Motor stall

[Savage420]

Hey, my motor idles real nice but when i go into gear it wants to stall out unless i hit full throttle real fast, but only sometimes this works.

Anyone have an idea as to whats going on?

My motor is a mercury 45hp 4cylinder 2 stroke.

 

[Tinlizzy]

Re: Motor stall

...Start with the basics Savage. Check your compression and spark for each cylinder. If those test O.K move to the fuel system.

Try pumping the primer bulb when the motor begins to die out and see if it picks up RPM, thats a sign of a fuel pump issue.

When were the carbs rebuilt last? It would be advised to rebuild/clean the carbs out, and check the float settings.

Post back the findings.

 

[Savage420]

Re: Motor stall

...Start with the basics Savage. Check your compression and spark for each cylinder. If those test O.K move to the fuel system.

Try pumping the primer bulb when the motor begins to die out and see if it picks up RPM, thats a sign of a fuel pump issue.

When were the carbs rebuilt last? It would be advised to rebuild/clean the carbs out, and check the float settings.

Post back the findings.

I have checked the spark on each cylinder and it has a nice blueish arc. Have not checked the compression yet but i will do that the next trip out on the lake .There seems to be good compression though as it a S.O.B to pull over 4 cylinders :redface: starts pretty good though.

I would need a buddy with me to pump the primer as i go and put it into gear and see what pans out LOL

Geeeez i wouldn't have a clue as to when the carbs have been serviced. If the other things work out i will tear down both carbs and see if theres just something stuck in one of the jets or the needle or the floats and set at the right hight like you said (i just did the carbs on my banshee). There was no in-line filter and the gas that was in the tank was dirty as all hell.

I got the Boat, motor and easy load tilt trailer for 500 BUX!!! For the deal that was, i couldn't pass it up. Get's me out on the lake so im happy with it, It's even sporting the pully/cable steering, i also just replaced the cable and pullys too and for what it has to do i'ts great. I will post up the findings.....thanx for your help so far.

Chris

 

[bgbass.1]

Re: Motor stall

before you go through pulling the carbs. run some seafoam through its worth a try. It could also be as simple as a carb adjustment.

 

[Tinlizzy]

Re: Motor stall

I would surely rebuild/clean the carbs. Most of the time it takes more effort taking the carbs off then rebuilding them

Check to make sure the fuel tank vent is open as well.

Also, I would still rebuild the carbs even if you run seafoam. The seafoam will do great at decarbing.

post your findings.

 

[hkeiner]

Re: Motor stall

You don't mention at what rpm your motor is idleing at. Perhaps idle rpm is set too low and the extra load on the motor when it is placed in forward gear brings the motor's rpm too low to run OK at idle. The idle speed rpms should be set to the specs with the motor idleing in the water in forward gear. While you are at it, confirm that all link and sync settings are correct.

 

[Savage420]

Re: Motor stall

So...this sea foam you guys talk of where do i put it??? do i just put a bunch in the gas tank and go for a ripp?

Also the gas tank that i have is a 6 gallon But the guy that i got it from had a rigged up gas cap that kinda sucks....should i get a new cap or is it good the way it is? also where is the vent?

 

[Tinlizzy]

Re: Motor stall

...Here is the URL for the FAQ guide on seafoam. http://forums.iboats.com/showthread.php?t=158076

The vent on a portable fuel tank depending on the make/model can be on the cap itself or the tank. Its usually a small thumbscrew that opens/closes to allow air flow.

If its a fixed tank the vent would be fixed to an opening on the boat itself. By means of a fuel line typically.

If the vent is in the cap, and its "rigged" they are not expensive, so I would replace them. Even if it is working properly just for a piece of mind. Thats my humble opinion.

 

[Savage420]

Re: Motor stall

...Here is the URL for the FAQ guide on seafoam. http://forums.iboats.com/showthread.php?t=158076

The vent on a portable fuel tank depending on the make/model can be on the cap itself or the tank. Its usually a small thumbscrew that opens/closes to allow air flow.

If its a fixed tank the vent would be fixed to an opening on the boat itself. By means of a fuel line typically.

If the vent is in the cap, and its "rigged" they are not expensive, so I would replace them. Even if it is working properly just for a piece of mind. Thats my humble opinion.

Ok thanx but are the fuel caps all sorta universal fit? Im going to go get some sea foam and a cap from the shop right now...Thanx again.

 

[Tinlizzy]

Re: Motor stall

Ok thanx but are the fuel caps all sorta universal fit? Im going to go get some sea foam and a cap from the shop right now...Thanx again.

...Just bring your old cap with you and match them up.

 

[Savage420]

Re: Motor stall

...Just bring your old cap with you and match them up.

Haha...thats the thing there is no old cap he just had a plastic bag with a elastic bad with some old bigger platic cap over that...lmao

anyway i will just measure it up and see what they have. Should i get a vented one because i dont really know if the tank is vented.

 

[Tinlizzy]

Re: Motor stall

...haha what comedy

Yes get a vented cap.
I would not be surprised if that was the majority of your problem =p

 

[hkeiner]

Re: Motor stall

If the motor runs OK at full throttle but stalls when placing the motor in gear at idle, I wouldn't think those would be indications of insufficient venting of the gas tank. Wouldn't insufficient venting also cause engine stall or bogging at WOT? Loosening the the cap to see if it stops the stalling would be an easy way to check this.

 

[Savage420]

Re: Motor stall

Well i just let it warm up a bit longer and it ran great from the get go.....i ran it pretty steady for about 20-30 min going up the lake then fished around for a bit...then fired it up to gome back to where the truck was parked and all of a sudden it started getting boggy and then cut out. Then looked back and the motor was steaming alot as it was real hot. By this time we were about 5K from the boat launch so we started to paddle Not fun at all....anyway about 1/2 hour into paddling we fired it back up and it started to go so i gave it some throttle and it went for about a minute or so then gave out again...did this mabey 4 times altogether and then looked at the back of the leg and the paint was peeling off dammit dammit dammit...well now i think my water pump is hoopered or something and i think i heard a sorta ticking noise just before it dies... hope i didn't "F" up the motor from over heating it...do you think it's worth getting someone to dig into it to see whats up with it like it might need a rebore and pistons and all new water pump stuff and other things it wont be worth it in my book, or should i borrow my buddys 20Horse to get me out there so i can drop this thing in the lake damn this sucks totally i just got the motor and have 2 days on the sucker...any help anyone...

Thanx
Chris

 

[Tinlizzy]

Re: Motor stall

I would start with a compression check on the cylinders.

The readings should be within 10% of each other. If that checks O.K I would go ahead and drop the Lower Unit and change the water pump.

 

[hkeiner]

Re: Motor stall

Do a compression test. That should tell you a lot.

 

[Savage420]

Re: Motor stall

Ok i will try that. But i hope it's not a totally screwed up. Are you guys sure its the impeller or what ever?

 

[Savage420]

Re: Motor stall

Also do they even make parts for my 1961 merc 400?

 

[Tinlizzy]

Re: Motor stall

...iboats marine store has a variety of parts. If they do not have the parts for your year you can check out: www.oldmercs.com

 

[Savage420]

Re: Motor stall

Ok thank you. so changing the water pump impeller and stuff something i could do myself as i know for sure i could do the topend if i had to as there pretty easy to do on my sled,dirt bike and quad, so.....im just hoping its not buggered up.