Johnson 25hp motor bogs down

[snakeguy46]

Hello, first let me say I read many threads here but not sure it helped. We were out in the water last week with fresh gas and oil and we were at 3/4 throttle and all of a sudden the motor gradually slowed down to a bit more then idle speed? We turned around and headed back to the direction of the launch and fished close by....no need to waste a day. I figured maby some dirt in the carb and when we go home did a good cleaning of the carb. This weekend we took it out and it took a few pulls to start but when it did I gave it some throttle and just bogged down to a stall? Again we fished in place and I took the cover off and started it again and notices when in reverse we have full power no bogging? but in forward get the bog? I think it is something simple but that were you pros come in? I then started it again and while in neutral and with my finger manually worked the throttle and it just bogged? I know you all have better things to do then answer silly questions. I heard it could be the fuel line and bulb but I bought a new one in the spring from a boat shop not wally world.

 

[racerone]

Always start with a compression test.----Post the numbers.----Does spark jump a gap of 3/8" on both leads.-----Does the manual fuel pump go hard?-----Water pump impeller needs to be replaced about every 5 years.

 

[snakeguy46]

May have to take to a shop for that info, did change water pump in the fall. I just thought if all worked fine in reverse should do the same forward? Thanks for the info.

 

[racerone]

In reverse there are exhaust bubbles in the water.----Therefor less work for the prop.

 

[snakeguy46]

Got it, thanks again.

 

[snakeguy46]

Not sure what you meant by fuel pump going hard? I thought about getting a rebuild kit for that. I have done it in the past with other outboards so I feel confident doing it. As for the gap I should be able to check the spark.

 

[stresspoint]

i would be looking at the fuel pump , if its been replaced with a china copy then its time to go OEM and solve your problem.

 

[snakeguy46]

This is an easy one for you, 6gal fuel tank is new with no build in vent on the cap? Should I leave cap tight or loose for ventilation? I have read through these forums both ways.

 

[snakeguy46]

i would be looking at the fuel pump , if its been replaced with a china copy then its time to go OEM and solve your problem.

Good idea,

 

[airshot]

This is an easy one for you, 6gal fuel tank is new with no build in vent on the cap? Should I leave cap tight or loose for ventilation? I have read through these forums both ways.

Try loosening the cap and see what happens

 

[racerone]

Carburetor should be empty when you launch the boat.----Operating the manual pump ( bulb ) should tell you if it is working properly.---Pumping fuel.-----It must go hard ( 4 or 5 squeezes ) and that tells you that carburetor is full and that there are no leaks.

 

[snakeguy46]

Ok, put new fuel pump on today and new bulb and hose. Pumped up the bulb and go good pressure after four pumps. Engine fired up and idled nice. When given fuel got misfire and stalling. This fuel pump came with a filter so I put it in the line just before fuel goes in the fuel pump and when I give it gas I can see quite a bit of bubbles? All the lines and tight and great no cracks? I got no leaks in the clips from the bulb hose so not sure what the issue is? As I stated before three weeks ago I had no issues at all with the motor?
I think the next step would be a carb rebuild kit and new gas tank. I did clean the carb very well but even if the gasket looked good I guess it could bring air in? Your thoughts?