Crank but no start

Someone will chime in with the big a$$ list for a crank no start situation.

Well there is only 3 things needed to run, fuel, spark, and compression. If you have those 3 things then it should start. You just had it running so obviously compression is good. I would test for spark as you crank it over and see if you are gettin a spark at the spark plug. Also make sure fuel is gettin to the carb as well.

I hope you got the car for a steal, because if you didn't you got robbed.

Sorry no big long hairy "Cranks OK but no start" checklist for carb cars. The wiring and workmanship of most EFI to carb conversions is so varied and often of such poor quality as to render the car unfit to drive.

Here's what I do have...

Cranks Ok but no start for carb’d cars.

Updated 17-Jun-2008 to include firing order diagram

Carb'd cars require an old time approach to troubleshooting.

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park. Remove coil wire from distributor & and hold 3/8” away from engine block. Jumper the screw with the red wire to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.
No spark, possible failed items in order of their probability:
A.) Coil
B.) Distributor PIP sensor or points & condenser
C.) Bad ignition Box or Duraspark unit
D.) No power to ignition system wiring or ignition box (if used)
E.) Bad ignition switch
F.) Bad fuse links.


2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

3.) Spark at spark plug, but no start.
4.) Pull the air cleaner and sniff for fuel vapor - look for signs of flooding. If so, then press the accelerator to the floor and crank for a while – if the engine is flooded, this will clear it out. You may want to have a jumper battery & cables handy.
5.) Electric fuel pump if you have one, is it getting power? Use a volt meter or test light to probe the wires at the pump.

Don't see any evidence of flooding? Then pump the throttle - does the accelerator pump squirt fuel? If so then you should have enough fuel to start the engine. If not look for fuel delivery problems. Check the fuel pump, and fuel filter. Remember that most carbs have a fuel inlet filter that protects the float needle valve from trash.

Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air cleaner, open the throttle, and spray the ether in it. Reinstall the air cleaner and try to start the car. Do not try to start the car without reinstalling the air cleaner. If it backfires, the chance for a serious fire is increased. If the engine starts now, you have a fuel delivery problem.

A warning about backfires: Holley carbs may have damaged power valves as the result of a backfire. The engine may be hard to start. Other symptoms are that it may seem to load up on fuel and be slow to accelerate until it clears out a bit.

6.) Fuel & ignition OK:
The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8





No crank checlist follows... keep in mind this is for cars with unmolested starter circuit wiring.

No Crank checklist for 5.0 Mustangs

Revised 05-Oct-2010 to update Fluke references.

No crank. slow crank and stuck starter solenoid problems have the same root causes – low battery voltage and poor connections. For that reason, they are grouped together.
Use the same initial group of tests to find the root cause of both no crank and stuck solenoid problems.

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…

1.) Will the car start if it is jumped? Then clean battery terminals and check battery for low charge and dead cells. A good battery will measure 12-13 volts at full charge with the ignition switch in the Run position but without the engine running.
A voltmeter placed across the battery terminals should show a minimum of 9.5-10 volts when the ignition switch is turned to the Start position and the starter engages or tries to engage. Less than this will result in a clicking solenoid, or slow cranking (if it cranks at all) or a starter solenoid that sticks and welds the contacts together.

Most auto parts stores will check your battery for free. It does not have to be installed in the car to have it checked; you can carry it with you to the auto parts store.

The battery posts and inside of the battery post terminals should be scraped clean with a knife or battery post cleaner tool. This little trick will fix a surprising number of no start problems.

The clamp on with 2 bolts battery terminal ends are a know problem causer. Any place you see green on a copper wire is corrosion. Corrosion gets in the clamped joint and works its way up the wire under the insulation. Corroded connections do not conduct electricity well. Avoid them like the plague...

If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstick and work normally for a while.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection while trying to start the car: more than .5 volts across a connection indicates a problem.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .



2.) Check the battery to engine block ground down near the oil filter, and the ground behind the engine to the firewall. All grounds should be clean and shiny. Use some sandpaper to clean them up.

3.) Jump the big terminals on the starter solenoid 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.

The rest of the tech note only concerns no crank problems. If your problem was a stuck solenoid, go back to step 1.

4.) Then pull the small push on connector (small red/blue wire) off the starter solenoid (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it cranks, 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



6.) 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.


Starter solenoid wiring for 86-91 Mustang



Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.


Electrical checks for the switches and starter solenoid

Remove the small red/blue wire from the starter solenoid. Use a screwdriver to bridge the connection from the battery positive connection on the starter solenoid to the small screw where the red/blue wire was connected. The starter should crank the engine. If it does not, the starter solenoid is defective.

If the starter does crank the engine, the problem is in the clutch safety circuit (5 speed) or Neutral Sense Switch (auto trans) or ignition switch.


Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds


You will need a voltmeter or test lamp for the rest of the checks. Connect one lead of the voltmeter or test lamp to ground. The other lead will connect to the item under test.
Look for 12 volts on the white/pink wire when the ignition switch is turned to the Start position. Check the ignition switch first.
No 12 volts, replace the ignition switch.

The next step will require you to push the clutch pedal to the floor (5 speed) or put the transmission in neutral (auto trans) while the ignition switch is turned to the Start position.
Good 12 volts, check the clutch safety switch (5 speed) or Neutral Sense Switch (auto trans) for good 12 volts on both sides of the switches. No 12 volts on both sides of the switch and the switches are defective or out of adjustment. Check the wiring for bad connections while you are at it.




Fuse links are next... also subject to the molestation of the previous owner...



Fuse links come with a current rating just like fuses. A clue as to what current they are designed for is to look at the size wire they protect.

Choose the fuse according to the wire size.

Wire size current table:
http://www.stangnet.com/mustang-for...-wire-gauge-current-capacity-lenght-chart.gif


18 gauge wire = 5-8 amps
16 gauge wire = 10-12 amps
14 gauge wire = 15-17 amps
12 gauge wire = 20-25 amps
10 gauge wire = 30-40 amps
8 gauge wire = 50-60 amps.

Keep in mind that the wire size in the chart is for the circuit itself, not the size of the fuse link. The packages of fuse link repair material you can get at the auto parts stores also will have a current rating on them.

See Ford Fuel Injection » How To Solder Like a Pro for some excellent tips of soldering wires for best electrical performance.

Aircraft type circuit breakers are designed for low voltage DC applications and would be an excellent choice to replace fuse links. They come as a push/pull to reset button, and range from 1.5 amps to 60 amps and higher.

See Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co. or http://www.wicksaircraft.com/catalogDetails.php or Home for circuit breakers and other items.

There is a store local to Orlando that does electronic surplus and has all kinds of circuit breakers. See index That's where I get most of my wiring supplies. There may be a similar type store in your area

For free automotive electrical training, see Automotive Training and Resource Site . I have personally reviewed the material and it is very good.

still a long friggen list lol

you can hold the coil wire (hold the end that connects to the distributor) with INSULATED pliers...hold it about 1/4-1/2 an inch from the block while someone cranks and see if the spark jumps the gap to complete the circuit (the block being ground).

If it does, you have spark. to the distributor. You could still possibly have a bad distributor cap/rotor, plug wires, or spark plugs, but I'd say the wires and plugs probably aren't it as it would still probably run (with a miss, obviously) if one wire/plug were bad.

The red/green wire used to power the stock coil has the required fused power. Try it and see if it works: if it does not, then the fuse link in the wiring may have blown open.

Try using a 14 gage wire and a 15 amp fuse for your rewire if the red/green wire does not work.

Diagram courtesy of Tmoss & Stang&2birds
Ignition switch wiring


Fuel, alternator, A/C and ignition wiring


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

VAFOX said:

Going though my old threads and thought I would update this one. Sent the msd box back to msd and turns out the wiring was loose and something internally was shorted out. It was the less than a year old msd box from the start...

Click to expand...

Now you know why I say that MSD means "May Suddenly Die".