Hi guys, thanks for all the previous input.
My '85 Coupé is still showing no sign of life, i seem to have fuel to the rail, a trigger signal to the injectors and a spark at the plugs i can reach, but I’m getting nothing, i tried ‘easy start’ spray and not even a cough… what am i doing wrong? It ran last week and is now deader than a dead thing.
Any thoughts? Pointers? Anything?
Can you hear the injectors clicking while trying to start?
Is the pump running while trying to start?
A Noid light or a LED with a 800Ohm resistance for the injectors and a test light for the pump can be of great help.
Hi,
I have made a noid lamp and can see the lamp going on and off as i crank, i had the rail off and bench tested all 12 injectors and they seem fine, i have 12v on one pin and 0v on the other pin of the injector plugs…
I have fuel at the rail (i can’t test the pressure)
I have a spark at at least two of the plugs.
I have a sore brain
The car has been pretty much faultless for the 17 years ive had her.
Hi… how do you know your getting spark?
If you are simply getting a spark to the plug doesn’t mean the plug is sparking.
I found that if I started and ran the car for multiple short times (whilst testing something) without bringing it up to temp, the plugs would carbon-up. I would have spark to the plug but as it was shorting I had no actual plug spark.
Solution…. Remove all plugs and clean.
Hi Trev, remove all the plugs? Well… that’s a wonderful dream, I’ll have to strip have the engine bay. But you do make a good point. Cheers,
P.
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Yes, but does the fuel pump run when you crank?
if it were just carbon fouled plugs, I would think it would at least try to catch, or run very poorly.
there was a useful thread devised earlier this year on ‘won’t start’ with a huge checklist. Anybody know where that is?
Fuel pressure and Coolant Temperature Sender are important for starting.
I think the CTS is my next thing to check. I am going to go back to the fundamentals and ensure sparks and fuel. I’m sure it can’t be timing cos ive not moved anything.
The check list you mention would be great.
Many thanks,
P.
Another “suddenly no starter” could be the FPR.
Mine had a bit of a leak until one day it refused to start again. Luckily I had just received a new one.
I haven’t been able to test them properly but there’s no leak to the vacuum pipes. Can they fail so that there’s no pressure behind them?
No leak usually means they are good, but only certain way to see what is really happening is with a pressure gauge.
No start checklist is on the v12 forum around April
I had an intermittent no start, I’m pretty sure it ended up being a bad CTS connection, due to the sender AND the plug. It may or may not work, but unplug the CTS and see if it starts.
Here is the thread for No Start Checklist:
Just throwing this out there,
If the MAF sensor in the ECU is good,
I would look at grabbing new ignition amplifier module from Your local GM dealership. I believe they say a 1985 K5 Chevy Blazer will work for half the cost, and also check out the condition of that coaxial wire.
Common failure points.
Then delve into the list posted earlier.
Gary, does an 85 have a MAF sensor?
P.
Here is what I got from your postings and testings…And…for continuity…you have some of your tests on a prior post, so some of the answers you are now getting on this post are redundant…because some folks may not have seen your prior post. So…
- You have spark.
- You have Noid light operation on the injector harness plugs.
- You have fuel at the FPR
- You have injectors clicking.
- If the amplifier was bad, you would not have injector operation.
- If the white coax wire was bad, you would not have injector operation.
You should check the CTS and the connector and the wiring as recommended several days ago in your prior posting. You should also check the vacuum line from the crossover pipe back to the ECU. Both are common faults. Are the plugs wet, an indication of overfueling ? Goes the exhaust smell like raw fuel ? Disconnect the connector from the CTS, use a short wire and plug it into the harness connector pins, then try to start. This will jumper the CTS and stop any overfueling from a faulty CTS.
But it will not remedy a fault in the connector or wiring. Ohm them out. SD Faircloth
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Good evening Mr Faircloth, thanks for the input, my next test will be the CTS, if i can reach it, the car decided to die inside my very small garage, i can’t push it outside as its on a slope and I’d never be able to push it back…
I am close to removing all the ancillaries from.the top.of the engine, then i can check the plugs.
Not that I’m an ECU expert here but I believe your year of car would have a 16 ECU that would have a MAP sensor that is built into your ECU and plugged in by the vacuum line at the ECU. I believe they were prone to fail on the older version of the ECU’s. At the very least you might want to double check that line connection or your car or it won’t run worth crap.
Others may chime in here.
Paul. Six years ago I found myself in your situation and I addressed the plugs with a success that has prevailed. Mine is an 82.
Suggestions:- unbolt the AC without disconnecting the piping and prop it up with a piece of wood to access the front plugs. I removed the TPS mount and ground a pathway through it to access the plug underneath in future. The modification to the TPS mount cannot be seen from above when it’s all back in place.
One of the risks of removing and replacing plugs is stripping the threads. To avoid this I only replace plus (for the first few turns) with a dowel and sleeve.
Last suggestion is to avoid starting the beast without letting it come up to temp.