battery to starter cable - 1.4V drop ?
Thread Starter
Instructor
Joined: Nov 2004
Posts: 217
Likes: 1
battery to starter cable - 1.4V drop ?
I just replaced a fuel pump in a 1985 911 (198K miles)
I used the car's jack to raise it as high as the jack would go to put 4x4" block under front wheel.
After completing this, the car would not start. I had a old battery in there with a questionable history so I replaced it.
Still not starting, barely turns over. So I measured the voltage drop battery ground to engine to be 0.5V when trying to crank. That seems ok.
Then I measured 1.4V drop + battery to solenoid. This seems to high.
Is it possible I damaged the + cable when jacking the car ?
Or did the engine suddenly seize ? Never had hard starting problems before except when starter was replaced a year ago.
I used the car's jack to raise it as high as the jack would go to put 4x4" block under front wheel.
After completing this, the car would not start. I had a old battery in there with a questionable history so I replaced it.
Still not starting, barely turns over. So I measured the voltage drop battery ground to engine to be 0.5V when trying to crank. That seems ok.
Then I measured 1.4V drop + battery to solenoid. This seems to high.
Is it possible I damaged the + cable when jacking the car ?
Or did the engine suddenly seize ? Never had hard starting problems before except when starter was replaced a year ago.
Pro
Joined: Jun 2001
Posts: 556
Likes: 1
From: Peoples Republic of Long Beach, N.Y.
when I have an issue with the 911 starting the first thing I do is a direct jump to the solenoid.
then there's an issue with using a good solenoid jump set like Snap-On vs cheap ones.
all in all after realizing this car has its starting nuances I installed an engine compartment high amp momentary Cole-Hersee marine switch, 10ga wire, etc for the solenoid jump.
voltage drop may be an issue and more could be said about it, but......
then there's an issue with using a good solenoid jump set like Snap-On vs cheap ones.
all in all after realizing this car has its starting nuances I installed an engine compartment high amp momentary Cole-Hersee marine switch, 10ga wire, etc for the solenoid jump.
voltage drop may be an issue and more could be said about it, but......
Burning Brakes
Joined: Nov 2007
Posts: 1,188
Likes: 11
From: Thousand Oaks. CA
I would blame this on the cable or weak battery. If you have a cable similar gauge/lenght attach it to the battery and see what the drop is. If its the same then you do not have cable problem. 1.4v is a little too much. If the drop is the same...maybe its the battery.
abe
abe
Last edited by abe; Mar 5, 2009 at 12:51 PM.
