Alternator/Earth/Running bad Problem
Discussion
Hi All,
I fear I am at the command of a couple of different faults.
I have always had the sometimes the fuel pump will prime, sometimes it won't issue. I have never managed to diagnose the issue as it is so intermittent. E.g. last night it would not prime this morning it would (after being on optimate). It is generally better when the car is used so perhaps the battery topped up to the max is the cure????
The car broke down on me with no warning lights. The running got worse and worse and window winder got weaker. On getting home on a low loader it was apparent that there was less than 12 v on the battery when running so appeared to be charging related.
Therefore, I believe the major problem I have is charging related. The charging system failed and the red charging dash light did not light up when the ignition was turned. I had volts at the brown wire so diagnosed a failed alternator.
I go a recon alternator which seemed to work at first (charging and dash charging light off) then became intermittent (the dash light went off if I reved it to 4000rpm) then failed altogether, through this time it would not rev over 4000rpm. I took it back and got my apparently fixed alternator back.
Having connected up the repaired original I get the the red dash charging light on (and it does not go off when the car is running), however, the car was difficult to start and seems to be running with a significant tappety noise.
I also changed the coil through this period and this made no difference.
I can only think the following:
I have disturbed the leads, or distributor while removing and refitting alternator. I have checked this an cannot see anything obvious.
I have fitted the coil wires in the wrong place (not sure how much difference this would make, the car now runs and I think I got this right...)
I have randomly got two or more faults at the same time and have knackered the cam/valves. I guess a compression test would show up any faults.
I have an ECU problem that is causing the intermittent fuel priming and the bad running problems.
I have an earthing problem somewhere which seems strange since the starter causes no problems.
I will have a goo play with it tomorrow and will post again. I would be enternally grateful for any words of wisdom....
Cheers,
Matt
I fear I am at the command of a couple of different faults.
I have always had the sometimes the fuel pump will prime, sometimes it won't issue. I have never managed to diagnose the issue as it is so intermittent. E.g. last night it would not prime this morning it would (after being on optimate). It is generally better when the car is used so perhaps the battery topped up to the max is the cure????
The car broke down on me with no warning lights. The running got worse and worse and window winder got weaker. On getting home on a low loader it was apparent that there was less than 12 v on the battery when running so appeared to be charging related.
Therefore, I believe the major problem I have is charging related. The charging system failed and the red charging dash light did not light up when the ignition was turned. I had volts at the brown wire so diagnosed a failed alternator.
I go a recon alternator which seemed to work at first (charging and dash charging light off) then became intermittent (the dash light went off if I reved it to 4000rpm) then failed altogether, through this time it would not rev over 4000rpm. I took it back and got my apparently fixed alternator back.
Having connected up the repaired original I get the the red dash charging light on (and it does not go off when the car is running), however, the car was difficult to start and seems to be running with a significant tappety noise.
I also changed the coil through this period and this made no difference.
I can only think the following:
I have disturbed the leads, or distributor while removing and refitting alternator. I have checked this an cannot see anything obvious.
I have fitted the coil wires in the wrong place (not sure how much difference this would make, the car now runs and I think I got this right...)
I have randomly got two or more faults at the same time and have knackered the cam/valves. I guess a compression test would show up any faults.
I have an ECU problem that is causing the intermittent fuel priming and the bad running problems.
I have an earthing problem somewhere which seems strange since the starter causes no problems.
I will have a goo play with it tomorrow and will post again. I would be enternally grateful for any words of wisdom....
Cheers,
Matt
There is a Great Big Fuse between the alternator and the battery, which tends to break down and produce an intermittent failure which gradually gets worse and worse. Mail symptoms are that the battery doesn't charge properly although all the components test OK on their own. Suggest you see whether yours has the fuse, and if so inspect it to see whether it's intact.
Thanks for the prompt response. I have been through a load of old posts and as a result I checked the 100 AMP fuse as the first point of call and all looks OK.....
As I understand it the starter is run through the 100AMP fuse and I have never had a problem with turning the engine over so have sort of ruled this out. Thinking back the issues started after a load of speedbumps so it is possible that something has come adrift. I will take another look tomorrow.
I am sure I had a problem with the alternator as no matter what I did after the initial bad running problems and no charge, the dash charging light would not illuminate (ignition turned to the point before turnover) unless I shorted the brown alternator wire to Earth.
With both recon alternators the charging light came on and I have had different results with each one (in fairness I have not really checked out the second recon as I have just had it ticking over badly with the dash light still lit up. I was told that the first recon alt checked out OK on the test machine....
I will give it a good going over tomorrow and will post again. The decorating can wait for another few days....
Cheers,
Matt
As I understand it the starter is run through the 100AMP fuse and I have never had a problem with turning the engine over so have sort of ruled this out. Thinking back the issues started after a load of speedbumps so it is possible that something has come adrift. I will take another look tomorrow.
I am sure I had a problem with the alternator as no matter what I did after the initial bad running problems and no charge, the dash charging light would not illuminate (ignition turned to the point before turnover) unless I shorted the brown alternator wire to Earth.
With both recon alternators the charging light came on and I have had different results with each one (in fairness I have not really checked out the second recon as I have just had it ticking over badly with the dash light still lit up. I was told that the first recon alt checked out OK on the test machine....
I will give it a good going over tomorrow and will post again. The decorating can wait for another few days....
Cheers,
Matt
Just to be clear, the 100amp fuse is between the alternator and battery, it has nothing to do with the starter motor. I would suggest you try and fix one thing at once and don't get sidetracked by a clattery engine etc. Low battery would cause fuel pump not to prime, poor coil performance leading to poor HT circuits etc.
All of this could be caused by poor charging and as much as I enjoy taking the p1$$ out of every problem being blamed on the 100 amp fuse (or stepper motor), the 100 amp fuse sounds like a good chance of being the culprit so I would strip the connections down and have a really good look at those and the fuse itself - these have been known have intermittent connections
With access to the battery, run the engine and put your multimeter (set to 20V DC) across the two terminals (carefully!) and you should see 14V or slightly more. If you don't then there is no charge. You can also repeat this at the back of the alternator (again, carefully) between earth and alternator output. If this all looks OK then the problem is elsewhere.
It is also possible your battery is knackered and needs to be replaced, taking a charge is one thing, holding it for any period is another.
Just be logical and try one tack at a time until you've exhausted it, then try the next logical thing. When you have run out of logical things, swear, shout, hurl abuse at it
and stomp off - sleep on it and start again next day..........
All of this could be caused by poor charging and as much as I enjoy taking the p1$$ out of every problem being blamed on the 100 amp fuse (or stepper motor), the 100 amp fuse sounds like a good chance of being the culprit so I would strip the connections down and have a really good look at those and the fuse itself - these have been known have intermittent connections
With access to the battery, run the engine and put your multimeter (set to 20V DC) across the two terminals (carefully!) and you should see 14V or slightly more. If you don't then there is no charge. You can also repeat this at the back of the alternator (again, carefully) between earth and alternator output. If this all looks OK then the problem is elsewhere.
It is also possible your battery is knackered and needs to be replaced, taking a charge is one thing, holding it for any period is another.
Just be logical and try one tack at a time until you've exhausted it, then try the next logical thing. When you have run out of logical things, swear, shout, hurl abuse at it
and stomp off - sleep on it and start again next day..........Right, just got under car and indeed the 100AMP fuse has gone.
So Orginal Alt seemed knackered, no charging light on dash before engine turned over. No charge measured at battery. Charging light came on if shorted to Earth.
100Amp fuse checked at this point and looked OK. A TVR owner friend of mine also had a look and came to the same conclusion.
1st recon alt fitted. Charging light came on and went off as it is supposed to do. 14V measured at the battery no problem.
Turned off and re-started charing light still illuminated. rev to 4000 rpm and the light goes out. No charge at battery.
2nd recon alt fitted. 1st try charging light stay on. after a short drive charging light goes off as it is supposed to do on every re-start.
14v measured at Alt. 11.5 (car running) measured at battery.
Fuse checked again and is broken.
Before anyone asks I have not shorted the Alt cable to the chassis at any time.
I am a little confused but HOPE that replacing the fuse will fix this little problem. I guess it is possible that the fuse despite being blown was touching enough to get the 14v charging when tested with the first recon alt?? I still struggle to explain the results of all my tests though.
The fuel pump priming issue has been around on and off for the past 3 years so I don't have it down as related to this.
Thank you for your help. I will post again when I get the replacement fuse...
So Orginal Alt seemed knackered, no charging light on dash before engine turned over. No charge measured at battery. Charging light came on if shorted to Earth.
100Amp fuse checked at this point and looked OK. A TVR owner friend of mine also had a look and came to the same conclusion.
1st recon alt fitted. Charging light came on and went off as it is supposed to do. 14V measured at the battery no problem.
Turned off and re-started charing light still illuminated. rev to 4000 rpm and the light goes out. No charge at battery.
2nd recon alt fitted. 1st try charging light stay on. after a short drive charging light goes off as it is supposed to do on every re-start.
14v measured at Alt. 11.5 (car running) measured at battery.
Fuse checked again and is broken.
Before anyone asks I have not shorted the Alt cable to the chassis at any time.
I am a little confused but HOPE that replacing the fuse will fix this little problem. I guess it is possible that the fuse despite being blown was touching enough to get the 14v charging when tested with the first recon alt?? I still struggle to explain the results of all my tests though.
The fuel pump priming issue has been around on and off for the past 3 years so I don't have it down as related to this.
Thank you for your help. I will post again when I get the replacement fuse...
If you need to rev the engine up to 4000 RPM for the warning light to go out, there's a problem in the exciter circuit. To magnetise (excite) the field coils in the alternator a voltage is supplied via the warning lamp. Above around 3000 RPM the alternator will self excite.
I recently had a problem where the battery lost charge while driving, with no warning light. I immediately suspected the 100A fuse but it was in perfect condition when I inspected it. However I noticed one of the terminals was loose. Tightening it solved the problem, so it's worth checking the connections as well as the fuse itself.
I recently had a problem where the battery lost charge while driving, with no warning light. I immediately suspected the 100A fuse but it was in perfect condition when I inspected it. However I noticed one of the terminals was loose. Tightening it solved the problem, so it's worth checking the connections as well as the fuse itself.
That is interesting.
Assuming I don't have any as yet unknown connector problems/mistakes I believe that:
The original Alt was knackered as it was not charging, no charging light with ignition on before turnover (100 amp fuse checked OK at this point). Exciter wire had volts
The second Alt had an intermittent problem with the exciter and your explanation of self exciting would back this up.
As far as I can tell so far the car exciter circuit is working (i.e. if I short it to Earth the light comes on and it has always show a voltage when checked.
With the second recon Alt if I start the car the light goes out as it should and I have 14v at the alt terminal. The two puzzling things are
1) The first time I started the car with the 2nd recon Alt the charging light did not go out.
2) When exactly did the fuse go. It is possible that I made a mistake when I first checked this....
Anyway, the fuse has definitely had it and I am waiting for delivery of a new one. Will post again after the weekend.
Cheers,
Matt
Assuming I don't have any as yet unknown connector problems/mistakes I believe that:
The original Alt was knackered as it was not charging, no charging light with ignition on before turnover (100 amp fuse checked OK at this point). Exciter wire had volts
The second Alt had an intermittent problem with the exciter and your explanation of self exciting would back this up.
As far as I can tell so far the car exciter circuit is working (i.e. if I short it to Earth the light comes on and it has always show a voltage when checked.
With the second recon Alt if I start the car the light goes out as it should and I have 14v at the alt terminal. The two puzzling things are
1) The first time I started the car with the 2nd recon Alt the charging light did not go out.
2) When exactly did the fuse go. It is possible that I made a mistake when I first checked this....
Anyway, the fuse has definitely had it and I am waiting for delivery of a new one. Will post again after the weekend.
Cheers,
Matt
Thanks you for all your help.
Well 100AMP fuse changed. My Chim owning mate who also checked the original fuse is also convinced it was fine so hopefully I did not waste the 120 notes on the recon alt.
Alternator charging.
Car running OK at tickover.
All seems well but I have not checked it on the move because while it was up on stands I have prepared and POR-15'd my outriggers which are now drying.
I think I have also identified the annoying starting issue as well. It seems to be the relay under the dash with the additional Earth wire.
So fingers crossed when I take it out tomorrow I will be back to owning a TVR car rather than a TVR statue..... I will post again if I have any follow up problems. Here's hoping I won't have to......
Well 100AMP fuse changed. My Chim owning mate who also checked the original fuse is also convinced it was fine so hopefully I did not waste the 120 notes on the recon alt.
Alternator charging.
Car running OK at tickover.
All seems well but I have not checked it on the move because while it was up on stands I have prepared and POR-15'd my outriggers which are now drying.
I think I have also identified the annoying starting issue as well. It seems to be the relay under the dash with the additional Earth wire.
So fingers crossed when I take it out tomorrow I will be back to owning a TVR car rather than a TVR statue..... I will post again if I have any follow up problems. Here's hoping I won't have to......
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