ST1300 Stalling Issue

I have been talking with a few people off line and thought I would post the issue I have been having here in the event that the resolution helps someone else.

Symptoms: Most of my riding is about a 35 minute commute a mix of riding in town and back country roads. At some point toward the end of the 30 minute or so ride the bike will stall when I pull the clutch to stop of a stop sign or stop light. I do notice that early on the trip that when I pull the clutch the RPMs drop to 1000 and jump back to 1100 where I have idle set. As I get further along in my trip the RPMs will dip lower and lower each time I pull the clutch when coming to a stop. Eventually, near the 30 minute mark the RPMs will dip to 500 or so and the bike stalls. The bike fires right back up and is fine from that point on. Though I haven't ridden for another 30 minutes. I suspect it would happen again around the 1 hr mark. There are no FI codes being thrown. MPG is normal (mid 40s) and power seems fine. In fact I pulled out from a stop sign with a little more throttle the other day and had the front wheel about 2' in the air and this was about at the 20 minute mark of my commute. Fuel level has no impact on if the issue happens or not. It doesn't happen every day or every commute but it does happen most of them.

Possible cause/notes about the bike: When I did the Moonshine SS1K I got what I suspect was bad gas in Fargo. My MPG numbers for that tank of gas were way off. I was getting mid to upper 20s. Though the SS1K my mileage slowly improved and when I got to Moonshine and the trip home I was back to normal. Infact the last leg from Des Moines to home I got the best MPG I have ever seen. It was in the low 60s due to a strong tail wind. Not saying the bad gas was the cause but it is in my mind. Another thing worth noting is that I do have an Audiovox Cruise that I recently added just before the Moonshine SS1K. It has been operating fine. Used it this morning. I did the install with a vac tank and check valve. The bike will tick over to 94,000 miles on the way home this afternoon. The bike has the Turbo City FPR.

What I have tried: I keep thinking something may be up from the fuel from Fargo back in April that has been plaguing me. So most of my efforts have been around the fuel system. Honestly I haven't tried much. Just the normal stuff. Normally I burn Non-oxygenated. On the SS1K I know I ran some E10. I should mention that the tank of gas from Des Moines was 89 cot E10 as that was the highest grade I could find and remember that turn out really high MPG numbers. Of course the wind was helping but I did have the cruise set to 80MPH. Since the issue has come up I have switched to E10 in hopes the Ethanol will mix with possible water in the tank and clear things up. I will say I have been through about 10 tanks of E10 92 octane fuel and there has been no change. I did run one tank of Seafoam. Then a couple tanks later one tank of Techron. This has caused no change in the issue.

What is next: I have to look in the service records but I think the fuel filter is original. I have one on hand but haven't changed it yet because the gasket has to be replaced as well. That is on order and should be in next week. I was talking with a local member here about the issue as he had a fuel pump issue in the past. He mentioned that the fuel pump is only sold as an assembly for something like $400 from Honda, which I knew. The fuel pump which is in the assembly however is a fairly common one used in cages but Honda won't sell it to us from some reason. He said that there are all kinds of cars and truck on the road from various manufactures that use this same pump. He mentioned an ebay listing for the pump and said that it can be removed from the assembly and swapped. This pump can be bought for around $65. For that price I opted to order one and swap it just because I don't want to have to go back in later to do it if the filter doesn't clear up my issue. I wouldn't do a $400 gamble but a $65 gamble I am willing to take. Either way there is close to 100K on this fuel pump so it can't hurt. So once these parts come in I will be replacing the fuel pump and filter. The only note on the fuel pump is that the aftermarket one doesn't come with a new sock filter on the pump. The one that is on there now can be moved over to the new pump but the sock filter isn't available as a part from Honda as they want you to replace the entire assembly. In addition to the gasket I also ordered what is called a fuel return filter. I wasn't sure what it is but it is on the parts list and was pretty cheap. $6 or so. I asked the other member if he recalled what it was when he had his fuel pump apart and he described it as a material kind of like stainless steel wool. It is there to capture big chunks of stuff. May not need it but I won't know what the inside of the tank looks like until I crack it open. Again willing to make a $6 gamble but not $400 at this point. If these parts don't resolve the issue I am having the next step will be to pull the FPR and swap back in the OEM one. I have it in the box o parts. After that we will see what is next on the list.

UNTMatt said:

Link for that fuel pump?

Can you do a quick compression check on the cylinders?

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If you do a search for ST1300 Fuel Pump on ebay you will find it listed. That way when the auction closes and the link no longer works others will be able to find any new listings. I was a little off on the price. $68 with free shipping. Here is a link to the auction that I bought from. It is still active as they have 10 listed. I bought the 7th one of the 10.

ebay link

I would have to get a compression gauge. I think the local auto parts store has them for loan/rent. If the current parts on order don't resolve it as I mentioned the FPR is the next thing. I might as well toss new plugs in it at that time as well. If I am doing that I can do the compression test then.

I plan on taking lots of pics of the replacement in the event it helps someone else along the way. I will also try and note any markings on the two pumps. I would imagine that this is something you could walk into your local auto parts store and they would have one. I did some searches on the part number listed in the auction and came up with pumps going for the same price. Since I am waiting on the gasket anyhow I figured I would just grab the ebay one. I had some money in my paypal account I wanted to use anyhow. I should have the pump today or tomorrow. I am a week out on the other stuff yet.

I would think a failing fuel pump would cause problems at higher speeds rather than at idle, where little fuel is needed, comparatively. Have you tried checking the plugs after it stalls? Could give a clue as to a lean or rich problem, though I suspect that would set a CEL.

There have been a number of starting, idling and driveability issues related to gunked up 5-way vacuum tees. Might pay to pull that and make sure it's clean and all the lines are secure and leak free. Tighten up the throttle body boots while the air box is off, I found mine several turns slack.

wjbertrand said:

I would think a failing fuel pump would cause problems at higher speeds rather than at idle, where little fuel is needed, comparatively. Have you tried checking the plugs after it stalls? Could give a clue as to a lean or rich problem, though I suspect that would set a CEL.

There have been a number of starting, idling and driveability issues related to gunked up 5-way vacuum tees. Might pay to pull that and make sure it's clean and all the lines are secure and leak free. Tighten up the throttle body boots while the air box is off, I found mine several turns slack.

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My guess at this point is more of a fuel filter issue. At least it would make sense to me based on the symptoms. Like I said it might (longer shot) be a fuel pump issue which is why I wouldn't recommend or do a $400 gamble on that. I am mainly doing it because at $68 it isn't that expensive and it does have close to 100K miles. From what I have read about the failures here they seem to be more of a total failure. The best way to determine the issue is with a Fuel Pressure Gauge. I looked into what needs to be done from the SM and it looked like you have to modify something on the banjo fitting where the fuel like comes out from the fuel pump. There isn't a simple hook it up to this port to test it.

The thing that I find off is that once it dies and refires, it pops right off and runs fine. From that point on I can pull the clutch and it dips to maybe 1000 RPM. However like I said I haven't done any longer rides to see if it slowly starts to work back down to dipping to 750 or 500 where it stalls. This weekend I will be going to Curt's service which is a 3 hr ride each way so I should get some more testing in. I am thinking that it is possible with the engine running that the pump is having a hard time keeping up so that the pressure is slowly dropping over time (30 minutes or so) then when the throttle is cut and load removed things get out of whack and it stalls. However like you mentioned I would think I would see it at higher speeds as well. Once stalled if it were a low pressure issue the pump would still be running and it could catch up. So it refires right away and runs fine for a while until pressure drops. The question is why. Well it could be the pump but a clogged filter could cause issues as well as there is too much resistance and the fact remains that I got some strange gas back in April. I would say it is pulling just as hard as usual which is why it is strange. If it wasn't for this stall I would say there is nothing wrong with the bike.

Another possibility is the FPR like I mentioned. I would imagine that they are designed to regulate pressure to a certain amount. If the fuel pressure from the pump were to get too high they should release and return fuel to the tank. If this were failing what could be happening is I am under load so the bike is using most of the pressure then I cut throttle and pull the clutch. The bike drops to idle so in theory the FPR should see a spike in pressure provided the pump and filter are fine. If the FPR is sticking a little or is having an issue it could let pressure drop too low and cause a lean condition and stall. If it is stuck and not releasing the pressure as it should it could cause a rich condition but in either case I don't know that it would be limited to 30 minutes or so into a ride and the bike firing right away after the stall. It should happen all the time. If rich I would image it would be harder to start the bike. Just a quick tap of the starter is all it takes to refire. It is like I bumped the kill switch. What I have been doing now is rather than engine braking as much I pull the clutch and keep an eye on how much it dips. That is why I know it starts out dipping to 1000RPM initially then over time eventually 900, 800, 700 until it gets as low as 500 when it dies. By pull the clutch and going to idle while I coast to the stop I am still carrying enough speed to let the clutch back out and bump start it should it stall. Once bump started I pull the clutch again and it will only dip to 1000RPM and right back to 1100 where idle is set. This is all within a second or two of it stalling.

As for a vac issue. That is why I mentioned the CSS-100. It was installed a week or two before Moonshine. It was working fine and still does. This however means that the vac line between the 5 way T and the MAP sensor has been cut and a T fitting installed to run the CSS-100, a vac tank that I made and a check valve. When I made the vac tank I did a vac test on it with my mighty vac and it help a vac fine over an extended period. Of course if I have to dive under the tank that is another thing to check. When I did the install I also did clean the 5 way T as I know about the issues with that. It is worth checking again if I go in to replace the FPR. Actually if I go in there I will be replacing the vac lines for the 5 way. I saw how some people extend them and label them to make the TB sync process easier. I like that idea. The boots can be checked at the same time but I did have the TB out last summer when I blew a coolant line in the valley of the engine. So they were tightened not that long ago.

The other day it stalled just as I was pulling into my shop at home. That would have been a prime time to check the plugs right after a stall being I was at home. If I can get it to do it again I will do that. Usually when it stalls I am a bit further from home.

UNTMatt said:

The reason I suggested a quick compression test is my Daytona had those symptoms as well. They got worse with time to the point where it became difficult to keep it running. The shop I was using at the time for the Trumpet, finally did a compression check and found that my valves on the number 2 and 3 cylinders were so far out of adjustment, they were stuck open.

It shouldn't take very long to do a compression check and it would eleminate that as an issue.

That being said, if this all started soon after the install of the CCS, that would be my first suspect.

As for the TT FPR, I've got one....in a box somewhere. I didn't notice a difference between the TT unit and the OEM after a few hundred miles. My speculation is that the ECU compensates for it, effectively negating any benefit from the higher pressure. If there is any difference, it is so minor, it's not worth the hassel. That's why I put the OEM back on.

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Yeah, vac issue is another possibility which is why I didn't want to forget to mention it. With your Daytona, did run fine for a while, then stall and immediately go back to running fine for a while? I did do a valve adjustment last year but with the miles I put on it is worth another check and will likely do that when I am down for this other maint. There is also the issue where some people have gotten a stuck valve due to carbon deposits. Maybe something is sticking. I will have to try and find the thread on that to see what they did to fix it. I thought it was some additive that was used to clear out the carbon.

As for CCS install. I did that late March early April. Don't remember the date. Then I think it was April 14 that I did the SS1K to Moonshine where I had the fuel issue. It ran fine after that for a few weeks and then I had my first stall. It has been getting worse. Now it is to the point where it does it once a day. It is random if it is on the way home or to work. Yesterday it was at the end of the driveway. Time before that was a couple miles from work the day before. It was fine this morning so it will probably stall on the way home tonight again.

I agree a compression test won't take long. I just have to find the time to get a tester.

I had a similar problem with mine. It was a huge hassle in stop and go traffic, I would have to keep the throttle barely cracked open to support the idle.

Mine turned out to be the FPR - fuel pressure regulator.

steve

Just a thought, here, and l'm no genius, but it's beginning to sound like the fuel tank vent line may be kinked and restricting air into the fuel tank, thus creating a vacuum. When it finally dies, there is enough time for the fuel tank air pressure to equalize, thus allowing normal operation; at least for a time. Could the fuel tank vent line have become constricted during installation of the cruise control?

Soontobeone said:

Just a thought, here, and l'm no genius, but it's beginning to sound like the fuel tank vent line may be kinked and restricting air into the fuel tank, thus creating a vacuum. When it finally dies, there is enough time for the fuel tank air pressure to equalize, thus allowing normal operation; at least for a time. Could the fuel tank vent line have become constricted during installation of the cruise control?

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It is possible. The tank was pulled for that install but it is a little odd that it hasn't started until more recently. Had no issues in the few weeks before Moonshine other than the fuel issue. Then it was a couple weeks after before the stalling started.

On the way home today it ran fine. There was one stop where it dipped really close to 500 but recovered before it stalled. Stops after that remained up near 1000.

The new fuel pump was waiting for me at home. I plan on sucking out whatever fuel remains in the bottom of the lower tank and letting it sit for a bit to see if anything separates out. Then cleaning out the tank best I can. At least I have another ST to ride while I work on the 1300.

I inspected the new pump. Unfortunately there are no markings on it. I will inspect the old one when I pull it out and see if there is anything.

My 05 did exactly the same thing - with a twist. All of your symptoms, plus once or twice out of every five or so cold starts, it would rev up to 3000 instead of the usual 2000. It would slow down to a normal rpm as it warmed up but --??

But I think I've got it beat. At least 99% think I've got it beat. I've only put about 125 miles on since I did the below and I think it's never run so good. Here's what I did:

I had the throttle body off to check coolant hose clamps as I have the typical ST 1300-cold-weather-coolant-leak blues (on a red bike). While I was under there, I checked the vacuum 5-way junction fittings. Someone on here posted a while ago that their's got plugged. So I took them out and blew them out. I didn't see anything come out, but I used full tank pressure, and it really wouldn't have to be much of anything to cause trouble.

Plus I removed my Audiovox CCS-100. Took everything related to it off and put it back to the way it was before. I never did get it to work properly - it would work well below about 60 mph, after that it was like it got progressively less responsive. Spent hours and hours on it. Now I don't have that (Audiovox) problem anymore.

And changed plugs. Installed NGK Iridium CR7EIX 7385 gapped at .035

So here's my conclusion: Maybe there was a tiny piece of crud blocking one of the 5-way vacuum junctions. Didn't see any so I'm not sure. Maybe there was a vacuum leak inside the Audiovox control thingy which would also explain why my cruise would never work properly. Dunno. Maybe the old plugs exaggerated one of the above conditions. (I think they were original at 30,000 miles.) Beats me. Main thing is my favourite scoot runs as it was meant to and puts grins on my face again.

Further to the reply I just posted; I'm becoming more and more convinced that my problem (and maybe yours too) is in that cruise servo assembly. I've not taken mine apart, but there's gotta be some kind of a bellows setup in there to pull the throttle cable. That and all of the vacuum controlling components would have to have a seal around all of it. Probably not even on the bellows because tthere would be no vacuum on it when you're not using the cruise.

Let's face it - these are not a high priced item and a small leak would not be impossible.

Can you easily get to your vacuum line that feeds the servo? If so, why not pinch it off, or disconnect it and block it off. That would at least eliminate one possibility.

Let us know what happens.

I'm going on a 3-4000 mile tour soon, end of next week, and I'll reply back here if I can eliminate the last 1% or not.

sennister said:

As for CCS install. I did that late March early April. Don't remember the date. Then I think it was April 14 that I did the SS1K to Moonshine where I had the fuel issue. It ran fine after that for a few weeks and then I had my first stall. It has been getting worse. Now it is to the point where it does it once a day. It is random if it is on the way home or to work. Yesterday it was at the end of the driveway. Time before that was a couple miles from work the day before. It was fine this morning so it will probably stall on the way home tonight again.

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UNTMatt said:

Yes, that's how it started. It progressively got worse as the valves got farther out of spec until the bike had difficulty idling at all. It shouldn't have gone that far but the shop I was using at the time wasn't very good and I wasn't nearly as edumacated about these things as I am now.

I'd also second the suggestion to disconnect the vaccum chamber for the CCS, taking the bike back to stock form, and seeing if that resolves the issue. I can also see where this could be the FPR but, as you found out, Honda didn't make doing a fuel line pressure test easy. You have to purchase a fuel pressure tester with the banjo bolt adaptor. If you have the OEM FPR, it's easier just to swap out the FPR than to do a fuel line pressure test.

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Yeah kind of what I am thinking. I had to run to the VA Hospital today and the entire way there it was fine. I was there for a couple hours and when I left and was coming to the stop light to leave the parking lot it stalled. That is odd usually I have to ride for a while before that happens.

Anyhow on the way home I was thinking about the CCS stuff. If it were in the CCS I could get to the vac line going to the unit and plug it. Better yet I could throw a vac gauge on there. I have a couple of those laying around and I think I have enough line. I will have to pull the inner cowl on the right side but it is possible. I guess I could have started with the FPR as I am still waiting on the gasket and return filter however I just topped off the fuel tank on the way home in preparation to the trip to La Cross for Curt's Services. Maybe on the way home I will do a partial tank to keep it empty and I can then lift the tank on Sunday or next week and have a look for kinked lines or anything strange and swap out the FPR.

Well no issues today on the ride to Curt's Service. As a precaution I bumped up my idle to 1500 RPM. The bike ran like a top. Not a long term fix but it worked well for the group riding. I didn't want to stall it out during the group ride through town. I may back it down to 1300 RPM and see how it acts while waiting on parts.

I had only 1 problem with 04 ST. it stalled last month. Only when warming up. Flashed 2 blinks code found vacuum line blocked with a black grease looking stuff to the map sensor. replaced all lines. order new sensor just to be safe.
After cleaning replacing lines problem solved. replaced Map sensor about 1,000 miles later bike ran the same. been good since.
Where the grease stuff came from I do not KNow? It's a vacuum line? That is why replaced Map sensor. Thinking it was some kinda packing for the sensor?

acedantinne said:

I had only 1 problem with 04 ST. it stalled last month. Only when warming up. Flashed 2 blinks code found vacuum line blocked with a black grease looking stuff to the map sensor. replaced all lines. order new sensor just to be safe.
After cleaning replacing lines problem solved. replaced Map sensor about 1,000 miles later bike ran the same. been good since.
Where the grease stuff came from I do not KNow? It's a vacuum line? That is why replaced Map sensor. Thinking it was some kinda packing for the sensor?

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What is the mileage on your 04 now Bob? 140,000?

acedantinne said:

Where the grease stuff came from I do not KNow?

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I think it's probably condensed and cooked down gasoline vapors from the intake tract. That's my theory anyway, there shouldn't be a souce of actual grease anywhere there.

I would consider the FPR - fuel pressure regulator as Steve mentioned before I put the new fuel pump on.
Ron

wjbertrand said:

I think it's probably condensed and cooked down gasoline vapors from the intake tract. That's my theory anyway, there shouldn't be a souce of actual grease anywhere there.

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What about oil sludge? I have seen it in some engines that looks kind of like grease.

Still waiting on the first round of parts. Mainly the gasket at this point for the fuel pump.

I didn't bump down the RPMs yet. Yesterday we took the kids to my Sister's cabin to play in the lake. It was pretty darn hot out. I haven't had a stall since bumping it up. I think 1500 is a bit high. It should be set to 1000 RPM +/- 100. I am thinking I will be fine at 1200-1300 for a workaround for the time being. Or I could just ride the 1100.

RONST1300 said:

I would consider the FPR - fuel pressure regulator as Steve mentioned before I put the new fuel pump on.
Ron

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I have a fuel filter that I want to change out on hand. The only reason I am doing the pump now is that it wasn't expensive ($65), it does have quite a few miles on it and I don't want to change out the other stuff to later find that I have to come back to the pump. Honestly I really doubt it is the pump. So reasons 1&2 are really the only reason it is getting swapped as I will be right there.

The two top reasons for the resolution are going to be a near tie between the Fuel Filter and FPR. Followed by a 3rd option of a vac/MAP Sensor issue. Don't think it is the sensor itself but rather an issue with the vac lines that go to it as they were modified for my cruise control install.

wjbertrand said:

I think it's probably condensed and cooked down gasoline vapors from the intake tract. That's my theory anyway, there shouldn't be a souce of actual grease anywhere there.

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Doesn't the crankcase vent plug into the bottom of the airbox? Maybe some oil residue from that source??