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Boat would not start in the cold.

Posted: Sun Apr 09, 2017 7:59 am
by terrible ted
This sucked Saturday morning a Florence. The plan was turkey hunt then do some fishing and riding. Carb was just rebuilt not but a few mouths and uses. VO540

So I have a question why does the accelerator pump cause this problem? Boat starts fin once the weather warms up.


Lake Florence is really low.

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 10:21 am
by GMAC 76
it is not always the "pump" that causes the accelerator pump problem......there is a check valve and a relief ball valve assembly and then the pump...I have been finding a lot of problems with the other parts of the accelerator circuit other than just the pump.....on the cold weather deal (now this is just my theory so bare with me)...if the acc pump is NOT working and spraying fuel up into the intake then the engine must draw the fuel out of the carb thru the idle jet and discharge nozzle up into the intake and then up into the cyls ...when it is cold the engine does not quite turn over as fast and the cold air is heavier making it harder for the engine to draw the fuel thru the jet/ nozzle up into to the cyls with the starter ....warmer temps imo makes all this easier ...just my theroy

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 7:30 pm
by terrible ted
I have twin bats and a 3.5 hp starter. I swear I can troll with the starter. It spins fine?

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 7:34 pm
by diamondback0320
for what it's worth ted my boat acts the same way when I'm camping in the cold..bitch to start & runs like crap when it finally does..then when i come outta the tree stand bout 10ish & weather has warmed up it starts & runs fine...this was even after a carb rebuild..never understood it myself.. I've tried leaning it out with the cable to no better results so idk either

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 8:01 pm
by terrible ted
my boat wont start at all. I like to find a solution this has happened before how fast to carbs crap out

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 8:32 pm
by diamondback0320
there was twice this past hunting season that mine wouldn't start so I could go to the stand & had to choose a different stand behind camp..came bk & it would start..i have always on 3 boats I've owned in 10yrs took my carb off once a yr & took it apart & cleaned inspected everything & replace all the gaskets...in the off season if i go frogging on a cold night & it's real damp out it will act up also... I've chased it since I've owned this boat..new intake gaskets etc.. & never have figured it out

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 8:58 pm
by Lwells
I'm like GMAC, I bet something isn't right with the carb but as a last resort have you considered putting a primer kit on it. I'm guessing we are talking about an aircraft engine for I seen something here 0320. You put a primer kit on it and it will still in O weather with the carb off it. I had an aircraft that was hard to start and I always had to use the primer on it for it wouldn't start without it but there again, there may have been a carb problem I didn't know about. good luck

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 8:59 pm
by Lwells
it will start

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 9:35 pm
by diamondback0320
ted how long has it been since carb has been gone thru..if you think maybe it needs some work greg(gmac) is definitely who i would send it to.. he's the man when it comes to carbs & mags :thumbleft: & very easy to deal with!

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 9:38 pm
by diamondback0320
does it have mags or electronic ignition... getting fire? maybe impulse spring..just an idea

Re: Boat would not start in the cold.

Posted: Sun Apr 09, 2017 10:37 pm
by diamondback0320
well i tried deleting my last reply but guess you can't do that anymore.. reread the original question & seen you said it will start after it warms up

Re: Boat would not start in the cold.

Posted: Mon Apr 10, 2017 6:04 am
by Gary S
Give it a shot of starting fluid.

Re: Boat would not start in the cold.

Posted: Mon Apr 10, 2017 9:32 am
by GMAC 76
terrible ted wrote:my boat wont start at all. I like to find a solution this has happened before how fast to carbs crap out

ted if the carb was rebuilt using quality parts, put together right and tested to be sure everything is working properly and you provide it with clean fresh fuel it should work trouble free for years...I rebuilt my MA-4-5 carb 6 years ago and have had no issues.....I also understand lwells idea about a primer system but if the pump system on your carb is working properly it will provide more than enough fuel for that engine to fire.....my entire theory was based on the idea that the pump system is NOT working right...also garys has a good idea if it wont start give it a shot of starting fluid if it fires then ya know ya got a fuel delivery problem if it don't then ya need to look at something else

Re: Boat would not start in the cold.

Posted: Mon Apr 10, 2017 8:37 pm
by terrible ted
when its cold even starting fluid shoot at the carb doesn't work, it is sparking. just had the carb redone. Last time it did this I was at the camp nothing worked. It is like no fuel get sucked up the intake. We put a new accelerator pump on the carb and bam it started no mater how cold. A fuel primer how does it prime the engine.

Re: Boat would not start in the cold.

Posted: Mon Apr 10, 2017 8:41 pm
by terrible ted
If your talking about a primer that just primes the carb it getting fuel.

Re: Boat would not start in the cold.

Posted: Mon Apr 10, 2017 9:49 pm
by Lwells
Aircraft primer kit is small lines from the primer assy that go directly to each cylinder so that when you unlock the hand pump and pump it the gas goes directly into the cylinder. But I agree with GMAC, if that carb is right it should start. I had a similar problem that your having and Greg showed me on his bench why my engine wouldn't start and my carb had just been rebuilt too. He held my carb on his bench and pumped the throttle, gas was suppose to go about 3 Ft out of the carb but was only going about a foot. He did some work on it and gas would come out of it and hit his ceiling. I put carb back on, 2 pumps and it would fire right up. But I'm not sure you got a fuel problem if it doesn't react to either.

Re: Boat would not start in the cold.

Posted: Mon Apr 10, 2017 9:51 pm
by Lwells
Spelling check keeps changing word carb, but I figured out I could edit it but couldn't get this to delete. :banghead:

Re: Boat would not start in the cold.

Posted: Tue Apr 11, 2017 12:12 am
by GMAC 76
terrible ted wrote:when its cold even starting fluid shoot at the carb doesn't work, it is sparking. just had the carb redone. Last time it did this I was at the camp nothing worked. It is like no fuel get sucked up the intake. We put a new accelerator pump on the carb and bam it started no mater how cold. A fuel primer how does it prime the engine.

so then if the accelerator pump circuit on the carb is working properly then the engine will start no matter how cold.....so then you solved the problem by making the carb work properly...I guess I don't understand what the problem is then

Re: Boat would not start in the cold.

Posted: Tue Apr 11, 2017 6:17 am
by Gary S
A new accelerator I believe is around $75.00. There are people that will rebuild one for a lot less. There are people that will say a used one is ok. My experience is to bite the bullet and spend the money to do it right the first time. Same thing applies to mags, new parts not recycled.

Re: Boat would not start in the cold.

Posted: Tue Apr 11, 2017 7:15 am
by terrible ted
GMAC 76 wrote:
terrible ted wrote:when its cold even starting fluid shoot at the carb doesn't work, it is sparking. just had the carb redone. Last time it did this I was at the camp nothing worked. It is like no fuel get sucked up the intake. We put a new accelerator pump on the carb and bam it started no mater how cold. A fuel primer how does it prime the engine.

so then if the accelerator pump circuit on the carb is working properly then the engine will start no matter how cold.....so then you solved the problem by making the carb work properly...I guess I don't understand what the problem is then



The question is why does it, the reasons. down to the science.

Re: Boat would not start in the cold.

Posted: Tue Apr 11, 2017 7:20 am
by terrible ted
Lwells wrote:Aircraft primer kit is small lines from the primer assy that go directly to each cylinder so that when you unlock the hand pump and pump it the gas goes directly into the cylinder. But I agree with GMAC, if that carb is right it should start. I had a similar problem that your having and Greg showed me on his bench why my engine wouldn't start and my carb had just been rebuilt too. He held my carb on his bench and pumped the throttle, gas was suppose to go about 3 Ft out of the carb but was only going about a foot. He did some work on it and gas would come out of it and hit his ceiling. I put carb back on, 2 pumps and it would fire right up. But I'm not sure you got a fuel problem if it doesn't react to either.



I sprayed it at the carb but not up it.

I also did not know the carb shoots gas that high.

Re: Boat would not start in the cold.

Posted: Tue Apr 11, 2017 11:00 am
by GMAC 76
yea ted....a good MA4-5 pump will shoot fuel 8-10ft so it would really get it up in the engine for starting and acceleration

Re: Boat would not start in the cold.

Posted: Wed Apr 12, 2017 9:39 pm
by terrible ted
so when it doesn't squirt just flows it out is it air density that stops it from starting when cold

Re: Boat would not start in the cold.

Posted: Wed Apr 12, 2017 10:18 pm
by GMAC 76
terrible ted wrote:so when it doesn't squirt just flows it out is it air density that stops it from starting when cold
...well Ted..... that's kind of my theory...... if the pump don't squirt then the engine has to draw the fuel out of the carb up into the cyls and the dense heavy cold air makes it hard to get the fuel up to the cyls and warm air makes it easier....but like you found out if the pump works right the engine will start and I think that is the really important thing to know

Re: Boat would not start in the cold.

Posted: Tue Apr 18, 2017 10:33 pm
by Lwells
I'm just guessing but your carb is on the bottom like mine. Car carb pumps gas out and it sqirts and drops down into the intake and runs toward the cylinders so the fumes are holding down below the carb and the butterfly is closed enough that there isn't much air to dilute the fumes and what gas went into any cylinder but when the carb is on the bottom of the engine the carb has to get the gas far enough into the intake above that the fumes off the gas will be close enough to the cylinder and rising when you crank and the cylinders will suck it in and fire it otherwise the cylinders will just suck air first and not get enough fuel or fumes to fire because there is more air close to the cylinders than fumes or gas so you have a very weak mixture to fire the engine. If I'm wrong about this you guys feel free to jump in on this and correct me