DBear

I've been having an intermittent starting problem for some time. Most of the time it starts fine, but occasionally all the dash lights will light up, but the starter won't even spin. If I keep trying, I can almost always get it to start (sometimes takes 10-15 tries). And when it does start, it starts right up.

I did a voltage drop test on the main starter circuit, and everything checked out OK. So it must be in the circuit that feeds the solenoid. I exposed the ignition switch and started carrying around a VOM. It finally refused to start again, so I measured the voltage at the ignition switch. I've got 12V at the main power line, but I only got 11.0V at the two other contact points that are fed in the Start position. (I forget which ones they are.)

Does this make any sense? I could understand if the switch wasn't moving far enough over to hit the contact point, but a voltage drop of 1.0 across a simple switch in a relatively low amp circuit? How does that happen?? (This ignition switch is only a few months old, but I guess that's no guarantee it's good...)

f550maranello2

iTrader: (2)

do this.. remove the switch and manually turn it with a screw driver or even the key itself..

if the car turns over every time then its the switch.. what happens is that the internal contacts wear away.. now when u move it with a srew driver or the key ur moving the contact further then u would with the key in the cylinder...

1v drop should be ok.. try what i said and report back with the results.. its probably the switch.. very common problem with these cars

DBear

I've thought of trying that. The problem is, the problem happens pretty rarely, so I can't be sure I'm fixing it. I thought I might put a little electrical tape along on side of the key slot on the switch, so the key would push it a little farther and hopefully make a better contact. Given the number of people who have had to replace multiple switches, it seems like the problem is probably not the switch itself, but the fit between the ignition cylinder and the switch, so just replacing the switch may not solve the problem for long.

First, though, I think I'll pull the fuel pump fuse and see how much of a voltage drop I get when the starter cranks. That should tell me whether the voltage drop is OK or not.

Double E

So ...you also feel pretty good that your starter is not about to crap the bed?

DBear

Yeah, I replaced it a few months back. And for a while I had patched in a wire just before the solenoid, which I touched to the battery. That worked fine, so I think the starter is OK.