engine stalled low gear oil


L

larry1954

New member
If anyone can throw some light on this problem, I would be grateful. We were using our 1997 271 Fastech (454 Magnum, Bravo 1) doing some wakeboard riding behind it when it suddenly lost revs and then stalled. It started again fine, but would not rev. Eventually, it would only start and then stop not much later after being put in gear. I checked the gear oil reservoir and found it empty. I refilled it, but that did not change anything. Still could start the engine but as soon as it was put in gear it would stop. I then put some more oil in the engine, though the engine oil level seemed all right. But the engine could then be started and I put it into gear and we limped back to the boat ramp and then it stalled again just near the ramp. Could not start it again because the batteries were flat by then.

What is wrong with it? Anybody know?

I did not hear any alarm for low gear oil, but I could just have not heard it. But if it was the low gear oil would that cause the engine to stop? And why did it not go again after the reservoir was topped up?
 
gear oil reservoir and found it empty
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Could use your engine serial number, being a 1997 model it can be a VST or Cool fuel MPI. This difference would also mean a MEFI 1 or 3 ECM.

Not hearing the alarm could mean its not connected or has gone bad. Low gear lube will not keep the motor from starting, but will put the motor in power reduction IF you have a MEFI 3 ECM.

Did you notice the oil pressure gauge?
What kind of maintenance was done on the boat this season?
 
I'm thinking the outdrive oil is not related to the engine issues. It sounds like your low level alarm is disconnected, otherwise it would have warned you when the gear oil got too low.

Fuel injected Engine?
 
Never disassembled a bravo drive but have seen the pieces. Without drive oil could the cone clutches have gauded and have too much friction until they cooled down to allow the engine to run. Just a thought, need someone more experienced to chime in.
 
Engine serial number 0K005781. It is MPI with a VST. AllDodge might remember that I only recently overhauled the VST, replacing the pump and filter. Wonder whether the high pressure pump just failed? It was an aftermarket one. Just checked it and it is getting 12V and whirring, so probably working(?).

Been reading about the IAC valve. I wonder whether it could be that? Never tried starting the engine with some throttle in neutral, just always with the throttle lever at its lowest point. Engine would always start fine and go up to about 1400 rpm at startup and then settle back down to idle, but then sooner or later after being put in gear it would stall. It progressively got sooner rather than later, until it would not even get to being put into gear and would stall. It began when we were doing about 2600 rpm and suddenly the revs were cut back to about 1500 rpm. I thought at first that maybe I had accidentally hit the throttle lever, but I hadn't. It progressively got worse from there, stalling and restarting and then not able to rev above idle, then not even able to maintain idle, in gear or out of gear. Until at last, after putting more oil in the engine, I started it again and idled back to the boat ramp, but stalled just as we reached the ramp. But we were thankful to be able to get that far. Had some trouble getting it on the trailer, but managed in the end and drove home and put the boat in the shed. Now try to figure out what went wrong ...

You can turn the propeller by hand when in neutral, but it will not turn clockwise when in forward gear, which I suppose one would expect since it is then engaged to the engine. Looking at the bottle of gear oil which I carry to top up the gear oil reservoir, it does not look like I added that much gear oil. So it may not in fact have been below the low level mark in the reservoir and so the alarm would not have sounded. But it is certainly overfull now.

Been reading about vapor lock problems with the VST. Could be that. Or maybe just a blocked vent line from the VST? Symptoms look very much like vapor lock symptoms as far as I can tell. This is probably the first time the boat has been extensively used since my work on the VST. Maybe I did something wrong in reassembling the VST? Or maybe just that the vent line is blocked and pressure builds up in the VST and the high pressure pump can no longer work?
 
Pulled the boat out of the shed today and started it on the hose and checked to see if it would rev to about 2600 rpm. Did so with no problems. I could not do that on Saturday when it was causing trouble on the water. But of course the engine bay and engine were now quite cool. So looks like some sort of vapor lock problem? Daytime temperatures here at this time of year are still quite warm, about 30 degrees C.
 
Sorry, took a while to get back with, Easter and a 500 mile round trip in 2 days, great to be home again

S/N great and thanks for the reminder

It's not vapor lock (VL), this only happens with heat soak. On a hot day your all running good and you stop for refreshments for 1 to 4 hours. When you stop the motors heat starts soaking into all the fuel lines and it starts to expand and boil (not really boil) getting air pockets. When you go to start up again, it may or may not start, but soon as you give it throttle to take off, it dies. The motor is now VL because all you have to burn is gas fumes. Can get into more into the related issues, but right now lets get back to your current problem.

I'm thinking now you may have a fuel related and/or pressure problem. Need to get a fuel pressure gauge on the fuel rail at the shrader valve.

The IAC will cause it to die at idle but not at higher speeds. Reving more in neutral to 2600 takes next to no fuel, but in gear takes a lot of fuel. If the vent line was blocked to the tank, there would be a restriction and not enough fuel. If it was the return line blocked you would be getting to much fuel and would see black smoke
 
Ok. I understand that about the VL, and yes, it is not those symptoms. It was running fine for about an hour and a half and then suddenly lost revs, and just got worse. Wonder whether I should take the VST apart again? Could that gauze have got blocked again? But when it was blocked before it reduced the revs, but it did not cut them entirely.

Certainly seems like a fuel supply problem. I could put the fuel pressure gauge on again, but until I can get the boat back in the water I am not likely to be able to tell much, and that could be a few weeks. But as I say, it did rev to 2600 rpm in neutral while on the hose at home yesterday and it would not do that on Saturday when the boat was in the water. That seems odd to me.
 
it did rev to 2600 rpm in neutral while on the hose
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I understand why most folks think this statement is correct, but its not. Moving a prop in the water and moving a 5000+ pound boat takes a lot of fuel. Reving the same rpm in neutral takes maybe 1/4 ounce

You can check the fuel pressure without going to the water. The fuel pressure should be the same, only issue is again with the volume. If pressure shows good on the hose, then need to check for codes, and if no codes, then pressure on the water
 
I understand what you are saying about the difference in fuel demand between being in neutral and the prop moving. But I should have said that when it was on the water I even tried to rev the engine in neutral and it would not do so. That is, I tried it when it was not in gear. But now, at home 2 days later it will rev in neutral to about 2600 rpm.
 
Thinking about it some more, I am really inclined to think it will be the filter before the high pressure pump in the VST. I replaced it last year, but I suspect that that fuel tank has still got rubbish in it, though I have tried pumping it out and filtering out the rubbish, but there is probably still more there, and with the wakeboard riding, going fast then stopping, it would probably stir up that tank. It certainly seems to have the characteristics of a blocked filter problem.

Probably should install an extra filter of about the same fineness as the one in the VST before the VST, and simply replace that filter every so often until the tank is clear, so I do not have to go to the trouble of opening up the VST.
 
Ok, got it
The motor was using a lot of fuel and something caused it to get a lot less. Place in neutral and there is still not enough to rev up. Gets so bad it will only idle back to dock. Now it revs fine but has had time. It might be the tank vent line and the motor was drawing a vacuum on the tank. Maybe antisiphon valve. weak low pressure fuel pump, restriction or VST internal issue.

If its the vent line, the motor will do it again and when it does, removing the gas cap you will hear air get sucked in, then it will run again
 
I tried simply reving the engine out of gear when we were on the water to see if it had anything to do with being in gear. But apparently not, because it would not rev out of gear or in gear. Whereas a couple of days later at home it would certainly rev in neutral.

I understand about the possibility of a blocked vent line. Symptoms do seem to match that because it just got progressively worse, until after a short delay (while I added gear oil and then engine oil) maybe it could draw in enough fuel to get back to the boat ramp and then a couple of days later it would rev fine. We did put more fuel into the tank just before taking it to the water and when I unscrewed the cap I noticed that it was rather loose, but after adding more fuel I replaced the cap tightly. So maybe there is something in that. (I certainly would not think that the filter in the VST would block so quickly as to account for the fairly rapid reduction in fuel supply which was evidently occurring.) The fuel tank vent line is difficult to get to in the boat. I think one has to take the panel off in the engine compartment that is in front of the engine and behind the rear seat before you can get good access to anything above the fuel tank. Cannot notice anything odd about the exit of the vent line on the side of the hull. (We get mud wasps around here which can build nests in breather lines, but cannot see anything like a nest on the exit of the breather line.) And if the line is kinked somewhere, one would think that it would have shown up before. But I guess you never can be sure.

The boat does not have an antisiphon valve - I removed that before when trying to track down the previous problem. That is when I also considered the possibility of the breather line being blocked.

The low pressure fuel pump was replaced not so long ago by the marine shop when I first got the boat. I have looked for restrictions in the fuel lines - cannot see any. I did replace the fuel line from the tank to the low pressure pump with the previous problem because someone suggested that it might be delaminating on the inside.

What could be wrong internally in the VST? Some unusual and very rapid blocking of the filter? I guess you never know for sure until you take it apart.

I wondered about getting this part just in case:

www.ebay.com.au/itm/FUEL-PUMP-Fits-...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

Seems a very cheap replacement pump and filter. Any thoughts?
 
Your motor should have a 10 micron filter before the mechanical pump, so anything smaller then that should not be an issue with the VST
 
Perhaps in theory that should be so, but it was the VST filter just before the high pressure pump which clogged last time with a very fine material - don't know exactly what it was, but I could not guarantee that there was no more of that in the tank. This boat had been sitting idle with the fuel in the tank for some years before I purchased it. I tried to get everything out by pumping the fuel out of the tank through a filter into a drum, but I do not know that I have got it all out yet.
 
I finally decided that the only thing to do was to take apart the VST, and this is what I found. No clogging of the fine gauze filter before the high pressure pump - looks pristine, which is good because it means that all my efforts to clean out the tank may have worked. But, when I tried to put the VST back together I was puzzled by the fact that the rubber gasket was somehow too big to fit in the groove of the tank. I noticed also that the gasket was evidently pinched in at least one place. Also, I did notice when I was taking off the lid of the VST that the screws holding it on seemed a little loose, or at least looser than they should be.

I am wondering whether the lid was a little loose and under pressure the gasket popped out and consequently the VST was no longer air tight. I know that the marine mechanic did not use the proper gasket when he originally took apart and reassembled the VST when he originally serviced the boat. He simply used some all purpose gasket in a tube. I assumed that was because he could not easily get the proper part here in Australia and so improvised. Well, I went to the trouble of getting the proper part from the US, but maybe I did not tighten those screws down sufficiently. Perhaps the gasket blew out under pressure and expanded with the heat and that is why it will no longer fit.

Could that explain the symptoms of the boat?

Should I go to the trouble of getting the correct gasket again, or just use gasket glue and this time make sure the screws are down tight and check them every so often?
 
I don't see the issue with being loose or the gasket causing the issue, because the tank is the same as a carburetor float bowl. The low pressure pump supply's fuel to the tank, and the HP pump inside uses that fuel to pump into the fuel rail.

I like using the correct gasket, but so long as the tank does not allow fuel or vapor to leak out you should be good
 
Those O-rings gaskets have a tendency to "grow" once installed and then taken apart again. On my old boat (twin 502's with VST), I was having some fuel issues and decided to check the internal VST filter like you did, and had the same thing happen.....O-ring was now too big to re-install. The big problem was that I was out on the boat at a cove when I decided to do this, so I needed to get it back together to get home. I ended up cutting the oring so it fit again, and then used some gasket sealant where the 2 ends of the O-ring now met. This held for 7 years, and is probably still holding. So if you aren't in a rush and can get another gasket, do so, but you can do what I did if you need to.

For your fuel issue, it is all a guess until you put a gauge on the Schrader valve and check your fuel pressure.

Do you have a spin-on type filter before the mechanical pump ? You should change it. Do you have a picture of your setup ?

How old is your fuel ? is the boat kept outside ? How is the O-ring on the fuel cap ? Water in the fuel will cause it to act this way.
 
Ok. Well, I guess the next step is the gauge on the Schrader valve. Maybe one of the pumps does not work. Maybe the high pressure pump, though it is less than a year old and has not been used much. The VST was full of fuel when I took it apart, so you would think the low pressure pump must be working. That pump is not that old either.

Yes, the boat is kept on the trailer in a locked shed, not outside. Fuel is not that old. Put fresh fuel in just before going to the water. O-ring on the fuel cap looks old but still intact. We do not use this boat off shore.

Just tried to test the high pressure pump while I had the VST out of the boat. I put fuel in the VST, pretty well full, just put the lid back on with pump attached (but did not put the screws in to secure the lid) and then connected 12V to the pump. You could hear the pump spinning, but nothing was coming out the out line. Should fuel have been pumped out? Or was there something else that needs to be done?

But if the high pressure pump is not working, would the boat still run on the low pressure pump and even be able to rev to 2600 rpm on the hose in neutral at home? Can the low pressure pump pump fuel through the VST without the high pressure pump working at all?
 
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