Help on a First Gen fuel issue

[mark_gober]

Hi everyone,  A little follow up is due.  I still have the same problem.  I previously mentioned a new fuel pump.  I've tried several times to make the motorcycle stay running, but the reality is that it won't.  When I disconnect the fuel hose and squirt some starter fluid in there, I can get it to start, but I get no fuel flow from the line.  The fuel pump will clack a few times when I energize the key, but nowhere near the 5 seconds that is required for the fuel flow test.  If I jumper the main relay, I can get the fuel pump to stay on, but that presented another problem.  When I do this, normally when the bowls filled up, the needle valves should seat an no fuel should continue to flow (despite the fuel pump continuing to pump).  When I jumpered my main relay and got the pump pumping, I looked down in my airbox and began seeing fuel flow up from one of the air tubes connecting the carbs together.  Clearly this is not desired.  I'm thinking on one of my carbs, the needle valve may not be installed correctly.  This requires a removal/partial disassembly to check. 

I REALLY wish that manuals showed the internals of the fuel cutoff relay, but I can't find it anywhere.  If I knew, I could simply jumper around it to test it, but I really don't want to fry anything else in the process. 

I guess on my immediate plate is a carb removal and inspection and possibly another fuel pump cutoff relay.  Anybody have an educated guess on the actual purpose of that relay?  I can't find a write up anywhere about it or it's purpose

I'll keep everyone posted and I'm certainly open to advice.

Mark

[dgc67]

I am thinking spark box is the culprit.  One of them controls the fuel pump relay.

[Charles S Otwell]

http://motors.shop.ebay.com/Motorcycle-Parts-/10063/i.html?_nkw=Magna&_dmd=1&_dmpt=Motorcycles_Parts_Accessories&_pcats=6028%2C6000&_sop=10&_rdc=1

This is one of my favorite parts sites on ebay.

Just curious, if you mentioned it I missed it , but will the bike run if you hook it up straight to gravity flow?

[SkyRide]

The fuel cutoff relay stops the fuel pump from running if the engine is stoped with the ignition on.  Good feature to have when the bike ends up horizontal like mine did last June.

The relay is controlled by one of the CDI ignition modules under the seat.  The other CDI controlls the tachometer.  Since both CDI's are identical, you can swap them and see if the fuel pump now works but the tach is bad.

Rick Frankenberger
83 V45

[silveradocowboy]

Only difference in the CDI units is that the one with the red plug is a rev limiter also.

[mark_gober]

The fuel cutoff relay stops the fuel pump from running if the engine is stoped with the ignition on.  Good feature to have when the bike ends up horizontal like mine did last June.

The relay is controlled by one of the CDI ignition modules under the seat.  The other CDI controlls the tachometer.  Since both CDI's are identical, you can swap them and see if the fuel pump now works but the tach is bad.

Rick Frankenberger
83 V45

I'm sure you've all had moments in life when someone recommends something that seems so simple that you wonder why your ignorant butt never thought of it.  This is one of those times.  I can't tell you how many times I've gone over these stupid drawings and focused more on the fact that the relay doesn't show me the internal workings.  I never thought about switching the CDI modules.  I'll give it a shot this weekend and hope/pray for luck.

On the gravity feed questions, I have not hooked up directly via gravity feed, but I have disconnected the fuel line and started the engine with starter fluid, only to get no fuel flow from the line.  I'll check the CDI modules and hopefully that'll produce some results.  I'll keep everyone posted.  Thanks for everyone's help.

Mark

[Charles S Otwell]

On the gravity feed questions, I have not hooked up directly via gravity feed

The reason I asked, I had a friend who's fuel pumped went out and he ran his straight off the tank, by passed fuel pump. If it won't run on gravity feed it's possible you got carb problems. Just a thought.

[a65bug]

This may sound like a stupid question, but have you checked to see if the fuel lines let fuel pass?  These 25+ year old lines can sometimes collapse and restrict the flow of fuel.  I'd start with the basics.  It sounds like you're getting power to the pump when you turn they key.  Sounds like the pump is good since it runs when you jump it.  Have you cleaned the lower tank to make sure you haven't sucked-up any old crud that collects there?  When I pulled my lower tank and cleaned it, I got tons of rust and crud out.

Neither of my Magnas will do much more than a tiny squirt of fuel when you turn the key.  That's normal.  I had much more luck filling the lines manually before trying to start it than ever letting the pump fill the lines.  That takes forever to do, turning the key on, then off, then on, then off.  I've given up after 5-10 minutes of doing that before. 

Honestly, to me it sounds like a carb problem, but you really need to try running it by hooking a gravity feed to it to make sure it runs off that.  If it runs, then it's definitely a fuel delivery problem, if it doesn't, then it's a carb problem (or another problem).  If you haven't cleaned that lower tank and flushed all the lines out before you tried running fuel through it, then it's likely the carbs are plugged again.  Ask me how I know this...

Report back and let us know what you find out, then we can try and diagnose it from there.

[bronco71]

I'm sure you've all had moments in life when someone recommends something that seems so simple that you wonder why your ignorant butt never thought of it.  This is one of those times.  I can't tell you how many times I've gone over these stupid drawings and focused more on the fact that the relay doesn't show me the internal workings.  I never thought about switching the CDI modules.  I'll give it a shot this weekend and hope/pray for luck.

On the gravity feed questions, I have not hooked up directly via gravity feed, but I have disconnected the fuel line and started the engine with starter fluid, only to get no fuel flow from the line.  I'll check the CDI modules and hopefully that'll produce some results.  I'll keep everyone posted.  Thanks for everyone's help.

Mark

[/quote]


Please update, I have the same problem on an 83 Magna and it is about to drive me crazy!!!