My DD, '74, doesn't always like to start with the key. The good news is that it already has an aftermarket relay system installed. It clicks every time I put the ign key in the start position. Sometimes it cranks right over. Sometimes I hear the relays click, but no go on the cranking. Try again, again, again, and sometimes it will crank. Othertimes it won't.

If I climb underneath the car and jump the solenoid to the main power lead with a wrench, it turns over 100% of the time.

So, it's just the solenoid, right? If so, I'll just fix that (I've done that before).

My brain hurts.

Thanks!

First thing I suspect when I hear a click with no crank is bad ground starting at the negative battery terminal.

But the fact you can jump it at the starter suggests otherwise, and also suggests the starter solenoid is fine (if starter solenoid was bad it wouldn't engage there either). So.... this points to a high probability that the plastic insert in the ignition switch is cracked, or the seatbelt relay and/or its connections under the passenger seat are iffy (on later model cars).

If the ign switch was cracked, then I wouldn't hear the starter relays click 100% of the time I go to crank it over. Maybe the add-on aftermarket relay has taken a dive?

It could be anything in the starting circuit... weak ground connection, ignition switch, seatbelt relay, addon relay at starter, and any connections in between that would weaken the current getting to the starter solenoid.

Rand! You're supposed to just know what it is. Duh!

Alrighty. Looks like I'll need to get the sig other to hop into the car while I start checking voltages. So much for my trying to be super uber lazy.

Now I need to spend the next day and a half mentally preparing myself to work in the cold garage.

What hot start relay did you use? I would bet money that the relay contacts have arc spots and are causing voltage drop. I say this because you said the relay operates 100% of the time, so the rest of the starting circuit is probably just fine.The key switch used to be the problem, now the relay is the problem. If you were to use a diode across the relay contacts to shunt the inductive spike, then that arcing problem would go away.
See the relay thread in my sig area.
Tom

Edit: changed back EMF to inductive spike, sorry if this confused anyone. Inductive or transient spike is the correct term for what is happening here.

The OO (Original Owner, w00t) had a shop install the relay system. Er, I'm sure it's old and worn out, causing the voltage drop like you've described. Let me take some voltage measurements before the relay and at the starter and see what I come up with. I'll report my findings.

Thanks!

Sorry man.

My first 914 came with a hot start relay and ironically my intermittent troubles went away when I removed it. The next time I had trouble it was the ignition switch.

The good thing is you ruled out the starter and the starter solenoid quickly by jumping it.

I would clean the battery terminals and the ground strap between tranny and trunk floor early in the troubleshooting process just because even if those don't fix it, knowing they are clean is good.

Don't you just love it when someone comes along stating the obvious and telling you what you already know? I know, big help.

Sounds like to the seatbelt relay (under passenger seat) ground may need to be cleaned. I had that once, all the other times it was a cracked ignition switch. Doesn't sound like the ignition switch in your case. good luck.

Which relay are you using? The Bosch Kit or a Ford relay? If it's a Bosch I would suspect that. Also a bit of a highjack here. Tom, do you plan on offering the diodes in another kit? I had this set up on my plane and had often wondered if it wasn't necessary for the 914's circuitry, also.

If all connections are clean and the starter is in good working order there is no need for the hot start thing. Porsche did not install one. None of my 914's ever had them and they start every time. It's just a band aid for another issue. Ditch it and find the real cause.

Ok, I got a pm about me comment and felt I needed to clarify my statement.

Porsche designed a simple car. Many of us have no issue with starting the car with the switch and wiring Porsche installed. Even after 35 + years.

Some guys over time have felt compelled to add a soft start feature to the factory system. There is nothing really wrong with adding the feature as an improvement but lets face it. Guys that add this are usually doing it because they are having an issue with what has been called "Hot Start"

I think this is a band aid and usually less costly than replacing a weak starter or a arc'd solenoid plate.

Here's what I see: Over time the grounds start to corrode causing high resistance in the start circuit. Eventually this kills the starter or solenoid. Oh, it will still work but it will be weak when the starter gets hot and the engine is hot and tight.

So in my opinion fix the source.

Really, someone PM'd ya?

I agree it's a bandaid. Unfortunately I don't have any history as to why the original owner added it. I could just remove it from the system and see what happens. I'm using a different starter, motor, relay board and grounds than what he had when he installed it. Maybe you're right. Just remove it and see what happens. If the problem is still there, start digging.

Ya, It was a very nice pm asking about how I came to my conclusion. I felt I wasn't clear enough here so that's why the second post.

I would pull it and start to check the loads on the system.

I need a "like" button for your post Rick.

I PM'd Rick because I didn't want to hijack your thread. I see we have a difference of opinion and that is OK. For info as to why I feel a relay is necessary see the starter realy thread in my signature and go the the aeroelectric link.
Tom

Will do Tom! I won't have time to dink around with the car until Sunday. I'll report back.

I guess I'll add my voice to the 'obvious answer' crowd. I replaced both the battery and tranny strap ground to fix a similar problem and made sure everything was clean when I installed the new straps...I've haven't had a problem for the last 10 years...

Tom, I can open the thread from the link in your post here. It looks like you put alot of thought in your "Hot Start" relay. I specially like the radio shack parts. I'm not an engineer or certified mechanic and I did not stay at a Holiday Inn last night. So I can't comment of the reason you felt compelled to add this to your car. I doubt it will hurt anything.

I'm not saying your relay or the ones that are sold through various Porsche and VW sites don't work. I'm just saying, to me, it's a Rube Goldberg devise. Lots of extra stuff to eventually start the car.

Many of us have 35+ year old switches in our cars and never have an issue with hot starting.

Maybe a guy that has been working on 914's since they were near new like the captn or Chris Foley could shed some light on why these things seem to find their way onto our little cars.

Rick,
This is one time I have ignored the KISS ( keep it simple, stupid ) principal. And that is usually a bad idea! I agree with your assement that adding more electrical items will usually just make for more problems down the road.
Did you open the solenoid page about the starting circuit? That is one of the reasons I decided to go ahead with my relay, even tho' I was having no starting issues.
Tom