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Honda 2007 BF90d requires periodic fuel priming.

S

Seachaser

Regular Contributor
After running a bit, the engine stops running from a lack of fuel. After squeezing primer bulb it starts fine. If I periodically prime, it will run all day. When I prime, the bulb it starts soft and will get firm.

Suspects? Air leak? Low pressure Fuel pump?

Is there a quick test for the low pressure fuel pump functioning?
 
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Yes...it could be any of the above.

Does this happen when you go a long time at slow speeds or when you are running high throttle under a heavy load?

Of course, make sure all of the fuel line connections are tight and the fuel bulb is laying horizontal or arrow pointing up while under way.

Check to see if you have the updated fuel pump. If you look at the hose from the fuel filter to the fuel pump, does the hose go to the upper pump nipple or lower pump nipple. If it goes to the lower nipple, you have the updated pump.

Do you have an external water separating fuel filter? Be sure that all is well there and the nipples and pipe plugs are sealed and tight.

If you do not have the updated pump but have an external water separating fuel filter, you can do a small test that will help you determine if the pump is really the problem. Get a 5/16" barb'd double nipple and bypass the fuel filter on the engine. Disconnect the fuel filter on the top of the engine completely and connect the two hoses together with the double barb'd fitting. We used this as a fix for the faulty fuel pump while waiting for Honda to come up with a new pump solution. This was only on early models like yours.

Take the motor out and run it. If the problem goes away, then you need the updated pump.

Even though I am pointing out the pump, there are many other potential causes. As long as the bulb is not collapsing, then at least you tank and venting should probably be ok.

If the pump does not seem to be the issue, you are probably sucking air from somewhere. That is where a clear plastic hose and a couple of double barb'd fittings will help....by placing the clear plastic hose in the fuel line at different points to see if there are air bubbles in the fuel. You can start at the fuel filter on the motor, run the motor without the hood and if there are bubbles, then move the clear hose along the fuel line toward the fuel tank. When you get to the point where the bubbles go away, you have just passed the trouble point.

I hope this was not too blithering at this late hour.

Mike
 
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This is exactly the information I need to get started and I appreciate this response any hour day or night. Hopefully I can start troubleshooting tomorrow.

It seems to occur independent of load, speed, or idle mode. They all require repriming the fuel bulb.
Bulb never collapses.
It does have an external Water filter. But, I'll be using a remote tank and eliminate most of the plumbing.


hondadude said:
Yes...it could be any of the above.

Does this happen when you go a long time at slow speeds or when you are running high throttle under a heavy load?

Of course, make sure all of the fuel line connections are tight and the fuel bulb is laying horizontal or arrow pointing up while under way.

Check to see if you have the updated fuel pump. If you look at the hose from the fuel filter to the fuel pump, does the hose go to the upper pump nipple or lower pump nipple. If it goes to the lower nipple, you have the updated pump.

Do you have an external water separating fuel filter? Be sure that all is well there and the nipples and pipe plugs are sealed and tight.

If you do not have the updated pump but have an external water separating fuel filter, you can do a small test that will help you determine if the pump is really the problem. Get a 5/16" barb'd double nipple and bypass the fuel filter on the engine. Disconnect the fuel filter on the top of the engine completely and connect the two hoses together with the double barb'd fitting. We used this as a fix for the faulty fuel pump while waiting for Honda to come up with a new pump solution. This was only on early models like yours.

Take the motor out and run it. If the problem goes away, then you need the updated pump.

Even though I am pointing out the pump, there are many other potential causes. As long as the bulb is not collapsing, then at least you tank and venting should probably be ok.

If the pump does not seem to be the issue, you are probably sucking air from somewhere. That is where a clear plastic hose and a couple of double barb'd fittings will help....by placing the clear plastic hose in the fuel line at different points to see if there are air bubbles in the fuel. You can start at the fuel filter on the motor, run the motor without the hood and if there are bubbles, then move the clear hose along the fuel line toward the fuel tank. When you get to the point where the bubbles go away, you have just passed the trouble point.

I hope this was not too blithering at this late hour.

Mike
Click to expand...
 
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The hose from the fuel filter to the fuel pump, does go to the upper pump nipple. Looks like I have the non-updated fuel pump. Do I need to upgrade it? Is there a retrofit kit?

IMG_20180719_110649~2.jpg

IMG_20180719_110643~3.jpg
 
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I'll be jumping out the fuel filter next. Just one interesting thing, this spring when I replaced the low pressure fuel filter; the original filter Barbs were straight through, the replacement fuel filter input and output Barb's were offset around 45 dgrees. Hmm?


LP Fuel Filter jumped out:
IMG_20180719_121556~2.jpg

Spring time LP Fuel Filter Replacement:

IMG_20180719_121957~2.jpg



Update: running with the fuel filter jumped out, after 11 minutes the primer bulb is soft again.

Update: put LP filter back, primed till hard, LP fuel filter only 1/4 full. Five minutes later bulb softer.

Update: it appears even without running the motor and after fully firm primers it gets soft. Is this normal?

Update: Now the primer bulb is staying firm in static non use situation 15 minutes. Bowl still only 1/4 full.
 
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Your old filter was for a carbureted 90. Your replacement filter the correct filter for your engine.

The bulb will be somewhat soft once the motor starts running. Normally a few pumps and it should be hard again.

The filter may not fill up all the way, but you should be able to see fuel flowing through it.

When you bypassed the filter, did the motor ever fail?

I can not say for sure that the pump is the problem, however if you change it, you will also have to change a couple of the fuel lines. The fuel pump assembly kit with the pump and hoses is 06167-ZY9-000.

Mike
 
Hi Seachaser,
Had exactly the same symptoms recently after fitting a new main wiring harness, engine kept spluttering and dying, would only run smooth on bulb priming, was blaming connector issues still, but eventually traced it to me tightening the jubilee clip too tight on grommet on front of engine after installing harness which had nipped fuel pipe closed, slackened it back a bit and engine was fine,

Regards,

Paul
 
Topcat256 brings up a good point. Checked for pinched or kinked fuel line, especially going into the engine. You should be able to pull the fuel line each way a small amount back and forth through the grommet with little resistance.

Mike
 
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