Hi: 90' F-150 4.9 I-6 EFI

Ok, I still have the slow (or no) cranking problem, but was able to start my truck last night on one of those "lucky bumps" when it was turning slowly. As i sat inside i noticed the needle in the volt gauge hovering directly over the N in the word "NORMAL" at the bottom of the gauge. Actually it's been in that area for some time, but this time i notice the needle slightly quivering back and forth over the N , not much but moving or kind of shaking. Also noticed that the battery light / battery symbol light keeps intermittantly trying to come on and fade out, glowing full when i would do something such as touch the electric window "close" button, with the window allready closed (putting some kind of load on?) Ran the truck about 15 mins, shut it off - then no crank at this time. Could this be an alternator problem? Thanks in advance.

 

I got the same truck(basically) but a '92. I've had alot of alternator woes, 7 or 8 Pep boys alts. in 7 years. That have caused a slow crank or no crank a couple times.

My original starter acted up,(I forget the problem), and I installed a re-manufactured starter. I began having intermittant starting problems within the week,I took it back and got another one and it was fixed.

I also had intermittant starting on the same truck, every 50 starts or so I would get nothing, no clicks, or any sign of the starter trying. It turned out the entire harness was shot. The Dealer replaced under warranty and I never found out which terminal was intermittant.

In essence, my point is this: beware any of the parts I mentioned and learn how the battery, alternator, starter, starter solenoid, and associated wiring function; then, troubleshoot very carefully. The integrated electronics and relays that hide in there can confuse you if your not sure exactly what's up.

You need a good multimeter( volts, ohms, amps)before you can start.
Measure your battery post voltage while the engine is running, The meter should read in the high 13VDC to low 14VDC range.Turn on all your lights and electrical stuff, and recheck the battery post voltage, should be close or a little lower than the original "no-load" voltage.This will give you an idea if your alternator is working.
You can check the starter by physically shorting the start relay.
If it always cranks over when you short the relay terminals, the starter might be ok.
Inspect all wires,terminals, components at or between the battery, starter and alternator. If anything looks loose,frayed, or corroded it should be fixed. GOOD LUCK/BE CAREFUL

 

ok thanks for all the good info. It will coe in handy cause tommorrow i'm getting a multi-meter and will check some things out. I had another battery that's fairly new and threw a 3 hr charge on it, popped it in, and the truck started right up with no lag. I'm still wondering about the volt gauge needle cause it still sits over the "N", but doesn't move anymore and the battery indicator symbol doesn't come on now. I'm leaving the battery connected tonight to see if it will hold and start in the morning. I will refer to your post and check everything out and reply back. Once again, thanks for the help.

 

My 1st impression would be a weak/bad battery. With the fuel injection and the pumps, it takes alot of juice to get these trucks running, so even a weak battery that had marginal amps (650 minimum, 850 better)to begin with may fail.

 

Ok everyone, i think i got it done, thanks for all the help. took a reading first of the battery (motor off of course) and looked like a good 12v. started up and put load on (lights,heater, etc.) and then got a reading of somewhere about 13, 13.5v and it fired up several times without any slow cranking. the only things i did were make sure a full charge was on the battery, and removed some of the connectors from the junction behind the batt and cleaned them (pretty oxidized with some gunky stuff on them). I also replaced the belt which was a bit cracked and noisy, but i got my good readings before i did that. Seems to be ok now, though i'm not sure why.