Dying when hot, broke down on highway... 3 times... in a row...

[DrDoot]

Alright, last week I posted a problem I've been having with my '85 GS550 when it's been running awhile, stopped, and then tried to start again shortly after. If I waited for the bike to cool down, I could get it going again.

Some suggestions I got were:
-a faulty igniter or ignition coil
-a rich condition in the carbs
-a "vapor lock sort of problem"

NEW INFORMATION

Since I do all of my driving in town and haven't had the bike out for a run in awhile, I thought I might possibly just be able to run out the problem. So I got on the highway and went out about 10 miles or so at 65-70mph, turned around, and headed back. About 3 miles into the return.. I lost all power from the engine. It was still idling, but that's it, I couldn't change power at all with the throttle, and the bike slowed to a stop and died. So I get off and look around and poke and prod and start thinking about calling for a ride. About 15 minutes later, I'm about to leave the bike and try to start it for the 5th time or so, and it starts right up. I hop back on, start heading back, I get a couple of miles and it does it again. I lose all power from the engine, bike slows until it comes to a stop and dies, throttle won't do anything(throttle cable is ok). Same thing as before, I wait 15 minutes, it starts again, I head back doing about 50 mph(wasn't too popular on the one lane highway) and get almost all the way back to my place before it dies again.

Does this narrow it down any? I'd really like to get this figured out to avoid having to push the bike into parking lots and sitting on the side of the highway waiting for rides. Thanks for any info.

 

[MelodicMetalGod]

Hard Starting - 1985 GS550ES

http://www.thegsresources.com/_forum/showthread.php?t=93229&highlight=1985

I'm working on a similar issue (See above thread title/link). I'm set to R&R the plugs, the air filter and the oil filter to eliminate those variables. The only other specific suggest that I rec'd was a possible dirty choke circuit.

 

[DrDoot]

This is while running though, it loses engine power, apparently when it gets to a certain temperature?

Also, I've been riding this bike regularly for over a year, about 5 days a week. Bike has not been sitting or had other problems like this.

 

[tconroy]

This is while running though, it loses engine power, apparently when it gets to a certain temperature?

Also, I've been riding this bike regularly for over a year, about 5 days a week. Bike has not been sitting or had other problems like this.

have you checked your floats? Do you have a vacumn line clog? Is the gas cap vent clear of obstruction.Does it do it if you stay off the throttle and go slower.Sounds like float is sticking in one of the carbs. Just a guess !

 

[DrDoot]

It did it even at low speed, when I was a couple blocks from home, doing 20-25 miles an hour. When the power cut out, it didn't matter if I let go of the the throttle and got back on it(several times in succession) or not.

 

[83'GK]

Ignition module getting hot?

 

[DrDoot]

The igniter? next to the regulator? that wasn't hot, I checked.

 

[semerm]

Sounds lean to me. Does it run very very hot? Are there any air leaks in our beloved air box or o rings?

 

[tconroy]

have you checked your floats? Do you have a vacumn line clog? Is the gas cap vent clear of obstruction.Does it do it if you stay off the throttle and go slower.Sounds like float is sticking in one of the carbs. Just a guess !

have you checked your petcock for a possible vacumn problem.
It sounds like you ran out of gas but didnt and then it starts right up.Are you running a fuel filter by any chance? Have you tried running it on prime when it starts to bog down? It sounds fuel related to me.Have you checked your vent hoses on the carbs for something in them like a spider web or something.Is it stock airbox and pipes?

 

[DrDoot]

have you checked your petcock for a possible vacumn problem.
It sounds like you ran out of gas but didnt and then it starts right up.Are you running a fuel filter by any chance? Have you tried running it on prime when it starts to bog down? It sounds fuel related to me.Have you checked your vent hoses on the carbs for something in them like a spider web or something.Is it stock airbox and pipes?

The gas tank hole(vent) was clear. Turning the petcock either up or down doesn't seem to make any difference in the way it runs. Which direction is prime and which is run?(yes, I should have sought the answer to this question long ago, but like I said it's never seemed to make a difference) Now that I've read about the Priming function, I think that might explain some of the not wanting to start when hot, but I don't see how that would cause the bike to completely lose engine power(doesn't die until it comes to a stop) while on the highway. The airbox and pipes are stock.

As for a fuel filter, there is a small, clear, plastic, cone-shaped piece with what looks like little pieces of metal strips inside. This is inline on one of the fuel hoses. I haven't been able to find it any of the diagrams in the Haynes manual, but I've always thought it was a filter of some kind. Are these necessary? And what is the easiest way to check for vacuum line clogs?

 

[dodger1]

I had a very similar problem - only happened after highway cruising for an hour or so. Because I had had the carbs set up by a "pro" (at a "pro" price) I went through everything else. Turned out the pilot circuit was set WAYYY rich and resetting cured the problem If over-rich is your prob., the spark plugs will show it up, providing you can remove them when it happens. (My 79 had different carbs but the principle is the same)

 

[Guest]

Fuel starvation, replace your petcock.

 

[DrDoot]

You sound pretty sure, but if it's fuel starvation through the petcock, why does it only have this problem when the bike has been running awhile and is hot, and then goes away after it cools a bit? Also, is it possible the fuel filter is causing this starvation?

 

[rgierer]

A few years a go I had a similar Summertime expereince. The petcock fixed my dilema.

 

[GS550joe]

does it still run but slows down ?

does it still run but slows down ?

as it begins to quit can you goose it and get a slight speed increase.. ??

could be the coils getting hot.... check them for cracks and tar(ish) leakage..

does the filter have gas in it when you get off and look at it????

fuel starvation sounds very plausible... my pickup had a similar problem.. it was due to a glogged filter... cleared when replaced..

Joe

 

[POULSEN]

I would go for the filter and/or fuelline problem too.
I had a similar problem last year. The bike was running o.k. until I reached the highway - then after a few Km it lost power, and I had to pull over.
Problem was a bent fuelline, being able to deliver fuel a low speed, but at the highway the consumption rises drastically, and the bowls were emptied.
If i could hold it in idle, it would solve itselv within few minutes. If it died, I had to go to PRIme position before i could proceed.
Moving the fuelline to a slightly other position solved the problem.
I now it sounds too simple...
And I can't explain why you have to wait 15 min - but do you really ?

Stig

 

[tconroy]

The gas tank hole(vent) was clear. Turning the petcock either up or down doesn't seem to make any difference in the way it runs. Which direction is prime and which is run?(yes, I should have sought the answer to this question long ago, but like I said it's never seemed to make a difference) Now that I've read about the Priming function, I think that might explain some of the not wanting to start when hot, but I don't see how that would cause the bike to completely lose engine power(doesn't die until it comes to a stop) while on the highway. The airbox and pipes are stock.

As for a fuel filter, there is a small, clear, plastic, cone-shaped piece with what looks like little pieces of metal strips inside. This is inline on one of the fuel hoses. I haven't been able to find it any of the diagrams in the Haynes manual, but I've always thought it was a filter of some kind. Are these necessary? And what is the easiest way to check for vacuum line clogs?

They are not nessasary (but) I run one anyway just in case.They do have to be put on a certain way.You only have one fuel line from the petcock and make sure they filter is on the right way.There is a little arrow on it that will tell the fuel flow direction and also make sure it is below the petcock and vertical not horizontal. The fuel must flow down the fuel line not sideways.Back towards the rear tire is prime and straight up and down is run and towards the front is reserve.It should be marked on there. You shouldnt have to use prime unless it sits for a few days.I would try a new filter or take it off completely and get a new fuel line.

 

[DrDoot]

as it begins to quit can you goose it and get a slight speed increase.. ??

could be the coils getting hot.... check them for cracks and tar(ish) leakage..

does the filter have gas in it when you get off and look at it????

fuel starvation sounds very plausible... my pickup had a similar problem.. it was due to a glogged filter... cleared when replaced..

Joe

I couldn't get any speed increase with the throttle when it lost power. I could just slightly change the noise of the engine, but RPMs were just enough to keep the engine idling, until it slowed enough to kill it. I didn't check the filter when this was going on.

And as to TConroy's post, it sounds like it's a good bet at either the fuel petcock or the fuel filter. Which of these is most likely given that the bike won't start after it's been ridden awhile and then shut off, and that the bike suddenly loses power on the highway(after running fine for 10 miles or so), dies, and needed about 15 minutes of sitting before it would start up and run fine again for awhile? (The bike has been ridden regularly for a year and has only started to have problems with the warmer weather)

?

Also, the fuel filter has been in a horizontal position the entire time I've had the bike, can/does this make much difference?

Thanks much, answers to those two questions above should send me in the right direction with this.

 

[DimitriT]

I had a fuel filter in the horizontal position for a couple of months last year. It gave me problems when I ran near wide open throttle. It would starve like you describe after about a minute at WOT. I repositioned the filter to sit between carbs #2 and #3, vertically, and the problem has disappeared.

 

[tconroy]

I couldn't get any speed increase with the throttle when it lost power. I could just slightly change the noise of the engine, but RPMs were just enough to keep the engine idling, until it slowed enough to kill it. I didn't check the filter when this was going on.

And as to TConroy's post, it sounds like it's a good bet at either the fuel petcock or the fuel filter. Which of these is most likely given that the bike won't start after it's been ridden awhile and then shut off, and that the bike suddenly loses power on the highway(after running fine for 10 miles or so), dies, and needed about 15 minutes of sitting before it would start up and run fine again for awhile? (The bike has been ridden regularly for a year and has only started to have problems with the warmer weather)

?

Also, the fuel filter has been in a horizontal position the entire time I've had the bike, can/does this make much difference?

Thanks much, answers to those two questions above should send me in the right direction with this.

even though the bike has a vacumn it is still gravity fed with fuel so YES your fuel filter should be vertical. If you always fill your tank up before parking the bike AND there is nothing wrong with the inside of your tank it would be safe to get rid of the filter completely and replace the fuel line.That should be the cheapest way to correct the problem.You should be able to check you petcock by watchin the filter and turning it to the "prime" postion and see fuel flow thru to fill up the carb bowls.If this is your problem you are probably getting an air pocket that will not let enuogh fuel flow thru as the bike requires to keep it running.More of an air lock than a vapor lock.