91 Accord LX...

Driving home from work one day my battery light came on. I parked the car for a few hours, drove it again, and no light. Then, a couple days later I was driving to work and the battery light came on again. After 15 minutes of driving, my lights started dimming (it was night time) and the gauges stopped working. After some testing, we figured the alternator was bad so we replaced it. Car was charging fine with the new alternator. The next night I was driving to work and the same thing happened - battery light on then lights dimmed. I checked the voltage and was only getting 9.5 volts everywhere - even at the new alternator. I jumped the car and tried to drive but the voltage drop was too much and the fuel pump wasn't functioning properly.

Now the car won't start. It cranks but won't turn over. Could this be a bad main relay? Was the charging system problem a sign of a main relay crapping out?

Any help is greatly appreciated. If you need any other information, please ask. I want to get this fixed as I plan on selling the car.

Thanks

 

Did the check engine light turn on? I would check for engine codes. See the common diy threads on top of this forum.

The main relay shouldn't cause the battery light to turn on.

I would disconnect the battery and clean all ends of both battery cables. EDIT: I would check the electrical connection to the alternator and the wiring harness to see if something got damaged in the alternator wiring.

You may also want to clean any grounds in the engine bay. I think there is one near or bolted on the thermostat housing that is an important one.

Did you get a re-manufactured alternator? If so, you may have gotten a bad alternator out of the box?

 

Did some testing today...
It seems the main relay is good. Someone who owned the car before must have had an issue with it because it is not mounted in its factory position. At any rate, it clicks when the key turns on.

The fuel pump does not seem to be turning on. I listened when I turned the key on and could not hear anything. I disconnected the line coming in to the fuel rail and there was no pressure. So, whether it's bad wiring or a bad fuel pump, the car is not getting fuel.

We checked for spark using a spark tester and we had spark on all cylinders. The timing belt is intact and is obviously turning since we're geting spark.

So it appears I have a fuel pump problem along with a charging system problem. I checked all the ground wires I could see and all appear to be OK. So to further diagnose the problem with the charging system, I have to figure out why I'm not getting fuel.

I'm lost at this point.

 

You have a few options. There is an electrical connector in the trunk near the back seat of the car. It has 3 pins. The yellow or yellow/black wire should get 12V to ground for ~ 2 seconds when you turn the key to the II position. The black wire grounds nearby and you should clean that ground.

You could also jump the electrical connector of the relay to see if the fuel pump will turn on. You will have to download a shop manual for your car. See the link in the common DIY threads on top of the gen tech help forum to get a 91 shop manual. The 94 manual may be easier to use and the main relay is the same between those generations. The honda-tech link has an active download.

If the electrical connector is getting 12V, then you likely have a problem with the fuel pump.

If no voltage, then the main relay or possibly the ignition switch.

 

I did get a check engine light before the car died. After I drove it to work and found I was only getting 9.5 volts across the charging system, I jump started it the next morning. I got about 1-2 miles from work and hit the gas and the car chugged (like it wasn't getting fuel). At that point the check engine light came on. I assumed it was because the fuel pump didn't have enough voltage to pump properly.

I did try getting the code, but had no luck. I'm going to try it again tomorrow when I really get to dig in to this thing and try to get it running.

As far as the connector in the trunk, we did find it to be getting battery voltage with the key on, although it seemed constant.

I'm almost hoping I had a short somewhere or something that was the cause of all the problems to begin with as that would be an easy fix. I'd like to avoid dropping the tank if at all possible, but it's looking more and more like I'm going to end up doing just that so we can test the actual pump.

Just for fun, I'm going to take out the relay and have my dad (electrical engineer) resolder the circuit board to see if that does anything.

I'm planning to sell the car, but I'd like to get it running first. The bitch of it is, the car ran EXCELLENT until the problem with the charging system.

I just can't help but wonder if it's all related and there's just something I'm missing...

 

You might have to remove the alternator and take it to the parts store and have it tested. I think they should be able to test them when removed from the car. Call before you go. I would also take the battery to see if that is the problem.

 

I was planning to do that with the alternator since I did buy a remanufactured unit. I had the battery tested and was told it was good. It seems to hold a charge real well so I've sort of ruled that out.

Tomorrow I'm going to run a few more tests and do a thorough inspection of all wiring. I also plan to remove the alternator to see if it is bad. Hopefully we come up with something concrete.

I'll keep you posted.