rtrylvr

iTrader: (2)

First let me start by saying that I have researched the crap out of this and while the information on here is very informative, I haven't found anyone that quite has the same problem. The problem I'm having is very similar to the click click start problem that seems to plague a lot of owners, but I mine is more like a nothing nothing nothing etc etc and sometimes it'll start. Sometimes it will turn over but not fast enough to fire the engine. Sometimes I get the click click symptom, but mostly it doesn't do anything. I've replaced the starter (ouch to my wallet), had my battery tested at 2 different places, bypassed the clutch switch and starter kill relay to no avail. I'm getting 12v to the activation terminal on the solenoid, I've cleaned all my contacts at the positive harness, the starter, and various grounds I've found. I looked at the diagram for the starter booster and it looks as if that just basically "jumps the solenoid". Even if I jump my solenoid, it still won't turn over so that wouldn't do me any good. There seems to be a power delivery type problem to the starter. Anyone have any advice? What are the odds that the 8ga thick wire running to the starter might be damaged? I've put a lot of time into this and am pretty well out of ideas. Thanks.

wstrohm

If you have +12 volts at the activation terminal of the solenoid (black wire with red stripe) with the key in the START position, what voltage is at the heavy (8 ga?) black wire at the starter at that time? If at least 9-10 volts, the starter should turn at about 300 rpm. If that voltage is OK but starter does not turn, starter is defective (open winding or bad internal switch). If voltage on heavy black wire is low or missing, either the connection to battery is bad, or starter is defective (shorted winding loading down battery). No other ideas here... sorry.

cewrx7r1

iTrader: (2)

(1) bypass the clutch switch (starter interlock switch)
(2) test to see if this fixes the problem.
(3) leave #1 active, bypass the starter cut relay by left foot.
(4) test to see if this fixes the problem.
(5) ignition turned on, jump the starter hot 12vdc to the starter solenoid.
(6) if starts ok repeatedly, then it is most likely the ignition switch.
(7) if no start, check voltage to starter, and or pull starter assembly and check it all out,

rtrylvr

iTrader: (2)

No offense intended, but if you read all of my original information, all those steps have already been performed. I do appreciate your response though. This is actually the 2nd new starter. I returned the 1st one thinking that I got another bum starter even though it tested fine at the parts store.

rtrylvr

iTrader: (2)

I think I already checked to see what the voltage drop at the starter was while in the start position and it was somewhere in the high 10's low 11's. I'm going to check it again with someone assisting this time to be sure it's accurate. Last time I was by myself so it made it a bit tough. I also considered actually hooking up a jumper cable from the positive side of the battery to the positive on the starter just to see what would happen.

AzEKnightz

iTrader: (24)

How about ground? I've worked a customer's car with VERY similar problem.

No click at times, and no start. Randomly it'll start.

Found out that the "ground" or there engine ground was no good. Hook up couple of grounds in various place of the engine, and bam! Starter works everytime.

-AzEKnightz

wstrohm

Interesting. According to the wiring diagram the starter ground is its case, bolted to the engine. Where were your grounds bad? Was it the connection from the battery negative cable to the aluminum bracket that mounts the A/C compressor?

rtrylvr

iTrader: (2)

I think I see where he's going with that. The starter is indeed grounded by it's case, which is bolted into the casing of the trans if I remember correctly. You would think that in itself would be good enough of a ground with how many points of contact with the chassis. However the supplementary grounds on the engine have to be there for a reason. Anyone have any details on where all the grounds are? I found about 3 and cleaned them, but I'm sure there has to be others. The wiring diagram isn't the most helpful at locating these.

AzEKnightz

iTrader: (24)

This was on a customer's jeep. I believe overtime the engine chassis/ground were not making a good contact. I basically removed all the ground harness from that engine, clean the area with sand paper and ground it with a thicker gauge wire.

A "good ground" is a ground circuit that has a resistance of zero OHMS.

Ground circuit resistance can be measured in OHMS using a digital volt OHM meter (DVOM). When using a DVOM, it must be set on the 200 OHM scale to obtain an accurate measure of the circuit resistance. Many meters have both a 200 OHM scale and a 200 K scale. The 200 K scale will not measure zero OHMS accurately. If the meter is an autoranging or self-scaling meter, read the meter carefully to be sure which scale it is setting itself to.

Before measuring resistance in any circuit, the resistance of the meter should be measured by touching the leads together. A meter with a good battery and leads in good condition will read less than .2 OHMS usually zero. If the leads measure anything more, an accurate measure of the circuit resistance may not be possible.

So once you've got the meter set up correctly, measure the OHM/resistance by placing the red lead on the DVOM to the ground terminal of the battery. Then the black lead on the DVOM to the starter case. Your reading should be close to 0 ohm or no more than 5 ohm. If you have a high resistance reading or your DVOM shows a fluctuating reading, you do not have a good ground. Clean up your engine and chassis ground and replace them with I'd recommend 4 gauge or bigger wires prefer.

I hope this helps.

-Eric

rtrylvr

iTrader: (2)

^^^^ That's actually a really good idea. I could also do that on the positive side to see if perhaps that wire has too much resistance. In a perfect world you would get 0 ohms, but wire always has some amount of resistance. I have some 8ga wire laying around from an old stereo install, and I was thinking about running some supplementary grounds with that. I'm not sure what I have for ring terminals at the moment though. I'll check it out with the multimeter for sure though. Thanks to all, and I'll report back what I find. I still have a lot of work to do before she's road ready for the summer, so the starter issue was last on the list.

mannykiller

iTrader: (93)

Good Info....I'm only running one Large guage ground wire from my rear rotor housing to the firewall. Maybe I need another..

wstrohm

As far as starter operation is concerned, the electrical connection between the engine block and the negative terminal of the battery is the most important "ground" connection, and needs to be as low resistance as possible.

rtrylvr

iTrader: (2)

I did finally get out there and take a resistance measurement on both positive and negative side of the starter to the battery cables and got .02 ohms on both. I think regardless, I'm going to run some extra grounds with some 8ga wire I have from an old stereo install.

rtrylvr

iTrader: (2)

I ran an 8 gauge wire straight to the starter housing and that didn't fix it either. Since I have the wire ran I might try switching it over to the positive and see what happens.

MGB11

iTrader: (9)

I am not sure if you have thought to look at your ignition switch, but you might want to pull that out and bench test the connections with a volt meter to make sure it is not defective.

boosted414

iTrader: (30)

Jump 12v straight to the starter with an 8g cable. That will at least take a faulty starter out of the loop. Briefly connect it to the big terminal opposite of the terminal you have the charging harness connected to.

If that turns ok, look at the alternator 12v connection. It runs to your starter. If its flakey then it won't send sufficient amperage to the starter. Amps is the key here. Not volts or resistance. I can run 12v thru a paper clip to the starter and get all if these readings.

rtrylvr

iTrader: (2)

The ignition switch should be ok. I'm getting 12v to the activation terminal on the solonoid (which I believe they call terminal S in the service manual). As far as the alternator harness is concerned, this is where I suspect the problem may lie. If I try and "jump" the solonoid I get the same result. boosted414, you are exactly right. It seems as if the starter isn't getting the proper amperage, which is why I'm going to switch the wire I ran to directly to the starter casing over to the positive terminal on the starter and the battery. That will completely bypass the alternator harness.

boosted414

iTrader: (30)

run a fresh wire from the alternator terminal or 12v battery, to the solenoid on the starter (same side as the charging harness). if it works, theres your problem.

rtrylvr

iTrader: (2)

Tried running the wire directly from the battery to the positive side of the solenoid and still no luck. WTF. Been through the whole system and bypassed everything only to find nothing.

SA3R

Dont want to steer you off course, but here is a post I wrote in my build thread, about my auto starting troubles, and what the issue turned out to be. Might give you some fresh ideas?

All has been good until today, when I took a long drive, about an hour away from town, just cruising at the speed limit. Got to the destination for lunch, went inside for about an hour.
Came back out to the carpark, got in the RX7 and hit the key- "CLICK" went the starter relay, and nothing. No crank. Tried it several more times, nothing.

Armed with only a small 1/4" drive socket set, 30 minutes away from the nearest town with a fuel station, and a bit less than a quarter tank of fuel left.

Checked the battery terminals, all good. Checked the terminals down at the starter, all okay.

Removed battery terminals, replaced. Car then started up. Phew.

Got to a fuel station, filled it, and the car started fine.
Got home and had a look. All seemed good. Couldnt find a fault with anything. All physically checked out.

Went online and found this service bulletin recall, which matches my problem to a tee:

Applicable Models: 1993 RX-7 A/T
Subject: NO START AFTER HEAT SOAK

APPLICABLE MODELS/VINS
- ----------------------
1993 RX-7

Automatic transmission vehicles with a VIN of JM1FD***P0200001 through
JM1FD3***P0210498.

DESCRIPTION
- -----------
Hard restart after running the vehicle at high speeds on hot days. Vehicle
restarts easily after engine compartment cools down.
This hard start condition is caused when heat from the engine increases the
electrical resistance in the starter wire. This decreases the amount of
current received at the "S" terminal on the starter.

To correct this problem, the starter harness length has been changed and the
amount of current applied to the "S" terminal during starting increased.

REPAIR PROCEDURE
- ----------------
If the condition exists, install the countermeasure starter wire harness.
1. Disconnect the vehicle battery.
2. Raise the vehicle on a hoist or raise the front end with ramps.
3. Disconnect the connectors at the starter.

[Picture showing where to disconnect the harness]

4. Connect countermeasure harness FDY1 67 SH0 as shown.

[Picture showing where the new harness fits in]

5. Tape off the OEM starter solenoid wire. Secure countermeasure harness
with 4 tie-wraps E018 67C92. Confirm there is no interference between
the brake and fuel lines.

[Picture showing where to install the tie-wraps]

PARTS INFORMATION
- -----------------
PART NUMBER: FDY1 67 SH0
DESCRIPTION: Starter Wire Harness
QTY: 1

PART NUMBER: E018 67 C92
DESCRIPTION: Tie-Wrap
QTY: 4



This is whats wrong. And as far as I know, this countermeasure harness is no longer available.

I made up two new ground straps tonight to test a solution, and ran them off the negative battery post bolt, one down to the engine block ground point (which I removed and cleaned up, and it looked fine) and the other strap from the battery negative post bolt to the ground bolt that the ABS grounds to, on the inner fender.

I expected to have to go further, but since making these two ground straps, I cant replicate the problem anymore, so I'll just keep driving and hope that this is all it needed.

*Disclaimer- in the past I have been 100% against "ground kits" "additional grounds" and all that stuff. I would call it absolute bullsh!t, and a waste of time and money. However, having read about this problem in a Mazda tech recall, maybe I'm not a complete skeptic anymore. Especially since my new ground straps appear to have actually fixed the problem, as far as I can see..

rtrylvr

iTrader: (2)

Do you have a link to your thread with that info with the pictures? I also noticed that applies to vehicles with automatic transmissions and mine is manual. The other thing I find curious is the section where it talks about not getting enough current at terminal "s". It would seem to me that current shouldn't matter at terminal "s". Terminal "s" should just activate the solenoid when 12v is received regardless of current. It is very a very interesting bit of information to say the least. I also have noticed that the problem seems to be worse with heat soak. I still have the problem from a cold start, but I've had times where after driving it for a bit of a distance it doesn't want to restart again. The thing that's really strange in my case is that even if I "jump" the solenoid I still get the same result. Jumping terminal "B" to "S" should provide more than sufficient current in any case. I noticed that your location is Australia which would lead me to believe that your vehicle is RHD, so is your ABS unit on what would be your passenger side?

rtrylvr

iTrader: (2)

After reviewing the FSM schematic of the starter the " This decreases the amount of
current received at the "S" terminal on the starter" makes a little more sense. It seems that terminal "S" activates a pull in/hold in coil. If there isn't enough current going to this current it wont function properly. I think the aftermarket starter booster that is sold for our cars is to address the exact issue that TSB talks about. The part that puzzles me is that "jumping" the solenoid *should* give it that extra current it needs to function, but in my case I get the same result. Since I'm running out of options I think I'll fabricate a starter booster just to see what happens. I just happen to have a relay lying around that was for a remote start install that I never ended up using.

SA3R

You got it right. Being in Australia, the driving positions are swapped, and the ABS is on the opposite side to you

Heat soak seems to increase the resistance in the wiring, which then reduces the amount of current that can get from A to B.

I know that the TSB I found was only relevant to auto cars, but the heat/wiring/resistance issue may be common to manuals as well. Because manual cars run hot too. And they have similar lengths and gauges of wiring in the engine bay.

I'd definitely be looking at some sort of starter booster, to see if this helps you out. Especially if the car fails to start during hot run/heat soak episodes..
Hope it gave you some more ideas anyways

Build thread link: https://www.rx7club.com/build-thread...hread-1023009/

rtrylvr

iTrader: (2)

I fabricated a starter booster over the weekend and even though I was very skeptical that it would work, it seems to have done the trick. What doesn't make sense to me is that when I would try and "jump" the solenoid with a screw driver before it still wouldn't turn the starter. No use worrying about why at this point I guess. Some things just can't be explained. Anyway, the starter booster probably costs me around $15 in misc materials. The hardest part was figuring out where to mount it. I'm not sure where Petit says to mount theirs, but I'm sure where I did mine will suffice.

SA3R

I think I'll put this here, just so I have the information down..

I spent a considerable amount of time today with electrical engineering books and reference materials, working out what happens under the FD hood during heat soak. Particularly in the wiring loom.

Turns out that the copper core positive cable that runs to the starter motor can carry as much as 90-100 amps during cranking of the engine.

Heat soak in the engine bay (assuming the engine is hot, and the water temps are in the 100C region) can introduce a lot of resistance into the positive starter cable. With the water temps at 100C, and the car standing still with no air flow through the engine bay, the starter cable will heat up. And its resistance will go up.

How much? Well, the heat soak resistance of the cable goes up, and I measured it only being able to deliver 39 amps when attempting to crank the engine. The service manual states a minimum draw of 90 amps to crank the engine. If you follow my logic here, the heat soak is increasing internal resistance in the starter cable, to the point it cannot deliver enough current to crank the engine properly.

Once the engine bay cools down though, resistance goes down again, and the cable will deliver the required amperage, and the car will start fine. These test results are repeatable too.

Maybe the results of my testing says the starter cable should be better insulated to keep heat soak out of the cable.

V=I*R. Where V=voltage, I=current and R=resistance.
Resistance is inversely proportional to I current, as when R goes up, I goes down.
What makes R go up? Heat.

So the game, at least for me, is all about stopping heat soak in the starter cable. This will stop the hot start cranking/click-no start problems once & for all