1999 Magna 750 Starting Problem

claytl · December 28, 2008, 01:30:00 AM

I just got a 1999 750 magna. It has set for years and of course the carbs were clogged up. I cleaned the carbs and found a plastic vacuum tube cracked. I replaced the tube and cleaned the carbs. I put it back together and it ran great. When I shut it down, I noticed a gas leak from one of the carbs. I pulled the carbs again and fixed the leak. When I put it back together it ran for three to five minutes and quit. I have not gotten it to start since. All carbs have gas in them, all plugs have good fire, compression is ok, but it will not fire even with spraying starter fluid.

TLRam1 · December 28, 2008, 02:53:07 AM

It must be too early in the morning....I'm blank and this should be easy...

TLRam1 · December 28, 2008, 02:56:19 AM

Is your air cleaner still apart? Can you put gas gas directly into each carb and try to start it? Maybe you are not getting enough starter fluid into each cylinder.

roboto65 · December 28, 2008, 07:04:32 AM

Has to be fuel related I would check to see if the vacuum line got knocked off to the cutoff valve and check your petcock turn it back and forth once or twice. Also make sure to check when you put the tank back on that you have not pinched the vent hose that happens too.

Greg Cothern · December 28, 2008, 09:21:18 AM

Where ya located? We are holding a wrench session in the DFW area Jan 10 (saturday).

I feel pretty confident its the carbs.

claytl · December 28, 2008, 04:00:14 PM

Thanks for the responses. I live in Colleyville area, and would love to attend the wrench sessions. I have tried pouring gas right in the carb mount and no fire. I have the carbs off again and have found no problem. All four plugs are getting fire. There is good compression, I am pouring gas right in the cylinder and still no fire.

roboto65 · December 28, 2008, 04:35:25 PM

I hate to say this but have you checked the run switch. Try moving it back and forth a couple times. You would not be the first to hit and go thru this LOL

claytl · December 28, 2008, 05:01:48 PM

It does not turn over with the run switch off. It turns over fine it just will not fire.

Curtis_Valk · December 28, 2008, 05:28:45 PM

Quote from: claytl on December 28, 2008, 01:30:00 AM
All carbs have gas in them, all plugs have good fire, compression is ok, but it will not fire even with spraying starter fluid.

I hate to say this since I'm not there and you are, but it appears as if you're missing something. If all of what you said above is true, it will start. One of those components (ignition, fuel, compression) is either missing or not there in the proper perportion at the proper time. Since starting fluid won't fire either, I'm leaning toward electrical. Put a good hard charge on the battery and try again. Sometimes there is enough juice to turn the starter smartly and still not enough left over for a good hot spark. If that fails, recheck all the other stuff. I can't help but think we're missing something simple if like you said, it was running before.

Curtis

Greg Cothern · December 28, 2008, 06:21:39 PM

Your within range to make it down to Seagoville for the wrench session then... If interested shoot me a PM and I will send ya directions on how to get here.

We will have plenty of folks here with a large knowledge base for which to draw from to get it running for ya.

claytl · December 30, 2008, 11:00:28 PM

I pulled the carbs again. I found a little bit of plastic in the carb from the vent tube. I cleaned the carbs again. They really looked good. I pulled the fuel shut off valve and found it was not releasing gas after vacuum was applied. I took it apart and it looked great. Put it together and it started working, guess it was stuck. Put all back together and it is running now?????

The only problem is there is some popping and hesitation at times, I think the carbs need to be syncronized now.

I may wait for the wrench session before trying this.

TLRam1 · December 30, 2008, 11:12:59 PM

Quote from: claytl on December 30, 2008, 11:00:28 PM
the fuel shut off valve and found it was not releasing gas after vacuum was applied.

I had a problem with mine recently, there's a post on here, I replaced mine. Good to hear you have it running. Still doesn't make sense when you put fuel in the cylinders it would not run...

claytl · December 30, 2008, 11:28:31 PM

Maybe flooded it when I poured gas in the carbs?

Don't know, but it went several days not trying to start.

Could be I did not have carbs fully seated on the manifold.

Should have tried to run but it was completely dead. Cranked but did not try to fire.

Thanks All

Larry

roboto65 · December 31, 2008, 08:06:52 AM

Glad you got it running yeah we can look at it at the wrench session no problem!!!!