# Does this sound like a carb issue?



## GatorBait (May 14, 2008)

Hi all,
I have between a 1987 & 1989 Suzuki DT75. Everything from my gas tank down to my carbs are brand new. Fittings, hose, primer bulb, fuel filter, fuel pump rebuild etc.. It does not want to start. I have to prime the ball about three times to get it rock hard. Then I have to squeeze the heck out of it more after that with my foot until fuel starts coming out of the top of all three of my carbs. Once fuel starts pouring out of all three carbs it cranks up and idles fine for around 10 minutes before puttering out and losing prime. All connections have been thoroughly gone over and there are no air leaks.. The last time I took it out it would not fully power up and get on plane. I have good compression on all three cylinders 130. Any tips will be appreciated. Thanks, Jason


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## BIGRIGZ (Oct 2, 2007)

sounds to me like the needle is stuck in the closed position in the float bowl? 

I'd try to remove the bowl off of the carb and look at the needle that's connected to the float, sounds stuck in the seat closed to me......


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## GatorBait (May 14, 2008)

I would surely have to pull the carb assembly off to pull my bowls to look. Would this require re syncing once I put the assembly back back on? This whole re syncing deal is what is keeping me from breaking them down and soaking in ultrasonic cleaner. I know nothing about re syncing..


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## BIGRIGZ (Oct 2, 2007)

don't know how yours is but, my carbs will come off of the throttle body assembly which has the butterfly valve in it. I can remove a carb and not have to re sync it.

From what I can tell, the "sync" refers to "having all of the carb butterfly valves move in perfect unison" and alot of carbs have a flat spot on the shaft that connects the carb linkage so it's not really that hard to get them lined back up.


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## amarcafina (Aug 24, 2008)

Is the vent on the tank OK ?


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## BIGRIGZ (Oct 2, 2007)

be sure to post back on this thread with the problem after you find it? so others can use this as a learning experience!


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## GatorBait (May 14, 2008)

I bought the tank last year from Cabelas. It's a 27 gallon Moeller. It seems to be fine. The cap does not have a vent like a typical 6 gallon tank. The fitting and tube can actually be popped up and out of the tank and the o rings seem to be fine. I have a manual so I will pull my bowls off Friday and investigate. Ill post what I find. Thanks, Jason


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## Trucker (Sep 25, 2008)

I had this problem and finally found the problem yesterday. I took the front plate off the fuel pump and there was a gasket there. Around the middle of the gasket was split. I replaced the gasket and the motor started the first time and kept prime. I took it out today on the river today and it started on first turn of the key. This is on a 115 Evinrude but maybe could be your problem also. Hope this helps.


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## The Maintenance Shoppe (Nov 5, 2007)

I would think it is a fuel pump issue. I would look at the fuel flow coming out of the fuel pump while cranking thew engine. It should produce atleast a quarter cup of fuel in 10 seconds cranking.


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## GatorBait (May 14, 2008)

Ok so I pulled each carb off one by one today. The specs i have for float height list 12mm (.47 of an inch). My float heights in each carb were much more around 17mm. I adjusted each one back to spec. The carbs looked clean as a whistle and all floats were not sticking. I will still most likely pull them back off and soak them in cleaner just in case since I know now how easy it is. I didn't have a chance to run the engine to see if it made a difference today so I will tomorrow. However I do have a concern. I have seen some people post that there are two different float height specs for this engine from two different manuals. I have a Seloc manual I am going by that I picked up at boaters world. Does anyone have the actual correct float height spec for this engine? I just want to make sure 12mm is correct. I will post results tomorrow. Thanks guys


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## GatorBait (May 14, 2008)

Hi maintenance shop,
I have a brand new diaphragm kit in it I installed a few weeks ago. I keep thinking fuel pump as well and scratching my head. I'll pull the hose off the first carb tomorrow and crank it over to see how much fuel is being delivered and post back. Thanks, Jason


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## GatorBait (May 14, 2008)

Results are in.. I submerged my engine in my tank today. She fired right off with a tad bit of choke and throttle which is a significant change already! Usually it takes me squeezing the heck out of the primer ball until my arms fill like Popeye. It was Cadillac cranking today. She ran and purred like a kitten and i had no issues losing prime. I was unable to run to open water to give it the full test but I have plans to in the am. If she runs good under load in the morning it's going to look like it was the incorrect float height that was giving me the problems. I'll post back and let you all know. Thanks, Jason


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## GatorBait (May 14, 2008)

I was able to take it out for a test run today. It fired right up and idled great. I do have two issues though. Sitting at idle it wants to lose prime slowly. It's ok if I walk back every four to five minutes and give it a couple pumps to keep the ball tight. The second issue is that I have to push the choke while cruising to get it completely full throttle and running max speed. If I hold the choke in for more than about 3 seconds it wants to bog down. Once I release it it's takes off again then slows back down. I can cruise it around just not full throttle unless I push and release my choke many times playing around with it. It also seems to hold good prime while I'm running it just not at idle. I'm thinking a good carb cleaning. My float heights are to spec along with my air screw adjustments. Does this sound like I need a good carb cleaning or something else??? All tips are appreciated. Thanks, Jason


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## The Maintenance Shoppe (Nov 5, 2007)

The high speed circuits are lean or a vacum leak in fuel system or too low fuel pressure.


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## GatorBait (May 14, 2008)

Hi maintenance, how would I be able to track down a vacuum leak? I can't find any place air could be coming in at. Everything is snug and tight with new hose and hose clamps. Also would it be possible for a fuel pump to go bad completely even though I replaced the diaphragm kit? I do have a 1995 dt75 for parts. The fuel pumps are a little different but would it work on my 1988? I pulled off my top carb today and it looks clean as a whistle. I broke everything down and I can easily visually see that all my passage ways are clean in all my jets etc. just starting to get a little frustrated with this thing. Thanks, Jason


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## GatorBait (May 14, 2008)

Also I can't find any markings on my engine to determine exactly what year it is. From observation I can say its between an 87 & 89. The fuel pump is the same from 83 through 87 then changes in 88 through 94 to a different pump. Perhaps I have the wrong fuel pump or perhaps when I got the new diaphragm kit I got the wrong one. This could also be a problem. I'll put my carb back on and test the fuel flow like you mentioned a few posts back. It makes me scratch my head because it ran fine last year with the exception of losing prime at idle


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## lucky (Mar 23, 2012)

I didn't think the bulb was supposed to be "hard" while running the engine. I would clean/soak the carbs anyways and blow them out well, all the jets. Youtube is a great resource for answers sometimes. Its worth a shot. Good luck.


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## Ocean Master (May 20, 2008)

I think you should just take it in and have it fixed. It would probably take just a few minutes once they started.


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## GatorBait (May 14, 2008)

lucky said:


> I didn't think the bulb was supposed to be "hard" while running the engine. I would clean/soak the carbs anyways and blow them out well, all the jets. Youtube is a great resource for answers sometimes. Its worth a shot. Good luck.


At idle the bulb will eventually empty completely and when I prime it I can feel/hear it sucking air and about three pumps its primed again. The person I bought it from is reliable and told me he bought it from a mechanic that serviced it completely before sitting it up in his garage including going through the carbs. The guy I bought it from never even turned it over. He sold it to me because he didn't have controls and decided not to invest in a third boat. I pulled the carbs and they look clean as a whistle. All jets are clearly open and not clogged. I did however just now notice that I am missing gaskets for each carb that connects to the silencer box. Would air coming in here mess my vacuum up?


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## Ocean Master (May 20, 2008)

No it would not.

It still sounds like you are sucking air from somewhere.


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## GatorBait (May 14, 2008)

I want to say thanks to everyone who helped me out. I really appreciate the help from this forum. The people here are great! I fixed the problem today. If I had of taken The Maintenance Shops advise earlier I could have solved this problem much sooner. An obvious mistake overlooked I should have tested a looong time ago. I pulled the fuel pump hose off today that leads to the first carb. I had my side kick daughter turn the key over while I held the hose over a measuring cup. The Maintenance Shop said 10 seconds of turning the key should produce 1/4 cup of fuel. Well..... Mine produced just enough to evaporate out of the bottom of the cup before I could get done. I was shocked. I have a brand new diaphragm kit and "assumed" it was not my fuel pump. I went and pulled my fuel pump off of my spare 95' model and hooked it up. Had my daughter climb back in and turn it over again while I held the fuel hose over a cup. This fuel pump filled the cup almost exactly 1/4 like The Maintenance Shop said. I ran the line up to my carb and hooked it up and fired off the engine. She purred like a kitten until i turned it off and never lost a bit of prime!!! I'm still astonished I think i may go crank it again for giggles. Thanks again everyone -Jason


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## knowphish (Apr 26, 2010)

I love a happy ending!!!:thumbup::thumbup:


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