I have an 87 with a manual transmission. Trying to start the engine after it reaches operating temp the engine cranks slow. sorta like the timing is too far advanced. I've checked the timing and it is dead on. Pulling the coil wire out of the distrubuter, and then cranking gives me the same result, so I have eliminated the ignition as the source of the problem. I have replaced the ignition switch, battery cables, starter solenoid, and starter. after the truck sits for about 10 minutes, it will start right up. Oddly enough, my friend Rick has an 85 4 x 4 with auto and a 302 and has a similar problem. Any help would be appreciated.

 

Check the starter. I have seen a few post here where the starter gets hot (I think due to the location of the exaust system) and it will cause your problem. Also, do a search as this has come up before.

 

https://www.ford-trucks.com/forums/s...d.php?t=247772 (This guy has same problem. )

Go back over your cable location and connections and make absolutely sure the mating surfaces are SHINY BRITE. Make sure your Pos & Neg cables are insulated from the exhaust.

If your battery has individual cell covers, pull the covers and check your individual cell voltages and water levels. Filling with Distilled water is preferred. Bottled water is 2nd choice. Fully charged battery should show 2.25 V DC (x6 =13.50V) per cell. Anything less is cause for an overnight charge and a recheck. If any of the cells show a low voltage after charging that cell is bad and you need a new battery.

Put a volt meter across the battery terminals when cranking. Cranking voltage shouldn't go below 10.5 VDC. If it goes below 10.5VDC and doesn't come right back up to 13.5VDC or the original test voltage, change the battery.

Larry

 

Thank you for the responses

 

Definitely check the starter. My 84 with 302 (okay, diff engine, but same could apply), that was difficult to start up when engine really warmed up (after a long drive), cranked slow. After a while, starter finally died. When I replaced it, the difficult warm-starting disappeared. One possibility....

 

My 84 had the same problem. The starter was bad. I also had the same problem on my 1978 Caprice back a few years ago.

 

Sounds like the starter is getting too hot while the engine is running. Heat increases electrical resistance, and that reduces current flow. Less current equals less magnetism, and therefore, less torque. If the starter is old and worn, then there might be too much resistance to overcome on a warm starter, but when it's cold it is low enough that it can get enough current flow. I'd do a few voltage drops on the system to be sure, but the starter is propably bad. By the way, to do the voltage drops:

Main Power: Use your multimeter to test for voltage drop between the positive battery terminal (red meter lead) and the "B" terminal on the solenoid (black meter lead). Should be no more than 0.2 Volts when cranking. Otherwise, there is excessive resistance in the cable.

Starter Solenoid: Hook your meter Red lead to the "B" terminal and the black lead to the "M" terminal and crank. Voltage drop should not exceed 0.1V.

Motor Cable: Hook up the red meter lead to the "M" terminal on the solenoid and the black lead to the Positive Pole on the Starter (where the cable bolts to the starter) and crank. Voltage drop should not exceed 0.2V.

Ground: Hook your meter red lead to a secure and clean spot on the engine (accessory brackets, block, head, intake, etc) and the black lead to the negative battery terminal and crank. Voltage drop should not exceed 0.2V.

If these all check out, then it is almost certain your starter is the culprit.

Note that none of these tests require breaking connections. These tests are for testing actual functioning circuits while remaining undisturbed.

 

Found two different problems. guess I was grinding on the starter for so long, the solenoid failed. I did follow all the suggestions above, new cable from the battery to the solenoid, new ground cable clamp. made all the connections shiny brite. I did notice that the down tube coming from the rear exhaust manifold is only about 3/4 inch away from the starter. I couldn't change that part, came from the factory that way. So I installed a starter blanket, an aluminized heat shield from the local speed shop. So far, I'm getting normal starts. Could a plugged up cat be causing excesive heat build up in the down tubes just before the cat? As I am the second owner, I don't know if the cats were ever changed, I did remove the rear cat, and it looked clean to me. Didn't see any welds on before or after either cat.