Help on a First Gen fuel issue

[mark_gober]

Hey everyone.  First post as a MOOT member.  I recently acquired my stepfather's 1982 Magna 750 that he purchased new off the floor.  It'd been sitting for quite some time when I got it.  Before I touched it, it would only run with the choke fully engaged and absolutely NO throttle.  Any throttle at all would kill it.  Assuming a carb rebuild was in order, I purchased the parts and rebuilt the carbs myself.  Other than the time involved, it really wasn't that difficult of a task.  Put it all back together, shot some starting fluid down the throat and it cranked right up, only to die quickly.  Assuming that the bowls were dry, I simply turned the key on/off/on/off several times to fill the bowls.  The fuel pump would "clack/clack/clack" a few times and then stop.  This brings me to where I am now.

I could get the motorcycle to run for around 10-15 seconds at the most and then it would die.  I assumed it was probably a fuel problem so I began looking at the pump.  The test for the pump says to disconnect the fuel line, energize the key for 5 seconds, turn the key off and multiply the volume you got by 12.  There is a standard volume that it should pump.  I was using a standard shot glass to fill it up and when energized, my pump would only clack clack clack three times and would put out about 1/4" of fuel in the shot glass.  If I was guessing, I'd say somewhere around 8-10cc's of gas. 

Then I had a genius idea.  I'll leave the fuel line in the shot glass, shoot some starting fluid in the intake and crank it up to see how much fuel I get out of the fuel pump when it's running.  I got none.  Absolutely zero.  After a brief look in my schematics, I see that the pump is powered by the main relay and a fuel cutout relay.  I figured I'd test the pump by disconnecting the wires and energizing it directly with 12 volts.  This turned out to be a horrible idea.  I got a spark and now my pump doesn't "clack clack clack" anymore. 

After getting over being mad about that, I started looking around for the fuel cutout relay and I finally found it dangling by it's wires near the fuel filter, just in front of the rear tire.  So all this has led me to write this post for some information.  Here are my questions....

1.)  Doesn't the fuel pump simply run on 12 volts?  Is there some special pulsing technique that it uses instead of 12volts?  I can't figure out why putting 12 volts on it fried it.

2.)  This fuel cutout relay....what is it for?  I can't find much writeup about it.  Is it designed to cut off power to your fuel pump if you lay your bike over?  The reason I ask is because it was dangling by it's wires.  This could have created a false situation where it thought the bike was laid over and thus would not energize the pump. 

I'm assuming that why the engine was running was that it was burning what little fuel there was in the bowl, but because the pump didn't run when the engine was running, it quickly used that up. 

Finally, does anyone have a good hookup for first gen parts.  I haven't called the local dealer yet, but just from looking online, I'm going to spend at least $145 for this new pump. 

Thanks for any insight/helpful info you guys can give me.  I look forward to hearing from you and finally getting this bike on the road.

Mark

[TLRam1]

Welcome to MOOT Mark, someone will be along to give you a better hand than I regarding this.

[mark_gober]

Anyone, anyone, Bueller?  How about I whittle down my questions.  Really what I want to know is the purpose of the fuel cutoff relay.  Is it possible that it being dangling by the wires made it think that the bike was laid over and thus would not energize the fuel pump?

[roboto65]

Well I am not the perfect guy for the first gens but I did stay at a Holiday INN  LOL. No really I had a V30 and had the fuel relay disconnected and the fuel pump ran fine shut it's self off and all so not sure why it is there other than to take the load off a circut or something. But when I sold her to Rod he replaced the ICU and it fixed all the problems I am not much of an electrical well car and bike electrical guy...

But to answer #1 yes it is 12 volts and will run off it there are points in the fuel pump they may be dirty

#2 Not sure like I said maybe to take the load off the circut

As far as parts Ebay I also have heard of people using a car pump but not sure which one!!!

[dgc67]

As far as parts Ebay I also have heard of people using a car pump but not sure which one!!!

I have heard of people using an early model Honda Civic fuel pump, like a 93 or so.
I know that the fuel pump is triggered from one of the spark boxes.  It does not run unless the engine is running.  Looking at the wiring diagram I have it appears the "fuel cut relay" is just a relay for power.  The spark box sends a signal to the relay allowing it to give the 12 volts (I assume 12v, not sure) it needs to run.
Hope this helps you.

[BudMan]

I have NEVER heard any sound form my pump.  That includes trying to see if it was running back when I first got the bike.  Unless there was a major change between '82 and '84 I think that "clack clack clack" indicates the last gasp for your pump.   (I hope not, but "I got a bad feelin' about this un".)

[Brad Badgett]

When I had the '82, turn the key on and there was a faint hum-the fuel pump-was on.

Brad Badgett
OK Region
MOOT #164
1996 VF750C

[dgc67]

I have never heard a sound from my fuel pump either.  If I watch the filter at the moment I turn the key on, or toggle the on/off switch, I see a quick, small, surge of gas.

[roboto65]

Well I would say that most of the time you might not hear anything true but if the carb bowls were empty I heard the clicking for a few strokes till the bowls were full !!

[silveradocowboy]

The noise from the fuel pump is normal, when it quits indicates the fuel line is pressureized but does not mean the line is full of fuel. To test the pump, disconnect the fuel line after the pump, unplug the fuel relay and jump the plug with a wire. Turn the key on and see if it runs longer, if it does then the pump is good. Jumping the relay can also assist in filling up the float bowls, just loosen up the float bowl drain screw.

IIRC it does not matter how the fuel relay is oriented with the bike but to be certain mount it with the plug side down. Again IIRC the only system that uses any type of lean angle sensor would be the turn signals but I don't know if they had that in '82 or not.

Parts.... ebay, servicehonda.com, maybe group members.

[mark_gober]

The noise from the fuel pump is normal, when it quits indicates the fuel line is pressureized but does not mean the line is full of fuel. To test the pump, disconnect the fuel line after the pump, unplug the fuel relay and jump the plug with a wire. Turn the key on and see if it runs longer, if it does then the pump is good. Jumping the relay can also assist in filling up the float bowls, just loosen up the float bowl drain screw.

IIRC it does not matter how the fuel relay is oriented with the bike but to be certain mount it with the plug side down. Again IIRC the only system that uses any type of lean angle sensor would be the turn signals but I don't know if they had that in '82 or not.

Parts.... ebay, servicehonda.com, maybe group members.

Silverado,

Thanks a ton for your help.  On the noise, I was pretty sure it was normal.  I bought another fuel pump and it does the same thing. (rapid clack,clack,clack)  My pump does currently squirt a little fuel when you turn the key.  (much like a car would)  In your post, you mentioned jumping the relay.  My relay has four wires.  I don't have my diagrams (laptop died and took my diagrams with it.  Until I get a new laptop, that info is unretrieavable)  Can you tell me which wires I need to jumper? 

Once again, I really appreciate everyone's help.  I'll keep everyone posted of the progress.

Mark

[MarylandMagnav45]

The noise from the fuel pump is normal, when it quits indicates the fuel line is pressureized but does not mean the line is full of fuel. To test the pump, disconnect the fuel line after the pump, unplug the fuel relay and jump the plug with a wire. Turn the key on and see if it runs longer, if it does then the pump is good. Jumping the relay can also assist in filling up the float bowls, just loosen up the float bowl drain screw.

IIRC it does not matter how the fuel relay is oriented with the bike but to be certain mount it with the plug side down. Again IIRC the only system that uses any type of lean angle sensor would be the turn signals but I don't know if they had that in '82 or not.

Parts.... ebay, servicehonda.com, maybe group members.

Silverado,

Thanks a ton for your help.  On the noise, I was pretty sure it was normal.  I bought another fuel pump and it does the same thing. (rapid clack,clack,clack)  My pump does currently squirt a little fuel when you turn the key.  (much like a car would)  In your post, you mentioned jumping the relay.  My relay has four wires.  I don't have my diagrams (laptop died and took my diagrams with it.  Until I get a new laptop, that info is unretrieavable)  Can you tell me which wires I need to jumper? 

Once again, I really appreciate everyone's help.  I'll keep everyone posted of the progress.

Mark

At least you acquired the bike for free...

I paid 3 grand for my Magna 4 years ago, and it was a lemon.  I spent another 2 grand making it work.

After getting practically everything repaired, I'm almost up to 100%...I need a speedometer

[silveradocowboy]

After looking through this "wonderful" Clymers manual I don't have a definite answer for you, it describes how to check the V65's fuel pump relay(3 wire) but not the V45(4 wire). My best guess would be to jump between the red/white wire and the black wire and then turn the key on.

Another thing I noticed, just a little fyi, was that a wire(blue) runs to one side of a coil. If that coil is going bad it "might" cause you some trouble, one way to be sure is to swap the position of the coils and/or do a continuity check on the blue wire to the fuel cutoff relay. I don't think this is your problem since you are getting power to the fuel pump. If you need me to I can scan the schematic and email it to you.

[TLRam1]

My best guess would be to jump between the red/white wire and the black wire and then turn the key on.

One tidbit Jeff forgot to tell you....if the wires melt, that wasn't the right way. 

[silveradocowboy]

One tidbit Jeff forgot to tell you....if the wires melt, that wasn't the right way. 

Well no wonder I didn't see a mushroom cloud