LUVTruck.com

Hello all,

I am the proud new owner of a badass 1980 Mikado. The truck was very well maintained and has no problems but at highway speeds when I take my foot off of the gas a little to maintain speeds downhills and in traffic the truck backfires and sputters. Otherwise the truck runs fantastic. I have my ideas what maybe causing this but before I say I would love any advice from the LUV gurus. Thanks

Check the timing.

Timing is a good one that I didn't even think of right off. When you are accelerating the vac advance would be active, but just maintaining road speed the timing would be sitting further towards retard. If it is off towards retard anyway, that could certainly do it. Check or replace the points while you are at it. They don't last forever, and they do affect the timing as well.

I was thinking to check around for vacuum leaks and that perhaps the smog pump might be screwed up. The smog pump malfunctioning can cause backfiring, but usually its between shifts. Vac leaks can cause all sorts of problems, and can usually be tracked down to a cracked hose someplace. Sometimes you will find a leak around the carb base or the intake manifold though. For those, spray carb cleaner around with the truck running. If you find a spot at the base of the carb or the intake to head junctions where the motor changes speed, you found a leak.

A general tune up might be in order, especially since the truck is new to you. Cap, rotor, points, condenser, plugs, and perhaps plug wires. Wires double the cost, but if the old ones look beat up they'd be worth it. I like bosch platinum plugs, but NGK or Denso would do fine. Just stay away from those +4 and splitfire deals, heard WAY more people talk about them causing problems than I've heard good. Come to think of it, I've never heard good about them. I've yet to try any of the new Iridium kind, but I expect they'd be ok if you got money to blow.

all badass luv owners are required to post pictures.
welcome to the boards.
800xl is a plethora of information.

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03Cobra

that could very easily be a vac leak around the intake /carb surface.....

get a can of starting fluid and spray a few squirts around the base of the carb....if the idle speeds up, you've figured it out.

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Thank you all for your input, it is very much appreciated. My ideas about what could be causing my problem were limited to the cat possibly getting clogged, but I didn't hear anyone mention that so I appreciate your collective agreement on the timing and points. Indeed 800xl is a plethora of info. and I will post pics of my LUV as soon as I figure out how to do something on a computer besides type.

I've never experienced a clogged cat, but the descriptions I've heard is that it acts sort of like a RPM limiter. The motor just won't be able to rev past a certain point. They also supposedly get extremely hot when clogged, which should cause the HEAT warning light on the dash to come on.

Was wondering how that buzzer and warning light on the dash were triggered, not thats its occuring for me but none the less- good to know

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