clogging jets, ethanol, stabilisers

[HalcyonS]

Like many of us, there are times, due to work, family responsibilities or illness, when my old A4 sits dormant for too long. I have learned long ago that if I run the engine every week, it starts and runs like a dream. As soon as it sits for over 2 weeks, trouble starts. 'Carbureter cheese' seems to be a by-product of gas with ethanol.

Right now she won't run, and before that it was obvious the idle jet was blocked. I don't mind doing improvements to my A4 but doing the same carb service too often annoys me.What is the recommended practice for saving this work? Run it dry or leave the float bowl full? Add stabilisers or keep away from them? Convert to fuel injection?

thanks!

[hanleyclifford]

Running dry after use is helpful, as is draining the bowl. An adjustable main jet is also useful as clogs can often be fixed by opening and closing the needle. Another trick is to remove the idle adjuster screw and blast with ether or carb cleaner (be sure to count the turns as you remove the screw). Stabilizer IMO is useless for ethanol issues.

[Al Schober]

Alcohol in the fuel seems to create two problems. First is the deterioration of non-metallic parts of the fuel system, primarily old hoses. This leads to debris in the fuel system. Fortunately, our filters catch most of this stuff. Second is the absorption of water, leading to phase separation in the tank and corrosion of parts of the fuel system. The lower separated phase is mostly water and alcohol which builds up in the tank and eventually makes its way to the carb, stopping the engine. The corrosion causes it's own debris which can also make its way to the carb, plugging the float valve and jets. Filters are of some use, but when the filters themselves corrode they lose their utility.
One good preventative maintenance is to periodically check what's in the bottom of the fuel tank, removing debris and the water/alcohol phase. How often? Well, as often as needed. But keep in mind that the clock starts again after filling the tank with a fresh dose of gas/alcohol. Aside from a leaky deck fill (admitting water), you'll eventually remove all the water/alcohol - leaving stable fuel.
So, keep your tank clean, replace old hoses, change your filters regularly.

[Bratina]

Multiple anecdotes are not equal to data however I run my carb dry each time, by shutting off the petcock at the tank. I run my A4 every couple of weeks and since I started to do that my ‘dirty carb’ problems substantially lessened (basically went away). This also gives my A4 time to cool off at the dock after running, and lessens the chance of a fuel flood because it forces me to remember to shut off the petcock. In addition, more than once in the bustle of leaving my slip I had fired up the A4, run it for a few minutes and then stalled (usually right after throwing off the final line), because I’d forgotten to open the petcock and it was running on the sediment bowl gas etc. This way it won’t even fire up until I open the petcock because the system is pretty dry. I have a manual fuel pump and prime using the bail before starting – it usually takes ~10s of cranking to fire up, and I don’t open the raw water until it’s started.

I run MMO at a little over the prescribed dosage, add Stabil over the Ontario winter and run etoh-free gas which is still fairly easy to find around here. I have a Moyer in-line filter ahead of the carb plus a Racor ahead of the fuel pump (I change the filter element annually), and leave my tanks filled (always) and drain a couple of pints of gas at each spring startup. I question whether Stabil has any benefit but, as it seems to do no harm, I continue to add it as extremely cheap insurance.

[joe_db]

I turn off my fuel pump when I am done for the day and let the engine run dry. I have no issue starting the engine after a week or 2 months.
That said, there might be something else going on. I have discovered that when our carbs get old, after a certain point they do a good job corroding and clogging themselves no matter how many fuel filters you have.
I have not tried their products, but this web site has an interesting explanation of ethanol issues:
http://www.drivenracingoil.com/news/...ur-carburetor/

[Dave Neptune]

I never have fuel problems and I do not EVER use additives or marina gas. I do use the E-10 regular only from a major brand gas station. I have a racor and a polishing filter that are now at least 5 or 6 years in service hooked to approved alcohol rated feed lines.
However at the end of each season I dump in my dinghy fuel which is 50:1 two stroke synthetic oiled fuel. This can be anywhere from 1~5 gallons and is the only time my fuel sees any kind of additive.
I run for about 8~9 months a season (over a 100 hours of motoring) and she sits in the water for 3~4 months and always starts right up.
I do run the carb out of fuel when she is going to sit in the marina and never when cruising!

When I do crack the carb open which is very seldom other that there is a bit of greenish yellow fuzzy powdery deposit that makes the bowl look dusty. This dust seems to disappear with the addition of fuel. What I have noticed more on carbs I have done for others in the marine environment A-4's to big blocks is a bit of green oxidation on brass fittings.

My experience with persistent carb problems has always led to the fuel tank or feed lines not the carb!!

Dave Neptune

[JOHN COOKSON]

Originally Posted by HalcyonS

. As soon as it sits for over 2 weeks, trouble starts. 'Carbureter cheese' seems to be a by-product of gas with ethanol.
.What is the recommended practice for saving this work? Run it dry or leave the float bowl full? Add stabilisers or keep away from them?!

Try doing the opposite of what you are doing now and see if it helps.
If you are leaving fuel in the carb try running it dry. Try an auxiliary tank with clean fuel in it. Maybe the fuel is picking up some "cream" in the tank, hoses, filters and turning to "cheese" in the carb upon sitting. My curent bet is for something going on in the boat's fuel system as mentioned in preivous posts. If you are using additives try no additives for a while. If you use more than one additive the additives may fight with each other.
FWIW: I use STP gas treatment (It "improves the quality of gas - what ever that means) and MMO in my gas. Never have had any fuel problems.

TRUE GRIT

[HalcyonS]

Thanks all for replies - I'm not getting email notifications of forum posts so I was unaware the conversation was going on with out me. (That and a very busy couple of weeks.)

I'd run gas heavily laced with carb cleaner through the pump and carb via a jerry-can in the cockpit. No dice. So I bit the bullet and set aside a day for an entire fuel system tear down from tank petcock to carb, wirth some substantial tank draining. Mine is an ancient but excellent monel tank. This process required flushing and testing every component in succession. Sounds fine in principle but requires endless working of hose clamps, hose barbs, screw fittings etc.

Fault 1 - some blockage at petcock inlet. I blew that out.

I took the opportunity to fit an ancient wilcox crittenden fuel/water filter upstream of my cannister filter. Some may scoff, but I'd wanted to make sure I got the big lumps out first and I had it sitting around.I figure it'll make the cannister last longer. Anyway, Ill get a good visual of the big lumps.

Fault 2. I knew the idle jet was blocked so I took the carb apart - again. No obvious 'cheese', but fine white dust in bowl and on floats. I blew out the jets with carb cleaner, then air, then carb cleaner, repeatedly, and reassembled.

It would run for about a bowl full. Then I noticed the fuel pump was making a dull brrr noise rather than its usual high pitch click. Flow test revealed spasmodic dribbles. It was not easy to get the pump apart - the gasket was heavily distorted and decomposed (see pic).

Fault 3. Testing the nylon ball revealed - as suggested - jammed. After 9 grueling hours on my knees in the bilge, the main fault took one second to fix. You have to be some kind of Zen monk to smile after that. Actually I think serious afourians are zen monks of a kind.

Is Facet is now using an ethanol resistant gasket? My pump is about 5 years old - what's the lifespan of these things?

I append a pic of my current fuel system including three filters. I know the auto polishing filter is non-standard but I like to see the fuel flow. Not seen - the oil pressure sensor bypass with switch for priming the pump. I ran with a squeeze bulb for years till this forum advised against it. Note also the non-standard spigot on the front of the cannister filter. I used this for draining, back-flushing, and running clean gas into pump and carb. Its a handy diagnostic and emergency feature.

She's running like a dream now, but I know from long experience that the longer I leave it, the quicker the system will degrade. Weekly starting - no probs. Leave it a month and I expect trouble.

[Marian Claire]

Having experienced two "stuck ball" issues on two different pumps over the last 7+- years. The most recent just a few months ago and both being standard issue Facets. I have to ask. Is a pump that has stuck once more likely to stick again verses a new pump? What is the cause of this issue? I can not easily blame it on E-10 or lack of use due to the type of gas I use and the frequency of use.The latest victim is now my spare and I plan to buy a new pump but this is getting old.
Dan S/V Marian Claire

[hanleyclifford]

Originally Posted by Marian Claire

Having experienced two "stuck ball" issues on two different pumps over the last 7+- years. The most recent just a few months ago and both being standard issue Facets. I have to ask. Is a pump that has stuck once more likely to stick again verses a new pump? What is the cause of this issue? I can not easily blame it on E-10 or lack of use due to the type of gas I use and the frequency of use.The latest victim is now my spare and I plan to buy a new pump but this is getting old.
Dan S/V Marian Claire

A few years ago Don Moyer suggested that I mount two pumps in parallel. I did, with appropriate valves to run one at a time. Now both get exercise and I don't have a "spare". (But I do keep a new one on board)

[joe_db]

I have two pumps as well. I started in series and then changed to parallel because the stuck ball issue would take both pumps out at once.
That said, the pumps are - in theory - good to go for ethanol. Facet/Purolator make any number of pumps other than the ones we use in the cube form factor with a variety of pressures, check valves, etc. etc.
http://www.facet-purolator.com/cube-fuel-pumps.php

Fuel Compatibility: All models of the Facet® CUBE® Fuel Pumps are compatible with gasoline, diesel, biodiesel, blended alcohol fuels and fuel additives.


IMHO these pumps would be as good - or better - than the ones we use. They don't have the internal filters, but we hopefully have good filters anyway. The old stlye pumps we use have been used for decades in aircraft and I can't say I ever heard of the stuck ball issue with avgas.

[HalcyonS]

Originally Posted by joe_db

the pumps are - in theory - good to go for ethanol. Facet/Purolator make any number of pumps other than the ones we use in the cube form factor with a variety of pressures, check valves, etc. etc.
http://www.facet-purolator.com/cube-fuel-pumps.php

Fuel Compatibility: All models of the Facet® CUBE® Fuel Pumps are compatible with gasoline, diesel, biodiesel, blended alcohol fuels and fuel additives.


IMHO these pumps would be as good - or better - than the ones we use. They don't have the internal filters, but we hopefully have good filters anyway. The old stlye pumps we use have been used for decades in aircraft and I can't say I ever heard of the stuck ball issue with avgas.

"the pumps are - in theory - good to go for ethanol" . This is what facet say in their flyer - see attached. But that does not explain the wildly distorted and softened gasket (pic above), which is presumably adding its own complex molecules to the mix.

Yes, I'd like to know about alternatives to the current standard pump, both facet and non-facet - as Marianclaire says, this stuck ball thing can get old.
Presumably the mechanical pump doesn't have this problem - but how are they doing with e-gas?

[hanleyclifford]

I have been using these pumps for years with no ethanol issues: http://www.summitracing.com/parts/crt-p74021

[HalcyonS]

Originally Posted by hanleyclifford

I have been using these pumps for years with no ethanol issues: http://www.summitracing.com/parts/crt-p74021

in-tra-sting. that exact pump? it says 5.5 psi - isn't that higher than recommended? I note it advertises 'low 4.5 amp draw' - that's low ?!

My line is short and the petcock is around 10" above the carb.

[HalcyonS]

any opinion on this one
http://www.summitracing.com/parts/atx-e8251/reviews

[hanleyclifford]

Originally Posted by HalcyonS

any opinion on this one
http://www.summitracing.com/parts/atx-e8251/reviews

If I were of a suspicious nature I might think that was the same pump being sold under a private label. Beware of psi specifications. I get 4 psi at the carb from those pumps and have plenty to bleed off into the tank return.

[thatch]

The tech, helpline folks at Summit are generally very good and should be able to give you an exact psi rating on the Airtex E8251 pump. It is listed as a low psi pump, so I'll assume that it's in the 4 psi range.
Tom

[joe_db]

http://www.amazon.com/Airtex-E8251-U...rtex+fuel+pump

Lots of info here. It looks like a good pump. As with ANY pump, you should have a pressure gauge. AFAIK you want between 2 and 4 PSI at the carb. Mine seems to hold steady around 3.8-3.9.

[HalcyonS]

Originally Posted by hanleyclifford

If I were of a suspicious nature I might think that was the same pump being sold under a private label. Beware of psi specifications. I get 4 psi at the carb from those pumps and have plenty to bleed off into the tank return.

psi - I don't need much. I'm more afraid of too much pressure.

Did some research, airtex has bad name.

What about Carter P4594 - 8 psi. 72 gph - overkill? What is the downside of too much pressure?

How does your 'bleed off' work - first I've heard of such a thing.

[hanleyclifford]

Originally Posted by HalcyonS

psi - I don't need much. I'm more afraid of too much pressure.

Did some research, airtex has bad name.

What about Carter P4594 - 8 psi. 72 gph - overkill? What is the downside of too much pressure?

How does your 'bleed off' work - first I've heard of such a thing.

That P4594 looks sweet; I like the rotary vane versus the pulse action. Don't worry about the pressure; just bleed it off into a fuel tank return line and get the benefits of cooling and multiple filtration.

[HalcyonS]

Hanley, thanks.
So can you tell about your fuel bleed line - or post a drawing/pic ?
I saw some drawings for hotrods, they include pressure regulators!
thx

[hanleyclifford]

Originally Posted by HalcyonS

Hanley, thanks.
So can you tell about your fuel bleed line - or post a drawing/pic ?
I saw some drawings for hotrods, they include pressure regulators!
thx

The valve on the right bleeds off fuel and sends it back to the tank. I have a gauge right at the carb so I can dial in the desired pressure. Black hose bottom right leads to gauge and carb.

[HalcyonS]

Hanley
wow, super clean, but a bit rube goldberg
I assume the black thing on left is tank? Why two valves into tank?
on right there is a small valve inline - that is the pressure regulator?
Are you using a standard needle valve as a pressure regulator?
And a big valve - slightly obscured - what is that?

Also, on the subject of gauges - cna I use a generic dry 0-15psi or do i need oil filled?
thanks!

[hanleyclifford]

Originally Posted by HalcyonS

Hanley
wow, super clean, but a bit rube goldberg
I assume the black thing on left is tank? Why two valves into tank?
on right there is a small valve inline - that is the pressure regulator?
Are you using a standard needle valve as a pressure regulator?
And a big valve - slightly obscured - what is that?

Also, on the subject of gauges - cna I use a generic dry 0-15psi or do i need oil filled?
thanks!

The small in line valve is just a final fuel shut off in case carb is to be removed without emptying system. Pressure is regulated manually with a ball valve. Some more pictures illustrate flexibility with two tanks and two pumps.

[hanleyclifford]

Originally Posted by HalcyonS

Like many of us, there are times, due to work, family responsibilities or illness, when my old A4 sits dormant for too long. I have learned long ago that if I run the engine every week, it starts and runs like a dream. As soon as it sits for over 2 weeks, trouble starts. 'Carbureter cheese' seems to be a by-product of gas with ethanol.

Right now she won't run, and before that it was obvious the idle jet was blocked. I don't mind doing improvements to my A4 but doing the same carb service too often annoys me.What is the recommended practice for saving this work? Run it dry or leave the float bowl full? Add stabilisers or keep away from them? Convert to fuel injection?

thanks!

Getting back to the original questions. As you can guess we have very different typical use habits with the A4. I run mine all day and constantly replenish tanks. You keep a tank of fuel for weeks and months. If I were in your position I would drain the carb after each use. Install a fuel return line with a filter. Filter the fuel just before the carb. At each starting before starting the engine blow the fuel thru the system for a few minutes so you have fresh fuel in the "batter's box". Fuel movement is your friend. On my boat fuel passes thru 3 filters before getting to the carb and since there is a filter in the return line most fuel is getting filtered 4 times or more as the day progresses. There is no such thing as too much filtration and since each filter imposes a pressure drop there is no problem using a pump that advertises 8 psi if you bleed off the excess. With your type of usage it is imperative to drain tank completely at the end of each season; then blast a little WD (or your favorite whatever) and then seal it up for the winter.