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About to give up - can't keep engine running

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About to give up - can't keep engine running

Old 11-25-2010, 06:57 AM
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Default About to give up - can't keep engine running

First off, this boat is VERY close to being sold for scrap.

I have an '88 Suzuki DT75 on a Cobia 177. I bought it from someone who had let it sit for a year, and it didn't run anymore. I have had the carbs rebuilt (TWICE), the fuel pump replaced, and replaced the entire fuel system. New tank, new lines, new everything. Also brand new spark plugs, and a fully charged marine battery. The compression is 120 on all 3 cylinders and it cranks over nice and fast.

The latest carb rebuild was finished last Sunday. Today I decided to try and take the boat out for the first time, seeing as how the boat ramps would be empty today. I wanted to warm it up on the muffs at home, but it was extremely hard to start.

But when it did start, it would only run for a few seconds at best. I tried revving it up to keep it running, but although it was pulling higher RPM it still would run strong for a few seconds and then die.

Holding the choke closed (by pushing in on the key - a very annoying way to choke an carb, if you ask me) seemed to keep it running longer, but it would still die after a few seconds.

Seeing as how the carbs were literally cleaned and rebuilt days ago, and the entire fuel system is new including the gas, what on earth could it be? It sounds like a fuel delivery problem, but I know for a fact that the fuel pump diaphragms are brand new as well as all the fuel lines, and basically everything else related to it.

For reference, my starting procedure was this:

-Pump the primer bulb until it was hard. (It never got THAT hard though?)
-Pump the throttle lever twice and return to neutral
-Push the key in to choke the engine (this didn't always work for some reason - occasionally I had to flick the choke plates closed by hand when the key was pushed in)
-Crank the engine. Sometimes it would fire, sometimes it wouldn't. I wouldn't crank it for more than 5-10 seconds at a time. Sometimes it would fire without closing the choke, but most of the time it wouldn't.

The primer bulb not getting that hard worries me, but I haven't been able to find any fuel leaks anywhere. I was using a portable fuel tank and the vent was open.

I'm very close to giving up, because this thing has been nothing but a nightmare and its beginning to turn me off to boating in general. I've NEVER had this much trouble with any other type of engine, so the problems I am having now are largely a mystery to me.
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Old 11-25-2010, 07:04 AM
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My bulb never gets hard also, though it never hampered the motor in anyway. SO maybe rule that out.

I would say that maybe you are sucking air from somewhere along the lines, most likely at a connection point as you said all lines are new. So I would not think you would have a hole in a line anywhere.

What about all the quarter inch black hoses going to the carbs? My Yamaha with 6 crabs have those hoses all over it.

Were those hoses replaced as well?
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Old 11-25-2010, 07:08 AM
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Since the rebuild have the carbs been adjusted correctly?
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Old 11-25-2010, 07:42 AM
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Slight update: i was messing with it some more, and I noticed gas leaks out of the top carburetor after it dies.

Perhaps the floats aren't set right?

I also noticed a very small fuel leak in the top of the fuel filter housing.

You're right, I didn't replace the fuel lines between the carbs....
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Old 11-25-2010, 07:44 AM
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The symptoms seem to point to one thing: Fuel starvation. Even if the carbs were gone through, the idle passages are small enough that they may not have gotten cleaned out and are still clogged.
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Old 11-25-2010, 07:51 AM
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Pumping the throttle? DOes a Suzuki really have accelerator pumps?
You didn't say about cleaning the tank. You can clean the fuel system all you want but leaving crap in the tank will just come back.
Have you tried a portable tank?
I've put a clear glass filter (walmart and everyone has) temporarily so you can actually see fuel flow.
Are the plugs bone dry? Another indicator of fuel situation. Dry plugs will mean no fuel.
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Old 11-25-2010, 07:57 AM
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great advice from all, I had the same problem, dirty tank, water, sludge and maybe Jimmy Hoffa.
I had the tank cleaned, new racor fuel filters and then carbs cleaned and wow, all problems over, clear skies, happy Wife.
Well ok, not a happy wife, but the motors ran great.
Best of luck.

Rocky
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Old 11-25-2010, 08:01 AM
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Originally Posted by kerno View Post
The symptoms seem to point to one thing: Fuel starvation. Even if the carbs were gone through, the idle passages are small enough that they may not have gotten cleaned out and are still clogged.

I'd get a shock treatment of SeaFoam into your float bowls and/or somehow shoot DeepCreep (Spray SeaFoam) into the idle passages.
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Old 11-25-2010, 08:38 AM
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Thanks for the replies everyone.

The gas tank is new, its a portable tank with fresh gas in it.

I'll see if I can pick up a clear fuel filter today; I had one on a Camaro years ago so I know which one you are talking about.

I have some SeaFoam, but since it won't stay running I am not sure how to run it through the engine. The spray-able SeaFoam, how would I spray that into the idle passages? Do the carbs need to come off to do this?

I'll check the plugs a little later on and report what I find.
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Old 11-25-2010, 08:56 AM
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Originally Posted by Gas Giant View Post
Thanks for the replies everyone.

The gas tank is new, its a portable tank with fresh gas in it.

I'll see if I can pick up a clear fuel filter today; I had one on a Camaro years ago so I know which one you are talking about.

I have some SeaFoam, but since it won't stay running I am not sure how to run it through the engine. The spray-able SeaFoam, how would I spray that into the idle passages? Do the carbs need to come off to do this?

I'll check the plugs a little later on and report what I find.
Am not familar with this engine...are there float bowls?

Get SeaFoam in tank anyhow just to get SeaFoam into system when it does run.

When I cleaned out my Honda 35hp I pulled off the float bowls and sprayed DeepCreep up into jet area, cleaned bowls too.

My bowls had overflow fuel hoses coming off float bowls. I even removed hoses and sprayed into overflow nipple as I cranked engine.

Engine had been sitting awhile and SeaFoam /DeepCreep cleaned out the gunk.


Also, a heapin' helpin' of PATIENCE!
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Old 11-25-2010, 08:59 AM
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could very well be an air leak.. That little filter will show that.
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Old 11-25-2010, 09:06 AM
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Get some of that clear yellow fuel line to replace and old lines.
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Old 11-25-2010, 09:08 AM
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I had a similar problem on an old '92 evinrude looper engine. Went through EVERYTHING. It urned out to be a split diaphragm on the primer solenoid. It was a $15 piece!! It will allow just enough air to prevent your system from pressuring up correctly and just enough gas out that it will starve. don't know if this helps with the suzuki..but it is worth the thought.
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Old 11-25-2010, 09:21 AM
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have you balanced the carbs -??

not just air adjustment but balanced so each carb pulls the same -- check your manuel for how to do this -

any place that lets gas leak out also lets air in under vacume --

the engine does not have a accelerator pump- you dont prime the carb by pumping the throttle handle-

your starveing the engine for gas- fix the leaks --
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Old 11-25-2010, 09:23 AM
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Originally Posted by CaptPeter View Post
I had a similar problem on an old '92 evinrude looper engine. Went through EVERYTHING. It urned out to be a split diaphragm on the primer solenoid. It was a $15 piece!! It will allow just enough air to prevent your system from pressuring up correctly and just enough gas out that it will starve. don't know if this helps with the suzuki..but it is worth the thought.
Thanks for posting that. I'm having a problem starting my 94 Johnson 48hp outboard and I think I've isolated it down to the priming system. On my last outing, turning the red lever on the primer solenoid to manual position did help in starting the motor after a few tries, but it started up easily when I returned home in the regular running position. Once the motor started, it ran great, but does die at idle once in awhile.
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Old 11-25-2010, 10:33 AM
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I suppose I'll stop pumping the throttle, since it isn't helping anything.

The carbs were balanced by the mechanic (supposedly - I'm not sure about anything he did now).

I'll stop by a Wal Mart today and see if I can grab one of those clear filters. I'll post the results of what happens.
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Old 11-25-2010, 11:04 AM
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install clear line with a vacuum gauge right before fuel pump and another clear line with low pressure gauge on output side of fuel pump and look for bubbles and locate leaks by moving gauges down fuel line before and after any kind of connection,(filter, fittings,primer bulb,etc.)
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Old 11-25-2010, 11:15 AM
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how much for boat and anchor
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Old 11-25-2010, 02:03 PM
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ouboard - will let you know if I can't get it going ;-)
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Old 11-25-2010, 04:01 PM
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id be interested in the motor and controls-- shoot me a price
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