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Put a little bit of diesel in by accident

2K views 20 replies 8 participants last post by  demsay 
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#1 ·
So I am a moron and wasnt paying attention to the fullest. When filling up, I accidentally put about 1 gallon of diesel in my tank, and filled the rest with gasoline. Its a 4 gallon tank. The bike is a YZF750. Being in the middle of nowhere, and the gas station not having a hose to drain my tank, I limped home (about 100km's). The bike ran fine at highway speeds, but idled poorly and smoked a bit when starting. Now I am faced with an even bigger problem. I drained the tank, drained the carbs and refilled with gas. And she wont start. So I pulled the carbs, cleaned them throughly, removed the starter jet, main jet, pilot jet, floats, sprayed contact cleaner through the jets and journals, put in new spark plugs and she still wont start! Does anyone have any idea what kind of damage I could have done? Right now I am thinking there may be valve damage (way out of spec) from the diesel needing higher compression to ignite. I didnt check the compression, and I didnt check for spark (assuming the diesel didnt affect the coils). I can get at plugs for cylinders 1 and 4 easy enough to check for spark, but it is a lot of work to get to the middle plugs (clinders #2 and 3). Would checking spark on just the 2 outside clinders be sufficient? (2 coils on the bike, one for clinders 1 and 2, the other coil for clinders 3 and 4. So I would essentially be testing each coil). The fuel pump is OK I think, I tried starting it, then loosened the carb drain bolts, and gas pours out, so there is gas in the bowls. I also lifted the tank with the fuel hose disconnected from the carbs, and hit the starter; A small, steady stream of fuel poured out. Should there be pressure in the fuel line? Maybe my fuel pump is clogged up, but again, there is gas in the float bowls, I just dont know if they are full. The bike will turn over but just wont start, like there is no spark. But I dont see how it can run fine, then after sitting for an hour, wont start back up. Anyone with any help would be great! thanks.
 
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#4 ·
I wouldn't be blaming the diesel in the sense that a valve went bad, this wouldn't be the case. Your cylinder compression didn't go high just due to the fact of adding the diesel, since engine compression is a fixed variable. Remember the triangle for causing something to ignite. It needs three things. Air, Fuel, Ignition. Air is never a problem, sounds like you have fuel so I would pull a sparkplug myself to check this avenue. When things just stop working, you have to review what changed since it was last working. Its possible that some component of the ignition was removed and then reassembled (is your kill switch on - I've done that before!) during your carb draining process, but do double check with one plug, my guess is that the ignition is fine. So you are left back at the fuel. Are your sparkplugs fouled? You can alway pour a little gas into the cylinder to give it a bit of help. Or put your hand directly over the carb inlet as you crank the engine over, it creates some mad vacuum and will suck the gas out of the carb and directly into the engine. Don't over do it though as you can quickly flood that cylinder.
 
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#5 ·
thanks guys. I just checked for spark, and I have spark. The plugs arnt fouled, I just put new ones in hoping that would solve my problem. The old ones looked black, buf definatly not fouled. I put a hand over one of the carbs and hit the starter and there wasnt any suction... I could feel air being blown out pilot air circuit hole in the front of the bell, but not much of a suction at all through the bore. These are CV carbs BTW.
CrotchetyRocket, what does this goo look like? I cleaned the carbs very thourouly with contact cleaner. Any recomendations on anything else to use? Right now I am suspecting there is something major clogging the carbs, but where could this clog be? Thanks
 
#6 ·
I doubt there is anything clogging your carbs. Diesel would not have caused a problem unless left in there for a long period of time. What exactly is contact cleaner? You have to be very careful as to what you use to clean carbs with. Some chemicals will destroy any plastic or rubber parts like orings, floats, diaphrams, and fiber washers. Usally a little ether (starting fluid), pipe cleaners, and compressed air is all you need. Ether breaks down the green goo (varnish) well.
 
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#7 ·
contact brake cleaner, goes by many names (brakleen, kleen flo, etc), but this is the generic name. I know it is probably not the best stuff to clean carbs with, but I have cleaned many carbs with it over the years and never had a problem with it destroying o rings. It evaporates VERY quickly.
 
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#8 ·
sounds like you got a vapor lock
or. no fuel coming in.
try putting gas in your cyclinders (not much) and then putting the spart plug in and then fireing it up. just 2 cyclinders are enough. it should fire up and run for 5 or so seconds and then die. keep doign that and it should have enough to suck in more gas eventually.

If you were running still, and did 100km at 1/4 diesil i would of just kept putting in gas and burned out the diesil. since it was still running.
 
#10 ·
Cycle the key. It will pump and then stop( it has a built in thermo switch) keep turning the key on and off until it stops pumping.

push up on the slides they should make the same sucking sound and have a consistent pushing feel to them.

Is the powervalve in the proper position?

Try some quickstart diesel engines start well on that stuff :thumbup
 
#11 ·
can u hear the fuel pump? last time i had my tank off the connector wasn't quite done up and she wouldn't start. pushed the connector together andp resto whammo she fired right away. also check the vacuum hoses are coorect ifyou have a vacuum operated petcock.
 
#12 ·
You should be able to feel some vacuum on the mouths of the carbs. Check out the connector manifolds between the carbs and the cylinder head to ensure they are seated well and the clamps are done up properley.

And another silly question. Does it have a vacuum operated petcock? If so did you put it onto PRIME so the float bowls would fill up? Remember that for a vacuum petcock ON is only on when the engine is actually running. Starter cranking isn't enough to get it to open.
 
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#13 ·
Im not sure about a vacuum petcock, but I dont have an ON/OFF switch for my fuel, just my ON/OFF on the key ignition. When I put the key to ON, nothing comes out of the fuel line, its only when I crank the engine over does fuel come out. but there is fuel getting to the float bowls. I pulled the fuel line off the carbs and cranked the engine over and a steady stream of gas came out of the fuel line, so my fuel pump is working. I will try a few more of your suggestions once my battery gets off the charger. thanks again!
 
#14 ·
With new plugs, freshly cleaned carbs and confirmed spark I'm at a loss.

Are you trying this with the airbox open? If so you may want to put the whole lot back together and try again. May bikes with large bore carbs won't suck any gas when there's no airbox vacuum.

Check the basics. Be sure you remembered to reconnect the "choke" cable (it's rarely a true choke these days but does the same thing) and that all the vent hoses on ram air bikes are properly connected and stuff like that.

Something is missing. You've hit all the main 3 sources of ignition but messed up one of them or not done it adequitely. You've confirmed the spark and that the carbs are getting gas and that it has new plugs (properly gapped?) so it comes back to something basic that is messed up. Either you missed a passage or two in the carbs or you put something back together wrong. Yes the last sentance is some "tough love" but it also means it's time to double check all your work with a very detached eye. DO NOT ASSUME ANYTHING!


:pS: a gallon or so is a LOT more than "a little bit".... :D
 
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#15 ·
I cant say 100% that everything is back together properly, but it is the best I can do. Brand new plugs are gapped right (.03"). The thing is that it wouldnt start BEFORE I even took anything apart. I rode it home, it ran fine at highway speeds bit ideled poorly and smoked a bit when starting. It stalled a few times at traffic lights but fired up right away like nothing. Then when I got home, I drained the tank by syphon with a long fuel hose. The tank was then empty. I then drained the carbs via the drain bolts on the bottom of the bowls. Then I refilled the tank with 2 gallons of 91 octane gas and it wouldnt start. Then I started pulling it apart. and that is where I am now. Something happened from the point when I got home and drianed the tank and refilled it, I just dont know what. Is it possible I cooked the valves, since diesel burns hotter then gasoline? Thanks again for the help, I really appreciate it.
 
#16 ·
maybe your carbs are so outta sync/adj from reassy. that your bike just doesn't want to start. i would try a wee bit of ether or cold start or even prime the carbs with a abit of fuel and see if you can get even a little kick out of her. and double check your spark plug lead orientation. it has happened to me.
good luck...
 
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#17 ·
Well she runs now. I took my fuel pump apart and cleaned it and she flashed right up. This whole ordeal was a good excuse to put new plugs in anyway. Now I just need a carb sync and it'll be good to go. Thanks again for all the help.
 
#18 ·
demsay said:
Well she runs now. I took my fuel pump apart and cleaned it and she flashed right up. .....
What did you find in the pump? And kudos to doing all this work yourself. You've got a lot more experience now than you did before the brainfart so at least the incident was good for something.

Years from now you'll look back and laugh at this but right now I'm sure you're just happy to breath a sigh of relief... :D
 
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#19 ·
Well, the only reason my bike didnt start was because when I drained the tank and the carbs, I guess the fuel pump couldnt re-fill the float bowls. So what I did was took the diaphram spring out of the petcock and put it all back together. Now the fuel flows freely, just being totally gravity fed. That let the float bowls fill up with the pressure from a full tank of gas above it. After it started up, I put the spring back in and it is all back to normal. I just took it for a ride and it runs like a champ. This is totally weird because I have run out of gas before while riding in front of my house, and I just refilled the tank and it was fine. But I am just glad it is running again, with no engine damage. I still think I need a carb synch though. FYI, the fuel pump mouting plate gasket is a one-time use gasket and a new one is $70. So make sure you have a dame good reason to take the pump out, because its $70 every time you do (for my bike anyways)! It wont seal, and leaks all over the place if you re-use the gasket.
 
#20 ·
Ummmm...... does your petcock have a "PRIME" position? If so all you needed to do is use that position to fill the carbs and carry on. This is exactly what the PRIME position is for. It PRIMES the carbs so it'll run. Once going turn it back to ON so it can shut off the fuel flow when not running. If it has a diaphragm then it's a vacuum operated petcock. And all vacuum operated petcocks have a PRIME position or equivalent.
 
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#21 ·
I've looked the petcock over and there is no switch, and there is nothing in the service manual about a prime position. I just an ON/RESERVE switch mouted in the cockpit. But regardless, its running, and running well, so Im not worried about a prime position ;)
 
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