I have been having weird intermittent electrical issues. I got a voltmeter at I am running at 13.7 or so volts w/o A/C and about 13.4 w/ A/C and other electrical things on. Most recently, I will drive, park somewhere for an hour, attempt to restart, and the engine is cranking but it wont start. I take off the negative battery terminal, clean it and put it back, and then the car starts. This battery terminal is pristine. I have also cleaned the terminal at the engine block and on the chassis.

So, I was thinking of running an extra cable from the negative terminal to the chassis. At least perhaps for a diagnosis so then I would just replace the OEM negative cable ($91.95 at FCPGroton). Any harm in doing this? Any other thoughts as to what could be going on?

 

I think it's more trouble than it's worth. If the negative cable can transfer enough electricity to allow the starter motor to crank properly than it's going to transfer enough for the much lower amperage systems like fuel and ignition.

Taking the cable off, cleaning and then starting the motor up worked once or has it worked multiple times when the engine wouldn't start ??

Is the no start the only intermittent electrical issue or are there others ??

First things first. When it doesn't start do you still have spark at the plugs ?? If not do you have it from the coil ??

Have you checked the fuel pressure when it's not starting ?? Can you hear the fuel pump running when you first turn the key when it's supposed to pressurize the fuel system ??

 

Taking the cable off, cleaning and then starting the motor up worked once or has it worked multiple times when the engine wouldn't start ??

This has worked 2 or 3 times now.
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Is the no start the only intermittent electrical issue or are there others ??

The other issue was the car was losing electrical power WHILE driving and would putter out and die. I think I solved this issue by running an extra positive cable from the alternator to the positive battery terminal w/ a 100amp fuse along the way. (hasn't happened again since I added that cable). I have a voltmeter which from the readings I believe is telling me that my alternator is working.
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First things first. When it doesn't start do you still have spark at the plugs ?? If not do you have it from the coil ??

How do I check this? I recently replaced the plugs and wires w/ OE parts.
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Have you checked the fuel pressure when it's not starting ?? Can you hear the fuel pump running when you first turn the key when it's supposed to pressurize the fuel system ??

I have not checked the fuel pressure and I didn't pay attention to the fuel pump. It happens so intermittently and cleaning the cables worked in the past so I just assumed it was that. How do I check the fuel pressure?

Thanks a lot for your response.

 

Sounds to me like your voltage regulator in your alternator is on the way out....... worn brushes etc........

 

 

I recently took out the voltage regulator and looked at the brushes--they seemed to be fine. Plus, I have a voltmeter in the cigarette lighter that consistently shows 13.7 with the car on and 13.4 w/ the car on plus electrical stuff like A/C, etc. Wouldn't that mean that the alternator and voltage regulator are working properly?

Also, reading on the forum some more it sounded like a bad fuel pump or fuel pump relay but I just checked it and it's working at least for now. The problem is intermittent. Could a fuel pump relay fail intermittently? I have an extra in my glove box so the next time the car turns over but won't start I will try to swap out the relay before doing anything else. I am thinking that the problem now is not electrical as kiss4afrog points out that if the:

negative cable can transfer enough electricity to allow the starter motor to crank properly than it's going to transfer enough for the much lower amperage systems like fuel and ignition.

I saw a video on how to check fuel pressure at the rail. I'll have to get all those parts somewhere and try that.

Now I will see if I have spark.

 

I have a voltmeter in the cigarette lighter that consistently shows 13.7 with the car on and 13.4 w/ the car on plus electrical stuff like A/C, etc. Wouldn't that mean that the alternator and voltage regulator are working properly?

No, no, no, no and NO !!
If you take nine "D" batteries and plug your cigarette lighter volt meter into them you will have roughly 13.5 volts. If you put those nine "D" batteries into a flashlight it will be very, very bright and likely blow the bulb.

If you take those nine "D" batteries and put them in place of your battery and hit the key, , , , nothing. Not even enough power to click.
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Now . . . checking the voltage is better than nothing but it's amps that do the work. It's amps from the alternator that charge the battery. If you have thirteen something it's likely the alternator is charging but the question is are you getting 1/3 of it's output, 2/3s or is the alternator working properly and capable of giving up to the 100 or so amps ours are rated at ?? That part you don't know and can't by just looking at voltage.

AC doesn't matter any more than seat heaters or rear window defroster. If you turn on everything you can and on high and you start to see twelve or eleven volts than voltage is telling you that the alternator isn't able to keep up. With everything on you might need to bring the RPM up a bit, like to 2K so the alt has a chance to get closer to that 100amps it's capable of. At 2K RPM the alternator should be able to keep the voltage above 12 volts if it's putting out the proper amps. Voltage can tell you it's bad but it can only guess if it's good.

Don't trust your idiot light. The idiot light will still be out if you're charging at all. Even if you are only putting out 33amps maximum (1/3) the idiot light won't come on as it's seeing a charge.

On to the fuel pump. Yes it can be intermittent and from most threads it usually is. If it just fails it's easy to find but the intermittent ones drive people nuts. Usually it's a hard start warm where they fail until they cool back down.

Call a local auto parts store. I'm not sure on Oreilly but I know Autozone has (had) a fuel pressure tester in their loan a tool program. Sometimes it's in a big kit sometimes it's just the tester.

Local auto parts store can also run a free test of the alternator for you

 

Is there a way to test whether the alternator is working at 100%? I've brought it to Orielly's and tested it 3 or so times (in the car) and it tests out OK.
Thanks for the tip on borrowing a fuel pressure tester as opposed to making one.

 

It would need to be load tested with a carbon pile resistor and then the amperage reading would tell you. In the car or out it's about the only way to absolutely know it's hitting 100 amps like it should. An automotive re-builder would have the equipment to test it off the car.

To replace that resistor turn everything electrical on, on high and watch your voltmeter. If it stays above 12.5 you are good. In our world that and the auto store hand help tester is about as good as you get unless you know someone who has or you are willing to buy an inductive amp meter to actually read the output.

I don't have a problem with saying from "here" that you likely have 99.5% chance of it being a perfectly good alternator and regulator. The auto store testers are testing at the battery cable battery terminals so they are taking into account the condition of the battery cables too.

There is always a chance it's something intermittent with the alternator but it's soooooo unlikely. When you took the terminal off and cleaned it did you charge the battery too ?? If not then the amount of "juice" in the battery didn't change and it's more likely something in the ECM or a relay reset.

I always doubt everything but in your case I don't think it's a battery or cable issue. When they do that test they test the battery first. It's the way the machine is programmed, battery test, starter test and then alternator. If you have had three tests then the battery has been tested and is good, the cables are passing enough current to be OK and the starter likely isn't dragging.

If you have a NAPA, Autozone, Pepboys ... in the area and you have the time you might try one more time with someone elses tester just in case but I'd say three times is good.

If you were going to run an extra wire I'd recommend a wire from the alternator to the battery. I do because I have a dual battery system but in most cars it's a weak link as it's just barely big enough not to fry if the alternator needs to push it's full output. Like after being jumped because I left the lights on.

 

I had the battery/starter/alternator tested 2 more times and they all passed. One thing I remembered living in Arizona was to check the water in the battery wells. They were indeed low but not empty so I refilled w/ distilled water. Could the low level cause my starting issues? I would sure hope it was that simple.

In the cooler morning I tested the volts at the battery and it was about 13.98 running. W/ everything on including the window heater, a/c, brights, interior lights, etc it dropped to 13.7.
Later on when the car was warmed up the numbers were 13.7 and then 12.6 w/ electrical stuff on. Never dropped below 12.5 like you mention above but it sure got close. Does that make sense if the cables are hot? Indication that alternator is ok or not?

Also, the reading from my voltmeter in the cigarette lighter never quite matches that at the battery using a multimeter (typically 0.2 to 1.0 volts lower at the cigarette lighter).

I tried testing the fuel pressure and qualitatively I see fuel spray out when I depress the schrader valve after priming but I could not get the gauge to get any readings. Not sure why or if the gauge or connectors were broken.

I'm hoping the issue was with low water in the battery. Running fine for now.

 

If the batteries level was low enough to cause a problem it would be a problem all the time, sorry.

Staying above 12.5 would indicate the charging system is in good shape and when you crank everything on wires will get a bit warm !!

The reading being a bit different is voltage drop due to the resistance in the wiring. It's totally normal to lose a tenth or two in transmission but doing a voltage drop test is how you do find bad wires or bad connection when the reading is noticeably different.

If it's running fine then you don't have a fuel pressure issue. You may still have a fuel pump relay issue that's intermittent but it's hard to find unless you have a no start and you can test it. You should look up how to jump the relay with a paperclip and have everything ready in case it doesn't start. Put the clip in and it starts, pull the clip and try the relay again and if it's no start you know for sure it's the relay.

 

Any luck with your problem?

I'm having lots of issues myself. Or should I say my car is.

My thread ... 96 850R stutters dies when warm

 

[QUOTE=silvajac;383970]Any luck with your problem?

I'm having lots of issues myself. Or should I say my car is.

My thread ... https://volvoforums.com/forum/volvo-...en-warm-75310/

 

Thanks a lot for all the responses. I tried turning on all the electrical components again and the voltage continuously dropped until about 12.2 and that was 10 mins w/ idling (as opposed to 12.5 as I wrote above). Not sure if that makes a difference in terms of alternator functioning. The car is driving fine for the moment. I have an extra fuel pump relay in my glove box so if the car fails to start on me I'll just swap it out and see if that does the trick.
Thanks again. Great forum.