Car dying at speed possible electrical/relay failure

Hi Can someone help with a persistent but intermittent fault.

My 83 Mk1 carb manual Golf is fine around town on short journeys but 30 or 40 miles down the motorway  I notice a power loss and it feels like its misfiring then it cuts out completely.

When you try to restart it, it behaves as though the battery is dead. Ie it cranks slowly but won’t start then after a few turns just goes click as though the battery is dead. But if you leave it a few minutes it starts up again as good as gold. But it’ll only get me a few more miles until it happens again.

Both the battery and alternator are new and have been tested so they are not at fault.

Ive been told that its probably one of the relays. Please can someone tell me which one it could be.

Has anyone else experienced this problem? Any help or advice will be very much appreciated.

I’ve called a few auto electricians but they have said that if the fault is not present while they are doing the diagnostic then they may not be able to find it but will still have to charge me.

Thanks

It might be worth checking the eaths from the battery to the body and engine earths. It's a shot in the dark but if you have a bad earth it could get hot as you use the car which makes the situation worse, causing the car to stop. When you try to start the engine hot there is too much resistance to earth meaning the starter hasn't got a good path back to the battery so it sounds as though the battery is flat. When things cool the resisitance drops again and the car will start.
As I said, it's a shot in the dark but it's where I'd start, it doesn't sound like a relay to me.
Keep us posted.

Just had a dizzy thought 💭 but more years ago then I care to share I had a car that would start perfectly and drive for 10 miles or so, start to lose power then stop.

Dead in the water, the engine would crank over, fuel fine but wouldn't fire again.

Over a few days I learned to leave it about 20 minutes and it would start and drive perfectly and then stop again… so you get the idea
…  🤔

Now Mr. Bill Gates was still sucking on the bootle back then so it took a long time to work out what the hell it was.

It was the dizzy cap!
It had developed a very fine hairline crack which was almost impossible to see with the human eye!

What happened was as it got hot the crack opened and the flash spark would track up the crack.

Put a new one on and hey presto perfect again. 😉

Now I'm certainly not saying it's the same problem but might be worth a shot and it's cheap!

Wouldn't it be great if it was something so simple that you hadn't thought of, personally I love those solutions. 😂

Good luck 👌

Sent from my Smartphone 📱

I've had a similar issue and it turned out to be a rubbish  electric fuel pump.

Is yours a GTI or a Carb model?

Ian

First thing I think of is Carbon Tracking.
Where water gets on the HV leads Cap Coil, Wires and even spark plugs.

When it is dark, or cover your open hood with a dark blanket, have someone start the car and look for sparking fairies dancing about the HV leads Cap, coil, plug bases, if you see them then you have to use sandy type paper and Break the track.  I have seen it cause no start conditions as well as cruddy running.

Hard to crank can be bad grounds, from the Battery to frame and frame to engine.  If yours are still original cables, (but I replaced the ends) the cables are unshielded and can corrode internally under the battery.

You can order a new one piece cable, or you can buy 2 off the shelf cables from your favorite parts place.

I buy the ones off the shelf that have pigtail wires that allow me to do away with the ring connectors on the nutted side of the cable.  Same with the positive cables.

Your Technicians are correct that it is hard to diagnose the intermittent issues, Lord knows that as a electrical computer nerd for years, I had my share of intermittents to deal with, troubleshooting those can be a shotgun of parts till you get the right one.  But the hardest things I ever had to figure out were the "Iffy" ground points.

Check for sparking fairies, replace the ground cables.

When I replace the Ground cables if they are unshielded I spray the entire "Bare" cable with Battery Protector Spray (usually red or Purple). Clean the frame stud with a wire brush, I attach the cables at the stud with 2 large washers on each side so I get maximum connectivity. then spray the whole mount area with the Battery paint to insure that I have limited to no future corrosion.

If you have never heard of differential metal corrosion then you can see it on the Battery posts as Steel Battery ends and lead corrode.  But the same thing can happen to the wires where the copper meets Lead, and or lead meets steel.

Thank you Saulty, Golf Cabrio, Borednow & Briano1234,

Very grateful for all your responses.

My car was originally a JB 1.5, 5sp, Carb, Manual. But I replaced the engine & Gbox from a clipper (convertible) so it is now an EX 1.8 Carb. It is since this change that the problems have started. Is there something with this type of transplant that my mechanic may have overlooked?
I have been back to him but he says that electrics are not his field and recommended the auto electrician.

Saulty, I’ve checked all the earths and they all seem fine with no corrosion.

Golf Cabrio, Ive had a good look at the dizzy as advised and cannot see any cracks - hairline or otherwise. However, as suggested I may replace this and the rotor anyway just in case. The only thing is the acid test is to take it on a long run but if the problem reoccurs Autonational  have said that they may have to charge me for assistance for a known/recurring fault.

Borednow, mine has a carb with a mechanical fuel pump. At one point I thought I had 2 faults, the fuel pump being one; but this was not the case as I changed the fuel pump and fitted a genuine Pierburg as I had had problems with cheaper ones (on a different Golf).

Briano1234, I will check for sparking fairies tonight and get back to you.

Thanks again for all your replies.

I would check what the others have pointed out as they are all possibilities but the thing that stands out for me is that the car acts as though the battery is dead when you try to restart it but after a while it is all ok. That points to a poor electrical connection to me. If you're sure the earths are ok then it would be worth checking the the lives off the battery positive. You have a big black wire going to the starter and then on to the alternator, I would check these conections and clean them up. Also follow the red wire that feeds the rest of the car (I think it goes to the fusebox but I'm  not sure) and make sure it's connections are sound including all connections on the battery itself.
I can't see that it's down to the type of transplant but may be down to something that's but knocked, loosened or not put back right or a faulty component.
Try the things that have been suggested and let us know how you get on, we'll get there in the end!  

Hi again everyone,

I hope you are still monitoring this thread I’ve now checked for sparking fairies and there are non.

Saulty, I have checked all the earths and positives that I can see under the bonnet and they all seem fine, my mechanic cleaned them all when he did the engine swap.

I also think as you suggest in your last post that it could be the positive connection that goes to the fuse box.

Can anyone help me identify this? Is there a guide/link or diagram that someone can direct me to?

Once again your help will be very much appreciated.

the way it slowly looses power and cuts out suggests carb icing to me. make sure the warm air pipe and shroud on the exhaust manifold are there and hooked up to the standard airbox, look at the vacuum hose from the airbox to the rear of the carb, and finally start the engine and visually check the warm air flap actually opens

for the starting issue make sure the alternator is chargign the battery, the battery light shoudl come on with ignition and go off when started. if it doesnt, then look at the blue wire from alternator D+ to the spade plug near the battery.

the fusebox live mentioned is the thickish red wirte on the live terminal that goes into the engien loom, the other end plugs into the back fo the fusebox its one of the 2 large spades back there with red wires. the other one is for the ignition switch.

Hi Rubjonny,

Thanks for your advice and apologies for the late response.

I think I’ve managed to sort the problem.

I ended up having to call an auto electrician and it turns out that it was an earth issue after all.

Although the existing earth cable looked in good condition with good clean solid contacts, the ammeter said otherwise. The electrician tried reconnecting it to different points on the gearbox until he found a better connection. This still was not good enough so he also attached an additional earth cable to somewhere on the lower side of the gearbox. It’s not very tidy and only cost me £72!

He said that I should replace the original earth cable but I’m a bit apprehensive just in case it gives me the same problems as there is no way for me to tell if the new cable/connections will be any better. So I guess I’ll just have to live with it.

I say, I think I’ve managed to sort the problem but I’ve only taken it on one long incident- free run since the fix so only time will tell.

Anyway thanks to everyone who weighed in and I hope this thread will help anyone else with the same probs. As Saulty & Briano1234 said, check all the earths and attach an auxiliary earth before getting fleeced like I did.

Running a new battery to frame, and frame to engine cable isn't that hard you can use 2 off the shelf cables, or get a oem one.  The issue with oem is that it will be a bare cable.  So you would need to clean the frame rail attachment stud 13mm, I would add a large flat washer on both sides, then Spray the whole cable with battery protectorant spray or undercoat to keep it from getting trash inside it.

I had a Oldsmobile that wouldn't start @ 50F and 100 50% humidity or greater, and I rebuilt the Diz, but it was still temperamental.  I got mad and slung my wet fisted hand at it, the spanner that was in the hand flew out, and Shorted out the negative post to ground, and I gor sparks….. Bad ground.    When I replace the battery to frame cable I sliced off the cable sheath, and about 6 inches behind the negative cable end was the prettiest color of Green and white corrosion that I had ever seen….

Years ago I had a Large Mainframe Computer (the size of a small house) that was occasionally acting up, not powering on, shutting off in mid run, and or not running the program deck correctly….. 4 or 5 techs before me swore they had fixed it….

Stupid me went and took a 4 gauge wire, and attached it to a water pipe, and then to the computer…. presto fixed….  Called an Electrician to get a good earth…(he said the one it has was fine and up to code….)  I said it may be up to your code, but it isn't correct to the computer, and I think I will have to bill you for an incorrect installation, and all the parts that have been changed… when he saw me writing up the Bill and saw about 6 zeros, he said I will earth it to your specs…


I had a machine that would power off.
I had all kinds of meters on it and it never burped when it was on the meters…… So I took the time to baby sit the computer, and when it tanked after 3 days, I checked wall voltages and saw 95 Volts a/c….. I started to smell coffee….  Well the coffee machine was causing the voltage drop due to incorrect wiring as they switched the Neutral for the ground at the plug…..

So I have been bit by "seemingly good" grounds a time or two.  One year I made over 20K USD going around the country and fixing ground issues……..

What do Divorces, good coffee, and electrics all have in common…… Good Grounds.  LOL

Thanks for the resolution… sometimes we all need to know the fix.

what I do for the main battery cables is visit the local scrap yard and pinch them from a mk3 golf 1.8-2.0. These are a bit thicker than mk1/2, have really nice battery terminals and are insulated from the factory so last a little better.

Take a live and get 2 earths, plus remove the bolt from the engine the earth is attached to. Cut the battery side off 2nd earth so you are left with a length of cable with a ring terminal either end.

Fit the 2 standard cables, swap the rear box bolt for the one you pinched off the mk3. Take the 2nd chopped down cable and run it from the chassis leg earth point and attach it to the middle ring on the main battery cable you just fitted with a nut and bolt