1989 780 Turbo for sale
zcorpion111Member2016-11-11 at 09:46Post count: 5
I’m selling my 89 turbo for 1500 OBO. It’s got 150,000 miles. It’s up on the registry with pictures under Tristan States. It has a small dent on the hood and a ping on the deck. Clear coat is starting to peel on the trunk. Seems to have some sort of issue starting- starts about half the time. All the electrics work and it’d probably be a great parts car. It’s located in Greencastle, IN and will need to be trailered. My phone number is (765) 720-6629 if anyone is interested.Carl StevenMember2016-11-16 at 17:36Post count: 27
Maybe I missed something but I haven’t been able to find and pictures of this car.
CarlDaviesKeymaster2016-11-16 at 21:51Post count: 149
He is referencing his registry details, which you can get to under the registry link above. His is the second car. But here is the direct link over: https://780coupe.com/vehicle_registry/tristan-stamets/Johan VlagsmaParticipant2016-11-20 at 15:09Post count: 108
“Seems to have some sort of issue starting- starts about half the time.”
This shouldn’t really be hard to diagnose and get working again. I’ve had the occasional poor start for a while and it turned out to be the mass cable from battery to block and body. Re-soldering the connectors made a huge difference. It now starts every time. Another thing to check is the white fuel relay (behind the ash tray) and possibly the fuel injector relay (confusingly called radio suppression relay, under the hood near the left shock tower). Here again the soldered joints often fail and can be mended by carefully re-soldering. Your car looks so nice, it would be a shame to take it off the road and use for parts.zcorpion111Member2016-11-20 at 16:49Post count: 5
I checked the relays and fuses, they seem to be in good shape. The car is now at the point that it just refuses to start. It cranks and you can hear it chug like it’s going to start, but it doesn’t. Really don’t know what it could be.Johan VlagsmaParticipant2016-11-21 at 02:15Post count: 108
Ok, so it can be weak spark or lack of fuel.
Weak spark: check the voltage across the battery (motor off), should be at least 12V. If it isn’t, replace the battery or charge it or jump-start the car. If that helps start the car you have a problem either with an old battery or with the charging system that causes the battery to be flat. With the engine now running, check voltage across the battery, should be at least 13.8 V. If it is too low check the voltage regulator on the back of the alternator, often the brushes go bad (normal wear, it’s an old car). Since you say the problem gets progressively worse this would be my first line of attack.
Lack of fuel: you did check there is fuel, right? not just based on the fuel gauge as it can fail. Can you hear the main pump prime when you turn the key?DaviesKeymaster2016-11-25 at 11:38Post count: 149
You say you checked the relays. The classic no start issue is a failing fuel pump relay (typically a white relay and on the back left side of the relay section). I would try another one if you have any doubt, as I’ve seen replacements fail as well.onakawMember2016-11-29 at 06:03Post count: 17
Throw some fuel down the intake and see if it fires, if it does you have a fuel pump problem.
A good test I use on troubleshooting fuel pumps is to take out the fuel pump fuse and make a hot lead from a good 12v source. When you jump one side of the fuse socket the front pump runs, then jump the other socket and the rear pump will run. If both pumps run its most likely the white relay. Almost any white relay can be repaired by popping off the cover and resoldering all bad jointszcorpion111Member2016-12-12 at 20:13Post count: 5
Sorry for the late reply, I’ve checked the fuel pump relay behind the dash, and its working. I changed get all the spark plugs, which didn’t help. The car cranks perfectly, and it “chugs” like it’s about to fire, but it just won’t. I think the problem may be the fuel injection relay, aka the radio suppression relay. I have tried to find it and where it’s supposed be, there’s some wiring and a fuse wired in that looks like one of the fuses from behind the radio. Is the suppression relay in the black plastic box with a single screw on it?DaviesKeymaster2016-12-15 at 11:10Post count: 149
Tristan, yes check that relay. On the turbo the radio suppression relay is mounted between the battery and the driver’s side headlight. There are two identical black rectangular relays. One is radio suppression and the other controls the cooling fan. I would just switch them and see if it makes a difference. If not you can test them with a test light to see if power is going through. I have had to change mine so if they are the factory original it could be an issue. Try the swap first.zcorpion111Member2016-12-15 at 17:32Post count: 5
I’ve swapped the relays, to no difference. I can hear a difference in the engine cranking when I remove the suppression relay, and when I remove the fuel relay. The engine makes a chugging noise when the relays are in place, and it will turn over and chug, but it won’t start. I checked the air filter and intake, and it isn’t blocked. Not entirely sure what else to check?Johan VlagsmaParticipant2016-12-16 at 04:49Post count: 108
If it is just chugging I guess the engine isn’t firing. I would first check if you have spark. BDP sensor can be the problem, the ignition coil, the electronic breaker module, or the HT wires or any of the involved LT wiring. Or perhaps just the plugs themselves. Have you checked compression?DaviesKeymaster2017-05-02 at 15:11Post count: 149
Tristan- what is the status of of the sale of your car? Still on the market? Did you get the starting issue fixed?zcorpion111Member2017-05-30 at 09:13Post count: 5
Apologies for the late reply, everyone. I was busy finishing up my junior year of college, but my attention has turned back to the 780 as a summer project. So, here’s an update (Spoiler alert: no start as of yet).
First I changed all 4 spark plugs, and replaced the fuel pump relay, as well as the radio suppression relay. However, these made no change, and testing revealed they were actually functioning anyway. I performed a compression test on all the cylinders in the B230FT, but they returned negligible readings on all cylinders (like 20psi!). From this, I gather that there’s either been a catastrophic head gasket failure, or the block cracked over the winter because the cooling system was filled mostly with water, not antifreeze, which expanded and cracked the block. I don’t think it’s timing belt/valve related because the cam does move when the car cranks. However, I’ve never seen a car lose compression in every cylinder, and it’s definitely left me scratching my head. The fuel pumps, relays, and sensors all check out. It’s been narrowed down to this.
An engine rebuild is beyond my means because I’m just a student, but I was able to source a B230 engine nearby from a wrecked 240. Would I be able to have my mechanic directly swap this into the 780, fitting correctly to the trans? Just to be clear, I would be swapping the non-turbo engine into the turbo car. The engine comes with the 240 ECU and everything except injectors, but I imagine that the 780 injectors would fit right on.
If anyone has any ideas, please let me know. I really want to get this thing back on the road- it looks so sad just sitting there. I’ll go sit inside it sometimes just because the interior is such a nice place to be. If anyone has any alternative theories (if I’ve mis-diagnosed the issue) definitely suggest them. If anyone’s interested in buying the car as a parts car or a project, let me know. It’s not the world’s prettiest 780, but there’s hardly any left. My friends/parents want me to junk it and I can’t bring myself to do that, but if I can and put the money toward another project, then I may just have to. Getting it back on the road, however, is my main goal.nckPOLMember2017-06-06 at 01:17Post count: 31
firts of all: is there a spark on a spark plugs when cranking? dooes it smell a gas, and is the gas on a spark after cranking?
If there is a spark and gas – it has to start, unless the timing gear is correct.
If there is no spark – check the spark distributor and the coil, and ignition wires, then check shaft sensor, hall sensor – for me it looks like a faulty shaft sensor or temperature sensor for ECU (you have two of them – one for dashboard and one for ECU)
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