VMax Journey Continues....

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o.k. just swapped the fuel pumps and I'm not sure what to think... We may be looking at 2 seperate problems. First, with the fuel switch in the 'on' position it will miss and spit and sputter like it is running out of fuel... I think it is. I switch it to the reserve and the fuel pump kicks on and things go back to the normal 4k-6k rpm miss. So what does it mean if the engine is off, but the ignition is on, the fuel switch is in the "on" position and the fuel pump doesn't click. I switch it over to reserve and the fuel pump starts to pump/click. Is that a bad relay? I'm going to hold off on the beers until I can get a few more test rides in.

HELP!!!!
 
You just found the problem that ties the fuel pump issue with the vboost. Did you know that the fuel pump relay and vboost are connected via a gray wire? There are two crimps. A gray wire goes from the tach to one crimp. From the crimp, there are two wires...one goes to the 2nd crimp and the other goes to the vboost controller. From the 2nd crimp a gray wire goes to the fuel pump and another gray wire is spliced to the gray p/u coil wire.

BTW, your fuel pump issue sounds like you're almost out of gas? I'm assuming it's not and the fuel light isn't on?
 
So really this points again to either a dodgy relay, or more likely a bad crimp, a break in a wire or a short. I'll say it again - it's harness time! ..there's prolly still mice in there using wire copper to play poker with fuel burritos!
 
Jeff,

Thanks again for all the help so far! I know your frustrated and trust me I can definetly relate!

With all the 02 parts on my bike I may have to ask for a title correction!:rofl_200:

Good luck and I hope you figure this ********** out! Call if you need anything.

Abe
 
Jeff,

Here is a response from the pelican parts forum from a guy with an FJ1200 who had similar fuel pump/relay issues...I hope it helps!

On the Yamaha FJ 1200 I had, the fuel pump relay was to turn the pump on only (supply power). The fuel pump itself has a pressure switch built into the pump and would run until pressure shut it off. This is on an 89 FJ1200 and I don't know if a VMax uses the same setup, but I would suspect it does since without the pressure switch the carb float needles will be overwhelmed at any pressure above 1-2 psi.
So, if the fuel pump runs on reserve it may not be getting fuel, and may getting fuel in the "ON" position, pressurizing the line and shutting the pump off.
I would start by insuring that your fuel pump actually pumps fuel in both "res" and "on". Once you have actual fuel flow, stick you're finger over the end and see if the pump shuts off, I believe it should, once again experience with the FJ talking here.
You mention turning the fuel pump "ON" and it sounds like it's been wired through another switch rather than the original design using the ignition switch, is this correct? Is this the original Yamaha fuel pump or is a low pressure fuel pump designed for a car? If it doesn't contain a pressure shut off switch, not just a regulator, then you may be flooding the carbs since it's extremely easy to force fuel past the stock float needles, especially if the pump never shuts off. ( I know this because I tried to replace the expensive Yamaha pump with a 2 psi pump and it doesn't work). Also, the stock pump will flood the carbs if the pressure switch fails in the "on" position.
If none of the above applies, then you've a definite electrical problem somewhere else. I would start by disconnecting systems, running engine and seeing if this has any effect. If one particular system does affect it, then you'll know where to concentrate troubleshooting. Don't forget to disconnect the fuel pump circuit.
If this doesn't work, I would remove the battery, disconnect EVERYTHING from the loom and begin ohming wires, from end point to end point and also, from end point to the frame or any ground. Also, if a single wire runs into a multiple pin connector, make sure that you go from the single wire end point to each of the pins in the connector and insure that you have no shorts wire to wire within the connector. This could indicate either bad connector or shorting of wires in the wire loom.
You'll have to use a wiring diagram since the grounds are often in the connectors and you'll want to make sure that those grounds actually are grounds. Check your battery cables too. You should have very little resistance, if any on individual wires, end point to end point, no more than maybe 50, if that. You should have no resistance to any ground for any ground wire. You should have infinite resistance between wires not on the same circuit and between ground.
A new loom may help or not, depending on the age and abuse it has been subjected to. Often, wires wear through insulation at points where they are tied to the frame, cause by engine vibes and pulling on wires during maintenance or tinkering. Failures are common at stess points (steering head, under the seat, etc) anywhere the loom is exposed to movement, and people poking at it. (People poking things ain't good.)
Don't forget to check your ignition and kill switch, the contacts may be tight enough to run but loose enough to vibrate intermittently. Replace all the fuses with new, old fuses can look peachy and be vibrating causing poor contact.
I would look very closely at your conversion of the coils to coil on plug. They may be arcing to the metal around the plug (head) if they aren't fully insulated, or they may be have a poor contact at the coil connection itself. If possible, try swapping back and see if results change.
One other thing, what fuse is it blowing? That would be helpful.
Hope this gives you some ideas/help.
 
I would look closely at the gray wire going to the fuel pump relay and to the vboost controller. The fuel pump relay uses the ignition signal so that it only pumps fuel for a few seconds when the engine is off. This is a safety feature. When the engine is on, the gray wire picks up ignition signals which tell the relay that it's okay to pump fuel depending on that pressure switch. That's why when the bowls are empty you have to turn the key on/off a couple of times to refill the bowls. This wire also feeds the vboost controller.....which is also giving you fits.
 
I'm hoping to get some work done on Abe's bike today, but I don't have a whole lot of time. A few buddies and I are going to the nickelback concert in the quad-cities tonight... work is going to be a ***** tomorrow!
 
Abe, I got a few more things done on your bike tonight but didn't get a chance to ride it and test it out again. My new job is taking up a lot of my time and I'm trying to finish up some house projects as well. I have missed out on two great days, but I'll find some time soon to work on it. This weekend will probably be too early to come pick it up so lets hold off another week (if that is o.k. with you). I am wondering if taking it up to the dyno shop would be a good idea. If we could use an inductive pickup on the spark plug wires, it may show us what cylinder is missing and exactly at what RPMs (to see if it is consistent and to see if we can replicate it). I want to try a few more things first, but I think we should keep it open as a possibility.

Jeff
 
Abe, I got a few more things done on your bike tonight but didn't get a chance to ride it and test it out again. My new job is taking up a lot of my time and I'm trying to finish up some house projects as well. I have missed out on two great days, but I'll find some time soon to work on it. This weekend will probably be too early to come pick it up so lets hold off another week (if that is o.k. with you). I am wondering if taking it up to the dyno shop would be a good idea. If we could use an inductive pickup on the spark plug wires, it may show us what cylinder is missing and exactly at what RPMs (to see if it is consistent and to see if we can replicate it). I want to try a few more things first, but I think we should keep it open as a possibility.

Jeff

No problem buddy. Just let me know.

Thanks Again,
Abe
 
This weekend.... I'm hoping to spend all weekend on this bike if needed! I finally got the last of the trim put on in our breeze-way so that project is done! I'll be able to put some items back in that room and get the garage cleaned up again so I can focus on your bike. Work today kicked my butt.. it's a little past 8 and I'm heading to bed soon.
 
Jeff,

No sweat brother. Take your time. Your doing ME the favor! However if it's NOT done soon I will come and take your 02 hostage:biglaugh::eusa_dance:
 
Abe.... I'm going to go crazy with this thing!!!!!!!!!!!

I swapped harnesses (not too bad of a job, but took a little time) and I go to fire it up and it starts, doesn't run the best, but runs, and then the diode assy starts to smoke and a green goo came out. I'm guessing I fried it, but I'm not sure why. (I have spares so it isn't a huge deal, but I would like to know why) I'm 99% sure this harness is off of an 86 so it should be the same, but I did notice there was only 1 ground wire next to the coolant res where your stock harness had 2 grounds. I think I am going to try and tear into your harness and just do some trouble shooting and try to find any problems. I keep finding small things, and I get excited because I think I found our problem, but it never is the case.:bang head: There is an electrical problem somewhere and I am going to find it, but first, I'm going to some friends house and am going to get my drink on! Tomorrow is supposed to be a nice day and I hope to get some more work done on it. I hate this bike right now, but I so want to get this fixed for you. You have way too much time and $$ invested in this thing to not get it running right. I'm bound to get it done though. I'm even putting off working on the drag bike to get this thing running well for you... and that is making things even harder for me. I did take my 02 out a few times today and blew off some steam. It sounds like rain this week, so maybe I'll get a few more days open where I can work on this (if I can't get it done tomorrow)

Sorry man, but I'm working on it!
 
Abe.... I'm going to go crazy with this thing!!!!!!!!!!!

I swapped harnesses (not too bad of a job, but took a little time) and I go to fire it up and it starts, doesn't run the best, but runs, and then the diode assy starts to smoke and a green goo came out. I'm guessing I fried it, but I'm not sure why. (I have spares so it isn't a huge deal, but I would like to know why) I'm 99% sure this harness is off of an 86 so it should be the same, but I did notice there was only 1 ground wire next to the coolant res where your stock harness had 2 grounds. I think I am going to try and tear into your harness and just do some trouble shooting and try to find any problems. I keep finding small things, and I get excited because I think I found our problem, but it never is the case.:bang head: There is an electrical problem somewhere and I am going to find it, but first, I'm going to some friends house and am going to get my drink on! Tomorrow is supposed to be a nice day and I hope to get some more work done on it. I hate this bike right now, but I so want to get this fixed for you. You have way too much time and $$ invested in this thing to not get it running right. I'm bound to get it done though. I'm even putting off working on the drag bike to get this thing running well for you... and that is making things even harder for me. I did take my 02 out a few times today and blew off some steam. It sounds like rain this week, so maybe I'll get a few more days open where I can work on this (if I can't get it done tomorrow)

Sorry man, but I'm working on it!


Jeff,

When we going to work something out on your 02? You can keep my lemon and give me that carbon fibre cherry. I can throw some jingle your way...:eusa_dance:

Thanks again and good luck with that ******!

Abe
 
You know, we could throw your plastic on my 02 and move a few things over and we'll just pretend that your bike is fixed.... we'll both feel better.
If ou didn't have so much invested, I would sell you mine and just part out this bad boy. Maybe we can get you down this weekend and work on it some more. Like I said before, I should have a few good days to work on it, and I hope to find a few things.... I'll be sure to keep you up to speed with anything new that I find!

Jeff
 
So I'm laying in bed thinking about Abe's bike and it is eating at me like you wouldn't believe. I'm going to go through his harness while it is off the bike and see if I can find anything. But I also had an idea.... could the pickups be bad? Could this be the cause to the 4500-5500 rpm miss? I wanted to check the starter clutch anyway, so maybe I can kill 2 birds with one stone. Does anyone know of a way to test the pickups? I also thought about getting out my timing light with the inductive pickup and see if I can find the miss that way, but I'm not sure how accurate that may be.

That's all for now, any comments would be appreciated.

Jeff
 
any comments would be appreciated.

Only thing I can suggest is working by process of elimination, meaning if you can swap parts you suspect that could be bad with parts from a good bike one at a time until you find the culprit.
 
So I'm laying in bed thinking about Abe's bike and it is eating at me like you wouldn't believe. I'm going to go through his harness while it is off the bike and see if I can find anything. But I also had an idea.... could the pickups be bad? Could this be the cause to the 4500-5500 rpm miss? I wanted to check the starter clutch anyway, so maybe I can kill 2 birds with one stone. Does anyone know of a way to test the pickups? I also thought about getting out my timing light with the inductive pickup and see if I can find the miss that way, but I'm not sure how accurate that may be.

That's all for now, any comments would be appreciated.

Jeff

Jeff,

I can't believe how big of a pain in the *** this vmax is turning out to be! Does the bike run better with the headlight disconnected still? I can ride during the day only...:clapping:

On a serious note I hope you find this dam gremlin and crush it's head!

Thanks again for all the help and once again I AM GONNA OWE YOU BIGTIME! Next time your in jail you know who to call...:eusa_dance:

Thanks Again!

Abe
 

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