Honda bf-40 cold starting?

JimCobb

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Jun 13, 2004
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Anyone know how the carbs compensate for cold starts. (2004 bf-40) There doesn't appear to be a choke, but the top carb has a brown&white wire and black wire running to some kind of electrical unit. Chasing the vague owners manual diagram these wires go to a (ptc heater and -bystar out- on the cdi).Whatever that means. Reason I ask my new motor takes 6 to 7 attempts at starting when cold, starts on first click when warm. Yes the fuel bulb primer is pumped up.<br /><br />Thanks,
 

cp

Petty Officer 1st Class
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Feb 1, 2004
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367
Re: Honda bf-40 cold starting?

There is a choke function.<br /><br />Do you have a tiller control or remote control for your BF40? The tiller control has a choke knob that you manually pull out to activate the choke. On the most common Honda remote control, the surface mount type with integral ignition switch, there is a separate choke switch incorporated into it (if yours doesn't have a separate choke switch, then pushing the idle speed lever all the way up should activate the choke - check your owner's manual). If you have a separate ignition switch then you push in on the ignition switch to activate the choke function. In all remote cases, hitting the choke switch energizes a choke solenoid which moves a linkage to close the choke valve (plate) in each carburetor's throat.<br /><br />My Clymer manual shows the wires to the choke solenoid as being brown and black/yellow. If you can locate the solenoid and linkages, make sure the linkages are not binding. Gain visual access to each carburetor's throat and you should be able to see the choke valve close when the choke switch is actuated. The choke solenoid should have resistance between 2.8 and 3.4 ohms.<br /><br />If the choke function is working, maybe your idle speed is set too low. This would best be determined using a tachometer, but may be roughly indicated by your engine starting and running on the first try, when you have the idle speed advanced.<br /><br />If your motor is as new as it seems, have your dealer adjust the idle speed (it's not real simple since all three carbs must be balanced, plus your motor should still be under warranty). :) If it's that new, maybe you shouldn't even mess with it - just take it in for them to fix? Good luck.
 

omhonda

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Jun 17, 2004
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Re: Honda bf-40 cold starting?

Originally posted by JimCobb:<br /> Anyone know how the carbs compensate for cold starts. (2004 bf-40) There doesn't appear to be a choke, but the top carb has a brown&white wire and black wire running to some kind of electrical unit. Chasing the vague owners manual diagram these wires go to a (ptc heater and -bystar out- on the cdi).Whatever that means. Reason I ask my new motor takes 6 to 7 attempts at starting when cold, starts on first click when warm. Yes the fuel bulb primer is pumped up.<br /><br />Thanks,
 

omhonda

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Jun 17, 2004
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Re: Honda bf-40 cold starting?

Cold hearted friend. I have a new 20 horse Honda with the same problem. What I have discovered is the device on top of the carborator which is called a heater basically is a metering valve that activated by 12 volt power from the engine when the engine is cold. The wiring diagram in the owners manual shows the circuts how the thermal sensor and the heater and the coil from the dinamo is suposed to activate this heater metering valve that enriches the fuel supply when the engine is cold. The problem is I am on my second heater and neither one of these heaters have caused the valve to open. Obviously this is a factory flaw in this device. This heater is retained by one small screw on top of the carborator and yes the heater does get hot when activated with the electical. I have removed this device and put my thumb over the hole and the engine will start just fine then with one crank of the engine. Honda needs to recognize this problem and fix it. If you take the heater out and apply 12 volts to it you should be able to see the pin valve move. I have been in contact with my dealer....Honda needs to know that they have a design flaw, that is in need of repair!<br />Contact your dealer about your problem.
 

cp

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Feb 1, 2004
Messages
367
Re: Honda bf-40 cold starting?

The BF20 is different from the BF40. The BF20 has an automatic choke per the owner's manual as stated, and the BF40 has a choke/fast idle lever per the owner's manual as stated.
 

JimCobb

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Jun 13, 2004
Messages
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Re: Honda bf-40 cold starting?

Thanks guys for your input,omhonda after conversation with dealer they said bring it back in as you are correct, the quote ptc heater is in fact an enrichment valve,and there is no choke on 2004 models.Will be out of town for 10 days will let you know later how the fix goes.
 

cp

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Feb 1, 2004
Messages
367
Re: Honda bf-40 cold starting?

That '04 BF40 must be so new the owner's manual is not available on-line yet? My bad :eek: . Should have asked for the engine serial number first to make sure applicable. Good luck on getting it fixed.
 

JimCobb

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Re: Honda bf-40 cold starting?

Thanks again for your input, dropped off boat at dealer. Should have it back in water around 1st week of July, then will let you guys know the out come.
 

Skinnywater

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Mar 7, 2002
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Re: Honda bf-40 cold starting?

Reason I ask my new motor takes 6 to 7 attempts at starting when cold, starts on first click when warm.
Looking forward to the follow up Jim. <br />It's valuable and appreciated information.<br />As pchonda previously questioned, tiller or remote control is relevant to your starting proceedure. Please include that info in your future contact. :)
 

hondon

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Jun 11, 2001
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Re: Honda bf-40 cold starting?

That engine should be turn key start after priming the bulb .Do'nt fart around with the fast idle lever or you will defeat the enrichening [can that be the right spelling] process and cause the trouble you are having.
 

Skinnywater

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Re: Honda bf-40 cold starting?

To clarify hondon, are you saying JimCobb's '04 has different means to cold start then previous years?
 

hondon

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Re: Honda bf-40 cold starting?

Yes, and alot of dealers or their techs are not aware of this so when the PDI walk thru is or is not done with the customer this info is not passed along and that tech is giving the wrong info to the consumer.Honda has not always been great about telling us when these kind of things are comming out but a good tech should be able to recognize them and make the appropriate reccomendations as to use and form and function.Then inform the sale dept.
 

JimCobb

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Jun 13, 2004
Messages
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Re: Honda bf-40 cold starting?

Hey Guys, I am still out on the road, but wife says dealer called found bad enrichment valve (she wasn't sure of exact nomenclature) and that it should cure my starting problems. It will be another week till I get home to try it out and give you all the details. Hondon your correct the owners manual does in fact say leave fast idle alone when starting cold motor.
 

stanstv

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Apr 19, 2004
Messages
22
Re: Honda bf-40 cold starting?

I believe having the same problem w/my new bf20 remote - will start immediately, go into somewhat of a fast idle and comes down real quick and stalls out - takes approx 4/5 times to restart and keep running. Dealer no Help.
 

JimCobb

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Jun 13, 2004
Messages
17
Re: Honda bf-40 cold starting?

Ok guys, got the boat back, dealer replaced (starter kit) basicly an enrichment valve. Oh yeah I do have a remote. Anyways instead of taking 6 or 7 attempts at starting when motor is cold. It now starts on second 3 second turn of the starter and keeps on running. Much better. And when warm still starts on first click of starter. Thanks for all your input.
 

Skinnywater

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Re: Honda bf-40 cold starting?

Thanks Jim, that feed back as exampled here is fine education.<br /><br />Hats off to the dealer for a first visit repair.<br /><br />BTW, some little things I've experienced with my BF50.<br />After break-in, (20hrs.) the valve adjustment included is needed, the valve clearance will be off. This is also the time for a synthetic oil.<br />And as experienced to me many times. My motor starts, idles, and runs much better using regular fuel over premium.<br /><br />Have fun and enjoy.
 

stanstv

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Joined
Apr 19, 2004
Messages
22
Re: Honda bf-40 cold starting?

Just had my enrichment valve changed on 2004 bf 20 - now starts ok and will keep running when cold, only if idles stays within limits (900 rpm +/- 50, which for me is too fast for trolling so i still will suffer with the poor starting to keep the idle at approx 800 rpm when normal operating temp.
 
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