Need Help No Start

[MPDano]

Hi All,

If you have been following my progression on my forums (http://www.porsche928forums.com/viewtopic.php?f=9&t=4), I have finally got everything hooked back up from an engine overhaul (original motor frozen when purchased). I replaced my ignition switch again since the eBay switch fell apart in my hand. My local 928 buddy helped me get the last pieces of the puzzle together (vac and elect. lines). When we first tried to start the car with the switch, we got nothing. I also didn't hear anything from the fuel pump. We did a quick jump from the harness and the motor turns perfectly. Ok, ordered a new ignition switch, starter relay and fuel pump relay. Still no start from the key. I turned the ignition on and checked the leads at the fuel pump (nothing). I am at a loss and can't figure it out. Anyone got any next step suggestions?

[rhjames]

sometimes the most annoying things will set you back----

did you use a fully charged battery?

have you checked/replaced the fuses? (you said you found bad relays.....)

did you reconnect the wiring (that you disconnected for engine removal) back to it's original positions?

are you now looking at a bad wiring harness?



as this was a dead car when you got it......you could be searching for more than just a batch of bad electrical parts, which would be hard to diagnose from the internet.

maybe this was why it was a dead car to start with, and then the engine froze up, or vice-a-versa......?


--Russ

[MPDano]

Battery is brand new. I never thought of charging it further. I disected the harness when I had it out and replaced all the bad wiring with followup testing. I am sure it's not the harness. All electrical was put back as original. I didn't look at the fuses. I guess that would be a great place to start. I didn't think of the relays having fuses behind them, good advice.

I think fuses are next to check! Thanks Russ.

Leo

[rhjames]

it's just a start...literally, no pun intended.

those fuses they used back then aren't the greatest.....

you know the starter works due to jumping. you know the fuel pump relay was bad do to jumping.

then you can move on to ground connections, hot connections, and more wiring.


keep plugging along until you eliminate the possibilities.

--Russ

[MPDano]

Well the fuel pump relay, I really didn't get it working via jumping. In fact, I never heard the pump run. I need to actually jump the fuel pump directly so I can eliminate a bad fuel pump. I did check the fuses and they all look good, but I went ahead and jumped it direct and still nothing. I have a feeling it will be the after market Alpine Alarm that was in there with the wires all cut up. I forgot about that piece. until I saw it tonight.

[whiteSC59]

I had to jump out the fuel pump relay once. If you do a search here youll find info. That will make fuel pump run if its good.If not, start there but fuel, air, compression are the BIG three. Lose one, no starty. Also you can make a jumper from a 12 volt cordless drill battery to pos/neg posts on the fuel pump but be carefull of spark around fuel. a quick touch will make it purr or jolt and get warm quick if locked up. Sometimes any fuel pump will pick up trash and lock so try reversing leads to blow in reverse. also if fuel is over 1 yr old, drain tank and replace with fresh fuel. varnish wont burn and really screw with injectors. good luck and let us know how it finally cranks.

[MPDano]

Both relays are new, so I don't think I need to jump any relays anymore. I am really leaning towards the alarm box for the starter not working from the ignition switch. The fuel pump may be the same, but will verify with some direct voltage to the pump.

Also, fuel tank was drained and acid washed.

[Danglerb]

OLD alarm systems are SUCH a PITA.

[MPDano]

Here is what I am looking at, first pic is the alarm box and all the miriad of wires. I do notice on the 2nd and 3rd pics that they are hooked up to 2 Relays just hanging. Does anyone else have relays in this area just hanging and not on the panel? If not, then I bet these are my culprit.

[Danglerb]

I don't know of any substitute for tracing all the wires. I took the file from the Jim Morehouse CD and printed them on the large format printer at Kinkos.

[futuresoptions]

From what I understand, and I may be wrong, but I think you need to check your ignition relay.... also I don't think that the fuel pump will activate because it gets a signal from the starter to come on when the starter is engaged. once the starter is disengaged it receives a signal i believe from the fuel injection system that the car is running and continues to keep the pump running. I would make sure that I had 12v at the switch and then I would make sure that the starter/ignition relay was getting that power... either you are not getting power at the switch or you are not getting power out of the relay. NOTICE: I had experienced this upon trying to start my 928 for the first time...... Look at the small wire that attaches to the starter mine was off and when I turned the key nothing happend. Put that little wire back on its little spade clip and run it did......

[MPDano]

Yeah, we verified all harness wiring, the starter has 3 poles (no spades), 1 large and 2 smaller ones. I also tried to test my fuel pump by putting a direct electrical leads to it and nothing, but I didn't remove the existing wires first. I will try it again without the existing wires hooked up to it.

[MPDano]

Here are the latest pics after removing the Alpine Alarm. The relays that were hanging, were from the alarm. Can anyone identify where some of these wires go to? The car didn't have a stereo in it so I am assuming some of these go to that.

[Danglerb]

None of that stuff strikes me as essential to starting the car. The empty yellow socket is I think sunroof or window switch.

Fuel pump should have run with power directly to it, sounds like its jammed or toast. Disconnect the wires and try reversing the direct power feed to run it backwards.

Not sure how much help it is, but I emailed you a current flow diagram.

[futuresoptions]

Danglerb is right, the fuel pump shoulda done something with direct power applied to it. It is probably locked up from sitting.... You can try soaking it and maybe it will let loose, if not, time for a new one..... As I stated in my previous post, if you turn your key on and go to the back of the car you will have no voltage... the starter must be engaged before you will get voltage.... The starter should have voltage once your key is turned to the right all the way.... I would start checking for 12v at the starter solenoid wire (small wire) at the starter while someone is turning the key over.... and work backwards until you find what is not letting voltage through. If you are getting 12v at the solenoid signal wire then make sure you have 12v and the main post of the starter. If you have 12v at both locations the starter should turn... if not then the solenoid/starter is bad... Let us know how it is going... A symptom of this on an american car would be the (Geez man brain fart, what are those large inline fuses on the positive lead to the starter on the hot wire called??? someone help me out here lol) Anyway I dont know if the 928's have these, but if they do and that motor was seized and someone at one time or another tried to turn it over, that coulda caused an open and you would not be getting 12v on the main post of the starter......

[MPDano]

Thanks guys, this gives me a great start on tracing this down. The starter is good since I can do the jump from the positive post and harness under the hood and the starter turns. I would think the soleniod is good too, since isn't the solenoid what makes the teeth engage the flywheel?

[futuresoptions]

Yeah that is what it does, but you need to make sure you are getting the 12v signal to the solenoid to make it engage. if you are not you will have to trace the circuit back till you find where the open is. Once you get the starter to turn, have someone crank it to make sure you are getting voltage to the pump. You will pobably need someone to turn the key to make sure you are getting voltage at the solenoid also.....

[MPDano]

Ok guys,

Heres the latest. I installed a new fuel pump and cranked her over (nothing). I got fuel as I smell fuel. Removed a spark plug and it's wet, so I am getting fuel to injectors. I grounded the spark plug on the hoisting eye and cranked it over, got spark. I am now stumbled. I will recheck my timing and plug wires to make sure I put them on correctly. It was also suggested to check the green wire as mine has a spot where the outer wire is showing and seems to have a kink in it. Any suggestions?

[N2O-SHARK]

Try taking the distributor out and moving it one tooth each direction to see if that helps. Try as I might, I always seem to get it back in one tooth off, when I mess with it.

[Danglerb]

Since you are pulling plugs anyway, check the compression.

Maybe put a timing light on the spark and see if it seems OK.

Careful you don't get too much fuel in the motor.