PITA MKiii that wont crank over

[ca5pa]

Hi Guys,

Before flaming me, I done searches and I searched other forums but to no avail.

I have a an MA71 with a newly installed Jdm 7mgte (Dunno if JDM n Adm are dif, previous was a mystery 7mgte.)

All the wiring hook up the same. After everything connected, it does not want to turn over. I can hear the starter engage (Click when I turn key) but no turn over. I have pulled the starter and run some tests, I know the gears pulls out and spins.

After messing with the starter relay for a while, I still cant figure this out. Now, I believe the power from constant and ingition go to 87 on the relay.

I starting to think the ecu is fried, but im hoping not. (Cant find my spare)

Please help!!

[lexsmaz]

Wont be the ECU it will crank regardless if the ECU is there or not ...

I'm thinking battery power is low or bad earths to the block or both ..

Before you do to much are the battery leads getting hot ? Is the starter motor the same one that came with the motor & trans you are putting in ( as in make sure its not binding, jaming on something on the ring gear or bell housing etc, if nothings been changed then just hook up jummper leads as mentioned below..

Hook up jumper leads connected to a car or good battery & run the positive to the battery positive & the negative jumper lead to the engine block & try that ..

[ca5pa]

Thanks Lex,

After my previous post, I tried 2 diff batteries. (One out of old mans rodeo and my xr8). I ended up running the power straight to the starter and bypassing the relay and I got a weak turn over. So you are possible right. Weak earth would explain the lack of "oomph" to crank it.

TBH after tracing wires and playing with starters all day I didnt think of the earth to the engine. I will be testing that in the morning and Will see how it pans out.

Cheers

[pete05]

be interested to hear how you go as mine does the same thing, I just pulled mine out but have not had time to test it.

[ca5pa]

def keep you posted pete. I was hoping to get it started today I can only get to the car every month or so as its at my parents.

[pete05]

I get the feeling it may be to do with the motor brushes or the mechanism that powers the brushes, if I flick my key on and off a few times it will kick over eventually. you can buy a kit that services these parts on ebay.

[ca5pa]

It doesnt cost much to reco a starter. I think you can get the parts quite cheap (if you know what you doing) otherwise a starter rebuild would be from memory 250-300 (its been a while, someone tell me if im wrong) If it does turn after a while, I would suggest that it is your start on its way out . May need to do an unloaded test to confirm. http://www.cygnusx1.net/Supra/Librar...aspx?S=ST&P=11 check this page out. Has the tests for a starter motor. If you didnt know, this website is of the Toyota Service Repair Manual. Helped me a great deal durring the years..

[pete05]

yep I have seen that manual, I actually had to pull my whole inlet manifold off as I could not crack the top bolt on the starter, was a real pain. I will strip mine and see whats going on.

[ca5pa]

Well so far today, I used better gauge wire and checked the earth to the engine. (one was looking dodgy so I moved it) and to start. I then Bypassed the relay again and it turned over with a bit more excitment but not as much as I would like. So I removed the relay and wired the relay up the same as it would if I were to start the car and checked it with a multimeter. Sure enough, the relay switch only hold open for a split second, thus not allowing power to go to the starter and only hearing the "clunk" when I engages.

I will try a new relay switch next time im up here and see how I go from there. Shame, I really wanted to get her started.

[lexsmaz]

You say you ran better gauge wire, how thick is it now it needs to be similar to the main battery power wire to the starter the thick one ..

Put a jumper lead from the solonioid thin wire at the starter to the main battery power lead at the starter & it should crank, no relays required if you do it that way as a trial & if it doesnt crank well then & the battery is good & all the big earths & main battery leads are good, the starter is dodgy or the motor is tight etc. have you seen this motor run at all ?? & if you pull the spark plugs out does it turn over easily by hand ??

[ca5pa]

I used some 3 phase i had lying around and ran straight to the starter. I bypassed the relay and it turned over. Engine can be turned by hand. Compression feels good. I have not seen this engine run, i hope its ok. Inspected the bottom end before putting it in, seemed ok. The turbs was in good condition. I guess i will get another relay for now, hopefully it will start.

I test the relay switch with a multimeter and she was screwed. The wires that run from the relay to starter were getting no power.

[lexsmaz]

You said in a earlier post it didnt turn over that well after you by-passed the relay ( better but still not flash ) with a new relay it will be no better than when you by-passed it .. How heavy a gauge are the main power wires & earth to block wire that you are using now ..

If the main power leads are all good & heavy duty i would be removing the starter & get i checked out as it sounds like it is the main cause ..

[CrUZida]

If the cables you've used are any smaller than 4gauge (~8mm diameter of the copper core) then upgrade.
Even 8gauge cable (~5mm diameter of copper) is too small.

[ca5pa]

You said in a earlier post it didnt turn over that well after you by-passed the relay ( better but still not flash ) with a new relay it will be no better than when you by-passed it .. How heavy a gauge are the main power wires & earth to block wire that you are using now ..

If the main power leads are all good & heavy duty i would be removing the starter & get i checked out as it sounds like it is the main cause ..

Well I ran the TSRM tests, and it was within spec. I think you might be on the money with the gauge wiring. The earth is quite thick. (8 Gauge? would have 8mm copper core) the power supply wire thats on the harness is quite thin, maybe 4 gauge? When I go back there in a few weeks, Im going to rewire the whole starter (just for kicks) and try eliminate and sort out freyed wiring and heavier gauge etc. I still need a new relay, I tested that and its kaput.

Im not ruling out the starter, Im just eliminating the wiring stuff first. Funny thing is, the person I bought the car off had wired this up himself years ago and has a bosch relay (not sure if standard). So I do not know what dodgies he has pulled...

Thanks peoples for your input btw.

[beatle]

Its pretty common in these for the contacts on the ignition barrell to wear out and not send 12V to the starter solenoid.
I just changed out the starter solenoid after having the same symptons as you, only to have it do the exact same thing still.
chucked in a relay and she was roses.