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90TLRY Prime Start clog and Speed Bog Down
Here is information about fuel related problems I have experienced with my Yamaha 2000 90 hp model 90TLRY....
This motor is on a 2000 Edgewater 155CC I have in Cape Cod, Massachusetts. The boat has a built in 33 gallon fuel tank with a Mercury style spin on fuel water separator that I change once a year at the beginning of the season. It is a really fun, solid boat that can handle whatever seas I throw at it.
But, in the past few years I have experienced sporadic problems with the engine. I would be running along fine and all of a sudden the engine would bog down - dropping from crusing at around 4,500 rpm's to no more than 2,000 to 2,500 At first I thought it was caused by the electronic control box, but I checked things out and found nothing wrong. I took it to a local dealer who, of course, couldn't find anything wrong with it. The problem seemed to magically go away and it would run fine.
Then, at the end of last season, I started to have trouble starting the engine from a cold start. I had to crank the heck out of it to get it to start, but I was finally able to get it started. It would cough and stall until it got warm them it ran fine and I was ableto get it out of the water for winter storage. I did my usual storage prep - added fuel stabilizer (Sta-Bil this year, but I may switch to the Star-Bright green stuff this year), ran the engine to get it in the carbs, fogged the carbs and cylinders, etc.
This model engine does not have a choke, but has an automatic cold start fuel enrichment system called Prime Start. Over the winter I read the owner's manual and found that there was an emergency bypass valve on the Prime Start pump on carb #2. I thought the problem might be in this system so in the spring I flipped the valve the the emergency start position and it fired right up. But this year, even after warming up, the engine had trouble running at idle. It would start up and run for a bit, then cough and die.
I tested the prime start electric plunger and it tested ok for both resistance and for operation when powered up. (Tests from the Clymer manual). I suspected that a little bit of varnish might be the cause so I drained the top two carb bowls (couldn't reach the bottom one) into a pan to take a look at the gas. I had never seen what gas gone bad looked like. What came out was a dark amber liquid. I thought I would try giving the engine a chemical cleaning to see if that would help.
I dumped a can of Sea Foam into an auxilliary 6 gallon tank, added fresh gas to it and mixed well. I hooked this tank up to the engine, test ran it at home and launched the boat. I ran the entire tank through and things seemed to improve. I used the boat that weekend to take my son and a friend water skiing. It still seemed sluggish out of the hole, but it ran well at speed. I figured another shock treatment with Sea Foam would do the trick.
I ran it hard again the next morning and just as I was thinking everything was going to be ok, the engine suddenly bogged down, dropping from WOT to 2,000 to 2,500 rpm's. The same sporadic probem I had in previous years'. I throttled back and limped back to my dock. Now I had no choice but to remove, clean and replace the carbs.
I ordered three carb kits from boats.net and planned to rebuild the carbs the next weekend. I stopped by a local auto parts store and picked up a gallon can of Gunk to use to soak-clean the carbs. A great setup - the solvent is in a one gallon paint-style can that you can reclose and save for reuse. Inside the can is a parts basket with a handle. I also picked up a spray can of carb cleaner and printed out the carb schematics from me service manual for guidance.
I was lazy and did not pull the boat out of the water to work on it. I did this job with the boat in the water, but it was risky. Luckily, while doing this job I did not hear the sickening "plop" of any parts accidently going in the water. I don't think there is any sound as sad as that "plop".
I took notes as I went along - noting what hoses I disconnected and identifying which carb was which (plain on top, primestart in the center, and the bottom one had a rod connecting it to the oil pump system). Also, when I removed the throttle sync rod that connects the three carb linkages, I put a piece of tape on the bottom hole of the rod, so I could identify how it went back on to keep the carbs in sync. I got all three carbs out and took them onshore to rebuild.
Once on shore I drained each carb into a glass bottle to see what the gas looked like. The gas looked much better - clear with a slight tint. It looked like the Sea Foam did it job in clearing out the gunk in the bowls. Working in a aluminium pan to catch any residual gas, I disassembled each carb one by one, removed the gaskets, float, jets and rubber parts. I then soaked all the metal parts in the Gunk as I disassembed the next carb. I used three paper cups labeled 1, 2 and 3 to keep the parts for each carb separate from the others. Note, a warning on the can suggested that all rubber or plastic parts should be removed before soaking to prevent possible damage.
Inspecting each jet as I removed them, I found what must be my problem - holding up the the intake hole on the main jet to the light, I could see that it was clogged. A spray with carb cleaner and a blast of air cleared it.
Working on one carb at a time, I removed the a carb from the Gunk and put the next one in to soak for at least 20 minutes. Once out of the Gunk, I gave it a squirt of spray carb cleaner and dried it off with paper towels. I then used a can of compressed air (found at most computer stores) to blow out all the passages in the carb body, top lid, and the jets. I carefully inspected each jet's holes by holding them up to a light to ensure all were clear and then reassembled the carbs with new gaskets. I found that if the gaskets had trouble staying in the grooves I could help it stay in position by carefully stretching the gasket gently.
I reinstalled the idle valves and set them to the specs listed in the repair manual (for my model carbs, it required seating the needle and backing out one and one half turns).
Referring to my notes, I installed the carbs back on the engine and connected the hoses, linkages and wires for the Prime Start valve.
I pumped my fuel hose to get new gas in the carbs. When it was nice and firm I gave the ignition key a turn and it fired right up! The Prime Start system was working flawlessly. I put the cover back on the engine and took her out for a test run. It was like I had a new engine! She ran like a top - once again a hot tiger out of the hole. The only adjustment I need to make is to drop the idle speed down a little.
So, the moral is, if you have any bog down problems, suspect a clogged jet and if you are mechanically inclined, don't be afraid to attempt a carb cleaning yourself.
One suggestion, leave the third carb intact until you rebuild your first carb so if you get stuck you can refer to the intact carb to see how parts are assembled.
Helpful items:
1) Yamaha Service Manual (.pdf version on Ebay for around $11) - print out the carb schematic and service pages for your engine model and year.
2) Clymers Yamaha Service Manual - a great book to have (around ($25 to $30).
3) Assorted screwdrivers in good condition to properly fit the screws and jets.
4) A can of compressed air (About $4).
5) Gallon can of Gunk with a parts basket (about $11).
6) A clean, level work surface with lots of room and newspaper to catch the drips.
7) Large aluminum pan to transport carbs and hold parts as you disassemble/assemble.
8) Note pad to make notes as you work.
9) Glass jar to inspect gas that drains from the carbs.
10) Lots of paper towels.
11) Three carb rebuild kits (around $17 each - total $51).
Total cost if you have to buy everything (including the manuals) is around $100 and an afternoon of your time. I would think to have a shop do the rebuild would run much higher - maybe $500 to $800?
This was not too hard to do - difficulty about a 4 on a five scale. It took time but the results were so good that I would not hesitate to do it again.
Good luck and please let me know if this has helped you.
This motor is on a 2000 Edgewater 155CC I have in Cape Cod, Massachusetts. The boat has a built in 33 gallon fuel tank with a Mercury style spin on fuel water separator that I change once a year at the beginning of the season. It is a really fun, solid boat that can handle whatever seas I throw at it.
But, in the past few years I have experienced sporadic problems with the engine. I would be running along fine and all of a sudden the engine would bog down - dropping from crusing at around 4,500 rpm's to no more than 2,000 to 2,500 At first I thought it was caused by the electronic control box, but I checked things out and found nothing wrong. I took it to a local dealer who, of course, couldn't find anything wrong with it. The problem seemed to magically go away and it would run fine.
Then, at the end of last season, I started to have trouble starting the engine from a cold start. I had to crank the heck out of it to get it to start, but I was finally able to get it started. It would cough and stall until it got warm them it ran fine and I was ableto get it out of the water for winter storage. I did my usual storage prep - added fuel stabilizer (Sta-Bil this year, but I may switch to the Star-Bright green stuff this year), ran the engine to get it in the carbs, fogged the carbs and cylinders, etc.
This model engine does not have a choke, but has an automatic cold start fuel enrichment system called Prime Start. Over the winter I read the owner's manual and found that there was an emergency bypass valve on the Prime Start pump on carb #2. I thought the problem might be in this system so in the spring I flipped the valve the the emergency start position and it fired right up. But this year, even after warming up, the engine had trouble running at idle. It would start up and run for a bit, then cough and die.
I tested the prime start electric plunger and it tested ok for both resistance and for operation when powered up. (Tests from the Clymer manual). I suspected that a little bit of varnish might be the cause so I drained the top two carb bowls (couldn't reach the bottom one) into a pan to take a look at the gas. I had never seen what gas gone bad looked like. What came out was a dark amber liquid. I thought I would try giving the engine a chemical cleaning to see if that would help.
I dumped a can of Sea Foam into an auxilliary 6 gallon tank, added fresh gas to it and mixed well. I hooked this tank up to the engine, test ran it at home and launched the boat. I ran the entire tank through and things seemed to improve. I used the boat that weekend to take my son and a friend water skiing. It still seemed sluggish out of the hole, but it ran well at speed. I figured another shock treatment with Sea Foam would do the trick.
I ran it hard again the next morning and just as I was thinking everything was going to be ok, the engine suddenly bogged down, dropping from WOT to 2,000 to 2,500 rpm's. The same sporadic probem I had in previous years'. I throttled back and limped back to my dock. Now I had no choice but to remove, clean and replace the carbs.
I ordered three carb kits from boats.net and planned to rebuild the carbs the next weekend. I stopped by a local auto parts store and picked up a gallon can of Gunk to use to soak-clean the carbs. A great setup - the solvent is in a one gallon paint-style can that you can reclose and save for reuse. Inside the can is a parts basket with a handle. I also picked up a spray can of carb cleaner and printed out the carb schematics from me service manual for guidance.
I was lazy and did not pull the boat out of the water to work on it. I did this job with the boat in the water, but it was risky. Luckily, while doing this job I did not hear the sickening "plop" of any parts accidently going in the water. I don't think there is any sound as sad as that "plop".
I took notes as I went along - noting what hoses I disconnected and identifying which carb was which (plain on top, primestart in the center, and the bottom one had a rod connecting it to the oil pump system). Also, when I removed the throttle sync rod that connects the three carb linkages, I put a piece of tape on the bottom hole of the rod, so I could identify how it went back on to keep the carbs in sync. I got all three carbs out and took them onshore to rebuild.
Once on shore I drained each carb into a glass bottle to see what the gas looked like. The gas looked much better - clear with a slight tint. It looked like the Sea Foam did it job in clearing out the gunk in the bowls. Working in a aluminium pan to catch any residual gas, I disassembled each carb one by one, removed the gaskets, float, jets and rubber parts. I then soaked all the metal parts in the Gunk as I disassembed the next carb. I used three paper cups labeled 1, 2 and 3 to keep the parts for each carb separate from the others. Note, a warning on the can suggested that all rubber or plastic parts should be removed before soaking to prevent possible damage.
Inspecting each jet as I removed them, I found what must be my problem - holding up the the intake hole on the main jet to the light, I could see that it was clogged. A spray with carb cleaner and a blast of air cleared it.
Working on one carb at a time, I removed the a carb from the Gunk and put the next one in to soak for at least 20 minutes. Once out of the Gunk, I gave it a squirt of spray carb cleaner and dried it off with paper towels. I then used a can of compressed air (found at most computer stores) to blow out all the passages in the carb body, top lid, and the jets. I carefully inspected each jet's holes by holding them up to a light to ensure all were clear and then reassembled the carbs with new gaskets. I found that if the gaskets had trouble staying in the grooves I could help it stay in position by carefully stretching the gasket gently.
I reinstalled the idle valves and set them to the specs listed in the repair manual (for my model carbs, it required seating the needle and backing out one and one half turns).
Referring to my notes, I installed the carbs back on the engine and connected the hoses, linkages and wires for the Prime Start valve.
I pumped my fuel hose to get new gas in the carbs. When it was nice and firm I gave the ignition key a turn and it fired right up! The Prime Start system was working flawlessly. I put the cover back on the engine and took her out for a test run. It was like I had a new engine! She ran like a top - once again a hot tiger out of the hole. The only adjustment I need to make is to drop the idle speed down a little.
So, the moral is, if you have any bog down problems, suspect a clogged jet and if you are mechanically inclined, don't be afraid to attempt a carb cleaning yourself.
One suggestion, leave the third carb intact until you rebuild your first carb so if you get stuck you can refer to the intact carb to see how parts are assembled.
Helpful items:
1) Yamaha Service Manual (.pdf version on Ebay for around $11) - print out the carb schematic and service pages for your engine model and year.
2) Clymers Yamaha Service Manual - a great book to have (around ($25 to $30).
3) Assorted screwdrivers in good condition to properly fit the screws and jets.
4) A can of compressed air (About $4).
5) Gallon can of Gunk with a parts basket (about $11).
6) A clean, level work surface with lots of room and newspaper to catch the drips.
7) Large aluminum pan to transport carbs and hold parts as you disassemble/assemble.
8) Note pad to make notes as you work.
9) Glass jar to inspect gas that drains from the carbs.
10) Lots of paper towels.
11) Three carb rebuild kits (around $17 each - total $51).
Total cost if you have to buy everything (including the manuals) is around $100 and an afternoon of your time. I would think to have a shop do the rebuild would run much higher - maybe $500 to $800?
This was not too hard to do - difficulty about a 4 on a five scale. It took time but the results were so good that I would not hesitate to do it again.
Good luck and please let me know if this has helped you.
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