Please help --which order of diagnosis for '87 740 Turbo No start !

The fuel pump relay can fail in two major ways. One is due to open solder joints on the circuit board which you took care of. The other is contact erosion. Take out that relay again and clean the contacts, especially one closer to the middle with 600 abrasive paper. I fold a piece on it self and cut a small sliver from it. Using tweezers I insert this double sided abrasive in between the contacts and work them smooth.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

void _-void-_ in the obvious place

It's an '87, so it has no flywheel sensor. Instead it uses a hall sensor in the distributor. First thing to check is if it has a spark, that's easy enough. If the engine wiring harness is original then it will need to be rewired or replaced, if that's not the problem now it will leave you stranded later.

I FIXED IT !!!!!!! I am so happy. The wiring harness is old and crumbly. The car wouldn't start and so I started to fiddle with that block terminal--- there' s two (maybe you guys can explain).

The one in the back that connects to the ignition coil-- it was tie wrapped under and I fiddled with it while I had someone start the car. It would start and then die. Start and then die. You had to give it gas on the pedal to keep it going. Well, anyway, with the ingnition in on position-- you could hear the injectors intermittently click.

I carefully pulled both connection blocks (the large grey one and small grey one) out and individually wrapped each of them in tiny spiral wrap plastic.

It starts ! yay!!!!! You don't know how glad I am----this has been going on for like 5 years I think !

NOW I HAVE TWO QUESTIONS:

1. Is this part of the wiring harness when bought? I mean can this portion be bought separately? Instead of the rip off dealer price for the whole harness?

1. Underneath the car I thought what I saw was a disconnected electrical plug--so I plugged it and the car started (I think this was just coincidence in moving the car creating the short) but I plugged it in and the over drive arrow light appeared on the dash and it wouldn't go out when pushing in the button. Is this somehow wrong?

I mean is the arrow supposed to be lit or not? I mean before the light would stay off and then you push the button and it goes on. But then why is it disconnected under the car then?

thanks guys for helping me figure it out---if I didn't find it by accident : )

aarrrrrrg!!!!!!!!! The car just broke down again : (

I went to put in gas and then it died. I tried to start it--it started up and then I gave it gas and it died. It just turns over and over !

Kind of a shotgun approach, but given the prevalence of problems and the sort of symptoms you have: check and/or thoroughly clean up the connections at the positive post of the battery. Our 85 has a separate wire that attaches to the clamp bolt itself, and when that ring terminal gets funky the engine dies. There is also a 10 AWG red or brown or orange (never could tell which) wire that comes away from that clamp that likes to corrode in two. Drove me completely crazy when it happened to mine.

BTW - a quick-and-dirty way of deciding whether to suspect ignition or fuel in these beasts is to watch for the tach kicking when cranking. No kick every second or so usually means no ignition.

Mike

The wiring harness runs from the ECU in the passenger footwell and snakes all around the engine under the intake manifold, over around to the air mass meter and interconnects with the ignition harness. If you found crumbling wires, I assure you there are more, if you remove the harness and split it open, the large bundle of wires under the intake manifold will have the insulation crumbling which causes bare ignition wires to mingle with bare injection wires and the end result is either no spark, no fuel, or intermittent gremlins. Remove, then rebuild or replace this harness, the car will never be dependable with it in its current state and there's no way you can repair it sufficiently with it snaked around the motor.

That sounds like the overdrive solenoid wire. The arrow should be lit only when the overdrive is disabled by pressing the button on the side of the shift knob. If the wire to the solenoid was disconnected then the overdrive would not engage regardless of whether the arrow was off or not, unless someone modified the solenoid to eliminate the sometimes troublesome and rarely used lockout feature.

See my last post, your wiring harness is shot.

Mike, the tach does jump on turning on the ignition--I thought it was the ignition as well, but I jiggled it while starting and it starts the engine turning over and over.

Okay, so what you're saying, James, is the arrow on the dash is lit most of the time while driving, and then when you use the overdrive (press the little button) it should go out, but it is enabled ?

That's exactly what it looks like, James--by the manifold the fat bundle of wires by the idle control valve---they're crumbly and bare---I'll look at this. Thanks for all the help you've been providing : )

No, the arrow should normally be off, if the arrow is on, then it means the overdrive is locked out, just like if you put the shifter to "2" instead of "D", 3rd gear will be locked out. The OD lockout (arrow on) can be useful if you're towing a trailer or going up some hills that cause the transmission to hunt, that is shift in and out of overdrive not able to decide which gear to stay in.

James, have you replaced the harness before? Is there a diagram somewhere, or should I just tag each connection before removing?

thanks

I just stretched my new one out on the ground before removing the old one, and used masking tape to identify the conectors. I started at the battery end, looking at the connector style, and matched each with the one on the existing harness. The fuel injector connectors are interchangable, so connect them where they reach best.

After I labeled them, I disconnected the big connector near the battery (oh - the battery was already disconnected at this point!) and connected the new harness there. I worked my way down, disconnecting the old and connecting the new as I went. I had to cut off the old injector connectors, because the old harness was too stiff to fit through the manifold there.

Look carefully where the wire connects to the starter. I put the wire on the wrong terminal and decided the starter went bad while working on the harness. D'oh! Also don't forget the oil sender wire, which also runs a long way around the engine. All told, including my starter error and working slowly, I spent most of a day doing the replacement. It could be done in an hour by a fast worker who wasn't so very cautious.

Mike

When I rebuilt my harness I left it connected to the ECU and just unwound it from the engine, taking a few digital pics along the way. The oil pressure sender wire looked ok, it was below freezing and I was working outside in front of my house so I just cut the wire and put a connector on it rather than jack up the car, remove the belly pan and muck with disconnecting the wire. I cut out all the damaged wires one at a time and soldered in new ones between the connector and a good section of harness by the firewall. If I'd had one on hand I would have just replaced the whole harness though, or picked up a used one and rewired it inside the warm house but this did get me back on the road.

Thanks, Mike and James---it's the dumb crumbly harness---I just got it started again !

I'm going by some spiral loom just to see if I can pinpoint where the faults are---I will order a updated OEM harness

P.S. the oil light flickers now ? I'll check the oil--but I read other's with flickering oil light, what's it mean?

Did you check and see if Dave Barton has any harnesses for that year car? He's the best deal I've seen as far as having what you need in stock and knowing it's the right part. You might get lucky on ebay or in a local wrecking yard but that's a gamble. If you're handy with a soldering iron you can pick up some wire and heatshrink tubing and rebuild an old harness, best to pick one up from a wrecker and rewire that so you don't forget how everything goes together.

The oil light flickering could be low oil pressure, a bad sender, or simply crumbling wiring, it's in the same harness.

That is disturbing - it is probably a sender or wiring problem, but you can't just ignore it. If the sender has a drop of oil on the terminal where it has been leaking you can be sure the sender needs to be replaced. If the light still flickers with the sender disconnected you know you have a wiring problem with it.

If the sender needs to be replaced you can do that easily enough. If the problem is in the harness you can live with it until you get a new harness in, but then how will you know if you really have oil pressure problems?

Mike

Right--actually since the harness was crumbling---I temporarily sprial wrapped it --and I think it's fine.

Mike, and James, I have a question. I think my turbo might blow up. I started a thread here:

I cleaned out the oil trap and now the engine has sucking at theoil cap like it should and no more fumes and smell and smoke in theengine area like before--- But I think the pressure is now blowing the hose out of the "Y' elbow nipple from pressure ?

It didn't do this before when it was clogged. How can I test the actuator or make sure it's opening. Doesn't it open after boost? maybe that's why whomever shaved a hole in the compressor side of the turbo?