Engine quit - request for diagnosis assistance

sennister said:
I wasn't going to throw George under the bus like that.... ;) But hey, at least he has healed up. Though his service manual has a bit more character now...

Here is what I would do if you opt to do a flow test. Try and include the filter as part of the test. Or do the test with and without the filter as a comparison. I assume you have the filter mounted where the OEM one goes so it should be pretty easy. Never know how much restriction something adds. I want to say that there is a spec that the fuel delivery needs to meet in the service manual. I have a Haynes and a factory manual if you need me to look and see what they say. They are out in the shop though. I am just thinking that the filter may be clean and fine but if it is too restrictive by design it could still cause an issue. Same goes for the air filter since it isn't OEM. Maybe there is one that you could swap out for a test as well. If you can't find one, if you can get it to fail while home, get it to fail and try and pull the air cleaner while it is failing and see if it starts. That would eliminate that as a possible cause. While not recommended to ride without an air cleaner you can see if it will start. Carb Syncs are done that way anyhow. It isn't a bad idea to do another one since it has been a while but odds are they don't go out of spec all that often. Though I spot check mine with a SK Flowmeter whenever I have the air cleaner off on my 1100.
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That was just my way of suckering him into this thread to defend himself...and then maybe he'd pitch in to help us think through things. :)
 
I ran out to the shop for something else. Here is the factory manual.

hyvydusu.jpg


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Nathan, any chance you could ride it down to my place on this Wednesday the 10th? We are going to be gone again from the 11th. to the 16th. ??
 
So 640cc/min is 0.169 gallons/min or 0.676 quarts/min.

That seems really low. But that is what it says. If that is the case and I did my conversions right. The fuel pump you have would provide way more fuel than what is needed so it shouldn't be the issue and I would highly doubt the filter would cause enough restriction to be the issue.


Oh and if you do this make note of the warning that George missed...
 
For the sake of discussion. I have had the same issue with my 98 ST1100A. Stopped for fuel in West Virginia 20-30 miles later the engine acted fuel starved and died after I pulled onto the shoulder. It seemed to me to be vapor locked.. I opened the gas cap, no fuel issue. After it sat about 10 minutes, did full choke and it started right up.. No issue since. That was during my SS1000 ride from Vermont to Casey Il. I follow with interest! Moe
 
snowdigger69 said:
For the sake of discussion. I have had the same issue with my 98 ST1100A. Stopped for fuel in West Virginia 20-30 miles later the engine acted fuel starved and died after I pulled onto the shoulder. It seemed to me to be vapor locked.. I opened the gas cap, no fuel issue. After it sat about 10 minutes, did full choke and it started right up.. No issue since. That was during my SS1000 ride from Vermont to Casey Il. I follow with interest! Moe
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Keep in mind that there are a few of the common issues that he has already eliminated. So don't forget those. The vac fuel cutoff is common and can be bypassed pretty easily. Many people either leave it bypassed or if they choose to fix it or are still running with it in place, they carry the bits needed to do the bypass on the side of the road. I am trying to remember what was needed for the bypass. I might be missing something but off the top of my head it would be a barb connector so you can hook the two fuel lines (input and output on the cutoff) together along with a couple clamps. Then something to seal off the vac line. I think it is just those three connections to it. So it isn't like you would need a ton of parts to be able to do a bypass on the road.

Fuel pump issues do also crop up.

There are a few others but these are common with fuel starvation. I guess there are also torn boots as well or a vac leak.
 
Another data point from last evening. Rode 5 miles to a weekly meet up of sport touring riders at a local restaurant. Bike started and ran fine on the way there and there wasn't really a lot of time for any heat to build up. Was there for 1 1/2 hours, so bike had plenty of time to cool back down.

Bike started just fine when I was ready to leave, but within the first mile of pulling out of the parking lot it started starving for fuel and died. This time I was able to pull off on a quiet side street and it would fire and run momentarily with choke, but wouldn't stay running. I left it there overnight, returned this morning and it fired right up and I rode it home 5 miles without any issues.

So this was the first time it had occurred on such a short little jaunt - all of the other occurrences had taken place after the bike had run for hours...

GaryZR is sending me a fuel pump relay off his '91 for me to swap out. I'm going to start there and see what happens. One thing at at time...

Nathan
 
Finally had the time to unzip the plastic on the bike and swap the fuel cut off relay that Gary sent me from his donor bike. When I got in there, I remembered that when my friend and I installed my Stebel, we slid that relay off the metal tab to which it is normally attached with the rubber sleeve and although it wasn't hanging by the connector or anything, we hadn't done anything to secure it...which may have allowed it to stress the solder joints inside of it causing cracks.

All speculation at this point until I ride it some to see if this intermittent issue pops up again. Will keep everyone posted!
 
Any chance when the new pump was installed, the mount was over-tightened ? I have heard of this happening with in tank auto fuel pumps and it can cause intermittant problems. The mount only needs to be snug. Did you re-install the rubber mount ?

BTW, I did a quck calculation and at 70mph/40mpg, only about 4 oz. of fuel is used every minute.

Also, BTW, when I installed my new fuel pump, I mounted it in the vertical position so the pickup was at the bottom of the tank :

http://members.triton.net/vandenbe/ST1100/Fuel Pump.htm ( having problems uploading pics, today )

No problems ( so far ) in about 4K miles.
 
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Jim Van said:
Any chance when the new pump was installed, the mount was over-tightened ? I have heard of this happening with in tank auto fuel pumps and it can cause intermittant problems. The mount only needs to be snug. Did you re-install the rubber mount ?
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I suppose it is possible that it was over tightened...and yes, it went back together with the rubber mount, just like the OEM. We'll see if the relay swap solves it and then if not i'll keep looking.
 
If I remember correctly, we trimmed some of the rubber mount when we installed it at the tech event, because we thought it would be too tight then. I think that the screw that holds it was a short one and would not fit until we trimmed the mount down.
 
I remember reading a thread like this one where it ending up being the kickstand safety switch and wiring I can't find it maybe it's on the other site
 
STranger said:
I remember reading a thread like this one where it ending up being the kickstand safety switch and wiring I can't find it maybe it's on the other site
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I've taken a look at that wiring and switch and it looks ok...but will keep it on the list.

I finally got the bike buttoned back up and took for a short 45 minute ride close to home this week. Ran fine, so we'll look at getting a longer ride in over the next few weeks to attempt to replicate the scenarios where it had been giving me issues.
 
When it dies, do all the lights go out? Is the bike dead or just the pump?

If the lights and all seem normal, I say the pump is still the culprit.
 
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Ron said:
When it dies, do all the lights go out? Is the bike dead or just the pump?

If the lights and all seem normal, I say the pump is still the culprit.
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Ron - the lights stay lit...so I agree it is a fuel delivery related issue. But the intermittent nature of it is the part that is confusing....


Another update. Rode in a stop/go city environment for 90 minutes last Friday. Never shut the bike off during that time and had no issues. At the end of that 90 minutes, I did shut the bike off briefly to chat with a friend before we split up. Bike fired right back up and I hopped on the interstate for 5 miles and the bike started running roughly. Not as bad as previous times when it would eventually die, but bad enough that there was a noticeable loss of power. I was at my exit anyway when it started happening, so I was able to exit the interstate back onto city streets for the remaining 11 miles home. Once off the interstate on city streets (lower speed and a bit more stop/go riding) the bike smoothed back out within the first 1/2 mile and I rode home without any issues the rest of the way.

??
 
The saga continues... :)

Haven't ridden much (at all) this season, but earlier this week I packed up the bike and headed towards Michigan to work an NCAA Track Championship. Thought this would be a good opportunity to test the bike on a longer ride to see if the fuel pump relay "fix" was actually a fix. Doesn't appear to be....

Nearly full tank when I left Indy...got approx 90 miles north running at interstate speeds and all of a sudden the engine begins to loose power and run roughly as though it was starving for fuel. Pulled off at an exit, left it running for a few minutes and it eventually smoothed out with a bit of revving. Hopped back on the interstate and had no problems finishing off the next 50 miles to my overnight location in NW Indiana.

Next morning the bike fired up just fine and I ran another 100 miles or so before stopping to fill the tank. Engine was shut off during the refuel. Fired back up just fine and I continued another 80 miles or so where I stop for breakfast. Engine off for about 20 minutes.

Starts just fine, but after I'm back on the road for 2 miles the engine begins running with a loss of power and eventually dies. Pull off to the side of the road, wait 5 minutes, attempt to restart and it fires back up running smoothly. Start rolling again and within 1.5-2 miles it dies again. Repeated this same process of waiting a few, restarting normally, engine dying in 2 miles about 6 more times as I limped back to the nearest town. Did not hear fuel pump "priming" noise when I restarted any of these times.

Pulled into the parking lot of a NAPA store to contemplate my options and bike was off for about 25 minutes as I made a few calls to arrange pickup in case I couldn't make it any further. Did triple check the fuel pump electrical connections on top of the tank and they were solid.

Started bike back up again without issue, drove it 1/2 mile to gas station to top off the tank (had only covered about 100 miles since last fill up). Fired it back up again after getting fuel and it ran normally for 45 miles where I stopped for a meeting and the bike sat for a couple hours. Started back up normally and I ran it another 10 miles where I stopped, engine off and topped off the tank again. Ran fine for 2 miles and started to run roughly, but I pulled over, revved the engine a bit and a normal idle came back. Finished off my riding for the day with 1 more mile to the hotel.

Ambient air temps were not hot at all - always between 50-70F. Was not in stop/go situations...so don't believe heat was an issue.

On those short 2 mile runs it seemed to run only long enough to run the fuel that was in the carbs dry...but if I wasn't hearing the fuel pump prime the system, why did it start back up normally after sitting for 5 minutes? Gravity able to work fuel back into the carbs?

Thoughts on this recent set of circumstances?

Fingers crossed that my voyage back to Indy on Sunday goes smoothly. :). Will probably replicate what I did last July on my trip from Indy to Atlanta when I faced the same issue - I had success just NOT turning the engine off the entire trip back - even during refueling stops. But when I get home I'd like to dig back into things to keep looking for the solution to the issue.
 
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