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Boat looses power, pops, backfires, gets all nasty


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Hey everyone,

2002 Malibu 21LSV, EFI monsoon.

This has been going on for 2 days. The first day it only happend once, and I thought it was a fluke. On saturday it happened several times and I am worried:

Several hours into the day (running the boat pretty hard, lots of people, lots of skiing and boarding), while under way, the boat would start to cough, sputter, pop, backfire, and ultimately loose a little power (but very noticeable). Reminds me of how a small engine runs when it is choked too much. Not enough to cause the skier to drop, but enough to make me shut it down immediately. Before shutting down I tried increasing the throttle, and this had little effect. No additional power was felt. After a 20 minute swim, the boat will fire back up and run fine for a few sets, then repeat.

A few things come to mind, and they are both fuel related:

1) Water in fuel. Not really sure how to check for this other than disconnect the fuel line after the pump and pump some fuel into a glass jar and look for the separation.

2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Anyone think of any other quick, easy, or cheap “fixes” or “tries”, before I drop nearly 400 clams on a fuel pump?

Thanks,

Chad

Edited by chadwick02
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For sure, hook up a cheap fuel pressure gauge to the fuel rail and see if you have any variation in pressure drop. I really don't think that is your problem, because you wouldn't get backfiring from leaning the motor out is what really is happening when you loose fuel pressure. I would check your spark plugs for any sign of fouling, raw fuel and lack of compression could cause backfire. I don't know how this could have happened but a cracked distributor cap could cause this also, I'm just throwing stuff out there for you. A bad plug could be caused by corrosion at the plug wire, you can tell everything by looking at your plugs. Start there and let me know what you find........Good Luck and also check your fuel filter before and after checking pressure, oh yeah and it's most likely not water in the fuel it's usually 5% or less of any bad running motor, but you still need to check to make sure.

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Also check your water temperature sensor on the top of the engine. If it sounds like it is running with the choke on (ie. your lawnmower analogy) (and you know that fuel injected engines have no choke), this sensor will cause the engine to run rich, as if it is getting a reading telling the computer the engine is cold, when in fact it is not.

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thanks guys. I picked up a fuel pressure gauge today, I'll check it in a few hours when I head up to the lake.

How do i check the water temp sensor?

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lots of people, lots of skiing and boarding)

Root Cause Identified.

LSV's were not meant for this activity, don't believe the salesman, or Edwin/68/NorCalWallyBu.

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thanks guys. I picked up a fuel pressure gauge today, I'll check it in a few hours when I head up to the lake.

How do i check the water temp sensor?

To be honest, I am not sure how to check it. I finally had to take my boat to have the dealer hook it up to his computer, but I changed the part rather than wait another day for something that toook all of 10 minutes to change out. I suppose you could use a meter to check it for contiuity at least. Other may have mmore indepth knowledge on the testing thing.

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2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

If you can hear it whining at the drivers seat, you may have a fuel pump problem and it may be on the way out and need to be replaced, BUT....

I had the whining fuel pump myself. It turns out there was a piece of debris (fuel line rubber, it looked like) lodged in the screen filter at the pump itself. If you can get to the fuel pump, just disconnect the line that goes into the pump at the bottom, and look up in there with an inspection mirror. Have some rags handy, you'll lose some fuel into the bilge. Removing the debris solved the noise.

You situation my be a candidate for debris in the filter because once you shut down, the debris may "settle" itself back down the line towards the tank, only to be sucked back up to the filter when under power for a bit....does that make any sense?

Regardless, if you can hear your fuel pump whine at the drivers seat, you need to take action. The fuel lubricates these pumps, and by not getting enough (hence the whine) damage is being done.

Do you notice the whine constantly, or just when the boat is acting up?

There is no pump in the tank...just the one on the side of the engine. Also, have you changed your fuel filter lately?

Edited by rts
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2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

If you can hear it whining at the drivers seat, you may have a fuel pump problem and it may be on the way out and need to be replaced, BUT....

I had the whining fuel pump myself. It turns out there was a piece of debris (fuel line rubber, it looked like) lodged in the screen filter at the pump itself. If you can get to the fuel pump, just disconnect the line that goes into the pump at the bottom, and look up in there with an inspection mirror. Have some rags handy, you'll lose some fuel into the bilge. Removing the debris solved the noise.

You situation my be a candidate for debris in the filter because once you shut down, the debris may "settle" itself back down the line towards the tank, only to be sucked back up to the filter when under power for a bit....does that make any sense?

Regardless, if you can hear your fuel pump whine at the drivers seat, you need to take action. The fuel lubricates these pumps, and by not getting enough (hence the whine) damage is being done.

Do you notice the whine constantly, or just when the boat is acting up?

There is no pump in the tank...just the one on the side of the engine. Also, have you changed your fuel filter lately?

Thank you!! Very good info there! I did change the fuel filter at the end of last season (less than 20 hours ago).

I will take a look at the inlet lines tomorrow and let you know what I find.

Here is what I found today:

From the initial start today it didn’t run correctly. It always starts and idles ok, but whenever I went to accelerate it lacked power. It was able to get up on plane alright, but it seemed like it was only operating at 75% of its power.

Fuel pressure at the rails is about 31-32 according to the gauge I bought. I have no idea what it is supposed to be at, but that seems low to me?

The fuel pump is wining like a banshee. Even louder than this weekend, and definitely noticeably louder than a friends 03' sporty. I disconnected the wire harness that goes to the pump, and turned the key one click to prime the system, and there was no noise, so the fuel pump is definitely the source of the noise.

I called ski DIM and they quoted me something like $380 (or there abouts) for the fuel pump. Anyone got any other options that might be a little less expensive? I will try a local auto parts store - they were able to find me a high-pressure pump for my last boat a year ago. Might be worth a call to the dealer too… Any other places?

Can someone easily confirm the part number as: INDMAR 53-6054? It was pretty tough to read…

Thanks all for your help!

Chad

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2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Do you notice the whine constantly, or just when the boat is acting up?

Oh, and yes, the pump whines constantly from startup.

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This is the fuel pump for your '02 Monsoon

Fuel Pump

If the whine is getting louder, I'm afraid your pump is on its last leg. They tend to do that before they go.

It's still worth a look at the screen on the pump, just to be sure, but if it's getting louder that would mean debris is piling up on the screen...unlikely, I'm afraid.

30+ psi would seem OK at idle, but remember these are two stage pumps, and perhaps your second stage is going south, hence the lack of power at the upper end.

The pumps are expensive, but your boat will not run once it gives up the ghost. Better, IMO, to replace it now, rather than have it fail in the middle of the lake.

They are pretty easy to swap out...just keep a container of some sort and some rags handy, as you'll lose fuel out of the lines when you start disconnecting things.

Edited by rts
Link to comment
Hey everyone,

2002 Malibu 21LSV, EFI monsoon.

This has been going on for 2 days. The first day it only happend once, and I thought it was a fluke. On saturday it happened several times and I am worried:

Several hours into the day (running the boat pretty hard, lots of people, lots of skiing and boarding), while under way, the boat would start to cough, sputter, pop, backfire, and ultimately loose a little power (but very noticeable). Reminds me of how a small engine runs when it is choked too much. Not enough to cause the skier to drop, but enough to make me shut it down immediately. Before shutting down I tried increasing the throttle, and this had little effect. No additional power was felt. After a 20 minute swim, the boat will fire back up and run fine for a few sets, then repeat.

A few things come to mind, and they are both fuel related:

1) Water in fuel. Not really sure how to check for this other than disconnect the fuel line after the pump and pump some fuel into a glass jar and look for the separation.

2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Anyone think of any other quick, easy, or cheap “fixes” or “tries”, before I drop nearly 400 clams on a fuel pump?

Thanks,

Chad

Link to comment
Hey everyone,

2002 Malibu 21LSV, EFI monsoon.

This has been going on for 2 days. The first day it only happend once, and I thought it was a fluke. On saturday it happened several times and I am worried:

Several hours into the day (running the boat pretty hard, lots of people, lots of skiing and boarding), while under way, the boat would start to cough, sputter, pop, backfire, and ultimately loose a little power (but very noticeable). Reminds me of how a small engine runs when it is choked too much. Not enough to cause the skier to drop, but enough to make me shut it down immediately. Before shutting down I tried increasing the throttle, and this had little effect. No additional power was felt. After a 20 minute swim, the boat will fire back up and run fine for a few sets, then repeat.

A few things come to mind, and they are both fuel related:

1) Water in fuel. Not really sure how to check for this other than disconnect the fuel line after the pump and pump some fuel into a glass jar and look for the separation.

2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Anyone think of any other quick, easy, or cheap “fixes” or “tries”, before I drop nearly 400 clams on a fuel pump?

Thanks,

Chad

I've had the same problem with my EFI Monsoon and found that the ethanol fuel absorbs alot of water during storage. Also chemical stuff going on when you mix different fuels. I tried putting a fuel/water seperator on mine and the problem went away. Racor has a 10 micron spin-on fuel filter available so you don't need the inline original filter. I've noticed a lot of different discussions on this site that may be related to this. Good Luck!

Link to comment
Hey everyone,

2002 Malibu 21LSV, EFI monsoon.

This has been going on for 2 days. The first day it only happend once, and I thought it was a fluke. On saturday it happened several times and I am worried:

Several hours into the day (running the boat pretty hard, lots of people, lots of skiing and boarding), while under way, the boat would start to cough, sputter, pop, backfire, and ultimately loose a little power (but very noticeable). Reminds me of how a small engine runs when it is choked too much. Not enough to cause the skier to drop, but enough to make me shut it down immediately. Before shutting down I tried increasing the throttle, and this had little effect. No additional power was felt. After a 20 minute swim, the boat will fire back up and run fine for a few sets, then repeat.

A few things come to mind, and they are both fuel related:

1) Water in fuel. Not really sure how to check for this other than disconnect the fuel line after the pump and pump some fuel into a glass jar and look for the separation.

2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Anyone think of any other quick, easy, or cheap “fixes” or “tries”, before I drop nearly 400 clams on a fuel pump?

Thanks,

Chad

I had a similar problem with my EFI Monsoon, I replaced the inline fuel filter with a fuel/water seperator similar to Mercruiser units. They have a spin-on filter that will take a Racor 10 micron filter for best results. Ethanol wreaks havoc on anything that sits for a month or two, absorbing moisture. Good Luck! I'm seeing other posts on this site with similar problems and it's an easy and cheap fix.

Link to comment
Hey everyone,

2002 Malibu 21LSV, EFI monsoon.

This has been going on for 2 days. The first day it only happend once, and I thought it was a fluke. On saturday it happened several times and I am worried:

Several hours into the day (running the boat pretty hard, lots of people, lots of skiing and boarding), while under way, the boat would start to cough, sputter, pop, backfire, and ultimately loose a little power (but very noticeable). Reminds me of how a small engine runs when it is choked too much. Not enough to cause the skier to drop, but enough to make me shut it down immediately. Before shutting down I tried increasing the throttle, and this had little effect. No additional power was felt. After a 20 minute swim, the boat will fire back up and run fine for a few sets, then repeat.

A few things come to mind, and they are both fuel related:

1) Water in fuel. Not really sure how to check for this other than disconnect the fuel line after the pump and pump some fuel into a glass jar and look for the separation.

2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Anyone think of any other quick, easy, or cheap “fixes” or “tries”, before I drop nearly 400 clams on a fuel pump?

Thanks,

Chad

I'm not sure if my message got thru, so I'll try again. I have a EFI Monsoon that was acting similarly to yours, I replaced the inline fuel filter with a spin-on unit like Mercruiser uses.Racor has a 10 micron filter for this unit also. Ethanol is causing problems with moisture in the fuel when not used for a couple of months. Good Luck!

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I had similar symptoms and it turned out to be crossed fuel lines under the gas tank. A full tank squished them together and restricted the flow.

Link to comment
Hey everyone,

2002 Malibu 21LSV, EFI monsoon.

This has been going on for 2 days. The first day it only happend once, and I thought it was a fluke. On saturday it happened several times and I am worried:

Several hours into the day (running the boat pretty hard, lots of people, lots of skiing and boarding), while under way, the boat would start to cough, sputter, pop, backfire, and ultimately loose a little power (but very noticeable). Reminds me of how a small engine runs when it is choked too much. Not enough to cause the skier to drop, but enough to make me shut it down immediately. Before shutting down I tried increasing the throttle, and this had little effect. No additional power was felt. After a 20 minute swim, the boat will fire back up and run fine for a few sets, then repeat.

A few things come to mind, and they are both fuel related:

1) Water in fuel. Not really sure how to check for this other than disconnect the fuel line after the pump and pump some fuel into a glass jar and look for the separation.

2) Fuel pump on the fritz (I really hope it is not this, they are not cheap!) I suspect the pump because I have a feeling that it has been getting noisier over the past few days. I cannot say what it used to sound like for sure, but I can very distinctly hear the pump wine all the way from the drivers seat now, and don’t recall that before. Is there any way to test a fuel pump? Can I somehow test the pressure at the rails? Are there other diagnostics or test that can be done to narrow (or eliminate) the pump as the problem. Is there a pump in the tank too?

Anyone think of any other quick, easy, or cheap “fixes” or “tries”, before I drop nearly 400 clams on a fuel pump?

Thanks,

Chad

I had a similar problem with my EFI Monsoon, I replaced the inline filter with a fuel/water seperator unit and spin-on tempo fuel/water filter. Racor makes a better 10 micron spin-on filter. No more problems afterwards, Ethanol won't keep long without moisture absorbtion. I also am using Starbrite Startron and I added a bottle of Drygas for good measure! Good Luck!

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Thanks everyone for the info.

- I replaced the fuel pump and filter – the noise is gone and the pressure is up.

- Replaced the cap and rotor

- Replaced the throttle position sensor. This did not eliminate the hesitation at slow to moderate acceleration around 1000 rpms. This is a different topic for another day.

- Checked the plugs – they looked fine. Not to grubby. I forgot to bring a plug gapper up with me, so I didn’t install the new plugs. Does anyone know what the gap is supposed to be for an ’02 monsoon?

And after all that, the problem is worse!! Now it acts all cruddy at anything above 1500 RPM. When I got to accelerate sometimes it bogs even worse. When I floor it it will run fine. Doesn’t seem to have any problems between 4000 and 4500 RPM.

Today it even totally stalled once, and then did not want to start up for about 10 minutes. GAH!!

Tomorrow I will

- Take the coil in and have it tested at a chevy garage. Maybe the coil is failing?

- Hook a small gas can full of fresh, clean fuel up to the input of the pump and run it. This will help eliminate bad fuel or water in the tank, fuel line obstructions, bad filter…etc.

- Is there any chance that the plug wires are bad? Any way to check them?

Anyone have any other ideas?? I am getting desperate, and we are having a family party at the lake this weekend and sure would like the boat to run!!

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Thanks everyone for the info.

- I replaced the fuel pump and filter – the noise is gone and the pressure is up.

- Replaced the cap and rotor

- Replaced the throttle position sensor. This did not eliminate the hesitation at slow to moderate acceleration around 1000 rpms. This is a different topic for another day.

- Checked the plugs – they looked fine. Not to grubby. I forgot to bring a plug gapper up with me, so I didn’t install the new plugs. Does anyone know what the gap is supposed to be for an ’02 monsoon?

And after all that, the problem is worse!! Now it acts all cruddy at anything above 1500 RPM. When I got to accelerate sometimes it bogs even worse. When I floor it it will run fine. Doesn’t seem to have any problems between 4000 and 4500 RPM.

Today it even totally stalled once, and then did not want to start up for about 10 minutes. GAH!!

Tomorrow I will

- Take the coil in and have it tested at a chevy garage. Maybe the coil is failing?

- Hook a small gas can full of fresh, clean fuel up to the input of the pump and run it. This will help eliminate bad fuel or water in the tank, fuel line obstructions, bad filter…etc.

- Is there any chance that the plug wires are bad? Any way to check them?

Anyone have any other ideas?? I am getting desperate, and we are having a family party at the lake this weekend and sure would like the boat to run!!

Did you replace both filters?

Put the wires back in the correct order on the cap?

Does it put out black nasty smoke when it is running lousy? You might check/replace the engine temperature sensor. A faulty one can make all kinds of wierd things happen, but mostly hard starting after warmed up.

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Did you replace both filters? Both filters?? I was under the impression there was not one in the tank. Is there?

Put the wires back in the correct order on the cap? Yea, it idles fine and runs above 4K pretty well. Im sure the wires are in the correct order.

Does it put out black nasty smoke when it is running lousy? You might check/replace the engine temperature sensor. A faulty one can make all kinds of wierd things happen, but mostly hard starting after warmed up. No black smoke to speak of. When it complelty stalled there was a strong smell of exhaust, and that smelled very rich to me (but im not really sure). There was quite a bit of carbon build up on the top butterfly valve on top of the intake.

Is the engine temp sensor an indmar specific part? Or can I go down to my local chevy garage and pick one up?

Thanks!!

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I think you need to change your plugs before jumping to something else, you never know they may look good but not be firing even though if that is the case they should look very black with build up. If you didn't check your wires with an ohm meter, your not going to know for sure if it's but it sounds like your plugs looked fine. I might have to agree with Baddog on the sensor now, there is a way to check it! But it's not worth it, just buy a new one.

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Thanks everyone for the info.

- I replaced the fuel pump and filter – the noise is gone and the pressure is up.

- Replaced the cap and rotor

- Replaced the throttle position sensor. This did not eliminate the hesitation at slow to moderate acceleration around 1000 rpms. This is a different topic for another day.

- Checked the plugs – they looked fine. Not to grubby. I forgot to bring a plug gapper up with me, so I didn’t install the new plugs. Does anyone know what the gap is supposed to be for an ’02 monsoon?

And after all that, the problem is worse!! Now it acts all cruddy at anything above 1500 RPM. When I got to accelerate sometimes it bogs even worse. When I floor it it will run fine. Doesn’t seem to have any problems between 4000 and 4500 RPM.

Today it even totally stalled once, and then did not want to start up for about 10 minutes. GAH!!

Tomorrow I will

- Take the coil in and have it tested at a chevy garage. Maybe the coil is failing?

- Hook a small gas can full of fresh, clean fuel up to the input of the pump and run it. This will help eliminate bad fuel or water in the tank, fuel line obstructions, bad filter…etc.

- Is there any chance that the plug wires are bad? Any way to check them?

Anyone have any other ideas?? I am getting desperate, and we are having a family party at the lake this weekend and sure would like the boat to run!!

Sounds like something is telling the computer to go to full rich under load. My guess is the engine temp sensor like Baddog mentioned.

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The other filter is not in the tank, but it is usually located near the tank and you have to disassemble the shelf thingy over the tank to get at it. Some here have relocated it to be more accessible.

Not sure if the temp sensor is an OTC part. I paid $25 through my dealer. 4 minutes to change it out.

Edited by Baddog
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Ordered a new temp sesor ($12) and a new MAP sensor that was also inexpensive.

A buddy at the chevy garage loaned me a "working" (so he says) coil to swap out and try. I'll give all that stuff a shot tomorrow afternoon and report back.

Anyone have any idea what the resistance per foot is supposed to be for the plug wires? Or is there some other way to test them?

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What about the timing? Could timing issues cause any of these problems?? I do have a timing light back at the house.

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Ordered a new temp sesor ($12) and a new MAP sensor that was also inexpensive.

A buddy at the chevy garage loaned me a "working" (so he says) coil to swap out and try. I'll give all that stuff a shot tomorrow afternoon and report back.

Anyone have any idea what the resistance per foot is supposed to be for the plug wires? Or is there some other way to test them?

But, but . . . . if you change all those things, how will you know which one was the culprit? Have you got the ability/desire/time to change only one thing at a time and test drive for results so we geniuses can know who was right or wrong. Not that it is a contest, but it will help diagnose others in the future.

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