cleaning fuel tanks

B

blackfish

New member
I'm having some problems with our honda 90
since we purchased our boat last Nov the motor has had a very bad hesitation to the point it will stall if you throttle up to fast (ANY RPM).
One of the carb floats was sticking so i had my mechanic clean the carbs
but unfortunately this did not solve the hesitation problem
so next i replaced the fuel filter , racor filter and fuel lines
still no good.
I've run the boat on a portable fuel tank and It runs great.
So this leaves me with the fuel tanks

my question;
is there a screen on the end of the fuel pickup line in the tank that could be clogged and how do go about removing the pickup line to inspect it
I've tryed turning the fitting with a wrench, where it enters the tank with no luck


thanks for any help
 
I had a problem with one of the antisiphon valves of the Tom Cat 255 right out of the box. It took some experimentation to find out that the antisiphon valve was bad. C Dory sent me a new one. I used a straight hose barb to bypass the anti-siphon valve (I now carry a spare anti siphon valve).

Yes, there should be a screen on the pickup, but not guarantee that there is one. I would look at the bulb as Dan suggests. Also check to be sure that there is no air comming into the line. Most tanks will allow you to remove the fuel draw tube from the top--not sure about the 22's tanks.
 
Blackfish:

I expect the problem is at least in part caused by bad fuel, but it's pretty easy to find out if that's the case, before you begin worrying about other components.

Here's what I suggest: fully empty one of your built-in tanks, either by siphoning out and transfering to the other built-in tank, or to your lawn mower, or, more pleasently, by doing a little boating. Then, confirm that you are still having the stall/hesitation problem on the built-in tank that has fuel remaining, and that the problem goes away when you switch over to the portable tank. Then, transfer the fuel from the portable, to the built-in tank which you emptied. Make sure you run the motor long enough to be burning the fuel which came from the portable, or drain the carbs and the racor, and see what happens.

If you want to run the test in reverse, empty the portable tank, fill it with fuel from one of the built-in tanks, and see how the motor performs on the portable.

It shouldn't take long to figure out the extent to which fuel is a factor.

Let us know, since this is a fairly common problem.

Good luck.

Alma's Only
 
With the spare hose, make sure you have a spare (new) quick connect that snaps/plugs into the motor. Old Raven Dave down here had fits because of a stupid little o-ring in the connector leaking air into the system. I got to tow him to port for it, though, so it wasn't a total loss.
 
Yeah, that's a :thup alright. But they had to do away with them on Suzukis because they suck more than Hondas. My '00 Honda still has the snap on gizmo, but maybe this gentleman's '04 doesn't.
 
Almas Only
I don't think bad fuel is the problem I've refilled both tanks at least twice since buying the boat and didn't seem to change anything.I also removed the old gas out of both tanks shortly after buying the boat in Nov.

dog on dory
I am also having a hard time believing both filler tubes are block
I have taken the fuel switch off and the fuel lines for inspection i'll replace the clamps and fuel lines at least I wont have to worry about any leaks in the near future

where is this anti-siphon valve located
and how would I go about checking it

thanks again for all the help
 
Blackfish:

I've frequently had the problem you describe with my Honda 90 on fresh fuel. I'm running smooth, then take on fuel, and within a little while, am having problems with hesitation/stalling upon acceleration. The motor starts, and otherwise runs fine, but will hesitate when I call for more power while underway, and occasionally stall when I try to power up from idle. Seems that a lot of fuel is "bad" as it goes into your tank, no matter how recently you bought it. If you have a fuel source which eliminates the problem (your portable tank), I urge you to use that same fuel to test other parts of your system, and confirm the extent to which the problems are related to fuel quality.

The other reason I've come to focus on fuel quality with a Honda 90, and only then look to other issues, is the manner in which the fuel is delivered.

If the motor runs fine at WOT, and doesn't flood when it is stopped and then restarted, it seems to me you can conclude the following:

1: There is fuel in all 4 carb bowls.
2: The fuel pumps work.
3: There is not a blockage in the fuel lines.
4: The fuel filters are not plugged or significantly restricted.
5: The fuel tank vents are not plugged.
6: The fuel quality is sufficient to allow ignition at high speed.

If your batteries remain healthy, then you can also conclude:

7: The batteries are capable of holding a charge, and of delivering current to the motor so it can start.
8: Something is charging the battery: either the alternator, shore power, or both. If you boat for any extended period of time, you know that the alternator is working.

I'm sure open to suggestions, corrections, or qualifications on these conclusions. But, if they stand, then you can also go a little farther.

If the fuel system is capable of keeping the carb bowls full at all throttle settings (idle to WOT), then any defects in that system, such as clogged filters, plugged tank vents, clogged or collapsed lines, leaking bulbs, etc., etc., are of no consequence. They might cause other problems, but not hesitation/stalling in the manner we're experiencing. It's a fuel delivery system, and if the components deliver fuel to the carb bowls, they are doing their job. They might be doing that job inefficiently, and therefore should be repaired/replaced, but the problems with motor performance with full carb bowls cannot, by definition, have anything to do with "upstream" components. If you have any doubts as to whether or not your system is capable of keeping the bowls full, just idle the motor, push the throttle forward, notice the hesitation/stall, and then turn the motor off, and drain all 4 carb float chambers. I've done this time and again, and they are always full. Therefore, I've concluded that my problem is not one of fuel availabliity.

I'd like to get some thoughts on what IS causing the problem, but since mine is affected by fuel quality, I'm pretty sure I need to focus on what's going on under the motor cover. I know I'm taking on fuel that's got alcohol it it, tends to accumulate water, etc. and that the problem comes and goes with different tankloads of fuel. I don't know what adjustments, if any, can be made to the Honda 90 to allow it to be less sensitive to fuel variations???????????????????????/


Alma's Only
 
Hi David,

You raise an interesting point. Can an engine be tuned to be less sensitive to the quality of the gas?

One way to investigate this fuel quality & hesitation would be to see if other Honda's with the same fuel as your boat had a problem.

We've cruised together and refueled at the same marinas. I don't recall that I've ever had a hesitation problem, though I've had flooded hot engine problems in past. Have you ever had the hesitation while on one of our cruises after we've refueled?

Rick from Maine
 
David-

The two things you haven't specifically checked yet (unless you've done as Dan suggests and by passed each component in the fuel delivery system one at a time with the extra hose) are the selector switch and the primer bulb.

The selector switch may be blocked, which would effect delivery all the time. (Mine rotates through six or more detent positions, not just the expected 3, and all but two of them are dry/shut off, so the valve is not a bulletproof component.)

The primer bulb could also be blocked, and it also is a single flow point/possible bottleneck in the system. There is an anti-siphon/check valve in the primer bulb which has given more than a few folks this kind of problem before. I'd just replace it or switch it with the one on the portable tank. Some have found that the primer bulb was installed backwards! There should be an arrow on the primer bulb which indicates the preferred direction of flow.

Just some more things to consider....

Good Luck! And keep us posted!

Joe. :teeth :thup
 
I have a 2003 CD22 with twin 50 Yamahas and had the same issues of stalling and difficult starting. After having my mechanic go through both motors, the problem persisted and he finally checked both fuel tanks finding that the pickups (plastic) had disintegrated on one and cracked on the other. I ended up siphoning all the gas (about 35 gals total) on both then removing both tanks and painstakenly shaking out the remainders of both pickups. Then I changed all the fuel lines to 3/8 hose and the fuel connectors and primer balls to BOTH motors also making sure that the fuel switch was not plugged. Seems like the factory pickup was not the right material and should have been aluminum. This solved the problem completely.

Vern
 
Vern-

Good information! Always great to get BTDT (Ben There, Done That) feedback from one who's run the course. Much better than open-ended speculation!

Interesting that you have a 2003 CD-22 and David a 2004 CD-22....... same old story- the same defects in materials cause the same problems, a standard principle in trouble shooting.

That's one of the things that make this site such a valuable resource, being able to touch base with others that have had similar problems and found solutions.

Now if I could just find someone who could tell me how to get my wife to let me live on my boats about 300 days a year!

Joe. :lol:
 
Here is another possibility,

If a carb is too lean at idle the motor will not accelerate properly.

I looked at a Honda carb expanded parts view for a Honda 40/50 and there is NO accelerator pump. I think the Honda 90 carb is similar.

Too lean at idle can be caused by partial obstruction of the idle circuits, or obstruction of the idle circuit only on one or two carbs.

To check for air leaks into the fuel system while running the motor, substitute a clear hose for the rubber hose between the primer bulb and the motor. Watch the clear hose while running the motor. A few very tiny bubbles are ok, but large bubbles are an indicator of an air leak into the system. It is possible for air to be drawn into the fuel system without gas leaking back out. Be sure to remove the clear hose after testing!

I have also experienced poor running after taking on fuel at fuel docks. Fuel docks don't sell as much gas as land stations, and if their fuel is old, the octane may have declined. Also the ethanol in modern gas attracts water and the ethanol/water mix is a poor fuel.
 
Thanks for feedback and suggestions on possible causes.

Rick: I’ll check credit card receipts, logbook, etc., and get some info on where I took on fuel, and began noticing the problem on our cruise. Maybe we can figure something out.

Joe: I don’t think the fuel selector switch is causing the problems I’m experiencing, but I’ll be sure to make some specific notes on this possible cause the next time I’m on the water (hopefully, soon!). Although the primer bulb can cause lots of problems, I don’t think that’s the case here. Mine does face the right direction (almost put it in backwards, but managed to see that big, old arrow). A failed anti-siphon valve should allow the fuel to flow from the bowls, back into the tanks, when the motor is turned off. That would result in hard start problems. However, once the motor is up and running, the fuel pumps are sucking fuel from the tank, and the anti-siphon valve doesn’t do anything, other than present a slight impediment to the flow of fuel from the tanks, to the motor. Seems like once the motor is running, the primer bulb is the functional equivalent of a bulge in the fuel line.

Vern: I’m wondering whether you also got hesitation when you tried to power up, or if the motor just quit running and wouldn’t start, as if it were out of fuel? I think I’m going to take along a portable tank of fuel I know to be good, and do some more experiments to see it I can pin this down a little better.

david
 
Anti-syphon valves,

Anti-syphon valves are not required if all of the fuel system hoses are above the top of the tank.

An anti-syphon valve is a check valve which has a ball and spring inside. The ball is held onto the seat by the spring and is pulled open by the vacuum provided by the fuel pump.

If the ball is steel, it can rust from ethanol/water in the fuel system causing it to stick in the closed position. Varnish deposits from old gas can do the same thing.

The primer bulb has to be soft enough to squeeze, however if the bulb is too soft, it can collapse under vacuum and not let the anti-syphon valve open(as per Dans post). An air leak into the fuel system can cause the same thing. Primer bulbs can become soft due to age or components of the gas like alcohol.

If the anti-syphon valve is removed and any of the hoses dip or are routed below the top of the tanks, a leak in the hose at the low spot can cause gas to syphon from the tanks into the boat.
 
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