Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

[ShellBack89]

Took boat out this past weekend. Had her running several times before taking her on the water at idli and was fine. Once on the water ran awesome for about 10 minutes then heard a backfire. She then began sputtering and died. Refired a couple of times but same thing. Good thing for Vessel Assist :facepalm: Once back on my trailer she fired up and ran at idil and even revving her up to 2500 RPMs and sounded good. Did the same thing when I got home .

Thought (still could be) bad gas. Gas is several months old (1/2 tank) and then I added super to fill off the tank. Today I pulled the fuel line to the carb to see if the strainer was clogged and it was bone dry. I then tool the bell housing off the fuel pump to replace the fuel filter and same thing bone dry. I turned her over to see if any gas would come out of the fuel line, nothing. Pulled the fuel line from the tank and there doesn't seem to be a blockage.

Thoughts.......

1. Bad fuel pump which needs to be replaced
2. Bad fuel which needs to be pumped out
3. Clean flame arrestor
4. All of the above

 

[Bondo]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Took boat out this past weekend. Had her running several times before taking her on the water at idli and was fine. Once on the water ran awesome for about 10 minutes then heard a backfire. She then began sputtering and died. Refired a couple of times but same thing. Good thing for Vessel Assist :facepalm: Once back on my trailer she fired up and ran at idil and even revving her up to 2500 RPMs and sounded good. Did the same thing when I got home .

Thought (still could be) bad gas. Gas is several months old (1/2 tank) and then I added super to fill off the tank. Today I pulled the fuel line to the carb to see if the strainer was clogged and it was bone dry. I then tool the bell housing off the fuel pump to replace the fuel filter and same thing bone dry. I turned her over to see if any gas would come out of the fuel line, nothing. Pulled the fuel line from the tank and there doesn't seem to be a blockage.

Thoughts.......

1. Bad fuel pump which needs to be replaced
2. Bad fuel which needs to be pumped out
3. Clean flame arrestor
4. All of the above

Ayuh,.... What motor,..?? I'm guessin' a 3.0l, by the fuel filter location,..??...

Get yerself a Canister type fuel filter, 'n plumb it into the gas line, just Before the fuel pump,....
Get yerself a remote fuel tank, attach it to yer new canister type fuel filter, 'n Try it,...

If the fuel pump, still don't pump,... replace it,...
If it does, there's a problem with the in-hull tank,...

The canister type filter does a Great job strainin' the fuel, just carry a spare til the old gas is gone, 'n the system is cleaned up,...
It might take a few filters,...

For on the water swaps, I carry a quart sized freezer baggie to drop the old 1 into,...
At shore, just tip it upside-down to look for water, 'n crud,...

Btw,.... a clogged flame arrester causes a Rich condition, not Lean,....

 

[bigdirty]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Don't know what kind of boat or anything.. got a pic of the fuel pump by any chance? There could be a check valve at the tank that is sticking (could be caused from the old gas) and idling and reving are one thing; a weak fuel pump or leaky line might not bother it, but under load it needs everything to be working properly or it will starve.. and if it was running, and you pulled the lines of the next day there should have been some fuel there imo.. Maybe a crack or split in one of the lines could be your problem? It would draw air, especially at higher rpm and load, and also allow fuel to drain back to the tank while sitting..

 

[ShellBack89]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Thank you both for your responses. Its a 1988 Sea Ray Seville 4.3 LH Mercruiser 205 HP I will definitely get the Canister Fuel Filter and plum it in. I want to confirm you talking about http://www.westmarine/fuel-filters/mercury-marine--w7-water-separating-fuel-filter-25-micron--5037429 ???

I'm also going to replace the fuel line from the fuel pump to the carb and also the filter in the fuel pump.

Here's a schematic pic of the fuel pump

What could be wrong with the in-hull tank??

 

[achris]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

You might want to check/replace the anti-syphon valve, and also check for air leaks in the system. If you have a leaky fitting/split hose, the pump will only suck air, as fuel is heavier and harder (relatively) to pump.

Also check that the pickup in the tank is still in place, and not cracked/fallen off, and that the strainer at the bottom of the pickup is not clogged.

Chris....

 

[ShellBack89]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Okay I've added a couple of pictures for comedic purposes. I'm sure once everyone looks at them they will have identified the issue of why my carb wasn't getting any fuel. I'm hoping by making those adjustments already noted and by adding a fuel/water separator that I'll be back on the water this weekend, especially since Dana Point is supposed to be in the 80s and the whales are in migration. This should have been addressed while I was refurbishing the boat so definitely my bad! The frustrating part is that I just had it tuned up so you would have thought the service center would have said something.


Yes this is my fuel line. If this was a heart artery, I'd be having bypass surgery






This is puzzling since it doesn't look like the stock version that I'm buying today but the people who owned this boat before me might not have changed it at all in the 25 plus years they owned it.

 

[Bondo]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Ayuh,... The top 2 pictures are the fuel pump Vent line, not a gas line,...

It's just a visual indicator that the fuel pump diaphragm has ruptured, if there's any gas in it,...

 

[ShellBack89]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Ayuh,... The top 2 pictures are the fuel pump Vent line, not a gas line,...

It's just a visual indicator that the fuel pump diaphragm has ruptured, if there's any gas in it,...

No gas but a ton of crap. I'm tracking now......#12 depicted in the schematic photo is the actual fuel line......duh.....Should have figured that one out since that's what is connect to the inlet that I'm removing and replacing the fuel filter.

I have come to the conclusion that since I'm going to all this trouble and will most likely need to pump out the gas that I'll replace the gas line from the tank to the fuel pump. The issue here is there is no screw in deck plate that I can access to remove the line or anti siphon valve. Its a little stressful to be using a drill saw hole around a fuel line.

Can anyone tell me if this is the safest (I'm speaking relative when dealing with fuel).

1. Have large fire extinguisher next to me
2. Disconnect battery
3. Pump out all the fuel
2. Clear the fuel vapors by filling up the tank with water forcing out all fuel vapors through the vent line
3. Wait 30 minutes for all vapors to clear area
4. Drill through deck
5. Replace fuel line and anti siphon valve
6. Install deck plate
7. Pump out water
8. Take shop vac (accessing through fuel float for better access) suck up all remaining water
9. Fill with Premium fuel (at $4.10 a gallon because I live in CA)

Thanks everyone for the advise. It is much appreciated. I don't know engines so having stuff pointed out is a huge help!

 

[Bondo]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

No gas but a ton of crap. I'm tracking now......#12 depicted in the schematic photo is the actual fuel line......duh.....Should have figured that one out since that's what is connect to the inlet that I'm removing and replacing the fuel filter.

I have come to the conclusion that since I'm going to all this trouble and will most likely need to pump out the gas that I'll replace the gas line from the tank to the fuel pump. The issue here is there is no screw in deck plate that I can access to remove the line or anti siphon valve. Its a little stressful to be using a drill saw hole around a fuel line.

Can anyone tell me if this is the safest (I'm speaking relative when dealing with fuel).

1. Have large fire extinguisher next to me
2. Disconnect battery
3. Pump out all the fuel
2. Clear the fuel vapors by filling up the tank with water forcing out all fuel vapors through the vent line
3. Wait 30 minutes for all vapors to clear area
4. Drill through deck
5. Replace fuel line and anti siphon valve
6. Install deck plate
7. Pump out water
8. Take shop vac (accessing through fuel float for better access) suck up all remaining water
9. Fill with Premium fuel (at $4.10 a gallon because I live in CA)

Thanks everyone for the advise. It is much appreciated. I don't know engines so having stuff pointed out is a huge help!

Ayuh,... Yer fears are Waayyy over-blown,... Yer drillin' through wood, no sparks there,...

'n it's gas Fumes that go Boom, not liquid gasoline,...

Now suckin' Anything outa the gas tank with a shopvac is gonna get ya killed,...

What tiny bit of crud, 'n water left in the tank will get caught by the canister type fuel filter,...
Don't worry 'bout it,...

I'd cut the hole, 'n pull the diptube,...
So long as the diptube is clear, 'n the anti-siphon fittin' at the top of it is clean,...
Put it together, 'n Run it,...

 

[ShellBack89]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Bondo - Thank you so much for your help. I'll update once the repairs are done and she's back running.

 

[BigDog98]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

You should also test you fuel pump to make sure its getting its 12volts. Even if its running it does not mean its getting the 12v that it needs. So you should def check the fuel pump after your done replacing everything.

 

[Bondo]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

You should also test you fuel pump to make sure its getting its 12volts. Even if its running it does not mean its getting the 12v that it needs. So you should def check the fuel pump after your done replacing everything.

Ayuh,.... ShellBack89 has a Mechanical fuel pump,..... :facepalm:

 

[bruceb58]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

By the way, filling up with premium in CA is a waste of money. It has the same amount of ethanol as regular fuel.

 

[wrench 3]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

If you want to test that pump, disconnect the fuel line to the carb, connect a vacuum gauge to the intake on the pump (were the line from the tank goes), and check the gauge reading while cranking the engine. You should have at least 15" of vacuum.

 

[ShellBack89]

Re: Backfire Through Carb, Sputters and Dies - Couple of Thoughts???

Thanks for all the great advice. Verdict: Bad fuel = Bad carbs. Pumped out the old stuff & rebuilt the carbs & now runs great!