Author Topic: FL400R - fuel 'pump' failure.  (Read 8007 times)

breezer

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FL400R - fuel 'pump' failure.
« on: March 18, 2012, 01:03:16 PM »
Hey guys, after almost a year of not being used, I was unable to start the Pilot.  I did the usual checks and isolated the error - the little silver 'fuel pump' (I guess it's a membrane - I'm used to carbs that have this on-board) box, on the front of the gas tank, appears not to be working.

I can suck fuel through it, and it's airtight as I can't blow the other way, but when I turn over the engine, it's not pumping any fuel through.  The fuel filter also has liquid in it, so there isn't a blockage in the tank itself.

Does anyone know what is likely to have failed in this - i.e. does it just get gunked up?  If so, does it come apart easily? Is there an easy fix or replacement part? 

As I understand it, the pressure from the crank case, which is linked by a small black pipe (which I checked for splits) causes the internals to spin, and fuel is drawn from the filter and pushed into the carb.  Am I miles off?

Thanks, Ollie

LiveWire

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Re: FL400R - fuel 'pump' failure.
« Reply #1 on: March 18, 2012, 05:10:19 PM »
I have been meaning to check if this fits the Pilot as well, but have not got around to it:
http://www.aftershockmotorsports.com/Honda-FL350R-Odyssey/Fuel-and-Air/Fuel-Pump-Rebuild-Kit

You could try taking the pulse line off and suck/blow on it to see if it pumps. What is your compression at? If your compression is low, that also means the pulse in the crank case is reduced.

Nothing spins. The membrane separates the pulsing crank case pressure from the fuel. There is a check valve in and a check valve out. When the piston goes up, it sucks on the membrane and pulls fuel into the pump. When the piston goes down, it shoves that fuel out of the pump. It works pretty much like those plastic air pumps you step on to inflate an air mattress.

breezer

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Re: FL400R - fuel 'pump' failure.
« Reply #2 on: March 19, 2012, 11:09:20 AM »
Thanks LiveWire, that's a great explanation for a simpleton like me! 

Compression should be fine - I only rebuilt the top end recently, and it worked brilliantly after that - also, anecdotally (totally unscientific!), it's still v. tough to turn the engine over using the pull cord.

Looking at POP, there's a replacement pump for a mere $30...

http://www.pilotodysseyperformance.com/view_product.php?product=DF44&cat_id=153

Do you happen to know the flow rate of the FL400R?  This replacement says 14l/hours but I have no idea what that relates to.  I'll ask Curtis, I guess.

LiveWire

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Re: FL400R - fuel 'pump' failure.
« Reply #3 on: March 19, 2012, 02:36:32 PM »

LiveWire

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Re: FL400R - fuel 'pump' failure.
« Reply #4 on: March 19, 2012, 02:40:30 PM »
I could not picture the Pilot pump in my head, looking in the service manual, it is not the same as the FL350 so would have to use the Mikuni pump. I'll have to see if I can find a rebuild kit for the stock Pilot pump too as well as make up mounting plates for the Mikuni pump.

Here is the flow rate of the stock pump:
50 cc(4.7 US oz, 4.9 Imp oz) /10 seconds at idle
« Last Edit: March 19, 2012, 02:43:05 PM by LiveWire »

breezer

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Re: FL400R - fuel 'pump' failure.
« Reply #5 on: April 06, 2012, 09:24:00 AM »
Well, I did some further tests (took the pump off) and ascertained that it's fine - the problem is that there's no pressure from the crank.
:(

It's one thing after another!  So bottom end rebuild it is.  I'm not sure I can do this myself, as I don't have any specialist tools. 

LiveWire

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Re: FL400R - fuel 'pump' failure.
« Reply #6 on: April 06, 2012, 11:21:57 AM »
It may not be the bottom end. It may just need a top end rebuilt. If the rings are losing compression, that also means they are not pulling a vacuum in the crankcase.

breezer

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Re: FL400R - fuel 'pump' failure.
« Reply #7 on: April 06, 2012, 02:04:42 PM »
Nah, compression is fine at the top end as I only rebuilt it about 4 hours ago.

I'm close to just selling it now to be honest.  The thing is perpetually in need of repairs.

KTM265

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Re: FL400R - fuel 'pump' failure.
« Reply #8 on: April 08, 2012, 07:11:12 PM »
Don't give up on it...do a little head scratching, do a few crazy modifications and make it a ton more fun. 
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.

Hoser [həʊzə] n 1. US slang a person who swindles or deceives others 2. Canadian slang an unsophisticated, esp rural, person

LiveWire

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Re: FL400R - fuel 'pump' failure.
« Reply #9 on: April 09, 2012, 07:59:47 AM »
Saying it has good compression because it was rebuilt does not mean much to me. It is just like when someone says their engine does not have air leaks because they just put in new gaskets.

If your crank seals are bad, they could be sucking/losing air as the engine rotates which would result in the fuel pump not working well. The chances this would toast your top end first is pretty good even if it had been rebuilt yesterday. I would check your compression and check for air leaks.

breezer

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Re: FL400R - fuel 'pump' failure.
« Reply #10 on: April 11, 2012, 04:17:14 AM »
Don't give up on it...do a little head scratching, do a few crazy modifications and make it a ton more fun.

Well, I also have a Z3M Coupe, which gets more use and is also horribly expensive to maintain, so I think I'll have to prioritise at some point! 

Saying it has good compression because it was rebuilt does not mean much to me. It is just like when someone says their engine does not have air leaks because they just put in new gaskets.

If your crank seals are bad, they could be sucking/losing air as the engine rotates which would result in the fuel pump not working well. The chances this would toast your top end first is pretty good even if it had been rebuilt yesterday. I would check your compression and check for air leaks.

Thanks, I'll look at that, but I think at this point I should at least stick it on eBay with a reserve and see what I can get for it.  My heart's just not in it anymore.

ttyR2

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Re: FL400R - fuel 'pump' failure.
« Reply #11 on: May 30, 2012, 12:59:31 PM »
To test the pump on my FL350, I used a squirt bottle to fill the carb and left the fuel line disconnected, redirecting it into a bottle. Fired up the engine on the fuel in the carb. If everything is Ok, you should get a lot of fuel squirting out of the pump.