I have a 91 f250 with the 300 inline in it starts fine when its cold but can run down the road for 2 miles and back and when I shut if off and try to restart it it won't hardly crank over but when it cools back down it will fire right back up..... now I've been told it could be the timing chain where it's old it's stretches out when it warm and keeps it from starting .... could anyone confirm this before I jump into this little project.... alternater is good, coil is good module on distributor is good... thanks for any info on this

 

You'll find all your answers here:

https://www.ford-trucks.com/forums/2...ngine-hot.html

Quite honestly, it's the first time I hear about the timing chain being responsible for it.

A. Moreno

 

MMmmm. I am pretty sure that a stretched timming chain is not your problem. The 300/6 has no timming chain to stretch. It has a futuristic design that prevents this problem. The 300/6 uses a set of timming gears.

If you feel that a bad ground cable is to blame just use one side of a set of jumper cables and clamp one end to the negative battery and the other to the engine and see if it helps to crank. More than likely you have corrosion under the insulation on either the positive or negative cables. And depending on where this corrosion is in the cables might allow your alternator to work fine but prevent a good portion of the electricity it makes to not find it's way back to the battery for a good recharge. The result will be a weakend battery adding to your poor cranking condition as a warm engine will have higher compression and load a weak starting system. You can rig a needle to the positive on the voltmeter and prob thru the insulation along the hot wire and watch for a drop in voltage. When it drops you will find corrosion. It is a problem in older trucks and compounded if you live where road salt is used. Dont forget to check the smaller hot wire to the starter selemoid. This is a problem with the wires that run to the electric fuel pumps as well. Ensure the connections at the starter are clean. You can also tap the starter with a hammer while a helper try's to crank. Many times a worn starter will spring to life with a tap of a hammer as they die a slow death. Another trick is to hit the down stream connection on the selenoid using a positive jumper cable to see if the starter will crank to eliminate a bad starter selenoid.

 

"Shotgun" is right all the way.
3 out of the 4 times this has happened to me, it's been a ground corroded cable or weak battery (battery may appear to be ok but amps are not enough at start up once they are tired)

good luck!

 

thanks for the help I'll recheck and replace again I might have gotten something faulty ( new wires, new battery, new starter, new coil, new plug wires, new module on side of distributor) ... I'll check about the timing chain or gears deal heard both sides some say yes and some say no lol

 

<i>I'll check about the timing chain or gears deal heard both sides some say yes and some say no lol</i>

No need to check shotgun knows what he speaks of, the 300 6 uses a gear set to drive the cam, no chain. Whomever's telling you different is jerking your "chain".

 

nice

 

ok well I'll recheck the electrical part of it all hopefully I'll get to it today

 

did you have any luck?

 

not yet when I get back off the road next my neighbor is going to help to find the prob cause where everything is pretty much new ..... he thinks in the alternater wiring .... cause the starter is new both battery cables are new and a new battery and such... so will let ya know ....

 

Ignor the alternator, If it starts after you let it set for a while then the alt is working fine.

There are alot of people saying alot of things about this problem here's the answer.

THE STARTER IS HOT, when the stater is hot it needs more power to crank the motor. Hot wires in the starter windings have more resistance(ohms) to elictrical flow(amps). Because of this it demands more of the battery, cables, and connections. The solution is to find and repair the weak link. Many times it's getting a more effecient starter, better cables, battery, or silonoid. If the starter is old and flakey replace it, If the battery is looking old get a new one (I very highly recamend the optima batteries), Better cables are almost always a good investment.(the best ones come from stereo shops, they are a finer strand, electricty flows on the serface of the wires, these have more serface).

To find your weak link use a voltage drop test. to do this attach a voltage tester to the posative battery post and the starter at the cable attachment. Then crank the starter and watch the voltage. It should read zero when not cranking and not go above 2 while cranking(zero is ideal lower is better). A voltage increase during cranking happens because there is resistance between the two points that the tester is connected.

Hopefully this will help, Good luck.