Occasional no-start

[Rock302]

Hello, new to the forum. My car occasionally has problems starting. The battery is fine, everything works and the charging system works.

I sometimes go and start the car and it won't even crank but all the accesories work fine (A/C, radio, lights etc.). I thought maybe I didn't have the clutch pressed all the way but that wasn't the case.

Does anyone have any ideas about the intermittent no-starts? The car runs fine and this no-start issue happens from time to time.

BTW, it's a 1990 5.0 5-speed.

Thanks

 

[jrichker]

Wait until the car won't start and then follow the checklist.

No Crank checklist for 5.0 Mustangs

Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…

Check battery, terminal connections, ground, starter relay switch (also known as solenoid) and starter in that order. The clamp on with 2 bolts battery terminal ends are a know problem causer.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection: more than .5 volts across a connection indicates a problem.
See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103 for help for help troubleshooting voltage drops across grounds.

1.) Will the car start if it is jumped? Then clean battery terminals and check battery.

2.) Check the battery to engine block ground, and the ground behind the engine to the firewall.

3.) Jump the big terminals on the starter relay next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

4.) Then pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it starts, the relay is good and your problem is in the rest of the circuit.

5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.
Typical start circuit...
Diagram courtesy of Tmoss &Stang&2birds

See http://www.autozone.com/images/cds/gif/large/0900823d80195963.gif for 88-90 year cars .OR see http://www.autozone.com/images/cds/gif/large/0900823d80195964.gif for 91-93 year cars. See http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-95 model cars.

6.) The starter may be hung, loosen up the bolts that hold it on, and give it a good whack with a big hammer. Tighten up the bolts and try again.

7.) If that doesn't work, use a jumper cable from the positive lead on the battery direct to the starter post where the big wire from the relay connects. If it cranks then, it is the power wire from the relay gone bad. This will be hard to do, since there isn't much room to do it.

8.) Pull the starter and take it to Autozone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.

 

[Matts89Notch]

I had this EXACT same problem. It was driving me nuts and then I asked for help here. They posed the info above and I followed the list.

When I would turn it to key on everything would turn on.....then try and start the car and nothing, not even a tiny click. Almost like the battery was disconnected to the starter.

Well I followed the list and when I got to I think step 4 I found out that my starter relay was bad. Well I was not 100% sure but according to the test it was bad. So I went to the parts store and picked a new one up for about $10. I took the old one out and cleaned of the wires with some fine grit to ensure a good contact.

Replaced it and she fired right up, has yet to do that again!

I say change it out and see what happens. I'm sure thats your problem and if it's not well one less thing to go bad and it won;t break the bank..

 

[Rock302]

Wow, that was a ton of info jrichker. I'll start trying some of that stuff on the list and see what happens. Hopefully I won't have to do more than what Matts89Notch did.

Thanks for the info guys!

 

[RYC CUKR]

Also check your battery cables.

I had the same type of issues as Matts89 but it turned out that I had a battery cable flaking out on me. Replaced both of the cables, they were the originals, and no problems.

 

[Rock302]

Yeah, I replaced both cables(+,-) when I got the car because I noticed some corrosion. When I checked out the car yesterday I noticed one of the grounding coming off the negative cable was loose. I tightened it back and and we'll see if it still happens.

Thanks!

 

[DucatiRdr]

I have what I think is a similar problem. I was going to go through jrichker's checklist but my problem doesn't happen consistently enough to duplicate. Occasionally when I turn the key I hear a loud click coming from what seems like behind the speaker on the driver's side. The lights don't dim, and nothing else changes except the no-start. If I turn the key to off then try again it normally starts. Sometimes it takes two cycles of key to off then on, but rarely. Is this the same issue you are having?