Hard Starting ST1100

Grabcon said:
The only time that I have experienced any issues with sputtering is at high RPMs in the 7500k range and higher. The bike has never stalled while riding. But I have noticed at higher altitudes 10000 feet plus that it does buck unless I drop a gear and get the RPMs up. This also started about the same time as the Texas trip. Although what I have notice is very erratic and broad range of MPG. Until the trip to Texas I was consistently in the 43 to 48 MPG range. While on the way to Texas and back I had a very broad range, as much as 51 down to 30 MPG. Since trip it has been up and down but nothings with any consistency. Yes there were some high winds along the way but I have run into them before without the extremely change in MPG. Maybe as low as 39 with two up.
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I'm no carb techie, but all those factoids sound to me like some fairly serious carb clean/rebuild may be in your future; I think 6000ft elevation is about where folks say you must get high altitude carb adj and/or different jets, so your Castle Rock location is right on the cusp...

I'd give the bike a couple good doses of SeaFoam, AND, I say, SeaFoam likes to SIT, i.e., just running a couple tanks (at approx one oz/gallon) doesn't seem that effective. I say put SeaFoam in, make sure it gets mixed around in the tank a bit, run the bike 5 minutes if possible to get the mix down into the jets, then let the bike sit for minimum 3 days, 4 - 5 being preferred. I think the molecular binding required by SeaFoam for deep cleaning (i.e., fine parts like jets) is probably a slow, difficult bind, hence the time requirement.
 
HelmetHead said:
Since the relay is in an intermittent failure pattern, sometimes one probably gets rolling, and even though the relay is maybe going on and off, it's on enough to keep the bowls supplied during off periods.
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With a background of many years playing with electrons, if I thought I had an intermittent relay OR fuel pump, I'd temporarily hook up a few leds with long enough leads to put them somewhere close to the handlebars. I'd hook one up to the output of the relay with one color and another color to the pump connector. Then when the problem decides to reappear, the leds should tell you what gets power and what didn't.
If both are still lit, look at the pump (flow rate) and elsewhere. Both out, relay or power to it. Relay lit, not pump......wiring. JMHO, but trying to help as if the problem were my own. ;)
 
Grabcon said:
Fuel pump pumps for a few seconds and then stops. Cycling the key or kill switch will make the pump cycle and pump gas. I have not tested fuel pressure but a finger over the fuel filter will stop the flow.
Vacuum fuel shut off has been removed.

So a question for Helmethead before I go and replace the fuel pump. What exactly did you do to by pass the Fuel Cut Relay? Was that just removing the Negative from the pump and connecting to Ground?
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A finger stopping fuel flow doesn't sound too odd to me, but, if it is anomalous, it might fit the failing relay theory, as such a relay may only be supplying minimal power even when working.

My bypass arrangement was this (I’m not looking at wiring diagrams now, so this is just a description of exactly what I did):

Grabbed some appropriate-looking wire, probably 20 gauge (definitely not 18 or larger) (insulated, of course), and a household light switch.

Standing at the left side of the bike, looking down at the gas tank top: there are three electrical connection. Leave the rear-most, top most alone (I believe it is part of the fuel level and light circuitry). The other two wires are spaded onto clips connected to round, white plastic thingies. The forward most/left most is the pump’s positive electrode, rear/right most being the negative/ground.

I made two lengths of wire, one easily twice the length of the other. Run the shorter wire from the pump negative to your battery negative. Then cut the longer wire in two, and attached one end of each resulting piece to the light switch’s input and output sides. Attach the free end of the switch output wire to the pump positive electrode. Switch the light switch into On position, and touch the free end of the switch’s input wire to the battery positive; you should hear the pump run, or see gasoline flow if gasline unattached somewhere in the filter vicinity. Presuming all is now as described, switch the light switch off, and attach the switch’s input wire free end to the battery positive. Check your light switch, on and off a couple times. Drive to nearest ocean and back for road test.

“Attach” doesn’t require anything fancier than duct tape, for temporary purposes, though beware duct tape may come free from metal fairly soon.

Don’t forget to label by location the OEM wires you pulled off the pump’s pos&neg, cuz when you put them back on later, if you do it backwards, the pump will probably run backwards.
 
Doodaa said:
With a background of many years playing with electrons, if I thought I had an intermittent relay OR fuel pump, I'd temporarily hook up a few leds with long enough leads to put them somewhere close to the handlebars. I'd hook one up to the output of the relay with one color and another color to the pump connector. Then when the problem decides to reappear, the leds should tell you what gets power and what didn't.
If both are still lit, look at the pump (flow rate) and elsewhere. Both out, relay or power to it. Relay lit, not pump......wiring. JMHO, but trying to help as if the problem were my own. ;)
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But, but, but...that would be the smart way. For those of us cutting wire with a kitchen knife, and never without our duct tape, ya gotta use The Duct Tape Cookbook...
 
HelmetHead said:
But, but, but...that would be the smart way. For those of us cutting wire with a kitchen knife, and never without our duct tape, ya gotta use The Duct Tape Cookbook...
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My father was a radioman in WW2. It's in my genes. I was raised with all kinds of related "stuff" and expect to die trying to keep up with the stuff. My father never told me about the Cookbook, he just said you can figure it out.......so I try~! :eek::
 
HelmetHead said:
When trying to start after the bike has been sitting overnight or more, the carb bowls are (mostly or completely) drained, I presume, hence the cold start failures
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This is one part of your theory that doesn't make sense. Why would the bowls be mostly or completely drained just from sitting overnight? Where is the full bowl of fuel going to go? I can see it all evaporating out of there in a month or so, but not overnight or even a few days.

To my mind, if it starts and runs fine when warmed up, there's nothing wrong with the fuel delivery system. I would be concentrating on a carb issue dealing with the enricher system. Never having had need to touch the carbs in over 18 years on my bike, except to R&R for coolant hoses, I have nothing else to offer.
 
From my point of view I don't even think the carbs are getting gas to fire the bike. I still have not been able to start the beast in over two weeks now.
 
Grabcon said:
From my point of view I don't even think the carbs are getting gas to fire the bike. I still have not been able to start the beast in over two weeks now.
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If the fuel pump is pumping, (check by disconnecting line at the filter/vac valve) then check a see if the vac valve is getting the vacuum it needs to open. If not, you can by pass the vac valve. It has been over 11 years since I had a ST1100 I am bit rusty on them. Mine never had any of the fuel relate issues.
 
I think I have things down to the Fuel Relay cut off.

With the Fuel Shut Off removed, I have good flow at the pump. 1.5 quarts per minute, Spec says .676 quarters per minute. I have no way to check fuel pressure.

Continuity checks between relay and pump are good. Continuity check between blue/yellow on relay and ignition control module are good.

I have a concern with the voltage at the black/white at the relay. Battery voltage bike off is 12.77 voltage at black/white at relay is 11.12. That is a 1.65 drop. The book say they should be equal. Hmm. How do you chase that down?

I have excellent spark at the plugs.

So this is where I sit and not able to start at this time.
 
One other thing. For the Fuel Cut Relay part number 36100-MN5-000 is there a cross reference to an automotive relay?
 
Grabcon said:
With the Fuel Shut Off removed, I have good flow at the pump. 1.5 quarts per minute, Spec says .676 quarters per minute. I have no way to check fuel pressure.
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Was this fuel flow measurement made with the existing relay still in use ? If so, then this result eliminates problems prior to the carbs.
I'd be pullin' the cover off to get where I can add something extra in the air intake to see if it'll fire that way. Sounds like you're headed in that direction anyway. YMMV
 
The flow was measured with the black/white wire and the brown/red wire jumped at the relay socket without the relay in place. This make the pump run continuously so the 5 second flow test can be done. All Tupperware, air filter assembly, etc. is off and everything is exposed.

I am going to the salvage yard tomorrow am to see if they have any older gold wings to get a relay from. The don't do ST stuff.
 
Tried any fuel or starting fluid down the intake ?
Hope the relay clears your problem, please keep us updated.
I'm not sure when spring arrives where you're located, but around here you've got lots of time to clear up this problem before the snow's gone.
P.S. I never looked at the wiring diagrams or testing procedures, but I think there would be another method to make the pump run using the existing relay for your test or use the test you've already done for fuel flow to see if it will fire the bike. I doesn't sound like the drop in voltage is enough to cause your problem (to me). YMMV
I'm older and hate to waste time to come to a "maybe" conclusion; and old enough to be patient and come to accurate end. Sorry, call me anal retentive, you wouldn't be the first. :eek::
 
I did try to make the fuel pump run without the relay and the pump did run but to do that the relay had to be disconnected. I jumped the same wires as for the fuel flow test. I am not sure if the relay completes a circuit somewhere that didn't allow the bilked to fire.

I found a relay locally and will have it late this week to try. More to the saga later this week.
 
Yea well I hate to say it but it was 60 today and expected to be like through Thursday. I may have to dig out one of the other bikes.
 
I just pulled the carbs on my wife's bike... similar problem. Horribly gunked up jets and fuel lines. Took a day, but got them off, cleaned, and put back on. Runs like a champ, and started at 23 degrees this morning, barely turning over twice.
 
Bush said:
This is one part of your theory that doesn't make sense. Why would the bowls be mostly or completely drained just from sitting overnight? Where is the full bowl of fuel going to go? I can see it all evaporating out of there in a month or so, but not overnight or even a few days.
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That's definitely irresponsible phrasing by me, conflating a couple things as only an amateur can do.

I've heard of these couple tubes called 'drain tubes' in the carb(s/assembly?), but I don't actually know what/when they do whatever. When I had the problem, I was parking the bike on a decidedly un-level patch of concrete, one that leaned decidedly left and forward, so I guessed I was getting some kind of bowl draining going on.

When I later figured out that the problem was the gradually dying relay, I decided the 'cold start' problem was because the relay had been in fail-state for the last leg home, such that when I powered down for the night, I had essentially empty carb bowls.

Much of my clumsy approach to resolving the problem was rooted in the notion that a relay couldn't fail gradually; coming from the computer world, I thought circuitry failures were essentially always a one-time, hard failure.

(In the world of circuit board circuitry failures, the only ones that aren't once, hard and forever, are those that involve movement, such as a board, often with an x-ray wide crack, swelling due to heat on or near the board; so the board works when first powered up, then fails until it's had a chance to cool down again. That said, I know of one network problem, between Palo Alto and Sacramento, that was only solved when folks realized the outages only occurred at high tide; turned out the AT&T cabling ran under the San Mateo bridge, and the connections at the west end moved out of position during very high tides. Boss bought somebody a few drinks when that one was solved.)
 
I had the carbs off last winter when I did the coolant leak and they were spotless. I put nearly 23k miles on the bike this year, it does typically sit more than a day or two and I would doubt it that carbs get that dirty as to plug up and not function. The filter is spotless so nothing is coming from the tank. But with that said anything is possible and honestly I think if the new fuel relay doesn't solve the problem I will look at the timings and valves. It is do for a valve gap check anyways. And then the carbs. They are such a pain to get off and on even with the new carb boots that I put on last winter.
 
If I were you I would jump the fuel pump again with everything connected (fuel lines etc.) and then try and start the bike. This would indicate if the relay is working or not. If the bike runs with the relay circuit bypassed and the pump running then you have solved the problem. I also think the fuel relay is wired into the tipover sensor which cuts the fuel and ignition if the bike falls over. There have been a few cases of the tipover sensors failing. Honda recalled to replace these sensor way back in the ST1100 history.

Dan
 
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