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Join Date: Apr 2007
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Odd. Added msd now fuel pumps buzz?

Really weird. My permatune failed, so I added the msd. Pretty much immediately heard a loud buzzing from the engine compartment. Posted threads about my Cdi buzzing, as it was loud enough to hear in the cabin with the windows up.

Went to harbor freight, and got the stethoscope they sell. Listened to the Cdi, and it was quiet. Listened to the fuel pump, and it was buzzing. Front, is louder also.

Really odd, as I have never noticed the sound before. The front fuel pump is actually new, as of this year.

Car runs fine, isn't lean. Afr is fine. If I pull either relay, car still idles though the running fuel pump gets even louder.

Is there any plausible way that adding an msd could have effected the pumps?

I plan to check the amp draw in the morning. May need to check the fuel filter, though that's less than 500 miles old.

Anything else to check? Fuses?

I know it could be a lot of things, but I swear adding the msd caused it. Before that, I had to touch the fuel pump to make sure it was running. I never heard it buzz from outside the car.

Any help appreciated.
Bo

Old 11-01-2014, 06:18 PM
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I would try running a wire from the battery directly to the fuel pumps and see if they run quieter while the motor is running.
If they do you know the MSD is taking power away from them the way it's wired now and you need to rewire them with their own fuses directly from the battery instead of the from the fuse box/relay panel 12 volt bus. You can do that and still use the 2 red relays to switch them on and off.
Old 11-02-2014, 05:35 AM
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I connected the red wire to the starter, per instructions. The ground was originally to the permatune ground in the engine bay. Thought this was causing issues, so grounded it to the motor. No difference.

Could the fact that I powered it off the starter lead cause this? I would think that's a direct draw from the battery?

Could it be a grounding issue? I posted in another thread that my Afr is acting up too. But it worked fine for a month...

Thanks for the help.
Old 11-02-2014, 05:55 AM
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Are you running solid core spark plug wires? If so, switch to resistor core.
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Old 11-02-2014, 06:06 AM
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Plugs wires say magnacore on them. I assume that's not a solid core?

Would a solid core make the pumps run different? Interesting thought.



Bo
Old 11-02-2014, 06:32 AM
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You've got your MSD wired correctly from the connection at the starter motor. Make sure those connections are clean and torqued tight, and that your grounds are as well. From the sound of things, your pumps are drawing too many amps and may not be running up to speed. Thus, lower fuel pressure and consequently lower AFR's.

Either that, or you lambda system has an issue....as evidenced when you unplugged the O2 sensor and all was well. Have you tried replacing the O2 sensor itself? You've got possibly multiple issues going on here (no surprise to you....huh?) with overheating wires, car not starting, car running progressively rich, etc. Try taking the lambda system out of the equation all together and see what happens. Unplug the sensor and tune your AFR's around it. Drive her, see if the symptoms persist.
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Old 11-02-2014, 06:55 AM
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Thanks mark. O2 sensor is new, came with the Plx afr meter. Same problem as before this was installed.

All of the issues are getting fixed one at a time. I suspect these are all connected somehow.

Car runs great with the o2 sensor disconnected.

What drives me nuts is that the issues are intermittent.

I do wonder if the fact that it's now cold has some bearing on this...

Can a bad alternator cause this? Plan to check voltages today. Voltage regulator is new, replaced 2 years ago... Wacky voltages could explain a lot.

Bo

As always, thanks for the help.
Old 11-02-2014, 07:22 AM
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non-whiner
 
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Magnacore makes both. Turn the ignition on and jumper the fuel pump relay. Does the pump buzz?

I assume you ran the heavy red to the battery and the thin red to the ignition only wire that originally went to your old ignition box? Also, how are you triggering the msd?
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Old 11-02-2014, 07:32 AM
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Can you tell by looking at the wire if it's solid core?

Bo
Old 11-03-2014, 12:10 PM
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Chk your fuel pump fuses- test them. Voltage could be off. My pumps were only buzzing when this happened and chk your coil- might not go with your msd. Go with an msd epoxy.
Let me add this also---I INMOP- these MSD6AL-ARE JUNK---For it to fail in less than 6yrs-(purchased new 2008) made USA-. Less than 2000 miles a year on the car... And a lousy 30-day warranty. Spoke with tech- regarding why so many parts had to be replace,,,Not much of an answer. The tech expressed the Box-needs air flow (Hugh --even though I told him I had in the cockpit.. NOT- much confidence in their product. A lot of racing blogs express the same opinions with little to no alternative for a 2nd choice.

Last edited by wjfk32; 11-04-2014 at 07:10 AM..
Old 11-03-2014, 01:14 PM
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I have the msd epoxy coil...

A drop in voltage may make sense, as I never heard the pumps prior to installing the msd.

Could something have been hooked up wrong, and the car still runs?

The msd draws power straight from the battery cable, and it's grounded to the motor. I had it grounded to where the permatune was grounded, but changed to see if it makes a difference. It didn't.

I will check the voltage at the pumps this weekend. If normal, I will check the flow and pressures.

Bo
Old 11-03-2014, 02:14 PM
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Test your msd box- maybe defective. I had my msd6al fail. Sent it them Texas. They tested it and gave me their test results and repair sheet. 43.05 dollars 4 repair.
Old 11-03-2014, 07:17 PM
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the MSD shoud not cause any problems. if anything it has made a problem you already have known. clean the battery posts, both neg and pos. clean the ground strap to the body. clean the strap from body to tranny. clean the connections at the starter.

check fp current
remove the FP fuse. set your meter to measure current. connect the meter in place of the fuse. leads dont matter, it will just read negor pos. pull one of the FP relays. remove the connector on the top rear of the AFM and turn the key on. read current and turn key off. swap relays and repeat. dont leave the pump on any longer than you have to.
current should be around 7 amps for each pump.

measure voltage at pumps.

another thing you can do is to remove the wires at the fuse block for the FP. clean the wire ends and clean the screw. clean the contacts for the fuse. you can also split the FPs to 2 fuses. i did it so that mine looks orginal. if you want the way i did it let me know.

if all is good i would not worry. the Fp in my 77s made lots of noise the entire 10yrs i owned it.

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Old 11-04-2014, 04:01 AM
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