Need some troubleshooting help

[qarnaj]

My girlfriend has a 87 Suzuki Savage that has been having some serious problems lately. It will start and run fine for a while, but in the middle of a ride it will start bucking and backfiring as if it was running out of gas. After 30 seconds to a minute of this it dies completely. It does this even on a full tank. It has an inline fuel filter and I can tell the gas is getting at least that far. Anyone have suggestions of what to check?

 

[FloydV]

I'm assuming it's not fuel injected. I've had bikes do this when the float sticks, or there is trouble with the needle and seat in the fuel shut off in the carb.

 

[bronc3]

Make sure the vacuum hose running to the fuel valve is in good shape. It is what actually opens the fuel valve. You could try running it in the "prime position", but remember to turn it back to run or reserve after shutting down to avoid leaking fuel. If it runs ok in the prime position, you have discovered a problem with the fuel valve or the vacuum being supplied to it. Beyond that, look for a carb problem. Could also be a remote possibility of a coil breaking down when it gets hot. My wife has an '03 Savage, but only 2k miles so far. No problems with hers as of yet.

 

[bronc3]

What kind of mileage, has it been sitting for an extended length of time, how long does it have to sit to refire?

 

[bronc3]

Also, any recent work or modifications?

 

[qarnaj]

Definitely not fuel injected. It's a single cylinder 650 so there can't be THAT many things that can go wrong. I'm thinking it has to be something with the carb but I'm far from an engine expert. Think taking it apart and giving it a good cleaning would help or should I just bite the bullet and haul it to a shop?

Hadn't thought about checking the vaccuum hose. I'll take a look at that when I get home tonight. I have tried running it in prime mode but that didn't seem to make a difference. One other symptom is that once it dies it adamantly refuses to start again until it sits for a while. I've tried cranking it and pushing it but it just won't catch.

 

[qarnaj]

Only 12k miles and she's been riding it a little bit every day or two for the past couple of weeks. It was sitting for a month or so before that, but it has run through at least a tank of gas since then.

No work since she bought it, and the dealership we got it from said they had checked it out. No modifications either.

 

[shenoyp]

spark plugs

 

[bronc3]

You could try a plug easy enough, but be sure to check out the fuel valve. Start by trying it on "prime". This effectively bypasses the vacuum valve and allows the fuel to flow to the carb unrestricted (the prime position is for starting a bike that has been run out of fuel). I haven't had any problems with ours, but have read about fuel valve problems on these. Might even be a service bulletin pertaining to it.

 

[qarnaj]

Do you have to leave it on prime for a while? I've tried the prime setting after it dies but it still refuses to start until it has been sitting for quite a while.

 

[BusaAdmirer]

check the floats in the carb. generally older vehicles that have been left untouched for a while have this problem..

 

[bronc3]

You can ride it on prime. If it doesn't eliminate the problem, disconnect the fuel hose at the carb, place the open end in a container, turn the fuel to prime. Fuel should flow freely from the hose.If fuel does flow freely, might try eliminating any inline fuel filters, after that you will have to take a look at the carb itself. If fuel does not flow on prime, there is a restriction in the tank /valve assy. Fuel should not flow with the engine stopped in the run or reserve positions. One other thing that must be checked is the tank vent. Not sure if the tank has a vent hose, or if there is a vent in the cap. I would have to take a look at mine when I get home this afternoon.

 

[qarnaj]

check the floats in the carb. generally older vehicles that have been left untouched for a while have this problem..

Can you give a quick and dirty how-to on what to look for? I'm mechanically inclined but don't know my way around an engine. IE: I could probably get the carb apart and back together again but wouldn't know how to tell if the floats needed adjusting or not.

 

[rubbersidedown]

check the floats in the carb. generally older vehicles that have been left untouched for a while have this problem..

Can you give a quick and dirty how-to on what to look for? I'm mechanically inclined but don't know my way around an engine. IE: I could probably get the carb apart and back together again but wouldn't know how to tell if the floats needed adjusting or not.

go step x step....follow broncs advice.

If you have never pulled a carb apart you could be in for it.
Dont use carb cleaner(which you'll need) on any of the gaskets or plastic parts. You'll need highlly compressed air to blow out all of the passes within the carb.

The vent check, when the bike stalls, open the tanks lid,if you here air getting sucked in, you have a vent prob.It should then start right up.

Plug check,when it quits on the road,change out the plug.

etc etc etc

My guess...fuel filter.

hav a good 1...RSD.

 

[bronc3]

It is pretty straightforward to pull the carb off the bike and remove the float bowl screws to inspect for dirt/debris. If it comes to that, any sediment in the bottom of the bowl is bad. This is a very simple carb. Just have to make sure all passages are clear. You should use spray cleaner & compressed air. Since it runs and dies, then restarts, if it does turn out to be dirt in the bowl, you may get by with simply cleaning out the bowl and puttin' her back together.

 

[bronc3]

Shouldn't be a need to make any adjustments if you simply clean out the bowl and reinstall the carb.

 

[rubbersidedown]

o ya, for the float check. You need to be deadly accurate.
remove carb
remove float bowl
inside you'll find a float it rides up and down on the level of fuel
with carb inverted,you need to measure the distance from the mating surface of the carb body and the float bowl to the top of the float....but here's the tricky part...most manuals require this measurement to be made with the tang of the float just barely touching the top of the floatbowl shut off.A little stem protrudes from the top of this needle, take your measurement without compressing this.
Have a new floatbowl gasket on hand,sometimes you can get away with re-using the old one, if you havent already destroyed it in the removal process.

good luck.... you'll need it RSD.

 

[bronc3]

Any luck? The more I think about it, the more I feel you should check & recheck the tank vent. Just my .02, but it is simple and will certainly cause the problem you are describing.

 

[qarnaj]

I tore it apart after work today. Fuel line and filter are fine. Carb seems nice and clean. Petcock seems to be working properly, fuel was flowing nice and easy when I turned it to prime. The only obvious problems I found were a bad looking spark plug and a really dirty air filter. I haven't got it put back together yet as I want to get that spark plug changed first and I haven't found anyone who has one in stock locally. The only official Suzuki dealership around is closed on Mondays so I'm going to give them a call tomorrow.

I haven't been able to find a vent on the tank. The mechanic I talked to at one shop immediately said "fuel starvation" when I told him the symptoms and also said to check the vent. I think you're probably right on with that diagnosis. Now I just need to FIND the thing. The mechanic said he thought it might be in the fuel cap but I don't see any holes in it that might let air in.

 

[FJRider]

Before taking it to the shop check the simple stuff like plugs (brownish) and fuel filters. Assuming carbs, a stuck float sometimes means you'll see fuel coming out the overflow tube, so check that.