Ski-Doo Snowmobiles Forum banner
1 - 20 of 52 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter · #1 ·
Hey guys correct me if I am wrong I'm new here but I could not find anything about this.

Just bought a 1993 Mach 1 670 was running very well other than the sled wouldn't idle by its self until it warmed up figured it would need a carb cleaning. So here's the story I was ripping the sled and it started slowly bogging out so I shut it off. Turned it back on and it just ran like crap and wouldn't go over 4000-5000rpm so I couldn't get the sled home.

This is the first time happening since cleaning the rave valves. I changed the plugs it ran for about 15 seconds normally and died out one more time. I currently have the carbs pulled and cleaned all that is need to do is to put them back in the sled. If this doesn't fix it does any one have any suggestions what else it could be? Also did a compression test 2 weeks ago before I took it out had 142 PSI for both cylinders. Please help!

Attached a video of the sled running and dying out all three times.
Thank you
 

·
Registered
Joined
·
960 Posts
FIRST....welcome to dootalk ... try checking the fuel pump and the spark on both cylinders...just a tought !!!. i am sure others will come up with some good advise to be taking a closer look at. good luck and keep up !!! :righton
 

·
SnomoSnob
Joined
·
2,756 Posts
-Check the compression again.

-Start the engine, as it starts to bog, pump the primer. If it fixes it, one of the two pumps may be dead\dying.

Also I see no video.

GutZ
 
  • Like
Reactions: Skittles17

·
Registered
Joined
·
27 Posts
Discussion Starter · #7 ·
-Check the compression again.
-Start the engine, as it starts to bog, pump the primer. If it fixes it, one of the two pumps may be dead\dying.
Also I see no video.
GutZ
Will do! I located both fuel pumps. Is there anything I can do to actually inspect the fuel pumps to see if they are working properly? Maybe clean them if that is an option. Thanks
 

·
Registered
Joined
·
4,873 Posts
Welcome to the forum.

Could be a couple dozen things causing your issues from fuel starvation to a crank bearing on it's way out. Let's double check what you've done so far.

Please explain exactly how you cleaned your carbs.

As for posting a video, upload it on youtube then post the link in this thread.
 

·
Registered
Joined
·
3,092 Posts
While carburetors are one piece of the puzzle there are plenty more pieces. With a sled over 25 years old a complete fuel system service would be in order if it was mine. By complete I mean pulling the gas tank off the sled and taking the fuel gauge out of the tank after draining and discarding any old gas and give the tank a thorough cleaning. I use "Super Kleen" or "Top Job" mixed with hot water and shake heck out of the tank. Then I rinse the tank with clear hot water, turn it upside down and let it sit a day or two to drain and dry. Clean or replace the filter on the pick up line using spray carb cleaner if you plan on using the filter over again. Replace the grommet where the line enters the tank with a new one. Remove the fuel pump(s) and disassemble the pumps and clean the pumps inside and out. Metal parts can be sprayed or dipped with carb cleaner. Blow out all the fuel lines with compressed air and replace any line which looks like it has varnish build up in it or feels hard. These lines should be soft and pliable.
The carburetors should come completely apart and be soaked in carb cleaner For an hour or so. Not too long though as there is a coating sprayed on the carb bowls and bodies which acts as a sealer for the porous die cast castings. Blow out all passages and rinse the parts in hot water and let them dry. Replace all gaskets and seals and the needle and seat assemblies and be sure the jets are clean and open. Adjust the float levels to specs. and reassemble the carbs. Check the vacuum hoses which lead from the engine base to the fuel pump(s) for cracks and replace any lines which feel stiff or hard. Use fuel resistant line with a firm sidewall if you replace the lines. Soft fuel line will collapse with the pulsing from the base vacuum ports.
Once the fuel system is completely serviced and up to standards you will have eliminated the fuel system as a cause of running issues and you will have taken a large step toward preventing an engine melt down due to a lean fuel condition.
If I missed anything here anyone is welcome to chime in and add to this. With phone calls and folks stopping by this AM it is hard to concentrate on anything. LOL.
Lynn
 
  • Like
Reactions: Daag44

·
Registered
Joined
·
27 Posts
Discussion Starter · #10 ·
Welcome to the forum.

Could be a couple dozen things causing your issues from fuel starvation to a crank bearing on it's way out. Let's double check what you've done so far.

Please explain exactly how you cleaned your carbs.

As for posting a video, upload it on youtube then post the link in this thread.
Thanks for the reply, both carburators are out what I did was completely was the outside of them with a wire brush to get them cleaned up. I removed the float bowls cleaned those with carb cleaner, remove both jets cleaned those with carb cleaner. After the cleaning process I used a bottle of compressed air to every little hole in both of the carbs. I've let both carbs sit for a few days since I didn't have time to put them back in yet but I wanted to make sure everything was try and no residue was left. Video link is now actually posted (lol)
 

·
Registered
Joined
·
27 Posts
Discussion Starter · #11 ·
While carburetors are one piece of the puzzle there are plenty more pieces. With a sled over 25 years old a complete fuel system service would be in order if it was mine. By complete I mean pulling the gas tank off the sled and taking the fuel gauge out of the tank after draining and discarding any old gas and give the tank a thorough cleaning. I use "Super Kleen" or "Top Job" mixed with hot water and shake heck out of the tank. Then I rinse the tank with clear hot water, turn it upside down and let it sit a day or two to drain and dry. Clean or replace the filter on the pick up line using spray carb cleaner if you plan on using the filter over again. Replace the grommet where the line enters the tank with a new one. Remove the fuel pump(s) and disassemble the pumps and clean the pumps inside and out. Metal parts can be sprayed or dipped with carb cleaner. Blow out all the fuel lines with compressed air and replace any line which looks like it has varnish build up in it or feels hard. These lines should be soft and pliable.The carburetors should come completely apart and be soaked in carb cleaner For an hour or so. Not too long though as there is a coating sprayed on the carb bowls and bodies which acts as a sealer for the porous die cast castings. Blow out all passages and rinse the parts in hot water and let them dry. Replace all gaskets and seals and the needle and seat assemblies and be sure the jets are clean and open. Adjust the float levels to specs. and reassemble the carbs. Check the vacuum hoses which lead from the engine base to the fuel pump(s) for cracks and replace any lines which feel stiff or hard. Use fuel resistant line with a firm sidewall if you replace the lines. Soft fuel line will collapse with the pulsing from the base vacuum ports.Once the fuel system is completely serviced and up to standards you will have eliminated the fuel system as a cause of running issues and you will have taken a large step toward preventing an engine melt down due to a lean fuel condition.If I missed anything here anyone is welcome to chime in and add to this. With phone calls and folks stopping by this AM it is hard to concentrate on anything. LOL.Lynn
Wow thank you so much for your reply. I am putting the carbs back in today and will clean the fuel pumps before putting the carbs back in as they don't look hard to reach. Cheers!
 

·
Registered
Joined
·
3,092 Posts
Wow thank you so much for your reply. I am putting the carbs back in today and will clean the fuel pumps before putting the carbs back in as they don't look hard to reach. Cheers!
You might want to plan on installing new kits in the pumps. The chances of getting the pumps apart without destroying the gaskets is slim. Aftermarket kits should be readily available for the pumps. Diaphrams and check valves stretch and lose their pliability over time. Better safe than sorry.
Lynn
 
  • Like
Reactions: Daag44 and MrGutz

·
Registered
Joined
·
27 Posts
Discussion Starter · #14 ·
You might want to plan on installing new kits in the pumps. The chances of getting the pumps apart without destroying the gaskets is slim. Aftermarket kits should be readily available for the pumps. Diaphrams and check valves stretch and lose their pliability over time. Better safe than sorry.Lynn
Good thinking I'm on the phone with my local shop as we speak trying to locate the rebuild kit for the fuel pumps.

Did you have a chance to look at the video I posted?

Thanks!
 

·
Registered
Joined
·
4,873 Posts
Thanks for the reply, both carburators are out what I did was completely was the outside of them with a wire brush to get them cleaned up. I removed the float bowls cleaned those with carb cleaner, remove both jets cleaned those with carb cleaner. After the cleaning process I used a bottle of compressed air to every little hole in both of the carbs. I've let both carbs sit for a few days since I didn't have time to put them back in yet but I wanted to make sure everything was try and no residue was left. Video link is now actually posted (lol)
Got it. Spray carb cleaner in a can is useless when it comes to the barely visible green "varnish" left from evaped gas. Point is, your carbs are still suspect. They have not been cleaned yet.

Research some youtube vid's on cleaning Mikuni carbs and follow the ones that include an overnight soak in a gallon of Berrymans or similar.

Like this... Liquid Human body Cosmetics Fluid Paint


Complete disassembly of the carb and overnight soak followed by spray cleaner and compressed air to include fine copper wire infiltration is how one cleans a carb. Otherwise you're chasing your ownass with a long stick.

A very recent post here is an example of exactly this. Swore he cleaned the carbs a couple times and sled kept pissing out. Turns out pilot circuit was gummed up. Cleaned it by pulling the jet and wicking the passage.

That said, nothing wrong with ripping the fuel system apart and cleaning all that up. Most older sleds could use that.
 

Attachments

·
Registered
Joined
·
27 Posts
Discussion Starter · #17 ·
Got it. Spray carb cleaner in a can is useless when it comes to the barely visible green "varnish" left from evaped gas. Point is, your carbs are still suspect. They have not been cleaned yet.
Research some youtube vid's on cleaning Mikuni carbs and follow the ones that include an overnight soak in a gallon of Berrymans or similar.
Like this...
attachicon.gif
Chem Dip.jpeg

Complete disassembly of the carb and overnight soak followed by spray cleaner and compressed air to include fine copper wire infiltration is how one cleans a carb. Otherwise you're chasing your ownass with a long stick.

A very recent post here is an example of exactly this. Swore he cleaned the carbs a couple times and sled kept "edit for bad language" out. Turns out pilot circuit was gummed up. Cleaned it by pulling the jet and wicking the passage.

That said, nothing wrong with ripping the fuel system apart and cleaning all that up. Most older sleds could use that.
Putting the carbs back together today. All the jets "seemed" clear of passage. If this doesn't fix I'll pull them apart again which doesn't take much time and let them sit over night in that chemical you posted above. Thank you for your replies helps a lot, also got the rebuild kit for the gas pumps that I am going to change out
 

·
SnomoSnob
Joined
·
2,756 Posts
Ok,

-Prime 2 pumps

-Pull primer out (Ready to Squirt another shot)

-Pull\start the engine.

-It'll rev, as it starts to bog, squirt 1/2 a primer, open throttle a bit. Close, open...

-As it starts to stall, squirt 1/2, pull primer again, Rinse Repeat till it is running\idling.

You'll get a "Feeling" for the engine and the warm up.

It's not a choke, it's just a one and done.

Later

GutZ
 

·
Registered
Joined
·
27 Posts
Discussion Starter · #20 ·
Ok,
-Prime 2 pumps
-Pull primer out (Ready to Squirt another shot)
-Pull\start the engine.
-It'll rev, as it starts to bog, squirt 1/2 a primer, open throttle a bit. Close, open...
-As it starts to stall, squirt 1/2, pull primer again, Rinse Repeat till it is running\idling.

You'll get a "Feeling" for the engine and the warm up.

It's not a choke, it's just a one and done.

Later
GutZ
Alright I will give that a try I most likely flooded the sled today pulled it over a bunch of times after putter the fuel pumps/carbs in. I pulled the sled over with both gas lines un hooked and gas poured out the lines. Sled was running but basically only on primer. I will try your method tomorrow. If this doesn't work I honestly have no idea what else more I could do. This is pretty much the extent of mechanical skills lol
 
1 - 20 of 52 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top