Weak Crank - won't start

[awesomesteven]

I'm having issues with the boat starting up ('86 supra 351w). When I turn the key the engine cranks like it has a weak battery and won't start. I have a new battery and its reading at 12.54 v. However, when the key is turned the voltage drops to around 9.5v.

Is this a bad starter or possibly a dead cell in the battery? Are there other tests I can perform with multimeter to rule out one or the other?

(I can't take them to get tested until tomorrow so this is more of a learning exercise - as I guess pretty much everything I've done so far)

If it does end up being a bad starter, has anyone bought a starter off db-electrical? Are they good quality?
http://www.dbelectrical.com/p-5917-n...d-engines.aspx

[wspeedin]

I have had the same issue. Turned out to be a bad starter. I know on the 454 the starter is rebuildable but not sure on the 351W.

[wotan2525]

I've always had good luck with the db electrical stuff. Usually cheaper than the rebuild that I can get locally....

[Jetlink]

Steven, are you just checking the voltage with a multimeter or are you using a battery tester? The battery tester places a load on the battery and actually works the battery whereas the multimeter won't really be able to do that.

[awesomesteven]

Steven, are you just checking the voltage with a multimeter or are you using a battery tester? The battery tester places a load on the battery and actually works the battery whereas the multimeter won't really be able to do that.

I did this with a multimeter. I don't have a battery tester.

[rideevol]

To find a voltage drop area take several multimeter measurements. I work from the battery and outward.
Start at battery post to post for baseline. Two persons on these tests is safer. In your instance if post-to-post shows 9.5 volt during crank you either need a battery charge or a replacement battery, 9.5 is a bit low during cranking.
Next step is + post to + battery clamp/cable terminal, yep on top of the battery. A little corrosion can do a lot of harm at this area. You should only see a tiny voltage drop, a few tenths of a volt. Follow the + cable outward in this manner.
The negative battery cable can also contribute a voltage drop so working outward from the battery post there as well. If it is cable or connection related, this is the method.

[awesomesteven]

Thanks for the step by step rideevol. I'll have to give that a shot when I get back.

BTW, was that the correct starter I had on the link or does the sunsport need a ccw starter?

[CornRickey]

If you have electronic conversion ignition a weak battery or bad starter taking to many amps won't allow enough energy to the ignition allowing it to trigger. Petronix needs 9 volts if I remember right. Rebuilt starters and alts are usually better than new, non-oem stuff. They tend to use better components. My local guy says his stuff is better than factory and I believe him.

[awesomesteven]

Rebuilt starters and alts are usually better than new, non-oem stuff. They tend to use better components. My local guy says his stuff is better than factory and I believe him.

That's interesting! I might start looking for a local guy if it turns out my starter is bad.

[rideevol]

My experience with local has been great. Took my 51 amp alternator to a local guy and it was returned, tested, with no needed rebuild, and no charge. If you find a local starter shop they will have all the specialized gear to test starters.
Two starter types were used up to 1986 on Ford engines, Delco_Remy and Ford. Reference Service manual PCM_engine_svcmanual 335 pages on site correctcraftfan.com This manual covers up to April 1986 if my memory is correct.