New to the forum so to speak. My Ford doesn't give me problems so I am hardly ever on here. So here is the deal. 1989 F150 with 5.8. If i run the heater on high beforre I shut it off it will not start. Turn the heater on low she will start. When it doesn't start it's like the battery is dead turns over slowly. Sometimes when she does start she turns over slowly for a few seconds then picks up and starts. I am thinking maybe the wires to the starter. I recently replaced both battery and alternater. Am I thinking right with the wires to the starter or should I look for some other culprit? It does have a push button starter as I couldn't find a nuetral safety switch that fit. If I need to add more info let me know.

Thanks in advance for the help,
Greg

 

Can't figure the connection between the heater blower switch and the starting problems.

With it turning over slow, the neutral switch should be off the list of possibilities. Suggest some typical culprits are cables (including the ground!), connections (make sure everything is clean), solenoid (burnt contacts), or starter motor. I try to start with the stuff that's cheap to replace and easy to get to.

 

WDE gave you a very good basis to start out with...I have another question.......if you shut it off with the heater on high and restart with all the ac/heat controls in the off position, does it still act like this?

 

i had a very similar problem to this. I changed my starter selenoid on the passenger firewall and had a bad positive connection and it fixed it. My truck is the 300 i6 but may be the same fix.

 

Ok to answer all questions. Yes it does it when the heater runs no matter what. I have changed the selonoid. I am really lost here. When I run the heater the volt guage drops down to 11 or so. Doesn't this truck have an internal regulator? If not that is the problem.

Thanks again,
Greg

 

Ok, then check the volts being held in the battery with the key off......It dropping to 11 is not as bad as you'd think....

 

I would do what he was suggesting in the second post, check the ground, it just runs down off the battery to the block under the alternator behind the air pump. Sounds like high resistance or a bad battery. Do what flareside suggested and check the volts across the battery with the key off. If your at 12 volts you should be ok, also check it with the motor running, if your not gettin 13-14 volts you alt is bad. Just because you replaced both the battery and alt doesnt mean they are good. We have replaced alts on cars here on the farm and had them go bad the next day. Same with batteries. Its possible you have a bad cell in the battery.

 

Bad cells in batteries are an auto parts store's biggest issue with batteries. Remember, just cause you bought a "new" remanufactured part from the parts store, doesn't mean that the little Taiwanese boy rebuilding it didn't screw it up in any way shape or form.

 

Ok I finally got to take readings with my multimeter. With the truck turned off it is showing 12.1v at the battery. With the truck running it shows 14.3v, that is with no extra load and with everything turned on still 14.3. With the battery showing 12.1v the truck will not turn over or should I say it turns over too slow to start. The cables from the battery are good, I replaced the negative cable 2 years ago. I am leaning towards the cable going to the starter or the starter itself. What do you guys think. One other thing I measured ac current at the battery with the truck running, I got flashing reading of 0.0 and 8.9 could this have something to do with it? I think it does but can't remember what.

Thanks for reading the paragraph and the help
Greg

 

You've got to have a bad connection in the wiring somewhere in the starting system then..........checking the starter wires is a good start......