engine stalled low gear oil
- Thread starter larry1954
- Start date
If nothing else at least the symptoms have become clearer. When the boat is left for a while the engine will start and seem to be normal, but eventually it will stall. You can restart it and it will run for perhaps half the time it ran for before and then it will stall. And so on, until you cannot start the engine at all, but only crank it over. If you leave it then for some time, and presumably the longer you leave it the better, you will be able to start it and it will seem to run all right, until it stalls. And so on. Looking back, I think these have been the symptoms ever since that Saturday. So something odd happened then. But at least, as I say, the symptoms seem to have become clearer.
AllDodge
Well-known member
This is how it should be. The 12.5V at first after start is what happens until the alternator is excited then the voltage comes up
Does look like this is an electrical issue. Are you checking for 12V at the VST on the Gray wire or another place?
Bypass the kill switch either by jumping across the switch or by going from the purple wire on the key to any other purple wire on a gauge.
Swap the main power relay with the fuel pump relay
Yes, I am checking for 12V at the VST with the positive lead on the grey wire terminal and the negative on the other terminal where the black wire is connected.
Checked the kill switch and thought I had found the answer. It did seem faulty. When I first turned the ignition on, no green light came on. I removed the lanyard and manually pressed the switch and then the green light came on, but not consistently. I checked the resistance across the closed switch and it was 0 ohms, but I found that if you fiddled a little with the leads connected to the switch with the ignition on then the green light could easily go off. So, I jumped the wires to by pass the switch entirely. Then started the engine expecting that all would be well, but it was not. It was still doing the same thing: run for a little while then stall, restart, run a shorter time, then stall, etc.
So, I thought that it has to be the relay and so I swapped the two relays, the hp fuel pump relay with the ignition/system relay. Started the engine and still the same symptoms occurred.
But I did notice that the engine seems to idle rather low. It appears to be idling at 700 rpm - difficult to know how to read the tachometer correctly below 1000 rpm, there are three marked divisions under the 1000 rpm mark and the needle is half way between the first and second marks below the 1000 rpm mark, so I am assuming that is 700 rpm. When the engine runs it certainly sounds like it is going to stall any minute, and sure enough it does. It has been a little difficult for some time. We would often launch the boat and I would put it into gear and immediately it would stall. I assumed that it was because it was still cold. It would start again fine and as it warmed up we had no problems, but I would not have thought for an engine with a ECU that that was not normal.
What I wonder is whether the reason it goes for shorter and shorter times is because, with the repeated restarts, it actually gets progressively more flooded, until it just will not start at all because the engine is quite flooded. I would not have thought that an engine with an ecu could do that, but I have a 2004 Ford with a 5.4l V8 EFI and I know that you can flood that engine so that it will not start and then you just have to leave it awhile. I wonder whether the same thing is happening with the 454 simply because the idle is too low. So it stalls and then must be restarted and then stalls again, and so on, until it is flooded and cannot be started until left awhile.
That would not explain why it originally lost power on that Saturday, but that might have been due to a faulty oil pressure switch and/or kill switch.
The other thing is that even if you try to rev the engine after it has got into this cycle of starting and stalling, it will certainly stall when you attempt to open the throttle. After the first stall, when I restart the engine it revs to 1400 rpm and then gradually drops back down to the 700 rpm.
Any ideas? I am fairly sure the oil pressure switch was faulty, though until I remove it and test the resistance with it removed, I suppose that one never knows for sure. Testing the resistance in situ is perhaps not the most reliable method though it is the method that the service manual appears to describe. I should perhaps add that in every case when the engine stalled in these last lot of tests the reading on the hp pump indicated 12.5V just as it stalled.
Checked the kill switch and thought I had found the answer. It did seem faulty. When I first turned the ignition on, no green light came on. I removed the lanyard and manually pressed the switch and then the green light came on, but not consistently. I checked the resistance across the closed switch and it was 0 ohms, but I found that if you fiddled a little with the leads connected to the switch with the ignition on then the green light could easily go off. So, I jumped the wires to by pass the switch entirely. Then started the engine expecting that all would be well, but it was not. It was still doing the same thing: run for a little while then stall, restart, run a shorter time, then stall, etc.
So, I thought that it has to be the relay and so I swapped the two relays, the hp fuel pump relay with the ignition/system relay. Started the engine and still the same symptoms occurred.
But I did notice that the engine seems to idle rather low. It appears to be idling at 700 rpm - difficult to know how to read the tachometer correctly below 1000 rpm, there are three marked divisions under the 1000 rpm mark and the needle is half way between the first and second marks below the 1000 rpm mark, so I am assuming that is 700 rpm. When the engine runs it certainly sounds like it is going to stall any minute, and sure enough it does. It has been a little difficult for some time. We would often launch the boat and I would put it into gear and immediately it would stall. I assumed that it was because it was still cold. It would start again fine and as it warmed up we had no problems, but I would not have thought for an engine with a ECU that that was not normal.
What I wonder is whether the reason it goes for shorter and shorter times is because, with the repeated restarts, it actually gets progressively more flooded, until it just will not start at all because the engine is quite flooded. I would not have thought that an engine with an ecu could do that, but I have a 2004 Ford with a 5.4l V8 EFI and I know that you can flood that engine so that it will not start and then you just have to leave it awhile. I wonder whether the same thing is happening with the 454 simply because the idle is too low. So it stalls and then must be restarted and then stalls again, and so on, until it is flooded and cannot be started until left awhile.
That would not explain why it originally lost power on that Saturday, but that might have been due to a faulty oil pressure switch and/or kill switch.
The other thing is that even if you try to rev the engine after it has got into this cycle of starting and stalling, it will certainly stall when you attempt to open the throttle. After the first stall, when I restart the engine it revs to 1400 rpm and then gradually drops back down to the 700 rpm.
Any ideas? I am fairly sure the oil pressure switch was faulty, though until I remove it and test the resistance with it removed, I suppose that one never knows for sure. Testing the resistance in situ is perhaps not the most reliable method though it is the method that the service manual appears to describe. I should perhaps add that in every case when the engine stalled in these last lot of tests the reading on the hp pump indicated 12.5V just as it stalled.
AllDodge
Well-known member
If its flooding that would account for the idle and stalling and once the motor is at higher rpm it should be able to stay there, just not have the same power. The exhaust should black and maybe some smoke. When it gets where it won't start, could pull some plugs and see if they are wet.
I'm headed to Mom's (80th BD) so will be off line for a while
I'm headed to Mom's (80th BD) so will be off line for a while
Thanks for the suggestion, AllDodge. Hope you have a good time visiting your mother on her 80th birthday.
Thinking over the symptoms of that engine again it occurred to me that they point directly to a vacuum building up in the fuel tank, especially the fact that when the engine is left awhile it will start fine and run a bit, then stall, then start again and run a shorter time, then stall, then start, then run a shorter time again, and so on, with the intervals that it runs before stalling getting progressively less. Looks very much like a vacuum is building up in the fuel tank. I cannot see any reason for why the fuel tank breather hose should be blocked, but the symptoms seem to indicate some such blockage.
So, I thought I might as well try to run the engine with the fuel filler cap off. So pulled the boat out of the shed and removed the fuel filler cap and started it and it ran 5 to 10 minutes and never stalled except when it was still cold. But once it warmed up there was no problem with stalling. 5 to 10 minutes might not sound long, but I could never get it to run that any where near that long before.
So, it must be the fuel tank breather line, is that correct? No other possibility? The boat does not have an anti siphon valve - I removed it last year some time.
If so, I will have to remove the breather hose and see how to remove the vent outlet on the outside of the boat (it is apparently just below the filler cap) and thoroughly investigate how or why it is blocked, and unblock it. That means, I think, that I will have to remove that panel in front of the engine and behind the rear seat in order to get proper access to the top of the fuel tank where the breather hose is located and connects with the vent on the outside of the hull.
I would not have believed that it could be that, but I cannot argue with the evidence. The symptoms disappear if you remove the fuel filler cap. I am sorry that I did not try such a simple test a long time ago. I think that you probably did suggest it.
Thinking over the symptoms of that engine again it occurred to me that they point directly to a vacuum building up in the fuel tank, especially the fact that when the engine is left awhile it will start fine and run a bit, then stall, then start again and run a shorter time, then stall, then start, then run a shorter time again, and so on, with the intervals that it runs before stalling getting progressively less. Looks very much like a vacuum is building up in the fuel tank. I cannot see any reason for why the fuel tank breather hose should be blocked, but the symptoms seem to indicate some such blockage.
So, I thought I might as well try to run the engine with the fuel filler cap off. So pulled the boat out of the shed and removed the fuel filler cap and started it and it ran 5 to 10 minutes and never stalled except when it was still cold. But once it warmed up there was no problem with stalling. 5 to 10 minutes might not sound long, but I could never get it to run that any where near that long before.
So, it must be the fuel tank breather line, is that correct? No other possibility? The boat does not have an anti siphon valve - I removed it last year some time.
If so, I will have to remove the breather hose and see how to remove the vent outlet on the outside of the boat (it is apparently just below the filler cap) and thoroughly investigate how or why it is blocked, and unblock it. That means, I think, that I will have to remove that panel in front of the engine and behind the rear seat in order to get proper access to the top of the fuel tank where the breather hose is located and connects with the vent on the outside of the hull.
I would not have believed that it could be that, but I cannot argue with the evidence. The symptoms disappear if you remove the fuel filler cap. I am sorry that I did not try such a simple test a long time ago. I think that you probably did suggest it.
AllDodge
Well-known member
Thanks, Mom had a great time. Have never seen her so sloshed 
the restaurant made her a stronger then regular drink
I don't see it being the tank vent. Generally this type of issue shows up under load using a lot of fuel, idling would take a long time. Now if your tank was seal real tight (cap and vent 100% sealed) then it could happen, but this would mean when the cap was removed prior to starting you would hear air being sucked in.
We only need three things for a motor to run, one of those is being lost or were getting to much of the one - fuel
the restaurant made her a stronger then regular drinkI don't see it being the tank vent. Generally this type of issue shows up under load using a lot of fuel, idling would take a long time. Now if your tank was seal real tight (cap and vent 100% sealed) then it could happen, but this would mean when the cap was removed prior to starting you would hear air being sucked in.
We only need three things for a motor to run, one of those is being lost or were getting to much of the one - fuel
Ok. I see your point. I know that idling you would never use up enough fuel to cause enough of a vacuum for the engine to stop. But what I was thinking was that on that Saturday we did use a fair bit of fuel, more than normal - wake board riding means getting the boat up on the plane and then dropping back down from it when the rider falls off etc., whereas in normal cruising you just stay on the plane. That tends to work the engine harder. I did not open the fuel filler cap (as far as I remember) until the last time I took the boat out of the shed to test it with the fuel filler cap off. Every other time the cap was untouched from when we bought the boat back from the river after the stalling episode. So, I was thinking that the vacuum was never relieved until quite recently, so that it might take very little to produce a critical vacuum in the tank again and maybe even idling would do it? That was just my thinking, but I know I could be wrong.
When we tested the engine the last time with the cap off and it seemed to be running fine, I thought to put the cap back on to see whether it would stall, but it didn't, but then I realised that it would take a very long time at idle to produce a sufficient vacuum in the tank for the engine to stall.
Could it be air supply? Blocked air filter on the EFI intake? I have always wondered why it takes about 3 goes to start. You start it and it stalls in a short while, then start it again and it stalls again in a short while, and so on for 3 times. It never used to do that, as far as I can remember. Also, as soon as you open the throttle after starting (even when still in neutral) it quite often stalls, though once the engine is warmed up you have no problems. I would have thought an ECU controlled engine would not do that, but would adjust for the conditions so that the engine idled smoothly even at start up. (We do not live in a cold climate - its sub tropical here.)
I did figure out a way to check whether it was an ignition problem: I got an ignition lead tester so that I could see when the engine stalled whether spark was lost before it stalled, so that loss of spark was the cause of the stalling, or only when it stalled, so that something else caused the stalling. But it never stalled on that last occasion (except on first start up when still cold).
When we tested the engine the last time with the cap off and it seemed to be running fine, I thought to put the cap back on to see whether it would stall, but it didn't, but then I realised that it would take a very long time at idle to produce a sufficient vacuum in the tank for the engine to stall.
Could it be air supply? Blocked air filter on the EFI intake? I have always wondered why it takes about 3 goes to start. You start it and it stalls in a short while, then start it again and it stalls again in a short while, and so on for 3 times. It never used to do that, as far as I can remember. Also, as soon as you open the throttle after starting (even when still in neutral) it quite often stalls, though once the engine is warmed up you have no problems. I would have thought an ECU controlled engine would not do that, but would adjust for the conditions so that the engine idled smoothly even at start up. (We do not live in a cold climate - its sub tropical here.)
I did figure out a way to check whether it was an ignition problem: I got an ignition lead tester so that I could see when the engine stalled whether spark was lost before it stalled, so that loss of spark was the cause of the stalling, or only when it stalled, so that something else caused the stalling. But it never stalled on that last occasion (except on first start up when still cold).
AllDodge
Well-known member
The flame arrestor (air filter) should be clean, but if its a little dirty it should still idle. If it was dirty you would really notice that the boat had less power due to using so much fuel. The main item for idling is the IAC and the port it mounts to being clean. You've given it more throttle and it still died or wouldn't start if I remember correctly.
Was the IAC removed to have a look at?
Pick up a resistor LED and paper clip. Connect them as shown, turn key ON (don't start) and count the flashes. If no codes are present you will see 12 (flash, pause, flash, flash, longer pause and repeat). If there is more then one code it will show after see 12.
Was the IAC removed to have a look at?
Pick up a resistor LED and paper clip. Connect them as shown, turn key ON (don't start) and count the flashes. If no codes are present you will see 12 (flash, pause, flash, flash, longer pause and repeat). If there is more then one code it will show after see 12.
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Thanks for that AllDodge. I checked for stored codes but there do not appear to be any - just the 12 x flash, pause, flash, flash sequence which then repeats. I watched it go through for 3 lots of 12 x flash, pause, flash, flash.
No, I have not yet removed the IAC to have a look at it. I am in the process of doing that. I have removed the air filter which does not look particularly clogged and apparently I must next remove the throttle body. Will let you know what I find.
No, I have not yet removed the IAC to have a look at it. I am in the process of doing that. I have removed the air filter which does not look particularly clogged and apparently I must next remove the throttle body. Will let you know what I find.
I am having some trouble removing the throttle body. The service manual says to remove the four mounting studs using a 'stud driver'. I bought a stud extractor which you can see in the picture below sitting on top of the plenum, but the studs do not seem very easy to remove. It seems I would have to apply a fair bit of force and I do not want to break anything.
But it looks like you cannot get to the IAC without removing the throttle body. So am I on the right track? Just use a bit more force?
But it looks like you cannot get to the IAC without removing the throttle body. So am I on the right track? Just use a bit more force?
Ok. Thanks for that. But seems like I should persevere and have a look at the IAC in view of the stalling at idle when cold, do you think? The major service done on the boat some time back after I first bought it does not appear to have included any work related to the IAC (though the plenum was removed). Or if the IAC was at fault would there still be a problem with the idle even when the engine was warm?
AllDodge
Well-known member
If we were just talking about idle issues, then yes it could be the IAC as causing these kinds of issues. Other things that can cause idle issues are vacuum leaks, and if the plenum gasket was not replaced, or if it has developed a small leak this will show up at idle more when cold then when hot. Reasoning, heat expands and also when the motor warms up, vaporization of the gas is better and takes less fuel to idle
What I was thinking was that I should at least address the issue of the stalling at idle, because the engine never used to do that, whatever else may be wrong and caused the sudden loss of revs on that Saturday. I understand how if there is a vacuum leak it would show up more when cold than when warm. I notice that the marine shop did replace the gasket when they removed the plenum.
I really need to check some more as to exactly what symptoms the boat is now showing. The last time I checked by running the engine there were actually none, except for having to start it 3 times before it would idle without stalling when cold. Though that was not out on the water, of course, but just at home on the hose, so it is not a very probing test.
As for the problem we had on that Saturday, I am still puzzled. Whether there actually was a vacuum build up in the fuel tank, I do not know. I do not see any reason why it should suddenly have appeared. I have not done anything that might affect the fuel tank vent line, as far as I know. I did replace the fuel line from the tank by pulling through a new fuel line in place of the old one - unless that somehow interfered with the fuel vent line. I did not remove the panel so I could not see what might have happened to the fuel vent line in the process, though I would not have thought it could have affected the vent line. Also, I now think that I might have released the fuel filler cap when we got home that Saturday. I do not remember hearing any rush of air. But when I started the engine a couple of days later it did not have a problem except with stalling when cold. But a few days after that it would stall even when warm and was back to the symptoms we saw on that Saturday. Yet some days after that and after again removing the fuel filler cap there were no problems except the stalling at idle when cold. Having read back over what I have just written, it really does sound like there is some problem with the vent line and maybe I should go to the trouble of removing the panel and checking. But then there is still some problem with idling when cold, so I should check the IAC and any possible vacuum leaks.
Anyway, that's where I am up to in my thinking on the problem.
I really need to check some more as to exactly what symptoms the boat is now showing. The last time I checked by running the engine there were actually none, except for having to start it 3 times before it would idle without stalling when cold. Though that was not out on the water, of course, but just at home on the hose, so it is not a very probing test.
As for the problem we had on that Saturday, I am still puzzled. Whether there actually was a vacuum build up in the fuel tank, I do not know. I do not see any reason why it should suddenly have appeared. I have not done anything that might affect the fuel tank vent line, as far as I know. I did replace the fuel line from the tank by pulling through a new fuel line in place of the old one - unless that somehow interfered with the fuel vent line. I did not remove the panel so I could not see what might have happened to the fuel vent line in the process, though I would not have thought it could have affected the vent line. Also, I now think that I might have released the fuel filler cap when we got home that Saturday. I do not remember hearing any rush of air. But when I started the engine a couple of days later it did not have a problem except with stalling when cold. But a few days after that it would stall even when warm and was back to the symptoms we saw on that Saturday. Yet some days after that and after again removing the fuel filler cap there were no problems except the stalling at idle when cold. Having read back over what I have just written, it really does sound like there is some problem with the vent line and maybe I should go to the trouble of removing the panel and checking. But then there is still some problem with idling when cold, so I should check the IAC and any possible vacuum leaks.
Anyway, that's where I am up to in my thinking on the problem.
AllDodge
Well-known member
Your thought process is good, I'm just of the opinion all these are related to something, and what that something is, is eluding us. I would like to see a fuel pressure gauge attached and just stay on until this is figured out. I'm still leaning to fuel pressure but not a vent line issue because its to erratic.
Have you pulled the distributor cap yet and had a look under it?
Have you pulled the distributor cap yet and had a look under it?
Just to check to see whether the symptoms were consistent, I pulled the boat out of the shed today and started and ran the engine on the hose, this time for 25 minutes without any problems, either idling or for short times at about 1600 rpm. Did not even have a problem starting, but that may have been because I initially tried to start it with the throttle wide open. I cranked it over quite a bit like that before I started to ask myself what was wrong, and then noticed the throttle position, and so set it back to idle and the engine started first turn of the key and idled stably.
Makes you wonder whether there is some electrical problem? If it was a fuel problem, how could it give trouble a week or so ago but no trouble now? In fact from how it ran this afternoon, you would never guess that there was any problem: there simply were no symptoms, just like the last time I tested it, but not like the time before that when it was idling and would stall and need to be restarted, etc.
Did try to remove the distributor cap, but need a rather longer screw driver for that job. Though according to the invoice from the marine shop, distributor cap, rotor and plugs were replaced at the major service. Could it be a failing ignition module?
Makes you wonder whether there is some electrical problem? If it was a fuel problem, how could it give trouble a week or so ago but no trouble now? In fact from how it ran this afternoon, you would never guess that there was any problem: there simply were no symptoms, just like the last time I tested it, but not like the time before that when it was idling and would stall and need to be restarted, etc.
Did try to remove the distributor cap, but need a rather longer screw driver for that job. Though according to the invoice from the marine shop, distributor cap, rotor and plugs were replaced at the major service. Could it be a failing ignition module?
AllDodge
Well-known member
The WOT keeps the injectors from firing but does allow the pump to run. It's one of the two that is failing and could be the module or the coil (item 8) in the distributor, or ECM.
http://www.mercruiserparts.com/bam/subassembly/31810/2336/7
http://www.mercruiserparts.com/bam/subassembly/31810/2336/7
I have recently replaced the coil. From reading elsewhere the symptoms do sound like they might correspond with a failing ignition module and apparently those GM ignition modules of that era are not the best and are prone to fail (apparently especially when they are hot). The other thing I noticed is that it did use a lot more fuel that Saturday than I would have expected (apparently almost 50 liters in only about an hour or a little more) and there was a smell of fuel about the engine that seemed unusual. I remember too that when accelerating to get the wakeboard rider out of the water I had to use about full throttle, and that surprised me, and that happened not long before the engine lost revs and then stalled.
I wonder too sometimes whether the engine is actually misfiring at idle. I do not think it idles quite as smoothly as it used to. But being a relatively large capacity engine an inexperienced person like myself might not notice the misfire so easily, though no doubt an experienced ear could tell.
Guess it could be the ECM also.
The only question I would have is that if it was the ignition module (or the ECM) would it not throw a code? And yet there seemed to be no codes stored.
Is there is a way to check the ignition module before replacing it?
I wonder too sometimes whether the engine is actually misfiring at idle. I do not think it idles quite as smoothly as it used to. But being a relatively large capacity engine an inexperienced person like myself might not notice the misfire so easily, though no doubt an experienced ear could tell.
Guess it could be the ECM also.
The only question I would have is that if it was the ignition module (or the ECM) would it not throw a code? And yet there seemed to be no codes stored.
Is there is a way to check the ignition module before replacing it?