M715 Stumble

[Hawaiian Style]

Original military 24v ignition. Runs fine at idle and low rpm and will rev up for a while but after about a minute of driving at normal rpms it begins to lose power and backfire. Gotta check the timing but wouldn't that be consistant from engine start to engine shut down? This thing is a lot older than what I'm used to working on and I'm in way over my head- That's what makes this fun though! :laugh3:

 

[over2land]

To me it sounds like the carb is in need of a good cleaning and tune up.

To check the initial timing, yes it should be the same, but the vacuum advance will change timing over the operating range.

Did you check www.m715zone.com?

Put this up in the stock tech. Or, search for it first. Odds are good someone there already had this problem.

 

[Hawaiian Style]

Yeah, I ran some carb cleaner through it and it's pretty filthy. I really need to take it apart a give it a real cleaning but I didn't have time today. Just seems suspicious that it will rev up for a while then lose power and backfire. My gut (and my nose) says it's drowning in fuel.

I searched the M715 zone but didn't post. I've always found this site to be great for help and support.

 

[over2land]

Well, if a float was sticking open, then the bowl could overflow into the intake...

Dunno about the revving up and then losing power.

And, for 715 related things, the Zone is the best place. Bunch of charecters, but they've done it before.

 

[8Mud]

The valve seals leak, they probably leaked when new, the probably leak now and probably will always leak, the plugs foul. If you have the stock motor.
Could be something else, but fouled plugs are pretty darned common. I used to carry around a couple of freshly cleaned sets, got pretty good at changing them out. A good high speed run, usually made things better, but traffic and idleing, gummed them up again quick.
Changing out the seals didn´t really help much and/or for long.

 

[Lawn Cher']

Drop a diesel in it!