1988 xjs 5.3 v12
#41
The following 2 users liked this post by baxtor:
Grant Francis (10-09-2017),
Greg in France (10-09-2017)
#42
I think the best course of action is to definitively find out if it is fuel pressure or spark that is causing it to die. A fuel pressure meter in the fuel line going to the rail is the best way.
Another less reliable way is to squirt some starter fluid (ether) into the intakes immediately after it has died and will not start. Then see if it starts.
If it does start on ether, you have a spark problem. If it does, you have a fuel problem.
Greg
Another less reliable way is to squirt some starter fluid (ether) into the intakes immediately after it has died and will not start. Then see if it starts.
If it does start on ether, you have a spark problem. If it does, you have a fuel problem.
Greg
I am currently in a NO START situation right now.
#43
Catching up, gotta luv this call out of retirement, NOT.
Inside the Ign Amp, attached by a philips screw, is a condensor cylindrical thing, remove it, throw it away.
It was originally a noise suppressor, and now its OLD, and they are attached to a +ve terminal of the module. They are known to "leak" to earth, thus reducing spark, and eventually stopping spark at all.
Nothing bad will happen. The engine may even keep running.
Weak spark can also be attributed to either of the 2 coils being bad. Seperate the LT leads that supply the coil out the front of the radiator, and start the engine once more. It will run just fine on that single coil, but stumble a tad above 3000rpm.
That star wheel gap is a tad lo at 0.009. I like them at about 0.014, and most feeler gauge sets have a plastic strip just for this task.
Check the spark integrity straight out of the coil. It should be a FAT, CRACKING Blue spark. If so, and you have a weak spark AT the plugs, then the carbon contact inside the cap may be affecting that end spark at the plugs.
On a HE engine, the spark plug cleanliness is paramount. If they are sooty, and black, clean them, as this engine will NOT burn clean a cruddy sparker.
Inside the Ign Amp, attached by a philips screw, is a condensor cylindrical thing, remove it, throw it away.
It was originally a noise suppressor, and now its OLD, and they are attached to a +ve terminal of the module. They are known to "leak" to earth, thus reducing spark, and eventually stopping spark at all.
Nothing bad will happen. The engine may even keep running.
Weak spark can also be attributed to either of the 2 coils being bad. Seperate the LT leads that supply the coil out the front of the radiator, and start the engine once more. It will run just fine on that single coil, but stumble a tad above 3000rpm.
That star wheel gap is a tad lo at 0.009. I like them at about 0.014, and most feeler gauge sets have a plastic strip just for this task.
Check the spark integrity straight out of the coil. It should be a FAT, CRACKING Blue spark. If so, and you have a weak spark AT the plugs, then the carbon contact inside the cap may be affecting that end spark at the plugs.
On a HE engine, the spark plug cleanliness is paramount. If they are sooty, and black, clean them, as this engine will NOT burn clean a cruddy sparker.
The following users liked this post:
Greg in France (10-09-2017)
#44
Catching up, gotta luv this call out of retirement, NOT.
Inside the Ign Amp, attached by a philips screw, is a condensor cylindrical thing, remove it, throw it away.
It was originally a noise suppressor, and now its OLD, and they are attached to a +ve terminal of the module. They are known to "leak" to earth, thus reducing spark, and eventually stopping spark at all.
Nothing bad will happen. The engine may even keep running.
Weak spark can also be attributed to either of the 2 coils being bad. Seperate the LT leads that supply the coil out the front of the radiator, and start the engine once more. It will run just fine on that single coil, but stumble a tad above 3000rpm.
That star wheel gap is a tad lo at 0.009. I like them at about 0.014, and most feeler gauge sets have a plastic strip just for this task.
Check the spark integrity straight out of the coil. It should be a FAT, CRACKING Blue spark. If so, and you have a weak spark AT the plugs, then the carbon contact inside the cap may be affecting that end spark at the plugs.
On a HE engine, the spark plug cleanliness is paramount. If they are sooty, and black, clean them, as this engine will NOT burn clean a cruddy sparker.
Inside the Ign Amp, attached by a philips screw, is a condensor cylindrical thing, remove it, throw it away.
It was originally a noise suppressor, and now its OLD, and they are attached to a +ve terminal of the module. They are known to "leak" to earth, thus reducing spark, and eventually stopping spark at all.
Nothing bad will happen. The engine may even keep running.
Weak spark can also be attributed to either of the 2 coils being bad. Seperate the LT leads that supply the coil out the front of the radiator, and start the engine once more. It will run just fine on that single coil, but stumble a tad above 3000rpm.
That star wheel gap is a tad lo at 0.009. I like them at about 0.014, and most feeler gauge sets have a plastic strip just for this task.
Check the spark integrity straight out of the coil. It should be a FAT, CRACKING Blue spark. If so, and you have a weak spark AT the plugs, then the carbon contact inside the cap may be affecting that end spark at the plugs.
On a HE engine, the spark plug cleanliness is paramount. If they are sooty, and black, clean them, as this engine will NOT burn clean a cruddy sparker.
I have removed the plugs twice now upon making changes to clean them before restart, each time they are back in, it will fire up almost immediately, then it dies again and now will not restart.
The two things that are of concern to me now seems to be quality of the spark, and the fact that my plugs are dry..
#45
I should have written "if it does NOT start on ether you have a spark problem".
The pressure gauge must be BETWEEN the pump and the fuel rail, plumbing it into the flexible line before the A bank of the V is the best place.
As it started after you fiddle with the dizzy, my money is still on the ignition system as the culprit. Could you list all the things you have done to it? Also are you sure the 12v feed to the new coil is connected to the right terminal (they are not very obviously marked) and that the connector is 100%, the copper inside the connector can break.
The pressure gauge must be BETWEEN the pump and the fuel rail, plumbing it into the flexible line before the A bank of the V is the best place.
As it started after you fiddle with the dizzy, my money is still on the ignition system as the culprit. Could you list all the things you have done to it? Also are you sure the 12v feed to the new coil is connected to the right terminal (they are not very obviously marked) and that the connector is 100%, the copper inside the connector can break.
Last edited by Greg in France; 10-09-2017 at 07:28 AM.
#46
OK.
The dry plugs can only come from inop Injectors. They may be "clicking" but may not be spraying any, or enough fuel.
BUT,
The fact it runs for 30 seconds and then dies is the puzzle.
Black plugs, either wet or dry, are from overfueling.
I will read this thread from post #1 and come back, need to catch up a tad more.
The dry plugs can only come from inop Injectors. They may be "clicking" but may not be spraying any, or enough fuel.
BUT,
The fact it runs for 30 seconds and then dies is the puzzle.
Black plugs, either wet or dry, are from overfueling.
I will read this thread from post #1 and come back, need to catch up a tad more.
The following users liked this post:
Mav0199 (10-09-2017)
#47
I should have written "if it does NOT start on ether you have a spark problem".
The pressure gauge must be BETWEEN the pump and the fuel rail, plumbing it into the flexible line before the A bank of the V is the best place.
As it started after you fiddle with the dizzy, my money is still on the ignition system as the culrpit.
The pressure gauge must be BETWEEN the pump and the fuel rail, plumbing it into the flexible line before the A bank of the V is the best place.
As it started after you fiddle with the dizzy, my money is still on the ignition system as the culrpit.
I am also starting to become a proponent of the ignition system being the culprit as i am not getting a "cracking" spark.
#48
Before the B bank regulator is fine, but there is hardly any flexible there to do it, are you SURE you have it between the injector rail exit and the FPR?
#49
Is there a way to to check (with numbers) the quality of spark i am getting at the plugs?
#50
If black plugs are from overfueling either wet or dry, then my problem is most certainly from the lack of spark?
BTW, as of right now, it will NOT start anymore. however, when it did run for a few minutes, my father said that when i revved the engine, it would emit some black smoke from the exhaust.. overfueling still?
BTW, as of right now, it will NOT start anymore. however, when it did run for a few minutes, my father said that when i revved the engine, it would emit some black smoke from the exhaust.. overfueling still?
#51
Take your voltmeter, Set it to DC Volts, and attach it to the +ve of the coil, and note the volts with Ign ON. You should be around 12v ish.
Crank the engine, and note the volts again, they will drop, but only 1V or so. If it starts, watch the volts, and when it dies, take note again.
If these notations are below 10V, and then drop way off as it dies, the wire itself, OR the electrical section of the Ignition Switch is dying due to age, very common.
One car here many years ago had overfueling issues, and eventually, over many beers, we established the car was just fine before new tyres were fitted, HAHAHA, but on inspection, the return fuel metal pipe, under the LH side of the car was flattened by the idiots jacking anywhere they chose. Once cut, and hose clamped into place the car was returned to normal. The reduced flow of fuel back to the tank, caused the rail pressure to rise too far and flood the engine. OK, you got 30ish PSI, but to look at this pipe is free.
Also, near the 5A Inlet track, is a fuel enrichment vac valve/switch, They fail, and 15% rich is the result. It is wired in with the micro switch at the rear of the capstan, so unplug them both electrically, and DO NOT join the wires to each other or anything else. That will stop the ECU from supplying a richer fuel mixture. Unplugging that fuel valve from the vac only will cause that valve to keep the ECU in the rich mode.
When it runs, and then dies, feel the temp of the Coil. Is it HOT, or about the same as the rest of the engine area?. Hot, means it is overloaded, and the module controls this, and I know its New, but, that can mean nothing, as there are lots of threads in here about these Modules being hissy right out of the box. The amp itself will get WARM, but if its HOT after that short burst, there is a coil, lead, plug issue causing a back feed to the system.
Crank the engine, and note the volts again, they will drop, but only 1V or so. If it starts, watch the volts, and when it dies, take note again.
If these notations are below 10V, and then drop way off as it dies, the wire itself, OR the electrical section of the Ignition Switch is dying due to age, very common.
One car here many years ago had overfueling issues, and eventually, over many beers, we established the car was just fine before new tyres were fitted, HAHAHA, but on inspection, the return fuel metal pipe, under the LH side of the car was flattened by the idiots jacking anywhere they chose. Once cut, and hose clamped into place the car was returned to normal. The reduced flow of fuel back to the tank, caused the rail pressure to rise too far and flood the engine. OK, you got 30ish PSI, but to look at this pipe is free.
Also, near the 5A Inlet track, is a fuel enrichment vac valve/switch, They fail, and 15% rich is the result. It is wired in with the micro switch at the rear of the capstan, so unplug them both electrically, and DO NOT join the wires to each other or anything else. That will stop the ECU from supplying a richer fuel mixture. Unplugging that fuel valve from the vac only will cause that valve to keep the ECU in the rich mode.
When it runs, and then dies, feel the temp of the Coil. Is it HOT, or about the same as the rest of the engine area?. Hot, means it is overloaded, and the module controls this, and I know its New, but, that can mean nothing, as there are lots of threads in here about these Modules being hissy right out of the box. The amp itself will get WARM, but if its HOT after that short burst, there is a coil, lead, plug issue causing a back feed to the system.
The following 2 users liked this post by Grant Francis:
Greg in France (10-09-2017),
Mav0199 (10-09-2017)
#52
Take your voltmeter, Set it to DC Volts, and attach it to the +ve of the coil, and note the volts with Ign ON. You should be around 12v ish.
Crank the engine, and note the volts again, they will drop, but only 1V or so. If it starts, watch the volts, and when it dies, take note again.
Crank the engine, and note the volts again, they will drop, but only 1V or so. If it starts, watch the volts, and when it dies, take note again.
One car here many years ago had overfueling issues, and eventually, over many beers, we established the car was just fine before new tyres were fitted, HAHAHA, but on inspection, the return fuel metal pipe, under the LH side of the car was flattened by the idiots jacking anywhere they chose. Once cut, and hose clamped into place the car was returned to normal. The reduced flow of fuel back to the tank, caused the rail pressure to rise too far and flood the engine. OK, you got 30ish PSI, but to look at this pipe is free.
Also, near the 5A Inlet track, is a fuel enrichment vac valve/switch, They fail, and 15% rich is the result. It is wired in with the micro switch at the rear of the capstan, so unplug them both electrically, and DO NOT join the wires to each other or anything else. That will stop the ECU from supplying a richer fuel mixture. Unplugging that fuel valve from the vac only will cause that valve to keep the ECU in the rich mode.
When it runs, and then dies, feel the temp of the Coil. Is it HOT, or about the same as the rest of the engine area?. Hot, means it is overloaded, and the module controls this, and I know its New, but, that can mean nothing, as there are lots of threads in here about these Modules being hissy right out of the box. The amp itself will get WARM, but if its HOT after that short burst, there is a coil, lead, plug issue causing a back feed to the system.
I am also going to re-adjust my plugs. when i set the gap to .025, the ground strap seemed to be at a downward angle and overhanging the center electrode. I am going to try and make the strap even across and file it so that it will end about the middle of the electrode. I am also going to see if i can find a KV plug tester. Should that coil be able to jump a 40KV gap? or what is the spec for the HE engine?
#53
Greg
#55
Greg
The following users liked this post:
Mav0199 (10-09-2017)
#56
The lump mechanism which is within the steel outer end of the cable is probably seized. It requires a steel inner to move within an outer, and the cable has to actuate it. The two steel bits seize through lack of use, lack of lube, etc etc. Sometimes they can be persuaded to move y disconnecting the cable and WD 40ing it and using two gips to try to get the thing unseized. If not new ones are available, though somewhat of a pain to fit. Perhaps get the car going and then do this smaller fix?
Greg
Greg
#57
UPDATE:
- Tested voltage to +Ve on coil with key ON = 12.4v
- Tested voltage to +Ve on coil whilst cranking = fluctuation between 9.8 and 10.4v
- while doing this test, she accidentally started! As soon as it started the voltage reading on +Ve was 12.2v
- Purchased a KV ignition tester. According to the spec, a GM ignition module and coil should produce around a 30 Kv spark (which is around 1-1/2” of air gap on the tool).... this is where it gets good! Running this test on the HT lead off the coil gives me a cracking blue/white spark that bridges the gap without problem. when the same test is performed out at a plug wire.... it will barely jump a 1/8” gap and is orange (With a new plug wire) and intermittent.
so I believe I have found the culprit! Now to figure out why....
- Tested voltage to +Ve on coil with key ON = 12.4v
- Tested voltage to +Ve on coil whilst cranking = fluctuation between 9.8 and 10.4v
- while doing this test, she accidentally started! As soon as it started the voltage reading on +Ve was 12.2v
- Purchased a KV ignition tester. According to the spec, a GM ignition module and coil should produce around a 30 Kv spark (which is around 1-1/2” of air gap on the tool).... this is where it gets good! Running this test on the HT lead off the coil gives me a cracking blue/white spark that bridges the gap without problem. when the same test is performed out at a plug wire.... it will barely jump a 1/8” gap and is orange (With a new plug wire) and intermittent.
so I believe I have found the culprit! Now to figure out why....
Last edited by Mav0199; 10-09-2017 at 06:28 PM.
The following users liked this post:
Grant Francis (10-10-2017)
#58
#59
I placed it on 40 amp just as I was trying to start it, it melted the plastic on the handles on the clamp and the insulation on the wire.
plugs have always looked dry. Black sooted.
It ran just as well as it did in the previous videos, seems smooth, then just dies. Spark to me doesn’t look very impressive, but it’s only a .025 gap, so I’m not really sure, I will make a video of that tomorrow.
plugs have always looked dry. Black sooted.
It ran just as well as it did in the previous videos, seems smooth, then just dies. Spark to me doesn’t look very impressive, but it’s only a .025 gap, so I’m not really sure, I will make a video of that tomorrow.
#60
Good you found the problem..............