Outboard Troubleshooting Part 2

[BrianW]

Recently, many of you helped me diagnose a carburetor float valve problem on my 2001 Honda 9.9 for my H26. (See attached link to topic thread) Well.... I thought I fixed my problem, but it appears I swapped one problem for another! Previously, the engine would flood out. It would turn over, but not start. When I unplugged the fuel line and turned the engine over a few times, and it started and run well idling and under load until the residual fuel ran out. I removed the carb, cleaned the float valve and the rest of the carb. After reinstalling it, the engine started, but the idle was a little rough. The big problem, is that it runs very rough and losses power when in gear, mid to full throttle under load (against dock lines). I've already cleaned out gas tank and changed out the gas. Any ideas? Thanks, BrianW

http://forums.hunter.sailboatowners.com/showthread.php?t=134371

 

[wetass]

SOunds like maybe its too rich. Too rich will run rough at idle and fast. Too lean will sometimes run good at idle but not at fast.

 

[Rick Webb]

Clogged Jet

Take it back off soak in carb cleaner and run a small wire through all of the passages. I am guessing either the high speed jet or the pump but clean them all. Then soak it again and blow all the passages out.

When your at the computer looking for somthing to do shop around for a new carb. If your lucky you will not need it but will know where to order it from in case you do.

 

[SycloneDriver]

Does it run any better or worse if you squeeze the primer bulb or if you put the choke on half?

Did you use compressed air (as in 100+ psi) when you cleaned it out before?

Does it smoke a lot? How much oil is in the gas?

 

[BrianW]

Thanks for the input so far! I've pulled the carb again and am soaking it in B-12 carb cleaner overnight. Man the water was rough while I removed the carb today! I do not have compressed air. I initially used aerosol carb cleaner (no soaking) and then blew it out with an aerosol can-type electronics dust remover. I'll try to hunt down a compressed air source. The engine did not smoke at all when running rough under load. It's a 4-stroke, no oil in gas. It also has an electronic choke (no manual choke). Lightly squeezing the full fuel bulb now has no affect either way. Before the first "fix", squeezing the bulb would flood it. The engine has a "pilot screw" for fuel/air adjustment. It can only be adjusted 1/2 turn. This is because of an environmental mandate. Rick, I'm pricing a new carb, but hoping I won't have to go in that direction. Thanks again for the great comments thus far! BrianW

 

[petersea]

http://www.boats.net/parts/detail/honda/H-16100-ZW9-816.html
http://www.boats.net/parts/detail/honda/H-16221-ZW9-000.html
honda 9.9 carb $150 will need two gaskets $5

 

[SycloneDriver]

clean it again

Try cleaning it again. Be sure to take it all the way apart.

How is the idle screw limited to only half a turn of adjustment? Maybe a pin or a locking cap, remove it before you clean it.

 

[BrianW]

Edited after more info received:

SycloneDriver, the pilot screw is covered with a limiter cap. The screw is designed to break off when the limitor cap is removed. The shop manual does not describe how to remove the screw with the head broken off. The Honda dealer/service shop says it takes a "special tool" and technique to remove it. BrianW

 

[sailcruiser]

Any chance of back pressure building in the fuel tank? My 8hp 4 stroke did this regularly. Frustrating. Does it die like it's starving?

 

[BrianW]

Sailcruiser, I used 2 different fuel tanks, both well vented... no back pressure. It dies mostly when I place it in gear. When I increase throttle in idle, and then shift into gear, it will run, but roughly and without much power. Thanks, BrianW

 

[Winkfish]

Have you checked the fuel supply ( like a leak or something restricting fuel flow at higher RPMs)? Sometimes you can have enough fuel flow to run at low RPMs, but when you kick it up, not enough fuel is supplied. Maybe the carb re-cleaning will help, but maybe check your lines and bulb for leaks.

 

[BrianW]

Photo of Restrictor Cap on Pilot Screw

Here is a photo of the Honda 9.9 carb pilot screw with restricter cap. The restricter cap only allows 1/2 turn of the pilot scre. The shop manual says that removal of the resricter cap will break the head off the pilot screw, but the manual fails to describe how to remove the broken off screw. BrianW

 

[SycloneDriver]

Make sure you didn't knock a plug wire loose. If the choke is electric make sure it is getting power.

I hate not being able to adjust the idle correctly. Maybe you could dremal the limiter cap and get full adjustment of the idle.

It sounds like you have a blocked main jet. Hopefully the second round of cleaning will do the trick.

 

[alexco38]

You should never have to adjust the idle beyond the set limit.

I think when you clean out the float valve, the arm may have be bent slightly. or the needle valve created a ridge where it sits on the carb body. It made the valve sits a little lower or higher thus the fuel level is either too low or too high in the bowl.



The engine vacuum draws fuel through the main jet. At idle, the throttle is closed. The engine doesn't have enough air flow through the main jet therefore an idle jet with much smaller diameter is used.

I rebuilt car carburetor in the old days. Some model need a gauge to measure the distance between the float to the carb body lip.

One of the Chrysler carb I rebuilt, has a copper float that leaked thus sit lower. That caused endless problem just like you described. Later model cars use closed cell foam block as floats.

One the Honda 8 that I owned before, the rubber diapharm in the fuel pump had a small leak cause low fuel flow to the carb. It also dump fuel into the crankcase. Check if can smell gas in the oil.

Apparently, the Honda fuel pump of certain vintage (early 1990s) had this problem. The replacement pump has a different color shade diapharm.

 

[sailaway78]

No one has suggested

I'm not familiar with that particular motor or carb. But almost all of them are pretty sensitive to the float level. A little too high will make it run way too rich, and little low will run lean at higher throttle settings.

 

[BrianW]

Vroom! I'm back in the saddle again! Soaking the carb overnight in B-12 and then spraying each passage with aerosol carb cleaner... then blowing it all out with compressed air did the trick! This was my first carb troubleshooting, removal, and cleaning.Thanks to all who hung in there with me until my problem was solved. BrianW

 

[Rick Webb]

Good to Hear

Now be more particular about your gas and you'll be set.

Does your carb have the drain screw on the bottom? Draining the bowl will help too.

 

[BrianW]

The permanent ethanol-free gas switch has already been done. My carb does have a drain screw, but I'll have to check to see if its accessable with just the top engine cover off. Thanks again, BrianW

 

[Tom J]

You're lucky you are in Florida, where Ethanol-free gas is an option. A lot of states, such as Massachusetts, don't allow it. I miss Florida.

 

[Ray Bowles]

Are you sure that you don't have a spark plug breaking down or higher that 8000 ohms resistance in the plug wires. It will do exactly what you describe. This is often overlooked.
Ray