MSD 6AL need help

[Hydro-Thunder]

Well I posted this at gearheads and I'm going to try my luck here also. Here's the problem I put in a MSD 6AL today and I cant get it to rev above 3000-3500 has anyone had a problem like this before? it has the adjustable RPM selector and it did the same thing at all of the settings, I also tryed to disconect the Rev limiter and the same thing, I could not get above 3000 or so. Any thoughts?
Jesse

[Jetboatguru]

Check all of your grounds. If they look good, check them again. Call MSD @915 857-5200 ask for tech

[project-speed]

I think you got a bad msd unit. just my 2 cts.

[hoolign]

did you try pushing the pedal ALL the way to the floor? j/k

[jim lee]

Jesse,
#1 like Jetboatguru says check your grounds! Is the battery the same as the engine block the same as the MSD box? Are the ground straps/wires big enough? And not corroded?
#2 Both of the big 'ol red & black wires MUST have a good/solid connections to the battery. I don't hink they have to be connected directly to it. (I like a power cut off switch between the battery and everything else.) But none of this, "Well there's power here, this should work.." Stuff. You need conenctins that can reliably handle quite a bit of current. The MSD works by converting a Ton of low voltage current to high voltage spikes. If its not getting a good current flow, it can't fill its capaciter. So your going to loose sparks.
When you ran the engine did it sit solid on one RPM? Like its being limied there? Or does it vary around some?
One thing you can do, for kicks and grins, is to take an "accurate" Volt meter, pull out whatever you have in the rev-limiter plugin, turn on the power and measure the voltage on both pins to ground. I one pin should be ground, and the other should be around 7 volts. That is, a correclty running 6AL is about 7 volts. If it is stuck at 3,000 RPM that would put it at.. {rustling of papers..} about 0.8 volts.
If you got this far, what do you read on the pins?
Hope this helps..
-jim lee

[Bense468]

Have you double checked the tach?

[Hydro-Thunder]

jim lee The engine is Defiantly being limited, I have double checked all connections and I did remove the rev controler but I did not check the voltage there I will try this later today. Thanks for the help.
Jesse

[HeavyHitter]

What ignition wires are you running? You're probably getting too much EMI noise at the box. 3000-3500 is where it transitions from multiple spark to single pulse. I've seen/heard this before. Sounds like dropping cylinders. Switch to carbon core wires if that's the case.

[DEL51]

I had a similar problem with an msd. It was a 6al with a pro-billet msd distributor. Check the 2 little wires that connect the distributor output to the msd. These may be reversed.It worked for me.Good luck and let us know what happens.

[Hydro-Thunder]

I talked to the MSD techs two times and I think we have narrowed it down to the plug wires and/or the plug gap. I ordered a new MSD coil and wires so I am keeping my fingers crossed until thursday (thats when I will get parts). I will let everyone know what it turns out to be.
Jesse