Troubleshooting Loss of Power

[Red69T]

Hello, all and thanks in advance for any feedback you are willing to provide. Here are the details - 69 911T, stock engine, MSD ignition, and odyssey dry cell batteries, which are probably 7 years old or so. Car gets out about once a week, but it was sitting for two weeks so I had it on a trickle charger over the last weekend. Took it out today in the AM, started fine, rode fine, though at one stop light RPMs dipped to 500 and the red light temp gauge was lightly aglow. Rode fine the rest of work which was another 20 minutes and pulled fine to red line after it warmed up. Was taking it home on the highway at 60mph for about 20 minutes when it lost power and red light came on full bore. Slowed to a stop and powered down about 10 seconds after the initial loss of throttle. No response when turning the ignition (no fuel pump kick on or turnover in engine). Had it towed home and it wouldn't start on a jump box nor on a jump connection to my SUV.......

Any thoughts on where to troubleshoot first? Let me know if you would like any more details.

Thanks again
Tim

[Haasman]

I'd start with battery. Make sure connectors are free of corrosion, ground cable as well. Test voltage across the battery- it should be 12.6 volts or higher. If you have a bad/undercharge battery it could only surface charge, not deep charge. You say you trickled charged, is your charger a basic automotive one, or one that can correctly charge Odyssey dry cell style batteries. It does make a difference.

Once you eventually get the engine running, check again across your battery to see what your alternator output is, especially above 1,500 RPM.

[Red69T]

I should also add that these are the stock T gauges with just the Temp reading up top in the 2nd to left gauge, and two circular lights, one red and one green on the right and left, respectively

[Red69T]

Haasman, thanks for the reply. The driver's side battery checked at 11.6 volts. The passenger side battery check at 12.6 volts. I pulled the fuse that the battery was running to as it looked slightly corroded, and swapped it with another. The car started right up. The wire that runs from the battery to the fuse box looked somewhat corroded/blackened at the end where it meets the fuse. I will go about cleaning these areas and then rechecking voltage when it is running

[Haasman]

So the driver's side battery is too low ... It is my understanding that both batteries should be quite close in voltage. Probably a bad battery but be sure that battery is receiving the same charge as the right side.

Yes, post what the running (charging) voltage is on both batteries.

[M_deJong]

The red light comes on when the alternator output is lacking... But the engine probably cut off because the fuel pump stopped or the ignition lost power.

None of the ignition wiring or the fuel pump is fused. It does sound like corrosion is your problem. Clean all the grounds too.

Ignition switch could be a suspect too.

[Red69T]

Well, the old Odyssey battery was not reading high even with the car started, so I swapped in a new one to test that. Car cranked right away on the new battery, but oddly the fuel pump was not coming on and thus the car would not start. To backtrack to what got the car started in the first place after it died, I pulled the third fuse (which had a wire running to the positive terminal of the battery) and swapped it with the first fuse which was equal voltage. That got the car started. Fast forward to today with car cranking, but no fuel pump running. I went into the fuse box and repositioned the first fuse, which was very loose. After repositioning the first fuse, it started right up. From my vantage point, a lot of the posts in the fuse box are just loose and/or not holding the fuses very tightly, so I am wondering if this is the prime suspect.

To follow up on the voltage question, after getting the car running at operating temps, both batteries read 12.6 volts at idle (700 rpm). At 2000 rpm, they read around 13.5 volts.

I am thinking next steps might be to put in a new fuse box that will keep the fuses held tightly. Right now even a gentle graze on some of them knocks them out of place. This obviously has me a bit concerned about sudden loss of power if i hit a bump etc.

Any other thoughts would be appreciated.

Thanks!
Tim