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Help requested for no start condition - how to perform a spark test


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I have a 2003 VFR800 with 18k miles.  10 years ago, the fuel pump stopped working so the bike was covered in a garage and received no attention.  I'm trying to get it running again, so I removed the fuel tank, drained it, cleaned it out and installed a new Quantum fuel pump, filter, strainer and replaced all the related hoses and rubber pieces.  I reinstalled the tank, filled with fresh fuel, changed the motor oil, oil filter and installed a new battery.  

 

I have it on the center stand with the side stand up.  I turned on the ignition, switched on the red run button and hit the start switch.  I heard the fuel pump prime and tried to start it several times with no success. I gave it a rest and continued trying to start it and the motor came to an abrupt stop and made a metallic knock sound.

 

I then removed the fuel tank (once again), removed the airbox, the injectors and the coils and spark plugs.  I turned the motor over with the starter and some liquid was ejected from the number 4 cylinder (I assume fuel).  The motor turned over fine with the starter (no odd sounds and no plugs inserted), so I'm thinking too much unburned fuel was dumped into that cylinder and stopped the motor from spinning?  I cleaned out the fuel rail with carb cleaner, back flushed, cleaned and tested each injector using this method: Cleaning fuel injectors

 

The injectors seemed to work well and did not show any signs of leaks.  The spark plugs also looked good.  I reassembled everything, thinking the excess fuel may have been caused by a stuck open injector, but no such luck.  I tried to start it with no success and after some time, the motor again came to an abrupt stop and made a metallic knock sound.

 

Now I'm thinking I have no spark and fuel is just being dumped into the cylinders.  I downloaded the Service Manual and it mentions a "spark test" but doesn't give the procedure.  Is this the proper procedure?

1.) Disconnect fuel pump 

2.) Remove all spark plugs and coils

3.) Connect one coil and spark plug

4.) Ground the side electrode of the spark plug using alligator clips and wire

5.) Turn on the ignition and hit the starter, observing the tip of the plug for spark    

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With  just one cylinder fuel-filled,  that would seem to indicate you have one injector that's not closing or 3 that aren't working properly.  Either way,  that would seem to warrant more investigation.  Fuel deteriorates with time and gums things up - electrical parts can sit for decades and still work just fine, so fuel is the more likely culprit. 

 

Your spark check procedure will work if you can hold the plug to the coil pack. You could probably tape it. Maybe an easier way would be to get a noid light you can plug in to each coil pack's wiring connector and see if the they blink.  If the coil packs are receiving current and signal to fire,  the plugs should be sparking.  Your coil packs are 3 wire vs 2  so you need a compatible noid light. The FSM should show a test procedure.

 

Regardless of how the spark turns out,  the difference in fuel going to the one cylinder should be checked out.

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If you're not getting a spark, make sure you have a solid 12v at the Black/White wire (ignition to On) and a good solid Ground on the Green wire of the coils.

 

If you have a spark then you may have a flooded engine. There is a procedure in the owners manual for a flooded start situation. This requires cranking the engine over with the throttle fully open, this will shut injectors off to purge the engine of excess fuel. See attached.

 

OR......

You may have a ruptured Fuel Pressure Regulator diaphragm. This will dump excess fuel into cylinders 3 and 4 via its vacuum hose.

 

IMG_1011.PNG

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Grum - I suspect you hit the nail on the head!  I removed the coils and spark plugs and turned the motor over and gas spewed from both front cylinders.  The rear cylinders were dry.  I didn't try the spark test this evening as there was too much gas and fumes in the area. 

 

I did some reading about the fuel pressure regulator and ran across some old posts about an aftermarket model from a "turbocity.com" which no longer exists.  It seemed to offer some improvements - is something similar still available or is it best to order a factory replacement part?  

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Hi ksteele. I haven't personally replaced an FPR, but if I was to I'd definitely choose OEM.

As mentioned a ruptured FPR diaphragm will dump excess fuel into cylinders 3 and 4 (both R/H side cylinders) is this the case? Should be easily identifiable.

FPR part no.16740-MCW-013.

Partzilla web site states in stock at $59.94.

You mentioned your bike is on the center stand with the side stand up. Lower your side stand switch on ignition, kill switch to run and see if your Fi light is flashing any error codes.

Good luck.

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It's a very easy job on a 6g. Once the tank is up it only requires common hand tools. You'll need to unfasten the airbox from the throttle body and either move to the side or remove. On the FPR loosen the clamp and remove the supply hose, pull the vacuum line, loosen the nut on the fuel rail that retains the FPR, and it's off.  You'll need a 24 mm wrench for the nut (15/16 will also work) or a suitably sized adjustable wrench.  Have rags or an expendable towel around to catch fuel spills.  I'd also try to get the tank as empty as possible to avoid it all draing while you're working.  You could also plug the hose.

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I performed the spark test by removing all coils and plugs, connecting them one at a time to the proper wire and observed spark on all 4 plugs.  Therefore, I do not seem to have an ignition issue.  As a reminder, I also tested all 4 injectors for leaks while cleaning them and found no leaks. 

 

The two front cylinders, 2 and 4 had all the fuel - I did not observe any excess fuel in the two rear cylinders 1 and 3.

 

I traced the vacuum hose from the fuel pressure regulator and it feeds the right hand cylinders 3 and 4 as you mentioned.  I can see how you would expect the fuel to be in 3 and 4 if the fuel pressure regulator had failed.

 

While I'm not sure how to test the fuel pressure regulator - here's what I did:

1.) Oriented the fuel tank so that the fuel pump would be submerged in fuel.

2.) Removed the vacuum hose from the fuel pressure regulator

3.) Connected a rubber hose to the vacuum port on the fuel pressure regulator and put the other end in a measuring cup

3.) Turned on the ignition and heard the fuel pump prime

4.) Three ounces of fuel came out of the vacuum port of the fuel pressure regulator.

 

Does this prove that the fuel pressure regulator is bad?

 

I'm still wondering why I found excess fuel in cylinder 2 as well.  Perhaps there any other shared connection points with vacuum hoses or engine internals? 

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Well done ksteele, you have 100% confirmed a stuffed FPR, ruptured diaphragm.:fing02:

 

Don't forget, once you replace the FPR your engine will no doubt be in a flooded state and possibly reluctant to start. You may need to go through the flooded start procedure I posted to purge the cylinders of excess fuel.

Good Luck.

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  • 3 weeks later...

Thanks to Grum and Cogswell I have it running again!  The FPR was definitely the cause of the cylinders being flooded with fuel.  I was also surprised by the amount of fuel that was in the exhaust system.  I really appreciate the help.

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51 minutes ago, ksteele said:

Thanks to Grum and Cogswell I have it running again!  The FPR was definitely the cause of the cylinders being flooded with fuel.  I was also surprised by the amount of fuel that was in the exhaust system.  I really appreciate the help.

Good news ksteele. Now you can get out and enjoy the ride.:fing02:

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