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1974 Jensen Healey Crank but No Start  Rate Topic 
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 Posted: 01-01-2018 07:39 pm
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Dave427
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Hi All,

Long time classic car guy (admittedly Corvettes and Musclecars) but new to the site and new to Jensens.

Helping a family member get his 74 Jensen Healey back on the road. It's been sitting for the better part of 25 years. All in all not in terrible condition though.

New battery installed, fluids checks/ topped off, marvel mystery oil added to the motor. Go to start the car and it will crank once and then nothing. Won't start. Try to turn the key a second time and again only one crank.

The car had an Ungo security system which we removed as my family member did not remember the code. There are a bunch of spliced wires under the dash / loose wires in the engine compartment. (see below pictures of the wires around the coil and a gray wire under the dash). Any idea where they go?

Being that the car will crank once I'm not sure it's a wiring issue however I would like to get the wires connected where they should be. What else could this issue be? I was thinking the starter but if that was the case I don't think it would crank at all. If fuel pump than it would in theory crank but never start. This is the first time working on JH so would love to learn the tricks of the trade.

Thanks,
Dave

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 Posted: 01-01-2018 07:41 pm
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Dave427
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I can't get the pictures posted. Any help would be appreciated.

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 Posted: 01-02-2018 12:28 am
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Esprit2
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Dave,

I have no idea what to say about the old alarm system, or any loose wires that may have resulted from removing it. Ignoring that may be over-looking the problem, but that's all I can do for now.

Have you stripped down and cleaned the carbs? That has nothing to do with getting the starter to turn-over more than a turn; however, I can just about guarantee that the carbs are gunked-up by 25 years of sitting around, whether Z-S or Dellorto. And if they're Z-S, I'd also be concerned about the condition of the rubber diaphragm that runs the whole show.

Without addressing the carbs first, I suspect that even when you get the starter to crank continuously, the engine won't start for lack of a combustible mixture.

Since the starter repeatedly cranks a turn, then quits, it may be that there's a bad spot on the commutator, or in one of the armature windings. The motor may require a rebuild, but before you go that far, try jumping the starter solenoid directly. Doing so will eliminate the rest of the car's electrical system and all the dangling wires. With direct power, the starter motor will run or it won't.

Start by removing the battery cables by disconnecting both ends and physically removing the cables. Clean the battery terminals. Use heavy gauge jumper cables to re-connect the battery.

Use the black cable to connect the battery's (-) terminal directly to the engine block... not to the chassis ground. If you can (try hard), clamp onto the block's rear flange where the starter bolts on, such that one jaw of the clamp actually bites down on the starter motor's rear flange.

Use the red cable to connect the battery's (+) terminal directly to the threaded brass terminal on the solenoid (where the red battery cable was formerly connected).

Make certain the transmission is in neutral. Then use an old screw driver you don't care about to bridge between the red battery cable on the solenoid, to the solenoid's small, 1/4" spade terminal where the white/ red stripe wire previously went. There may be an arc when the screw driver makes contact with the terminal. Don't freak out... and that's why you're using an old screw driver you don't care about.

If the starter is ever going to run... it should run now. If it doesn't...

1) The solenoid could be bad. But since the starter has been running one turn at a time, I'm thinking the solenoid isn't the problem.

2) The ground connection between the starter motor housing and the engine block could be corroded and not making electrical contact... ie, where the joint/ connection where the starter bolts to the engine block. I've "fixed" several starters that wouldn't run simply be cleaning that joint. Remove the starter. Clean the rear flange with a wire brush. Similarly, clean the mating flange on the engine block. Apply a light smear of copper Anti-Sieze to both mating faces, and bolt them back together.

Number 2) is why I recommended that you attach the negative jumper cable to the engine's rear flange such that the jaw also bites directly on the starter's mounting flange. Presuming the connection between the starter and the block is corroded, try to attach directly to the starter motor housing or a mounting bolt.

Do all of that...

3) If the starter still doesn't run, then remove the starter and take it in to an automotive electric repair shop. Worst case (??), replace it with a new one. If you go that route, then I strongly recommend one of the aftermarket Gustafson geared starters that are available from Delta Motorsports, JAE, or Dave Bean Engineering.

4) If the starter runs when directly jumpered, and when the solenoid is directly shunted to 12 volts, then you've confirmed it's not a starter problem. Then, if you remove the jumper cables and re-install all the original wiring, and the starter reverts to not working, then you can be pretty confident that there's a problem in the wiring harness. Good luck with that... I hate electrons... or, at least working with them.

One easy thing to check is the chassis ground. The black cable from the battery's (-) terminal goes to the chassis ground point. Then a braided cable jumps around one of the rubber engine mount (usually the right), and connects to the engine-side of the mount. If that braided cable is missing, broken or has a poor connection, then the engine is isolated by it's rubber mounts, and not grounded. That would affect all engine electrics, including the starter.

I like to buy a heavy gauge black cable with eyelet terminals on each end. Not one of those little pencil-thin cables, but a real, manly cable (ALL battery cables in the car should be 'manly'). Then run it from the chassis ground (where the black battery cable connects) to one of the starter mounting bolts. That will ground both the engine and the starter, and give the most direct ground possible to the starter motor.

Regards,
Tim Engel

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 Posted: 01-02-2018 12:39 am
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Esprit2
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Dave,

How large is the photo file? The forum won't allow attachments larger than 102400 bytes (102.4 kb).

Don't use the 'Quick Reply' option at the bottom of the page. Instead, click on 'Reply' in the top or bottom border of a preceding message. When the 'Post Reply' dialog box opens, look for "Attachment:" below and to the left of the text box. To the right of that, you'll find a gray 'button' with "Choose File" written on it. Click on that button and select the photo of your choice from your computer's "My Documents" folders.

If you're working from your "Smart Device"... good luck with that, I'm not "Smart" enabled.

Regards,
Tim Engel

Last edited on 01-02-2018 12:40 am by Esprit2

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 Posted: 01-02-2018 01:43 am
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Dave427
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Hi Tim,

Thank you very much for the info. I was thinking about testing the starter next but still interested to know what the guru's think about the electrical topic.

The carbs have not been touched. I will have a look at them the next time I am over at the car. I will also test the starter and begin to diagnose / rule out.

Best,
Dave

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 Posted: 01-02-2018 02:48 am
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Art DeKneef
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Dave,

Send me your email address and I will send you a wiring diagram done by one of the members that should help in figuring out the electricals.

Art

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 Posted: 01-04-2018 06:05 am
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Esprit2
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Dave427 wrote:
The carbs have not been touched. I will have a look at them the next time I am over at the car. I will also test the starter and begin to diagnose / rule out.Dave,
The carbs won't be an issue until after the starter is cranking consistently. But given their age and length of storage, it's almost a certainty they'll need work.

Regards,
Tim Engel

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 Posted: 01-04-2018 05:34 pm
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redracer
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Tim's reply should get the trouble narrowed, but please keep a fire extinguisher VERY handy since the carbs will almost certainly leak. (the rear carb. sits right over the solenoid--instant fire)

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 Posted: 01-04-2018 05:36 pm
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Dave427
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Thanks. That's always next to the car when starting a long term sitting project.

Best,
Dave

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 Posted: 01-04-2018 08:12 pm
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answerman
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I'm a little late to the party, and I don't know if this has been addressed or if it could be related, but...

First thing I caught was that it's a 1974 (just like mine). That was the one year that all cars sold in the USA required a seat belt interlock (you couldn't start the car without fastening your seat belt). Most of the JHs out there have had this bypassed, but it's possible that either (a) yours still has it or (b) it was bypassed which explains the extra wires and it's not done right.

Try buckling the seat belt and see if that makes a difference. I don't remember exactly what the interlock disabled in the starting circuit, but it's just a thought.

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 Posted: 01-04-2018 08:23 pm
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Dave427
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answerman wrote:
I'm a little late to the party, and I don't know if this has been addressed or if it could be related, but...

First thing I caught was that it's a 1974 (just like mine). That was the one year that all cars sold in the USA required a seat belt interlock (you couldn't start the car without fastening your seat belt). Most of the JHs out there have had this bypassed, but it's possible that either (a) yours still has it or (b) it was bypassed which explains the extra wires and it's not done right.

Try buckling the seat belt and see if that makes a difference. I don't remember exactly what the interlock disabled in the starting circuit, but it's just a thought.


That's really interesting! And makes so much sense as to why the car isn't starting. I will have to investigate this weekend and head back over to where the car is.

Thank you!
Dave

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 Posted: 01-05-2018 01:59 pm
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redracer
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Tim's reply should get the trouble narrowed, but please keep a fire extinguisher VERY handy since the carbs will almost certainly leak. (the rear carb. sits right over the solenoid--instant fire)

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 Posted: 01-06-2018 02:47 pm
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redracer
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Concerning the "seat belt interlock system": I have posted this before on this site somewhere, but here it is again:
btw, if you're car "cranked", i.e. turned over, the interlock system was NOT the problem. If that were the problem, you would not even get the starter to crank.
Interlock:
1)there are 12 numbered positions on the round(usually white) plastic plug near where your left knee would be(look closely with a flashlight as it might be difficult to see the numbers)
2)locate the last 2, #11 & #12(one is the white with red stripe ignition wire which runs to the relay nearby, which may also be a problem as the cars age). Cut/splice/whatever #11 & #12 together. This will bypass the interlock control.
3)If the "buzzing" sound from the interlock system is annoying, remove/cut(and end cap) #4, a purple wire which is always "HOT".

Let us know how Tim's "hot-wiring" works, as this should locate the problem

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 Posted: 01-07-2018 04:10 am
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answerman
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OK, so the interlock keeps it from cranking. I wasn't sure about that or if it somehow defeated the ignition to keep it from firing. Mine was removed before I took ownership so I have no experience in how it worked.

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