i bought a 98 f150. it always started right up. couple days ago after starting a few times, i was unable to start it. i hear one click and then the starter does not engage. i removed the starter and had it tested. it tested ok. i wiggled the wires on the firewall relay for the starter and jumped the 2 wires on the relay and truck started. then it started fine for a few days. now it will not start again. could it be relay? what can i test to see if it is bad? also, the battery is brand new. thanks

 

Check all connections from the battery to the starter for corrosion and tightness. It very well could be the relay starting to go, but clean and tighten the connections first.

 

i actually just put all new terminals on the battery cables. everything is tight and clean. i will just have to replace solenoid and see what happens. thanks!!

 

Your new terminals may or may not be making a good connection. There may be corrosion up inside the insulation. I know it's expensive, but you would be better off replacing the whole cable.

 

Yes glc is right the large red cable that attaches to the starter can develop corrosion internally (you can't see it) just above the area it connects to the starter. The 97 and 98 models had a known random problem with this which develops over time. My 97 had the same symptoms you are having, intermittent start. If this is the problem with yours then replace the entire cable to resolve the issue.

 

i just checked the wiring with a test light. i am getting power to the starter from the solenoid when i turn the key. the solenoid is making a loud click when trying to start. could it be the starter failing? or a bad ground at the starter? thanks!!

 

If all connections are good, it could definetly be the starter. I had the same clicking noise about 3 years ago, and it was the starter solenoid, not the relay on the firewall.

 

Start off replacing the $10 firewall relay.

 

i did replace the firewall solenoid. i am getting power from the firewall solenoid to the starter. i will have to check the other positive wire going to the starter. could a bad ground cause problems?

 

Before buying any more parts yes you should make SURE every connection is tight and corrosion free.. The positive connection on the starter is known to corrode..

 

Yes and the positive cable can supply enough juice for a test light but not enough for the starter to function if it is corroded internally.

 

That was most of my problem! I replaced the wire and took starter in to retest and it failed 3 times on the tester. So new starter and cable. Starts now. Although now it makes a screeching noise when starting. Wonder if it needs a shim in the starter

 

recheck the starter mounting bolts lossen and retighten each a little at a time.I have never had to use shims on the modular engines for the starter.