1999 750SS not starting - Ducati.ms - The Ultimate Ducati Forum
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post #1 of 12 (permalink) Old Aug 23rd, 2019, 7:10 am Thread Starter
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1999 750SS not starting

Dear all:

After a few years of storage I decided to get my low-mileage, almost-brand-new looking 1999 750SS out for a ride. First it didn't start and I noticed the fuel pump was not priming...so I changed the pump/filter and lines in the tank. I took it out for a ride and it worked great (or so I thought)... So the next weekend my wife and I decided to attend a local Cars and Coffee car meet, her in the car and me on the Duc...but the motorcycle died on the freeway. At first I thought it was out of gas, so we put fresh gas in and headed home. The motorcycle died several more times on the way back.

It was "coughing" and sounded as if the noise was coming from under the gas tank (air intake). It also would rev down when I opened the throttle. I replaced the spark plugs and now it will not start at all.

I am desperately looking for advise as I hate to think I have a giant useless paper weight in my garage.

Any wisdom will be greatly appreciated. I am in Lexington Ky in case there are any ducatisti in the area...
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post #2 of 12 (permalink) Old Aug 23rd, 2019, 8:04 am
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If you didnít drain the fuel from the carbs when you stored it, then consider yourself lucky it started at all. Narrow it down: Do you have spark ? If you do, were the plugs wet ? Iíll assume also that you checked for obstructions in the air filter housing. You didnít mention battery, have you done a voltage check ? Itís probably gunked up carbs. You can try removing the mixture screws and spraying carb cleaner in the idle passage. Beyond that, youíre probably going to have to remove and clean the carbs .

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post #3 of 12 (permalink) Old Aug 23rd, 2019, 1:58 pm
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Quote:
Originally Posted by duc96cr View Post
Itís probably gunked up carbs. You can try removing the mixture screws and spraying carb cleaner in the idle passage. Beyond that, youíre probably going to have to remove and clean the carbs .
99=injection.
I vote tank vent not venting and creating vacuum in the tank that the pump eventually cannot over come. But that's just a guess.....sean
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post #4 of 12 (permalink) Old Aug 23rd, 2019, 3:33 pm Thread Starter
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Thanks Guys!!!

Fuel was not drained upon storage, so I agree obstruction from old fuel sediment/varnishing may be an issue. I put fresh gas with Sea Foam (after draining cleaning the tank). I believe I have spark, but havenít done a spark test. I replaced the old plugs with new, but not the wires as of yet. Battery is new. No visible obstructions in air intake. Being new to motorcycle DIY and not having a detailed book to use, I havenít attempted to dismantle anything. I released the gas cap (in case the fuel vent was obstructed), but that didnít seem to make any difference...but I am not sure that is a good way to test for negative pressure in the fuel system.

Any idea where I can get a mechanics manual for a 1999 750SS?
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post #5 of 12 (permalink) Old Aug 23rd, 2019, 5:14 pm
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There are plenty of Haynes manuals on Ebay right now I looked and saw a bunch

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post #6 of 12 (permalink) Old Aug 23rd, 2019, 7:46 pm
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Haynes and LT Snyder manuals is must have but I don't think either will fix your problem for now, it is not the time to start taking things apart yet.

You are not squeezing the fuel lines shut beneath the tank? Disconnect all the electrical connectors that you can see, spray some WD40, reconnect, double check battery terminals, earth.

You sure that new battery is okay? Are you using the correct plugs, is the gaps set correctly? If there is spark and fuel it must start. Wash it.

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post #7 of 12 (permalink) Old Aug 23rd, 2019, 10:43 pm
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Originally Posted by noavt View Post
Thanks Guys!!!

Fuel was not drained upon storage, so I agree obstruction from old fuel sediment/varnishing may be an issue. I put fresh gas with Sea Foam (after draining cleaning the tank). I believe I have spark, but havenít done a spark test. I replaced the old plugs with new, but not the wires as of yet. Battery is new. No visible obstructions in air intake. Being new to motorcycle DIY and not having a detailed book to use, I havenít attempted to dismantle anything. I released the gas cap (in case the fuel vent was obstructed), but that didnít seem to make any difference...but I am not sure that is a good way to test for negative pressure in the fuel system.

Any idea where I can get a mechanics manual for a 1999 750SS?
It may not be necessary to change the HT leads - but it does pay to check that the leads are screwed in tight to the coils, and the plug caps are screwed on to the leads nice and tight. If the plug caps come off with no more than a gentle pull, then cut back the HT lead by 10-12 mm (1/2") so the internal wires are back to nice and fresh, and screw the caps back on. If you can touch/hold the plug leads when the bike is running without feeling anything, then the lead insulation is fine.

Re the manual - try Haynes.

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post #8 of 12 (permalink) Old Aug 24th, 2019, 2:25 am
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when you turn the key on, does the fuel pump run? if so, that indicates the fuel pump electrical (also coils and injectors) is working as it should, and ecu power, etc, is ok. this is a timed ecu activation, the pump does not run until it builds pressure as many assume - there is no fuel pressure sensor.

if there is no pump, go looking for why. use a test light and check for power with stuff plugged in. unplugged there's no load, and relays, etc, may test as ok for passing voltage with no load.

when you crank the engine, does the pump run? this tests the rotation sensor that tells the ecu the engine is turning over. if not, it's likely a bad rotation sensor / crank sensor / cps / or whatever else people like to call it.

if the pump runs and the coils have power, test fuel pressure. if you can't do it, don't just assume it must be ok. find a way to do it or pass it on to someone who can. do it tank up and down. i've seen fuel pressure go up massively when the tank goes down for instance with kinked hoses.

years ago i recall seeing an ssie with the top of the tank sucked in - blocked breather (often the little rubber under the cap not sitting correctly) lead to it still running while the fuel was hot, but when the tank cooled and it all contracted and the vacuum from the fuel being pumped out overcame the tank and down the top went.
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post #9 of 12 (permalink) Old Aug 25th, 2019, 3:50 am
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Originally Posted by ZADSS View Post
Haynes and LT Snyder manuals is must have If there is spark and fuel it must start. Wash it.
Wash it...lol. As many of the members know, I just went through a similar situation and highway break downs. I know my carbs are different, but it was the carbs due to a rusty tank.

Getting a Haynes was the best thing I did...that and getting to know a local friend thanks to this forum, who has helped me too many times to count...thanks Fredsmoot23. Yes it would be great if you could find help locally.

Ducvet, Fredsmoot, Iwannaduc and others on here talked me down off the cliff a couple of times.

You couldn't have picked a better forum for helpful people who truly love Ducatis. Hang in there you will find it!

Ducati 1993 750ss/cr
The past: Honda 1000RR Fireblade F2 Yamaha R6 xj700 xs400 Suzuki GSXR600 Kaw 750 550

Last edited by ifly65; Aug 25th, 2019 at 4:02 am.
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post #10 of 12 (permalink) Old Aug 25th, 2019, 7:02 am
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Yes, wash it, give it some love man, previously I explained why it is important to give your bike a good wash once in awhile, after all, did you not wash your tank and carbs to get it running again.

This is a '99 750SS we are talking about, the most underrated and most reliable Ducati ever, they don't just break by standing around, unless the OP is omitting something, like a developing condition prior to parking it for a few years, there will be no reason to start any kind of serious dismantle, not the kind that you need a manual for anyhow.

Get the very basics sorted first, OP have not even tested for spark yet.

Batteries that are not healthy can wreck havoc with these bikes and a new battery does not guarantee anything unless you verify (I replaced the starter solenoid on mine just to learn that my new-ish battery was no good).

Yes I'm sure that this forum will get the OP sorted, but he need to cover the basics first and he need to communicate on his progress, and yes, who knows, maybe while washing his bike he may just notice that connection hanging loose somewhere.
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