Sputtering issue and rust

FastST

FastST

Joined
Oct 28, 2024
Messages
192
Age
63
Location
NJ
Bike
ST1300
2003 ST1300 52k miles, I've noticed the bike is sputtering under power. Not too often but nevertheless was doing time to time.
I got most of the gas out and pulled the fuel filter. What I see is a good chunk of rust on the bottom of the lower tank. Cleaned it out and replaced the fuel filter. When I cut open the old filter, it was all black inside.
After replacing it, the problem didn't go away, and I think got even worse. Today I thought it won't make it up the hill.
Should I replace the pump (and the mesh under it)? Clean injectors? Anything else?
 
On my 2004, I've had rust in the lower tank twice. Mainly because I left the bike sit for several years. The first time I cleaned out the tank and replaced the fuel pump/filter. And then, let it sit again. The second time, I replaced the lower tank, fuel pump and filter. And the bike is running fine.

Since I'm no longer commuting and putting 125 miles a day on my bikes, I use a couple of ounces of seafoam in my tanks, every now and then. And make sure the tank is full, to keep it from rusting when it it sitting.
 
The upper tank shows signs of rust too, but the prev owner said that he replaced the pump before selling it. it was never a problem in 5 years I'm owing the bike. I wouldn't want to deal with replacing tanks now. Was thinking of selling the bike anyway now.
 
IIRC, aftermarket pumps go for as low as $60. That's what I've read here and that price is probably a year or more old. The only problem with Amazon's cheap pumps is the fuel hose is not rated for submersion in gas and it will swell and deteriorate in a month or two. You also have Honda auto fuel pumps to choose from, if you prefer a better brand that is cheaper than the OEM item.
 
SMSW said:
You also have Honda auto fuel pumps to choose from, if you prefer a better brand that is cheaper than the OEM item.
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Which Honda car/ year has the same fuel pump?

Can it be that the rust is sitting in the pump too, and in some fuel lines stopping the flow?
Can it clog the injectors?

I've ran the seafome but no help.
 
FastST said:
Which Honda car/ year has the same fuel pump?

Can it be that the rust is sitting in the pump too, and in some fuel lines stopping the flow?
Can it clog the injectors?

I've ran the seafome but no help.
Click to expand...
If the bike is running , then the pump is running and not likely blocked with rust. It can however be pumping pressure that is below spec, which could be causing an issue. If rust particles did get through the filter and into the injectors, The Telltale sign Will be that The fuel pressure will bleed off when you shut the engine off and it will take a few seconds for it to build again When you start it. If this is happening you will also end up with fuel in the oil. Pop the oil cap off and try sniffing in there and see if you smell gas. If rust gets through further, It can cause a problem with the pressure regulator which will also cause low pressure. If the bike starts right away without endless cranking then I would bet you don't have any blockage in the injectors or the regulator. You could either get the equipment and do a fuel pressure test or Take that money and go ahead and buy a new pump if you're certain it's a fuel delivery issue. Take note of the rubber hose and make sure that it's in good shape and either reuse the factory hose or make sure you get a section of hose that is spec'd to be submerged in gas. Can't add much beyond that because I can't see how much rust there was. If it was really caked in a lot of rust then you could have lots of problems. If there is only a little bit of surface rust then the old filter probably caught it. When you cut the old filter open, what was the inside of the metal casing like? Did it have rust on the casing. Pictures might help here.
 
Bmacleod said:
Take note of the rubber hose and make sure that it's in good shape and either reuse the factory hose or make sure you get a section of hose that is spec'd to be submerged in gas.
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When I replaced the filter the houses looked in as new shape.

Bmacleod said:
Can't add much beyond that because I can't see how much rust there was. If it was really caked in a lot of rust then you could have lots of problems. If there is only a little bit of surface rust then the old filter probably caught it. When you cut the old filter open, what was the inside of the metal casing like? Did it have rust on the casing.
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The rust was on the bottom lowest part of the lower tank. I could clean it out wit a wet towel.

20250609_141210.jpg
 
FastST said:
When I replaced the filter the houses looked in as new shape.


The rust was on the bottom lowest part of the lower tank. I could clean it out wit a wet towel.

20250609_141210.jpg
Click to expand...
Yeah, thats not too bad. Does the bike start right away or does it take an extended period of cranking to start?
 
FastST said:
It sarts right away
Click to expand...
I wouldn't give too much thought to rust in the system then. I would look more toward your fuel pressure due to possibly a weak pump, but I would also consider it being something other than a fuel delivery problem. Could be an ignition/electronic issue. Have you checked the 5- way "t". Maybe check rubber insulators at the base of the throttle bodies for cracks.
 
I checked 5-way T about 3-4 years ago and theywere perfect..
I may check again, but it cuts off mostly under load and especially going uphill if on more gas.
Can a pump be working fine for 5 years and mow became weak?
 
I heard that the fuel pump of 1999 Honda Civic is the same as the st13?
 
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