Logo
FULL SITE MENU

90HP Honda Four Stroke Losing Power

B

BlueblazeSS

New member
We have a 2007 90HP Honda 4 stroke with about 100 hours on it. We get this same issue every year and normally a new primer bulb fixes it. But not this year. I tried a new bulb, seafoam, and 0 ethanol fuel. No luck yet. Any time it goes over 4k RPM it will sporatically cut power and the Rpm's will drop quickly then resume back to normal. I posted a video to youtube. Please help! Thanks!




http://youtu.be/v8KPfK9tkdI
 
Every time lack of power we can guess fuel issue, Water separator inside the boat, fuel filter in the engine, If all ok check fuel flow to carburetor(pump primary bulb and see). then go to carburetor cleanup. if long time not sued the fuel in carburetor vaporized and some gum kind of things stay remain in the carb system,so that will clog the small hols in the main jets and small passage of fuel path.
so first check the filters and just open spark plugs and see
 
Simple things first.

Next time it does that open your fuel tank filler cap and see if that straightens it out. If so, you have a clogged fuel tank vent. Clean it out with a piece of string cleaner or 400 lb. monofilament.

Check your primer bulb and see if it is partially collapsed. If so, you have a blockage on the end of the fuel pick up tube in your fuel tank. For a temporary fix, blow low pressure compressed air back through the fuel line into the fuel tank. Be sure your filler cap is loose before doing that.

When running poorly, squeeze the primer bulb rapidly several times. If that straightens it out, then you may need to fix or replace the low pressure fuel pump.

If none of that works, then come back at us and we'll get into more diagnostics.
 
I will try all of these. Thanks to both of you for the quick response. I will report back with my findings!

chawk_man said:
Simple things first.

Next time it does that open your fuel tank filler cap and see if that straightens it out. If so, you have a clogged fuel tank vent. Clean it out with a piece of string cleaner or 400 lb. monofilament.

Check your primer bulb and see if it is partially collapsed. If so, you have a blockage on the end of the fuel pick up tube in your fuel tank. For a temporary fix, blow low pressure compressed air back through the fuel line into the fuel tank. Be sure your filler cap is loose before doing that.

When running poorly, squeeze the primer bulb rapidly several times. If that straightens it out, then you may need to fix or replace the low pressure fuel pump.

If none of that works, then come back at us and we'll get into more diagnostics.
Click to expand...
 
I tested out some of these tonight. When the thing started acting stupid, I removed the gas lid which didn't help. Next I have the primer bulb a few good squeezes and it fixed it! Temporarily though. The next time it did it was about 5 minutes later. Once again, squeezing the primer bulb corrected it, temporally. So is it the low pressure fuel pump? Where does one buy one and where is it located? Hard to change? Thanks for the help!
 
Since you said that you had a 2007, I assume that your motor is fuel injected. If you serial number is in this range...BBCJ-1000001 ~ 1012697 then you have the old style fuel pump that has issues at high throttle and heavy loads. Although, from my experience the motor usually dies from running out of fuel unless you back off the throttle. Yours seems to recover on its own. It could be a border line case.

Your fuel pump is on the port side top rear of motor. There is a low pressure fuel filter just to the left of the fuel pump. If the hose from the low pressure fuel filter goes to the upper nipple on the fuel pump, you have the old style pump.

If so, you will need a kit which reroutes and changes a couple of fuel hoses along with the new pump. I think the kit comes with instructions...and is not hard to change. Part # 06167-ZY9-000.

Mike
 
I got got the pump changed out and the filter. Do these hoses look like they are in the correct place?
This is on the front side of the motor. The hose on the left was just hanging and it appears it just goes in the plastic case.
image.jpg

image.jpg


hondadude said:
Since you said that you had a 2007, I assume that your motor is fuel injected. If you serial number is in this range...BBCJ-1000001 ~ 1012697 then you have the old style fuel pump that has issues at high throttle and heavy loads. Although, from my experience the motor usually dies from running out of fuel unless you back off the throttle. Yours seems to recover on its own. It could be a border line case.

Your fuel pump is on the port side top rear of motor. There is a low pressure fuel filter just to the left of the fuel pump. If the hose from the low pressure fuel filter goes to the upper nipple on the fuel pump, you have the old style pump.

If so, you will need a kit which reroutes and changes a couple of fuel hoses along with the new pump. I think the kit comes with instructions...and is not hard to change. Part # 06167-ZY9-000.

Mike
Click to expand...
 
Well here we go! The boat ran great for about 5 minutes. I dropped my mom and dad off at the ramp, hit the primer bulb a few times, and my dad backed the boat off and dropped the hammer! Zipped up and down the river several times. The thing was running great. They picked me up at the dock as we were being flagged down to help 2 jet skis that were broken down and in the direct path of an oncoming barge. As we get out to them the motor dies. I thought, this isn't really happening! All it will do is crank, tries to start, but nothing. The primer bulb isn't staying full either. I tried priming it several times but no luck. Were we sold the correct fuel pump? (honda part 16700-ZY9-013). I'm at a loss. Help! Thanks in advance.

chawk_man said:
Let us know if that fixed the problem.
Click to expand...
 
Did you put in the kit or just a new pump?

Double check your hose connections on the engine.

Are you sure that the bulb is moving fuel when you pump it?

Hold the arrow on the bulb pointing up. If the bulb does not get hard, then it is not pumping fuel, fuel is leaking somewhere between the bulb and the vapor separator ---maybe from the fuel pump itself into the crankcase, or the float in the vapor separator is stuck open and excess fuel is flowing out the vent.

Mike
 
I can see fuel going into the plastic reservoir in the front of the motor. Is that the separator? It's clear plastic. All lines are hooked up correctly. I only did the pump, both filters, and new plugs.
 
That is a good start. Can you see it going through the fuel filter next to the fuel pump?

If you open the drain to the vapor separator, will fuel come out of the drain tube, if you lift the motor up?

Can you hear the high pressure fuel pump run for two seconds when you turn the keyswitch to on?

Mike
 
Just i want let you something,i had same problem,pump the fuel till bulb get hard,run the engine for 5 min engine stall and stop try to pump but very fast bulb get hard and no changes in the motor.

I opened fuel out hose from the low pressure filter(white filter on top of right hand side) and pump the bulb its squeezes but full pump very little.

then i trace the fuel line from that place to fuel prime bulb,got the problem fuel hose is pinched,where the all cables,wires and fuel hose run in to engine through rubber grommet,we fix plastic duct hose cover all stuff and tight with hose clamp,that thing partially pinch the fuel hose because in BF 90 fuel hose run down place of the grommet.

you can check that also.if you have same rigging installation stuff.



wajira
 
I took several of the fuel lines loose and tested a couple things. When I hit the key to crank the motor no fuel is pumping to the plastic filter beside the fuel pump. If I squeeze the primer bulb fuel is getting to the filter and out. I pulled the line on the outlet side of the pump and hit the key and no fuel is coming out. I'm at a loss.
 
Let's back up a little. You said that you replaced just the fuel pump. Your new fuel pump is the newer updated fuel pump. You said you did not get the kit. The kit changes the in and out of the pump.

Maybe you already had the newer one....but here is how the fuel should flow.

When you squeeze the fuel bulb, the fuel goes through the clear water separator on the front of the engine up to the fuel filter on the top of the engine. Then the fuel goes to the fuel pump and it pumps it down to the vapor separator.

Here is the part that changed with the update.

OLD PUMP

With the old pump, the hose from the top fuel filter went to the top nipple of the fuel pump and the bottom nipple of the fuel pump went to the vapor separator.

NEW PUMP

With the new pump, the hose from the filter on top of the motor goes to the bottom nipple of the fuel pump and out of the top nipple to the vapor separator.

So, if you want to see if the pump is pumping, connect it like I describe in the NEW PUMP squeeze the fuel bulb to get fuel to fill the filter....put a hose on the top nipple of the pump and run it to a container (pull the safety landyard to cut the spark...we do not want a fire) and crank the engine and see if fuel pumps out of the pump.

I may be going down the wrong path, but if you replaced the old style pump with the new..and you did not buy the kit, you have pumbed the pump in backwards. I just do not understand how the motor ran at all after you did that.

Mike
 
I noticed the the original pump had a "3" marked on it and the new one had a "2" marked in it. The plastic that surrounds the metal piece on the pump (not sure what you call it) had a cut out on a different location also. I'm not sure if that's part if the new design or not but those were the noticeable differences. I will try what you listed and report back. Thanks for all the help!

hondadude said:
Let's back up a little. You said that you replaced just the fuel pump. Your new fuel pump is the newer updated fuel pump. You said you did not get the kit. The kit changes the in and out of the pump.

Maybe you already had the newer one....but here is how the fuel should flow.

When you squeeze the fuel bulb, the fuel goes through the clear water separator on the front of the engine up to the fuel filter on the top of the engine. Then the fuel goes to the fuel pump and it pumps it down to the vapor separator.

Here is the part that changed with the update.

OLD PUMP

With the old pump, the hose from the top fuel filter went to the top nipple of the fuel pump and the bottom nipple of the fuel pump went to the vapor separator.

NEW PUMP

With the new pump, the hose from the filter on top of the motor goes to the bottom nipple of the fuel pump and out of the top nipple to the vapor separator.

So, if you want to see if the pump is pumping, connect it like I describe in the NEW PUMP squeeze the fuel bulb to get fuel to fill the filter....put a hose on the top nipple of the pump and run it to a container (pull the safety landyard to cut the spark...we do not want a fire) and crank the engine and see if fuel pumps out of the pump.

I may be going down the wrong path, but if you replaced the old style pump with the new..and you did not buy the kit, you have pumbed the pump in backwards. I just do not understand how the motor ran at all after you did that.

Mike
Click to expand...
 
As I said, I may be sending you down the wrong path. What is your frame serial number? That way, I can tell if you had the old pump on the motor. I guess, by the time you check the serial number, you will have already checked the plumbing of the fuel pump....so we will know one way or the other.

Mike
 
Thanks. Yours does fit into the category that I was talking about.

Again if you did not get the kit, the existing hoses may not reach the correct nipples on the fuel pump. You may have to get creative to get them to reach.

Mike
 
Well after testing the old vs new pump plumbing theory, I'm happy to say we have success!!!! I moved the top hose to the bottom of the pump, pulled the spark lanyard, left the top nipple on the pump open, hit the key, and out came the fuel. Attached the old bottom hose to the top, put the lanyard back in, primed it a few times, and she started right up. Ran smooth as can be. I let it run for about 15 minutes and no issues. Thanks to everyone for all the late night help as I have been racking my brain for days over this. :D:D:D

hondadude said:
Thanks. Yours does fit into the category that I was talking about.

Again if you did not get the kit, the existing hoses may not reach the correct nipples on the fuel pump. You may have to get creative to get them to reach.

Mike
Click to expand...
 
Hi all,
I think I have the same problem on my 2006 Honda bf90d.

Engine behaves exactly how Hondadude explained above.
I’ve taken the low pressure pump apart and can’t see any signs of damage?!?!
Should I?

I’d really appreciate the help as I’ve had this issue quite a while now.
 
Back
Top