis above, and provide analysis?

​​​​​​It's apparent that the fuel pump needs to be replaced, but I want to make [as near] certain that there's nothing else that is at issue other than the fuel pump alone.

Thanks for reading.

 

Put the black clamp on the negative terminal, otherwise you are introducing unnecessary resistance. Think about charging a 12v battery outside of the car - of course the only way to do it is connect the clamp to the post. This might be coming into play on Step 3, might explain why you're not seeing continuity.

If you're giving the fuel pump 12v directly, and it has a good ground then I would say the fuel pump is bad. What I would do in this situation is give the fuel pump direct power and ground via some 10' leads straight off the battery to make sure the fuel pump isn't kicking on.

Continuity setting on the multimeter usually looks like this: https://www.wikihow.com/images/thumb...tep-2.jpg.webp

When placing the probe on a part of the car that is painted, you most likely won't see continuity to ground because paint is a good enough insulator for 12v DC. This is the same reason I would place battery charging clamps onto the battery posts themselves instead of the car's body.

That's concerning, you measured for voltage while the key was in the on and start position, right? You could have something amiss with the ignition circuitry. Since you have the Honda Service Manual lookup the page for ignition circuit testing. There's a chart with continuity checks for the ignition harness. I would suspect the fuel pump (or the ground) since in step 9-10 there was voltage and the pump didn't turn on.

 

Hey Smackin,
1. I set the correct setting on my multimeter to get continuity on Step 3 of page 11-112. There is a body ground (10 mm nut) next to where the main relay connector is, so I used that as the touch point. So that worked.

2. If I give direct power from a 12V battery to the fuel pump, what is your suggestion on how to do this? Do I disconnect the 5P connector from the fuel pump and place the positive feed to the YEL/BLK terminal and the negative feed to the BLK terminal? Or, do I just keep the connector intact (i.e. not detached) and place a connection point from the rear of the connector housing to feed the voltage? What would be your method? And when you say 'good ground' are you referring to the ground wire that is connected to the thermostat housing? (engine ground?). Or is there some other ground connection you are referring to? I inspected the thermostat housing ground, and the connection looks & feels snug and secure (but I obviously can't see the rest of the wire that is embedded & bunched up with the main engine wiring harness), so I can't say that it's 100% certain a good ground. However, I was able to determine that voltage was going to the fuel pump by doing the test shown on page 11-110 Step #4, which should indicate the ground is good. Right? Let me know if you think otherwise.

3. Lastly, I have not done the ignition switch test yet. I need a multimeter that beeps to give me easier confirmation. Let's say for the sake of argument that the ignition switch is bad. Could this be the cause that is preventing the fuel pump from activating/priming? If so, will replacing the ignition switch get the fuel pump to activate again? Or am I dealing with two separate issues that have no direct correlation?

I know it's a lot of questions, but I am relatively inexperienced with cars having electrical issues, so your patience & understanding is much appreciated.
Thanks, E. Lee

 

Yes that's exactly what I would do. Don't feed voltage - back feed as you said - that could damage something.

You've got voltage there, then the pump should kick on for sure.

If your ignition switch was bad, I would not think it would give you 12v at the fuel pump connector. As far as the multi-meter goes, you don't need one that beeps, just measure ohms. Usually 0.04 and below is good. I'm sure you've made some progress on it by now though. Let us know how it went. Sorry for slow response, life gets in the way. Working on the house and a baby on the way are the priorities lol.

 

Can anyone tell me where [on the car] I need to check the ground connection for the fuel pump? I'm about to replace the fuel pump, and I need to have a contingency plan in the event the car won't start after the fuel pump has been replaced and the car still won't start. Thanks.

 

I have a question for anyone who has bench-tested a fuel pump - either an original [failed] unit that was removed from the gas tank, or a new unit prior to installing it into the tank. The purpose would be to verify that the fuel pump is working (i.e. the new pump), or not working (the old failed pump).

What are the procedures and the tools needed to conduct this bench test? My limited knowledge tells me that I need a 12 volt battery as the source of power and a voltage tester/probe to connect the red probe [voltage power] to the red wire connection prong on the connector, and the black probe [ground] to the housing assembly of the fuel pump. I'm not sure which connection from the voltage tester gets connected to the 12 volt battery. This is where I am confused, and need help.

Can someone explain to me, in the simplest way possible, how to perform a test on a fuel pump that has been removed from the tank to determine whether it's working or not? Thanks.

 

Simple way to test the pump - could you just submerge the pump in a jar of gas, attach a small hose to the fuel feed metal pipe into another empty jar and apply voltage straight from the battery to the pump and see if it works?

 

Yes, that is exactly what I did, and was able very that the old fuel pump did not work at all, and the new pump works as expected.

So I'm very glad to know that the bad fuel pump was the issue all along, and dropping the tank was worth the effort.

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