Engine cutting out at speed

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SHOOTER72

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Jul 10, 2006
Messages
11
Ok, so heres my issue...first of all I'll tell you i have a Merc I/O 185 merc 3.8L GM motor

I took the boat out this weekend and had a problem, boat ran smooth for 3 hours or so and then it started to cut out when I was going 25 and over....??...really strange......i would throttle it forward and plane off and get up to speed and maybe a minute into going at least 25 and over, the engine started to cut out, almost like it wasnt getting enough fuel....it would rev up and down, rev up and down and again so i had to pull it back and basically stop.....it did it numerous times with a few times stalling and when it stalled it started up and idled good, as soon as i gave it some power to get up to plane it cut out.....at first it was ok at low speed so i ran about 5mph back to the dock but on the way it also started to do it at low speed, but not at just idling....it would idle fine. Again I'll say it ran fine all day for at least 3 hours, and also took her out 2 other times this year and no issues at all either time.

I do have a water seperator on it and checked it and it was clean, not sure where if any other fuel filters are located...

Any ideas??..fuel filter? coil?? something electrical??

any feedback you can give me will help out .....

Thanks
 
Haut Medoc

Haut Medoc

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Jun 29, 2004
Messages
10,645
Re: Engine cutting out at speed


I would check the fuel screen at the carb, the anti siphon valve & especially the screen on the fuel tank pickup.......
Oh & the tank vent as well.....
There is no Merc. GM 3.8 185 that I am aware of, what do you really have?.......:confused:​
 
S

SHOOTER72

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Uraijit

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Re: Engine cutting out at speed

Sounds like a fuel delivery issue to me. Check the filters and pump, and report back.
 
Bondo

Bondo

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Re: Engine cutting out at speed

almost like it wasnt getting enough fuel....
Click to expand...

Ayuh,..... I Agree,.....

It could be Anything from the Fuel Tank to the Carb itself......
 
G

gdombroski

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Sep 18, 2007
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134
Re: Engine cutting out at speed

Replace the anti siphon. Sounds like its sticking. Your symtoms match what I had. About $15 and it fixed it
 
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SHOOTER72

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Re: Engine cutting out at speed

gdombroski said:
Replace the anti siphon. Sounds like its sticking. Your symtoms match what I had. About $15 and it fixed it
Click to expand...


Will do thanks...and this might be a dumb question...but....

where is the anti siphon???


and thanks to everyone for the responses....
 
S

SHOOTER72

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Re: Engine cutting out at speed

Ok, well today i was able to look at a few things and everything looked ok, water seperator was clean, no water, fuel filter was clean and i was able to locate the anti siphon valve, but dont think it has one.....it sure didnt look like one.....i took off the elbow thats screwed in top the gas tank and the hosebarb that connects to that elbow and there was some small debris in the screens that could have been causing the fuel restriction...cleaned it all out, put some seafoam in the gas and the oil and ran it in the driveway but it of course ran fine so i really wont know til its on the water and i can run it under load.......stay tuned....
 
O

ottawamerc

Petty Officer 2nd Class
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Sep 16, 2004
Messages
128
Re: Engine cutting out at speed

I too had a similar problem I rebuilt/ replaced just about every thing fuel and spark related but to no avail. I finnaly found out that the wire from the distributor to the coil was broken down inside the casing. It too would idle all day long but as soon as I would put a load on it it would stumble.
Just a thought!

Scott
 
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SHOOTER72

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Re: Engine cutting out at speed

ok so took her out today for about 4 hours and all is well....but...

why am i having a hard time believeing that the tiny microscopic debris in the fuel tank pick up that i cleaned out was causing the fuel restriction ??.....that little of debris can cause that??

either way she ran great all day...no complaints but i hate having that thought in the back of my mind thats saying...uh-oh is it gonna happen again??...
 
S

SHOOTER72

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Messages
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Re: Engine cutting out at speed

can that little of debris in the fuel pickup screen cause that much of a fuel restriction???
 
Bondo

Bondo

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Re: Engine cutting out at speed

can that little of debris in the fuel pickup screen cause that much of a fuel restriction???
Click to expand...

Ayuh,....... Is it Running Better,..??..??
 
E

ernie36564

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May 18, 2008
Messages
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Re: Engine cutting out at speed

i am also having same problem but i can NOT get the elbow loose at the tank to check the pickup screen. i can get the hose loose but that is all i can get loose. anyone have sugestions. it is aluminum.

:confused:
 
M

ml8163

Seaman
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Jan 21, 2008
Messages
71
Re: Engine cutting out at speed

I was experiencing very similar problems and found that the flame arrestor was extremely dirty and caked in grease/oil from the crankcase ventilation hose, which was not allowing it to breath. While trouble shooting out on the lake I found that if I took the flame arrestor off, the boat ran perfect at wide open throttle. So, I cleaned it in some mineral spirits today and it looks brand new. I'll lake test it this weekend.

Something to think about...
 
S

SHOOTER72

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Re: Engine cutting out at speed

ml8163 said:
I was experiencing very similar problems and found that the flame arrestor was extremely dirty and caked in grease/oil from the crankcase ventilation hose, which was not allowing it to breath. While trouble shooting out on the lake I found that if I took the flame arrestor off, the boat ran perfect at wide open throttle. So, I cleaned it in some mineral spirits today and it looks brand new. I'll lake test it this weekend.

Something to think about...
Click to expand...


the flame arrestor???
 
M

ml8163

Seaman
Joined
Jan 21, 2008
Messages
71
Re: Engine cutting out at speed

The flame arrestor is what sits on top of the carburator. It looks like an air filter like you would find on a car, but upon closer inspection you will find that it is a bunch of sandwiches medal instead of an actual filter.
 
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