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Running out of fuel...


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1998 Sunsetter VLX used primarily for surfing.  As soon as I feel the motor stumble while surfing, we dump ballast and have just enough fuel to get back to the dock.  The next day when refueling, I can only get 17-18 gallons in it.

I can't find any fuel tank spec info in any of the manuals I have, and everything I find online says 35 gallons with about 32 useable.

It appears to be the stock tank... but based on the above, it seems like I have a 21-22 gallon tank, not 35.

Pickup issue?  Any ideas?

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The stumbling that happens while surfing is just the initial warning sign that it's time to head back.

If we are still pretty far out from the dock, even after dumping ballast it will stumble on the way back at higher speeds.  If I cut throttle and fuel sloshes around, I regain power.

If I don't heed that initial stumbling, I'll usually be looking for a tow back to launch.

Edited by gvb
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For reference we had a 97 sunsetter vlx that we surfed heavy and we could get around that 30 gallon range.  I agree, check you pick up, maybe it moved or cracked.

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Very strange...

Tank is 35 gal:2i9l2t0.jpg

And it is half full (makes sense with the 17-18 gallon refills):2yngvic.jpg

Pickup looks fine, is in the back center of fuel tank, and appears to be the correct length (hits the bottom of the tank with about a 1/2" to spare):2d1mx09.jpg

Not sure what is going on, but the last 4 outings have produced pretty much the exact same results.  Out of fuel symptoms and then a 17-18 gallon refill next time out.  What am I missing?

Edited by gvb
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Change the inline fuel filter. You get less head pressure with lower fuel amounts to push fuel through a clogged filter. You should change it annually.

 

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10 hours ago, Sailvi767 said:

Change the inline fuel filter. You get less head pressure with lower fuel amounts to push fuel through a clogged filter. You should change it annually.

 

That would make sense and explain the consistent issue I'm seeing.  Thanks!!

I normally do a full tuneup every year but the boat sat for 2 years with no use after the last one so I only did fluids this season.

Was planning on draining the fuel tank, replacing both inline filters, plugs, and cap/rotor.

Hopefully that resolves it!

Edited by gvb
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UPDATE:

- Pulled fuel tank pickup and cleaned metal screen at end of pickup (looked clean though).
- Verified pickup is long enough, about 1/2" deeper than tank, so it hits the bottom and turns towards the driver side of the boat.
- Replaced low pressure filter with Wix 3482.
- Replaced high pressure filter with Wix 3481.
- Pulled fuel pump intake and cleaned screen (looked ok before cleaning).
- Replaced plugs, cap, and rotor.

Ran the boat for about 5-6 hours yesterday before experiencing the same problem again... loss of power, sputtering, back firing, etc.  I could rev the boat in neutral, but as soon as I started forward with just a little bit of throttle, the symptoms appeared again.  I haven't refueled yet or pulled the floor to check tank level, but I assume I'm probably about 1/3 full and should have plenty of fuel in the pickup still.

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I think i read where the pickup tube could be cracked and would start sucking air at that point. Otherwise i wonder if the level of fuel gets low and causes fuel pump prime issues by being harder for the pump to pull a lower level of fuel. 

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Hmm... that would also explain the issue happening around the same time.  I'll check out the pickup look at replacing with fresh parts... thanks!

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4 hours ago, gvb said:

UPDATE:

- Pulled fuel tank pickup and cleaned metal screen at end of pickup (looked clean though).
- Verified pickup is long enough, about 1/2" deeper than tank, so it hits the bottom and turns towards the driver side of the boat.
- Replaced low pressure filter with Wix 3482.
- Replaced high pressure filter with Wix 3481.
- Pulled fuel pump intake and cleaned screen (looked ok before cleaning).
- Replaced plugs, cap, and rotor.

Ran the boat for about 5-6 hours yesterday before experiencing the same problem again... loss of power, sputtering, back firing, etc.  I could rev the boat in neutral, but as soon as I started forward with just a little bit of throttle, the symptoms appeared again.  I haven't refueled yet or pulled the floor to check tank level, but I assume I'm probably about 1/3 full and should have plenty of fuel in the pickup still.

I'm thinking vapor lock. My guess is you have a routine going. Do you take like a 20-30 minute break before this happens? Is the air and water temp a bit warmer than normal?

Steve B.

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I can tell if my tank has gas by looking at the tank by the vdrive and rocking the boat. 5 hours surfing in my 96 vlx with 1800 lbs of ballast, several passengers and I'm just about out of gas. But if you see gas...... I wonder if after a while your pump is getting weak?  Check fuel pressure before and after the problem starts?  My fuel pump slowly went out but would work intermittently.  Not sure if a partially clogged vent would cause this but u could always pull the gas cap and see if the problem stops?

Edited by Shastasurf
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Is this a carb boat engine?  If so I think you will have a setup off the oil pressure pickup. It sends oil pressure to the gauge and the other sends it to the ECU. Pull the part that the oil pressure is being picked up on 0ff. the one that sends it to the ECU has a  valve in it that can hang up.  if it does the ECU will think you oil pressure is low and it will shut down the fuel pump.

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11 hours ago, Steve B. said:

I'm thinking vapor lock. My guess is you have a routine going. Do you take like a 20-30 minute break before this happens? Is the air and water temp a bit warmer than normal?

Steve B.

I can't say that with consistency it happens after a 20-30 minute break... typically I think it happens during the middle of a surf session.  I'm in SoCal, so it's always warm :)

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Just checked the clock... 5.3 hours of run time from a topped off tank.

Pulled the floor and the tank is about 1/2 - 1/3 full... definitely enough fuel to reach the pickup either sitting flat or while running.

Gauge works, replaced sender a few years back, but it is still fairly useless.

Pump was replaced a few years back as well (doesn't mean it isn't going bad, but I would expect more erratic behavior).

EFI, not carb.

Will bring fuel pressure gauge next time and check before/during pressure.

Will try popping gas cap when symptoms occur and see if it gets better.

I'd like to replace the entire pickup assembly from the valve to the screen... just to eliminate the possibility it is sucking air once the tank level drops.  Is this going to be something I have to get from a dealer?

Any other thoughts on vapor lock?  How to diagnose?

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Does it run fine once it cools down? In otherwords, could you take it as it is with the low fuel and it cold and get it to run fine? If not, then its not heat induced vapor lock. That said, if there is a crack in the pickup, then it could be causing air bubbles to feed into the input of the fuel pump which will heat it up fast and prevent running.  

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I just checked your pic again. I believe i have the same size and shape tank in my 01 and its pickup is longer. The yellow hard plastic part is at any rate. When installed, i believe it curves to the left side of the tank but pretty much stays in the rear 1/4 of the tank. In fact, i hink the hard plastic goes almost to the bottom of the tank. Well, not to the bottom but i remember the pickup plastic tube seemed longer than what yours looks in the pic. 

Edited by williemon
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On 7/23/2017 at 10:56 AM, williemon said:

Does it run fine once it cools down? In otherwords, could you take it as it is with the low fuel and it cold and get it to run fine? If not, then its not heat induced vapor lock. That said, if there is a crack in the pickup, then it could be causing air bubbles to feed into the input of the fuel pump which will heat it up fast and prevent running.  

I pulled the entire pickup assembly out of the boat... it doesn't appear to have any cracks/leaks from end to end (hose barb end of ball valve to end of rubber fuel hose that goes into tank) using crude testing methods.

To answer your question, I'm not sure... I assume it would behave exactly as it did when I pulled it from the lake last week.  I NEVER have any issues starting the boat, only in gear under load.  If vapor lock, I would expect that to happen more during the middle of the day when temps are peaked, and an inability to start the boat.  I frequently pop the hatch in between riders and while stopped.  It never feels very hot back there, but I haven't focused on the fuel pump and metal fuel lines.... I'll keep that in mind next time.

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13 minutes ago, malibu2004 said:

Did you end up replacing the rotor, plugs and wires? 

How much gas did you put in after 5.3 hours of run time? Most boats average 6 to 7 per hour.   

Rotor/Cap/Plugs were changed... not wires.

I have not refueled since the last outing, so I am not sure.  Should be out Thursday.

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On 7/25/2017 at 3:02 PM, gvb said:

Rotor/Cap/Plugs were changed... not wires.

I have not refueled since the last outing, so I am not sure.  Should be out Thursday.

Change your wires.

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With that size tank after 5.3 hours of run time I still think he was nearly out of fuel. That engine burns 6 to 8 GPH under a normal load. If you are checking the fuel visually on a trailer or lift it's not valid. Check the fuel level sitting in the water.

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Physical/visual inspection of plug wires looks good.  I'll check resistance of them and replace if needed.

I'm also starting to consider that my fuel tank vent (which is pretty much submerged during listed goofy surfing) is filling the fuel tank with water.

Today I hooked a suck pump directly to my fuel pickup and sucked out about 10 gallons of fuel... no obvious signs of water though.

Hitting the water tomorrow with a fuel pressure gauge, and will be blocking off the fuel tank vent (venting manually via gas cap).

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