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Discussion Starter #1
I am so bummed out right now. i'm a newbie rider and i took my monster out on the freeway for first time today and when i turned into issaquah the bike died on me at an intersection and it wouldn't start back up! :-/

after the bike cooled down it started up and i got back home. this is the second time that this has happened. the last time the forward spark plug was fouled so i assume the same thing happened today. the last time i took it to the shop the mechanic measuered the exhaust and he said everything was fine. i have aftermarket high pipes which merge then go back into separate pipes. Could this be skewing his readings if the forward carb is off and the pipes merge?

btw motorcyclist are so helpful. i had two guys offer to help me out and one guy followed me home to make sure i got back all right.
 

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I had a vapor lock a few weeks ago, bike did the same. Open tank when that happens and a rush of air escaping means vapor lock. Check fuel line placement, check for kinks. Bad fuel filter. You also should list model and year of your bike as there are differences over the years. Had you just started out? What was temp outside, in teraffic or open road.
 

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What year and motor are in your Monster?

I agree that it sounds like a fuel issue. Check the lines.
Also, do you know if the fuel pump has been rebuilt?

But, then again if you are fouling plugs you're probably getting plenty of gas.
 
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Discussion Starter #4
I'm definetly fouling the plug. it was pretty hot today and i was riding for awhile (mostly freeway). the last time this happened the bike was pretty warm since i was doing alot of stop and go traffic. Once the bike cooled down i was able to start it up again. It died on me 3 times in two outings. 2 times in traffic waiting for a light and the 3rd time on the freeway (after having it die earlier the same day at a light and then waiting for it to cool down and i was just trying to make it home).

The first outing when it died it must have been 70-80deg f with alot of stop and go. Today when it died it was around the upper 80s but with mostly freeway riding.

My bike is a 98 monster 750 with carbs. Thanks!
 

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since you have after market pipes, did you re-jeted the carbs?? also what about the air filter/air box????
 
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Discussion Starter #7
I just bought the bike a few weeks ago so and it came with the aftermarket pipes so i'm not sure if the carbs where rejetted and what was done to the airbox. i'm a complete motorcycle newbie so all of this is new to me.

howie,
why do you think that the fuel pump needs rebuilding? i assume that fuel is getting to the plugs since the forward one is fouling? is the rebuild something that i could do myself?
 

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I just bought the bike a few weeks ago so and it came with the aftermarket pipes so i'm not sure if the carbs where rejetted and what was done to the airbox. i'm a complete motorcycle newbie so all of this is new to me.

howie,
why do you think that the fuel pump needs rebuilding? i assume that fuel is getting to the plugs since the forward one is fouling? is the rebuild something that i could do myself?
really can't say. the shop manual has no pressure/volume test, or any other diagnostic test. judging from other people's exprerience, it's probably a good idea as preventative maintenance on a bike of that age. the rebuild is easy, but only you know your abilities. do a search on this board, going back a log time. this topic has been covered. there are even some picks.
 

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Wouldn't dumping too much fuel into the motor or skewing the air/fuel ratio to fuel cause both overheating and fouling the plugs?

What grade gasoline are you using?

What would cause the bike to run too rich? A fuel pump failure should do the opposite, no??

I know if the choke is cranked halfway the same thing happens...this is from alot of guys who claim similar symtops when they dont have time to properly warm the bike before riding and think riding on it with a half engaged choke is the answer.
 

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Wouldn't dumping too much fuel into the motor or skewing the air/fuel ratio to fuel cause both overheating and fouling the plugs?

What grade gasoline are you using?

What would cause the bike to run too rich? A fuel pump failure should do the opposite, no??

I know if the choke is cranked halfway the same thing happens...this is from alot of guys who claim similar symtops when they dont have time to properly warm the bike before riding and think riding on it with a half engaged choke is the answer.
yep. somehow i forgot about the horizontal plug fouling. forget the fuel pump. lean causes hot, though.
 

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Hey there Tone.... hard to understand how you can be fouling a plug if you are traveling on the freeway ?? Vapor lock, pinched fuel line are good posibilities.. If the bike has pipes it has most likely been jetted already. how many miles on the bike ? You say it is new to you, are you using the choke properly ? most likely little is needed especialy on warmer days in order to start the bike.. make sure it is all the way off when riding.. If the plugs did foul, replace them don't just clean them. If you have a vapor lock situtaion you would hear air pressure released when you open your gas cap.. Good luck, if you need more help feel free to give us a call..
Ducati Seattle 206 298-9995
 

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Tone,

I think DucSea may have hit it.

I had the same problem; extended cruising on a warm day and she just cut out. Happened three times. No power in the left lane in heavy freeway traffic is NOT fun.

Problem was quickly identified when I described the symptoms to two mechanics and another customer in the shop: pinched fuel line.

If the line is bent too tightly, it can remain open when the rubber is cool and stiff, but when the engine soak heats the rubber, it collapses and cuts off fuel. Sitting by the road for 10 minutes allows it to cool enough to open up again!

Replace the fuel line making sure to have enough length for gentle bends and be careful when you put the tank down that it doesn't get fouled.
 
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Discussion Starter #14
fouling the plugs, this could be another candidate for checking the needle jets. when they get ovaled the bike will run rich. (foul plugs)
 

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it'd be nice to rule out one thing or another. seems like there's some thought about fouled plugs (too rich) as well as suggestions about pinched line. it's possible both could coexist but i think you should segment these. 1st check the fuel lines and try to find any possible restriction. after that, then move to the mixture. excess temp can be an indicator of several things only one of which is lean mixture.
i have known of people who wanted sound and knew nada about performance so pipes went on without jets (or computer).
monsters tend towards lean mix anyway so increasing exhaust can effect mix pretty significantly so having the jets checked could be important.
best of luck
 
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Discussion Starter #16
"95 M900 Carbs

1. Check your fuel line isn't lying on your crankcase before it goes up into the fuel pump. This happened to me (same symptoms) and raising the line off the case sorted the problem. ;)
2. vapour lock...what's with this ? ??? If you've high pressure in the tank, it should "push" gas down to the pump, not stop it.
If you have a vacuum in the tank (ie the breather lines blocked, stopping air getting into the tank as the fuel's used up) I can understand you may get a problem with reduced fuel flow.......???
3. I overhauled my vacuum pump recently and it made the bike run much smoother at low throttle. Vacuum diaphragm was well shaped into a disc and probably not pumping much at low vacuum pressures. The kit's only US$5.99 or thereabouts, so's it's pretty worthwhile. Overhaul's easy...the tricky bits removing the sucker ! Tape around your frame before you start (...good tip, whomever suggested it !)

Just my two cents worth...

,...Simon
 
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Discussion Starter #17
Thanks for helping me out guys!

It sounds like i got two separate problems then. I checked the fuel lines and the line that goes into the bottom of the fuel pump was rubbing right against the vertical cylinder head of the engine. when i moved the line away i saw few tiny pieces of melted rubber on the cooling fins on the engine case. i will do a more thorough check out for kinks in the fuel lines when i get a chance.

I may try the vacuum pump overhaul. There's a great picture tutorial on how to replace the gaskets and membrane but nothing on how to get the darn thing out of the bike! i have no idea on how i'm going to get at those screws though!

Duc-Sea
I'm definetly turning the choke completely off when i ride. i only use the choke when i'm starting the bike up. the bike has 14k miles on it.
 
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Discussion Starter #18
Tone,
My method of pulling out the fuel pump (by no means the best, probably !)
1. Turn off fuel at fuel shut-off valve. Remove downstream fuel line and empty fuel out.
2. Disconnect two of the three lines on the vacuum pump while the pump's in-situ. These are (a) the vacuum line to the back (facing the forks !) of the pump casing (this line was quiet hardened by age and split on the join to the pump nozzle when I tried to pull it off)...and (b) the discharge line up to the carbs.
3. Tape up frame around the pump !!!!
4. Unscrew fasteners at top and bottom of pump to frame. The top one needs an Allen key, and pulls out OK. The bottom one needs an Allen key at the RHS (as you kneel at the bike) and a open ended / thin ring spanner on the nut on the LHS.
5. Once free, struggle like F*ck to manoevre the pump out. I found rotating it 90 degrees towards me, then moving it forward and through the frame bars the best.
6. Strip as per the pictorial website (forgotten where...?). Hardest thing was to fit the new round valves to their rubber "pins" without distorting the plastic.
BTW - the kit I got didn't have rubber diaphragms, but had a harder plasticy material diaphragms. Also it didn't have the two smaller valve spacer pieces that were fitted to the original pump.
7. Check pump operation by mouth before re-installation.
8. Re-install (ah, such a short description of a finger twisting operation !) and TEST for LEAKS !!!
Good luck... ;D

...Simon
 

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We don't see that many fuel pump failures on Monsters but I have seen a jet kit "wear out" after some miles, the needle wear into the needle jet or passage way causing the cylinder to run rich.. usualy on the horizontal cylinder. Tone said it is a 98, not sure of the miles but the pipes were on it but this is also a possibility..
 
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Discussion Starter #20
simcor,

Thanks for the tutorial on the fuel pump removal. i'll give it a shot when i get the kit. i just ordered it so i should get it in a week or two i'd imagine.

DucSea,
My bike has 14,000 miles on it. Is it bad for the bike if i'm running with a fouled plug? i think i'm gonna to have to take my bike to your shop pretty soon because i've never messed with carbs before and i definetly want to get it all sorted out.
 
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