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| Dead electrics and starting problems | Rating: 
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| Posted: 10-02-2009 05:12 am |
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1st Post |
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jarnol123 Member
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New to the forum. I have a 1975 Jensen Healey that was running then one day as I was driving dow the road it started spluttering as if it was out of gas but it wasn't. Upon inspection I established that gas was getting to the carbs and I installed a new pertronix coil and hooked everything up correctly. I noticed that I was getting only 6 volts to the coil before and during cranking. I ran a wire to the coil directly from the battery to ensure I got 12 volts. Now, I turn on the ignition and there is nothing - the battery is fully charged. I checked the 3 fuses and they look fine. Anyone have any ideas what could be the issue here?
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| Posted: 10-03-2009 06:58 pm |
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2nd Post |
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dwalls1 Member
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Hello and welcome to the forum! I am no expert, so can't be much help, but many here can help and will surely jump in soon. I think, if you are checking voltage after the ballast resister, then you will only be getting six volts. I believe there are two circuits, one that puts twelve volts to the coil by bypassing the ballast resistor during cranking and the other through the ballast resister during running. Hope one of the resident experts here will jump in, as I am probably just compounding your problem. Don't be dicouraged and good luck.
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| Posted: 10-03-2009 09:25 pm |
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3rd Post |
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subwoofer Member
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It could very well be the Prince of Darkness is playing tricks on you. I had a problem in the fuse box, where the fuses were fine, but the circuit was broken. Trouble turned out to be the liberal amounts of grease some DPO had drowned the fuses in, combined with a bit of corrosion. Clean the contact surfaces in the fuse box, e.g. with a small bronze brush, and replace the fuses to make sure there is good contact. The fuse box is of such a hopeless design that only one prong in each clamp is actually conducting! Also (I am not accusing you of anything): Did you hook the battery to coil lead to the right terminal? -- Joachim
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| Posted: 10-04-2009 04:37 am |
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4th Post |
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jarnol123 Member
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Thanks for the reply. I'm going to replace the 3 fuses (using english fuses) and check all connections again. Wil let you know what happens.
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| Posted: 10-04-2009 04:59 am |
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5th Post |
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JodyKerr Member 
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Jarnol123, I would also double check the wiring for the ignition. I found on my JH before I replaced the wiring that it would die on me periodically. The connector between the ignition and the main wiring harness would vibrate itself loose. That in combination with sketchy wiring caused it to fail all the time. I'm in Tempe, so if you ever need an extra set of eyes give me a holler. And if you're ever really bored you can come down and see my piles of parts, err, cars. Jody
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| Posted: 10-19-2009 04:44 am |
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6th Post |
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jarnol123 Member
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Ok, now I have nothing at all. I turn on the ignition and there is nothing. I replaced all 3 fuses with authentic 35amp fuses. Please help?
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| Posted: 10-19-2009 06:17 am |
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7th Post |
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subwoofer Member
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Did you clean the terminals in the fuse box well? Changing the fuses will not help if corroded and dirty terminals is the real problem. I discovered the problem while tracing the voltage with a multimeter. When I was measuring on the terminals, things would work, when I let go they didn't... You really have no other way to go about this problem than to start at the battery and trace your way through the wiring loom. You're likely to find the problem quickly, since nothing works. DPOs may even have installed workarounds for electrical problems, look for wire that looks fresh. In 18711 some DPO had bridged the green and purple circuits at the coil to keep the car running with a flaky fuse box. What I saw was that the tach was sometimes reading, sometimes not - as I found out due to different wires providing power to the coil at different times. -- Joachim
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| Posted: 12-04-2009 05:43 am |
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8th Post |
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jarnol123 Member
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i replaced the 3 fuses with the correct UK 35A fuses. The battery is fully charged and still nothing. I turn the key and there is nothing...no power to anything, eg not even the headlights come on. I've looked at all the wires and checked connections and nothing. Am i missing other fuses here (i though there were only the 3 main fuses) . Is there anything around the drivers side area that I should look at. I can't find any shorts anywhere and i'm just stuck.
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| Posted: 12-04-2009 12:35 pm |
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9th Post |
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Dan (Florida) Member
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Start from the battery, check that inline connector in the cable to the starter. it can corrode. Check the spade connector wire on the starter solenoid, it can come unplugged (but it should still crank). check the ground cables and bonding straps to the engine and body. Is the battery ok, full and reading around 12v? short between the big terminals on the starter solenoid with a screwdriver. it should spark but crank over . if not , the solenoid may be bad but usually not. cast a baleful eye on that British alternator. probably the worst part on the car. Life was easy after I replaced mine with a single wire american Delco unit. ( the red ignition light on the dash shows that the brit alternator is recieving voltage so that it can produce electricity. has noting to do with the ignition system) If you get discouraged, go to healyracing.com and look at the pictures of the racing JHs when they were winning championships. owning a JH is a life long learning experience if you are up to the challenge. good luck Dan
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| Posted: 12-05-2009 04:14 pm |
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10th Post |
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dwalls1 Member
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I had issues with my fuse box. Turned out to be connections behind the gadget that holds the three fuses. A real pain to get at and solder, but I've had no problems since.
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| Posted: 12-05-2009 05:56 pm |
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11th Post |
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subwoofer Member
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First of all have a look at John Kimbrough's simplified schematics, those are a real life saver at times.http://home.comcast.net/~jrkengr2/html/wiring.html It has already been said: Check that ground strap. Since nothing works, it could easily be the problem. This is the time to get yourself a multimeter, a 20$ one will do nicely. You need DC voltage readout and a continuity checker. There is no alternative to starting at the battery and working your way outwards to find out where the open circuit is. My bet is the fuse box - either corroded fuse clamps of a break on the rear. -- Joachim
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| Posted: 12-07-2009 01:26 pm |
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12th Post |
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jarnol123 Member
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Ok, well i got power back and i can now turn the engine over, (there wasn't a good connection at the positive terminal on the battery). One thing i did do was run a wire from the + terminal to the ignition coil (new pertronix) because I wasn't getting 12V there. Still won't start but when i turn the key off the fasten seat belt light stays on (guess that's due to the wire i just ran?) so i have fuel to the carbs, i had compression before all this happened, so it must be spark. as i said i've installed a new ignition coil. i have the old Allison electronic ignition which worked fine before. all the spark plugs seem good. what else could it be?
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| Posted: 12-07-2009 01:59 pm |
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13th Post |
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Brett Gibson JH5 20497 Member
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Well lets see, you have gas, you have power, but do you have spark ???. Turn the engine over by hand and lign up the timing mark on the crank shaft to TDC. make sure the cam marks lign up as well, pull the number #1 spark plug to confirm the piston is at the top, check the distributor to make sure #1 it is seated all the waY IN and #2 that the rotor is aligned with the #1 plug wire. If it does'nt start after that then start checking each plug wire to see if you have spark, if not you might have an issue in the dizzy or coil. Just take your time there are no short cuts to tracing back issues, you really need to confirm the basic's. Brett
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| Posted: 12-08-2009 02:31 am |
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14th Post |
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jarnol123 Member
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ok i'll give it a go at the weekend and report back.
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| Posted: 03-28-2010 04:07 pm |
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15th Post |
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jarnol123 Member
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Well, I think the electrics are ok now. I think it's a fuel problem, ie when I turn the engine over fuel is getting to the dellorto carbs but i don't think it's getting to the engine. I opened up the choke and turned it over. When I pull any of the plugs they're dry as a bone. Maybe there's a blockage in the carb. I remember when the jensen broke down initially it ran fine then started spluttering and died.
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