Honda VF1100 Magna Fuel Problem

I have an 83 magna that I’ve cleaned the carbs, adjusted the valves,tested the fuel pump and relay.It will start and idle perfect,but when I ride it it will go a little ways and run out of fuel. I will let it sit for a few minutes and sometimes the fuel pump will prime right away,sometimes it wont.
once it primes, it will go until the bowls become empty again. I feel like I’m missing something,that the answer is right in front of me, but I cant seem to get it. Any ideas or suggestions would be appreciated

Honestly that sounds like a faulty fuel pump to me. Those symptoms are VERY common of a fuel pump that is on it’s way out. I would take a volt meter and put it on the fuel pump, turn on the ignition, watch the voltage, start the bike, watch the voltage, ride the bike, watch the voltage – as long as power is getting to the pump, then the pump is the problem.

However – one thought – if the fuel screens in the tank are clogged up it will limit fuel flow and can cause similar problems. Check fuel flow out of the tank and make sure it’s stable

fuel flow is pretty good out of the tank- sitting still.Do you think it may be possible that the fuel line is resticted or slightly clogged? The pump must have some kind of pressure switch or way of being able to tell when it needs to come on.The bike sat for a while before I got it.I had replaced the original pump with a used one. I am going to try the voltage tests also Thanks for the advice


Looks like the fuel pump is a self contained unit in the Honda VF bikes from the early eighties.

I think it’s unlikely that the fuel lines are clogged unless you have an inline fuel filter that is dirty. However, it’s real easy to check – just pop the lines off and blow through them.

My bet is still on a faulty fuel pump.  Why did you replace the original fuel pump? Was it exhibiting the same symptoms?

Another possibility is a clogged tank vent. Try riding with the tank cap open and see if it has any effect.

Evan,I replaced the fuel pump because it would “burp” fuel when idling,I have a glass filter right before the pump. I was told that it was supposed to do that. At that time,I hadnt adjusted the valves yet and the bike would cut off whenever I let go of the throttle. When I first opened the fuel filter the fuel coming out of it was very dirty(cloudy),but now it looks pretty clear.I am going to drain the tanks and try to clean them out. I thought of the tank vent and did ride it with the cap open, but it had no effect.I’m going toput the original back on to see if it has any effect. Thanks for all the advice, I’ll let you know how it turns out.

Hi Evan, I took off the pump and switched it back with the original, and left everything hanging and rode the bike with no problems. When I went to put the pump back in I saw that the fuel line was kinking. It had braided lines that had worn and was allowing it to bend. I replaced the lines and it runs great with no problems. Thanks for the advice. Dave

Glad you were able to solve the problem. I love when it turns out to be a simple solution.

On most of my bikes I replace the stock fuel lines with clear fuel. I usually keep a few feet handy, it’s only a couple bucks to have a length of hose around. Whenever I’m working on carbs I will ALWAYS replace the fuel lines with clear so I can monitor the fuel flow and make sure the fuel is clean.


Evan Fell

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