I purchased this 88 F150 v8-302 last winter. It never had a problem cranking the starter enough to start until recently. It seems that the summer heat is making the problem worse. I just replaced a 2 year old 850 CCA battery with a new one and the problem is still there. It will occasionally crank the starter over when cold, but a booster battery will generally get generate enough cranking power. The booster wont always crank the starter when truck is warm. It seems to take a few seconds for the starter to really get up to necessary speed, if it is going to turn at all. When the motor is hot it is worse. Does this make any sense? Any help or suggestions would be appreciated!

 

You may have a bad starter. Does Auto Zone check them for free? I know they will check an alternator; not sure about the starter. Take if off and have it checked.

 

It does sound like a bad starter. The heat will increase the resistance in it, so when you get it tested at autozone it may test ok. The starters are cheap so it wont hurt to replace if it hasn't been replaced in the last few years.

It could also be a starter relay on the fender going bad.
Maybe even a cable corroded or broken.

 

Well...first I replaced the fender wall relay (and cleaned all the wire connections to it) and that helped...the first time! Then back to the same symptoms...solenoid would grind and/or engage the starter weakly and/or strongly! I put in a new starter...cleaned more wires...now it turns over strong but the starter will not disengage even when I shut off the ignition (I had to stop it by pulling the neg. cable off the battery). Don't know where to go now? Wondering if I messed up the new relay when trying to start it before changing starter out...it was clicking/grinding before it would engage the first starter! Any suggestions? Somehow it looks like I fixed one problem and created a whole new problem by switching everything out. Is there a typical place to look if solenoid/starter are getting continuous power (starter will now turn when I reconnect the battery neg cable...with keys out of ignition!) HELP!

 

sounds like the relay is wired up wrong or something is bad with it. check to see if you have continuity between the two big posts, you shouldn't. Check to see if you have power at the little wire on the front. This should only have power when you turn the key to start.

 

I just reread your post. The relay may have gone bad because when you started it with the old starter it may have drawn too many amps and arced the contacts inside the relay and basically welded them together.

 

OK
...changed out the solenoid/relay on the fender wall and turned the key...truck started instantly BUT again starter would not disengage! Pulled the neg batt cable to stop it...and as before the starter will now turn without keys in ignition if i re-connecet the battery terminal...where do I go next?...still can't imagine how original problem is solved but now starter won't disengage...any help appreciated...thanks to the earlier replies!

 

should the small wire connected to the solenoid (red/blue) have constant power to it? or only when starting? thanks

 

The small wire has power only when the key is turned to the start position and held there. If it has power all the time i think the ignition switch at the base of the steering column could be bad.
Check the wire to make sure it is staying hot before you buy anything else.
If it is then check to see if the rod between the key and the ignition switch is rubbing on some thing. if that is ok then look at the ignition switch and see if the slider is damaged or sticking. These switches do go bad and crack. If i remember correct they are about $15.

Basically, when you turn the key, a rod moves down the steering column and moves a slider on the ignition switch at the base. This sends power to the relay through the small wire. this then energizes a coil and magnetically closes a contact what allow a large current to flow to the starter through the 2 big terminals.

Any more questions, feel free to ask

 

OK
maybe i am barking up the wrong tree here...I tested the current going to the different posts on the relay by touching the black probe ot the tester to the battery neg post and the red probe to the posts being tested...I did this with the battery ground wire DISCONNECTED to the battery...in this config all posts were showing current...when I re-tested the small post on the solenoid for voltage with the BATTERY ground wire reattached it had no voltage...except when the key was turned to the start position...then about 9 volts...the only constant now is that both large posts are continously energized. This is the second new relay that has the starter side post hot continously...of course I threw out the original relay that didnt have this problem (still rummaging through the bags for it) but is there any condition possible that could be welding the inside of the relay on both the new units? Thanks again for the info!

 

alright...just invested another 7.99 on a solenoid so I could test each step of the way...when I test for current at the newest relay as explained above with the battery ground wire disconnected (positive battery wire connected to the relay) and my black tester probe contacting the battery ground post, all three relay posts show 12.54 volts of current...when I connect the battery ground wire and re-test then only the post with battery positive connect shows current (as things should be) if things go exactly as before when i turn the ignition key the starter will crank and will not stop unless I disconnect the negative batt cable...I am hoping to hear back on some ideas before I turn the ignition key and mess up another solenoid...any feedback appreciated! Steve

 

You need to check the voltage with the neg. cable connected or you will be checking the voltage drop.
Check to make sure its wired correct. the little red/blue should be on the small post, if there is another small post then it should be grounded. the big wire to the starter should be on one side and all the others on the other including the battery cable.

Check the continuity between the 2 big post on the other bad relay. You need to check it in ohms. good would be OL. and if it reads say less than 10 then it is sticking or welding the contacts.

 

thanks for the contrinuity clarification...the relay is not being welded closed but the best i can come up with by testing is that one eyelet that connects along with the pos. batt cable at the relay is "hot" even with battery unhooked. Is this wire capable of completing a circuit? Doesnt make sense to me (it is the eyelet that connects to one yellow wire and one dark blue or black wire and is labeled as a fusible link) I tried hooking everything up except that eyelet and there is no power when I turn ignition seitch to run or start position...so that is not an option...UGGH! Can i hook up a dash mounted starter button? getting very frustrated here!! Relay does not need to be grounded does it? mounted to painted fender I figure no unless mounting screws provide ground...thanks for the replies and patience!

 

don't know why more folks dont post their final solutions...would make these boards that much more invaluable...anyways...gotta love Fords...switched around all the wires on the relay completely backwards from the relay that was originally on there and backwards from the paper instructions that came with the relay and she works just fine!!!! LOL thanks for all the help!!!!!!!

 

Glad you got it fixed! Thanks for the closure!

Curt