Mrmerlin

OK lets get things straight,


I am talking about a STARTER relay NOT an IGNITION relay. Replace the starter relay

If your having to jump the car for any reason then your risking frying your engine computers, and or damaging the one or more of the diodes in the alternator.


this would lead me to belive that your STARTER relay may be going bad as the car wont start quickly and thus has to turn over more to make the engine run,
this is one thing that kills the starter relay.

Beyond that roll down the windows and look inside the doors, to see if the rear door lights stay on you might have a pin switch thats not shutting off.
Do the elex cleaning as outlined

danglerb

When you "jump" where are you hooking up the cables, to the battery or the jump post?

If the jump post then the "change" from jumping assuming your battery is charged, is that you are bypassing the wiring from the battery to the starter (positive and ground). Check the ground straps (one at battery and one from engine block to chassis near the starter) and the positive cables. Usually its the ground strap thats corroded under the plastic sleeve or making a poor connection.

kx02wr

Mrmerlin thanks like i corrected myself in later post starter relay is new and clicking.

I am jumping directly from battery. which is new.

with some flucuation in voltage with accesories, and noticed when my charging gauge will start jumping around is when car won't start which only happens when car gets hot I'm pretty sure it's altenator. will change on tues and know for sure. Thanks for all the help guys.

WallyP

The odds are greatly against the alternator being the problem.

You can continue randomly poking around, or I can give you a detailed troubleshooting plan to nail down the problem - your choice.

kx02wr

I would apreciate a detailed trouble shooting plan. Let me reitterate what is going on with vehicle as I am still pretty convinced it has to be the altenator and also had an electrical specialist check it out yesterday and he seemed pretty certain it's the altenator as well. Car always starts cold cranks super solid and starts right up. It only won't start when i get fluctuation in charging gauge and have verified fluctuation in voltage with multimeter again only when vehicle is hot and it doesn't happen all the time. When not hot there is no voltage fluctuation.

kx02wr

Battery new starter new ground strap at battery checked ce panel checked and starter relay new. 14 pin checked and seems fine. When the issue happens I can put a jump on it and it start right up. I know I don't know everything but a bad ground shouldn't be fixed by adding more voltage. And again once it cools down it will always start without jumping. Car has no drivability issues except when it hot charging gauge will jump around and this is when I can replicate the issue and using accesories seems to make it a little worse again doesn't do it all the time. Car never stalls out.

SteveG

It doesn't seem like this is the problem, but a ground strap can look fine, and show corrosion under the rubber. Or not show it and be defective.

Doesn't hot no-start indicate fuel pressure regulator? Or damper. Pull vacuum line from same and if it is wet or smells of gas that is a problem.

I've also heard of heat contributing to connectivity of starter. How to trouble shoot that other than checking the connections to the starter, I don't know other than bench check of starter at shop.

Charley B

Would jumping pin 14 to the jump post when in the no start condition help eliminate or confirm the starter as the issue?

kx02wr

I will look into the fuel thing however if that was the problem I don't see how the car would start every time with a jump if not getting fuel. The voltage jump leads me back to the altenator every time though. The starter is a rebuilt bosch that has not been in the car more than a month but i guess i can't totally rule that out yet. Tuesday the altenator is coming out and bringing it to my electrical tech to be bench tested. thanks guys

James Bailey

The starter solenoid uses magnetism from an electric current to...."The starter solenoid receives a large electric current from the car battery and a small electric current from the ignition switch. When the ignition switch is turned on, a small electric current is sent to the starter solenoid. This causes the starter solenoid to close a pair of heavy contacts, thus relaying a large electric current to the starter motor, which in turn sets the engine in motion.[1]

The starter motor is a series-wound direct current electric motor with a solenoid switch (similar to a relay) mounted on it. When low-current power from the starting battery is applied to the starter solenoid, usually through a key-operated switch, the solenoid closes high-current contacts for the starter motor and it starts to run".....Lifted from Wiki...

Note that heat causes the solenoid to be less efficient. Very common on motor homes where the engine is in a box or 914s where the exhaust pipes pass to close to the starter to need a "ford" seperate solenoid (relay) to be added to solve the problem. When your rebuilt starter was rebuilt it was tested cold and probably uses the original solenoid. Jump starting adds more juice and magnetism.
Sometimes new parts do not work and more often "rebuilt" parts do not as there are no real standards about what makes a rebuilt..rebuilt !

If you had a charging issue it would eventually stop running stall as the drain continued.

Landseer

^^^ I have 5 of these 928 cars, god help me, all heavily serviced from an electrical perspective. The voltage meter bounces, shifts and moves with changes in temperature and load. Normal.



Separately, you might take a uility knife and gently remove the plastic cover on your ground strap. Post a picture. It can be a rather suprising deviant force.

Strat_928

I had a similar problem, (see Odd starting problem on 928OC forum) except that when mine did not a start a jump would not help at all. All I heard was the starter disengage. It was very intermittent but always when it was hot or had been hot relatively recently. No real rhyme or reason though sometimes. Really hard to get a read on what was going on.

1 - I had a loose oil sending wire (right by the oil pan, 2 rubber wires, one going in and one going out). Fixed it but it still happened, but less
2 - I changed the starter relay, the fuel injection relay and the fuel pump relay. Found the fuel injection relay to be a little "bubbly" on one of the blades. They were all original looks like.

Has not done it since.....if that is not it, then it may be the yellow wire from the 14 pin connector on the passenger side near the front of the engine compartment to the starter. Or the 14 pin connector itself as it can get corroded etc. There are write-ups on this by search.

For sure though - read Wally's paper.....that will likely do it for you.
Good Luck

ElReyos

The short answer to your question is yes. I have done it, just remember to plug the connector right away to avoid damage to the alt.

jon928se

Yes and No

If jumping +ve at the hot post in the engine bay and using -ve attached to the engine block you are taking all the ground straps out of the equation.

If jumping direct to the battery posts all the cars wiring remains in the equation and potentially suspect.
If jumping direct to the battery posts you may also be inadvertently tightening the connections to the cars own battery - thus making it start and not really jumping it at all.
If jumping direct to the battery posts the additional current available may be compensating for high resitance in a duff ground strap (batt to body or engine to body) or duff +ve cables going batt to starter.

Worthwhile bypassing each battery to starter cable in turn using a jump lead to see if that makes a difference - after you've cleaned and tightened the battery connections.

WallyP

The problem as I understand it:
The starter always functions properly when the car is cold.
The starter often fails (no starter action) when the car is hot.
Jump starting at the battery causes the starter to function after hot failure.

When you turn the key to START, the following sequence of events must occur:
- Power must flow from the ignition switch 50 terminal to terminal 86, the operating coil input, on Relay XIV, the Start Relay.
- Terminal 85, the ground for the operating coil, must be grounded thru the Neutral Safety Start Switch on the transmission. If so, the coil is energized, and the relay operates.
- Terminal 30, the input for the relay contacts, must be connected to battery power. If so, battery power is applied to Terminal 87 of the Start Relay.
- From Terminal 30 of the relay, power flows to a yellow wire on Terminal O5.
- Power flows on the yellow wire to Terminal 14 on the corner of the 14-terminal connector near the jump start terminal.
- Power flows from Terminal 14 to Terminal 50 on the Starter Solenoid. This is one side of a heavy-duty solenoid that both slams the Bendix gear on the starter into engagement and operates a heavy-duty switch connecting the starter motor to the battery connection on the starter. For the solenoid and the motor to operate, the other side of the solenoid must be properly grounded to the chassis. This occurs thru the bellhousing, engine block, and the ground strap connecting the engine block to the chassis. When the solenoid operates, there is a noticeable "clack".

From your descriptions, you hear the "click" of the start relay, but you have never mentioned hearing the "clack" of the starter solenoid.

This gives us some possible causes for the problem.

-As James Bailey suggested, it is possible that the starter solenoid (the heavy solenoid on the starter) needs more power to function than it receives when hot.
- The wire between Terminal 14 and the solenoid may be faulty. The wire harness containing this wire is known to suffer from corrosion and heat damage.
- One or more of the connections and wires between the Start Relay and the solenoid may be heat-sensitive and limiting the power flowing to the solenoid.

One of the major irritants with intermittent faults is, "If it ain't broke, you can't fix it." Since it might not be practical to get under the car to check the power at the solenoid when it fails to start, we need a test rig.

One good way to do this is to hook a test light to the 50 terminal. Get 4' of lamp cord - the brown or white two-conductor wire used to hook a table lamp to the wall outlet - and a 12 volt light bulb. Solder the bulb to one end of the wire so that it burns when power and ground are applied to the other end of the wire. Note how brightly the bulb glows when connected directly to the battery. Attach one conductor to the yellow wire on the 50 terminal of the solenoid, and the other conductor to the solenoid, starter or engine as convenient. Run the wire up the side of the engine and out from under the hood. Tape or wire-tie it to the base of the driver's windshield wiper arm so that the bulb is visible from the driver's seat.

Watch the bulb as you start the car. If the starter fails to operate, there are two possible conditions:
- The bulb will not glow at all, or will glow very dimly. This will indicate a probable fault in the wire harness, or somewhere before that. Move the wire to the output side of Terminal 14 in the 14-terminal connector (the yellow wire on one corner) and repeat the test. If the bulb now glows brightly, but the starter does not work, the harness is the most likely cause, but don't forget the possibility that the ground strap under the engine is faulty when hot.
- The bulb may glow, but the starter does not operate. If the bulb glows, but not as brightly as it did when you tested it on the battery, it may be time to install a Ford starter relay. If the bulb glows brightly but the starter does not operate, the starter solenoid may be failing due to heat. This isn't too common, but can happen.

I hope that this helps...