power loss

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Very strange I'm losing power at wot but the motor will run fine at 4000 rpm just when I try to open her up I'm getting loss of power like she wants to go but than backs down what can I do I have a Johnson200txl77c btw just happened the other day after a full up could this be a vent issue ?
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

Anyone have a idea on this one for me going crazy with this
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: power loss

Is it running on all the cyl's ?? Do a cyl drop test on it when it acts up and see if you find a bad cyl.
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

Don't think I can really test that because it only acts up when I'm driving and only at wot runs fine other than that. Was wondering if this could be a stator problem or fuel pumps ? Only asking because this just happened when I did the last full up. Also I pulled my gas tank to fix my sender that's when this started to act up
 
Last edited:

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

Boobie have any idea on this one or anyone else only asking again so when the guy comes tomorrow I don't get the run around
 

nphilbro

Petty Officer 1st Class
Joined
Dec 19, 2011
Messages
304
Re: power loss

I had a similar problem with my 140. Initially I switched fuel tanks. Then, I ran seafoam through it. In my case, it was all fuel/carb related. Somehow I lost both highspeed jets. Then one recovered, finally the second.
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

I had a similar problem with my 140. Initially I switched fuel tanks. Then, I ran seafoam through it. In my case, it was all fuel/carb related. Somehow I lost both highspeed jets. Then one recovered, finally the second.
so what do you think I should do all was fine you don't think it could be a vent or stator problem right my carbs where just rebuilt so I should tell the guy to check my high speed jets
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: power loss

The carbs might be running out of fuel. You may have weak fuel pumps. They may not be ablt to supply enough fuel to run at WOT. Next time out and you are over 4000, have someone constantly prime the fuel hose bulb. This will force extra fuel into the carb bowls. If the engine runs fine over 4000 as long as you constantly prime the bulb-you've got weak fuel pumps, or even a fuel restriction. A fuel restriction might be fuel hose which is only 5/16" in size or a defective anti-siphon valve on the fuel tank.
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

The carbs might be running out of fuel. You may have weak fuel pumps. They may not be ablt to supply enough fuel to run at WOT. Next time out and you are over 4000, have someone constantly prime the fuel hose bulb. This will force extra fuel into the carb bowls. If the engine runs fine over 4000 as long as you constantly prime the bulb-you've got weak fuel pumps, or even a fuel restriction. A fuel restriction might be fuel hose which is only 5/16" in size or a defective anti-siphon valve on the fuel tank.
Ok after I do that if that doesn't work what is my next step ?
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

So can anyone tell me what to check after I try the bulb ? Would a stator cause this or no ?
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: power loss

Also possible that you are losing spark to one or more cyls after the engine heats up to normal operating temps. Weak ignition components tend to fail once they heat up.
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

Also possible that you are losing spark to one or more cyls after the engine heats up to normal operating temps. Weak ignition components tend to fail once they heat up.
that would cause the motor to bog than pick up than bog ect... At wot ?
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: power loss

Not sure if you have tested for a fuel delivery problem yet. It's either fuel or spark and the fuel issue is easier to check. Best to eliminate the fuel issue before you move on to a spark issue. A spark issue is something else. It's really hard to tell about misfiring. Unless you do a cyl. drop test on the water, or have an inductive timing light with you to check the spark-it's difficult to analyze an ignition problem. Once you get the engine up on plane, the cooling system floods the powerhead with extra cooling water. If you have a temp guage hooked up to the block, you will see the engine will significantly cool off at WOT. That cooling might be enough to get the weak ignition component to start working again. As soon as you come of plane (back to idle) the block will heat up again and the weak component may quit working..
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

Not sure if you have tested for a fuel delivery problem yet. It's either fuel or spark and the fuel issue is easier to check. Best to eliminate the fuel issue before you move on to a spark issue. A spark issue is something else. It's really hard to tell about misfiring. Unless you do a cyl. drop test on the water, or have an inductive timing light with you to check the spark-it's difficult to analyze an ignition problem. Once you get the engine up on plane, the cooling system floods the powerhead with extra cooling water. If you have a temp guage hooked up to the block, you will see the engine will significantly cool off at WOT. That cooling might be enough to get the weak ignition component to start working again. As soon as you come of plane (back to idle) the block will heat up again and the weak component may quit working..
ok thanks going to check fuel first than I'll report back
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

ok can someone post a link for a correct stator test please
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: power loss

The stator tests are found in the factory service manual. You may have some luck at this website: cdielectronics.com.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: power loss

Simple stator test.... You should have a ohm reading between the brown wire and the brown/yellow wire. You should not have a ohm reading between either of those wires and ground.

Also, do a visual check of the stator to make sure that it isn't cracked and dripping a sticky looking substance down upon the powerhead area.

However..... your explanation of the problem does not indicate a stator problem, it does indicate a fuel restriction problem, especially when you say all was well until you did some work on your built in fuel tank. Note that there are two different ID size fuel line hoses... the V6 engine demands the larger size. If you installed the smaller size, therein lies your problem.

It's possible that you may have either kinked the air vent hose or the fuel line, or the anti siphon valve is sticking. Do you receive any kind of warning from your warning horn setup? Check to make sure the warning horn is functional as follows.

Engine not running, key in ON position, ground out one of the TAN wire that you see protruding from the cylinder heads (heat sensor). The horn should sound when that TAN wire is grounded... if it does not, find out why.

Note that the fuel primer bulb normally has a tendency to flatten out when a fuel restriction takes place.
 

mobgod

Petty Officer 2nd Class
Joined
Sep 20, 2011
Messages
179
Re: power loss

Simple stator test.... You should have a ohm reading between the brown wire and the brown/yellow wire. You should not have a ohm reading between either of those wires and ground.

Also, do a visual check of the stator to make sure that it isn't cracked and dripping a sticky looking substance down upon the powerhead area.

However..... your explanation of the problem does not indicate a stator problem, it does indicate a fuel restriction problem, especially when you say all was well until you did some work on your built in fuel tank. Note that there are two different ID size fuel line hoses... the V6 engine demands the larger size. If you installed the smaller size, therein lies your problem.

It's possible that you may have either kinked the air vent hose or the fuel line, or the anti siphon valve is sticking. Do you receive any kind of warning from your warning horn setup? Check to make sure the warning horn is functional as follows.

Engine not running, key in ON position, ground out one of the TAN wire that you see protruding from the cylinder heads (heat sensor). The horn should sound when that TAN wire is grounded... if it does not, find out why.

Note that the fuel primer bulb normally has a tendency to flatten out when a fuel restriction takes place.
Joe the horns are working I also have a temp gauge installed this is driving me crazy going to check the bulb at WOT when I can get someone to come with me, I did order fuel pump repair kits just to be on the safe side. Boat does run fine at 4k rpm but at wot she bogs that picks up ect ... Going to take a picture tomorrow and show a piece I think it could be just so I can have some more input
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: power loss

Another sidebar comment. The original rubber fuel components on that 1977 engine were not made to handle the ethanol in today's fuels. Over time, the ethanol will break down/degrade the hoses and the bladders in the fuel pumps. Replacement hoses/fuel pumps from Bombardier are made with ethanol-resistant rubber parts. If you have any original rubber fuel parts left on that engine, you may want to replace them.
 
Top