82 Magna will only run for 7 minutes, then promptly die.

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Pork-Chop Overdrive
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82 Magna will only run for 7 minutes, then promptly die.

#1 Unread post by Pork-Chop Overdrive »

Good day, I'm new to the forums, and both a novice rider and amateur DIY mechanic. I'd been reading the accounts you guys have hear, and you seemed the right group of people to ask about my mystery malady. I have a fairly beat up 1982 Honda Magna v45, and recently ran it dry (Emergency situation). After getting a gallon of gas in it, it ran for about three blocks, then began to lose power and die. Repeated attempts to restart it (I thought it might have been flooded or something) showed that It would only run for a couple minutes at a time, and then could not be restarted for at least 10-15 minutes. I though maybe it was the filter, so after replacing some frayed hose and the filter, was surprised to find that it would still only run for a bit, and then die (also required a bit of choke to keep operational). After a lot of poking around, and trying the fairly heavy cleaning additives my mechanic recommended, I've got the exact life span down to 7-8 minutes of run-time, before the bike inexplicably, and without preamble, dies. I can hear and feel the pump going, even after it cuts out.

Any body have any ideas? Because after three days, I'm pretty stumped.

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Re: 82 Magna will only run for 7 minutes, then promptly die.

#2 Unread post by GS_in_CO »

I don't know this bike so this is generic information which may not apply-

If it was running well before running it dry - you probably switched to Reserve. And likely Reserve hadn't been used in a very long time.
So there probably was a volume of water (and rust?) at the bottom of the tank that normally didn't get flowed to the carb.
When you turned on Reserve - that went to the carb and now is in the carb bowl.

Having to use some choke suggests the idle passageways are plugged.

Drain the carb bowls. There typically is a screw on the bottom or bottom side of the carbs to allow draining without removing.

If you didn't activate Reserve then it could be a dose of bad fuel. A recent incident here in Colorado saw a tanker truck driver put Diesel in the gas tanks and gas in the diesel tanks at a gas station. Messed up both fuels.(and many vehicles)
Ron

Current: 1988 BMW R100GS (the 'numberplate' model)

Past: 1987 Yamaha XT350
1983 Honda CB900F
1980 Honda XL185S
1979 Suzuki GS425E

Pork-Chop Overdrive
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Re: 82 Magna will only run for 7 minutes, then promptly die.

#3 Unread post by Pork-Chop Overdrive »

That's great advice, thanks for the heads up. Because of the weird set up where it has a pump specifically for the secondary tank (primary tank is high, reserve is low) I had been concerned about that. Flow from the secondary tank looks clean, but I'm wondering if something didn't get gummed up in the carbs, because it may not actually have run out of gas wholly, if I retroactively calculate gas volume. I'm gonna have to get some help and drain it to check. Thanks for the info, GS_in_CO. :)

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Re: 82 Magna will only run for 7 minutes, then promptly die.

#4 Unread post by Johnj »

Hello and welcome to the forum. Have you tried cleaning the tank vent?
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Re: 82 Magna will only run for 7 minutes, then promptly die.

#5 Unread post by BRUMBEAR »

It might be a fuel pump. I believe it has an electric pump and when they suck air it usually means curtains.
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Pork-Chop Overdrive
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Re: 82 Magna will only run for 7 minutes, then promptly die.

#6 Unread post by Pork-Chop Overdrive »

I will look for the tank vent, that one hadn't occurred to me. Concerning the pump, do you have any tips about diagnosing or correcting the issue? I can probably replace it if I must, but... '82's are almost wholly OEM, and I think Honda used to subcontract for Mitsubishi pumps, so I'd love to avoid that... Also, thanks guys, I've got 560 pounds of dead primary vehicle in my driveway, and you all are really helping me to keep my hopes up and keep pluggin'.

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Re: 82 Magna will only run for 7 minutes, then promptly die.

#7 Unread post by Pork-Chop Overdrive »

Actually, there's an interesting development regarding the pump. I checked the air intake and vacuum hoses, and everything seemed solid, no cracks, obvious leaks or heavy wear, but upon trying to fire up the bike, something new transpired. The pump was rattling away, priming as soon as power was engaged, starting up with mid choke, an firing 3-4 times per second. In short, the pump seemed to suddenly function normally. However, it eventually shut down (winding down instead of suddenly stopping) when I backed off the choke. It could be restarted in rapid succession two more times, but died rather shortly, and was not able to be restarted after the third attempt. I intend to clean out the primary tank and tank filter, and get a friend to help me check out the carbs while I'm at it, but I'm not sure what to think about the pump...

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Re: 82 Magna will only run for 7 minutes, then promptly die.

#8 Unread post by BRUMBEAR »

I am gonna say the pump is bad and the short starts were fuel in the line or bowl. I hope I am wrong here though.
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