3 day old Gremlin.... Electrical help needed

[EMD_DRIVER]

Thursday morning, I went to fire the beast up to go to work. Temp was 53 degrees and I know my return lines are letting the fuel drain back towards the tank, due to air leaking in (Will be fixed, next paycheck).

After about 15 minutes of 15 second cranking, with 1-2 minute cooling pauses.. Batteries were dead. I tried jump-starting it with my Explorer, but couldn't get it to crank fast enough for it to start. Had to drive my Explorer to work, for the first time in 5 weeks ... That evening, I looked for possible causes of the thing not wanting to crank and found that the positive battery terminal connector had a lot of corrosion, in the wire leading into it. Took it apart and cleaned the end of the wire really good, as well as where it seats into the connector itself. I then put both batteries on chargers for the night.

Next morning, I had a little trouble starting it, but it did start. After work yesterday, the batteries were almost dead again. Jump starting it did work, but just barely. Put the batteries back on chargers, again last night.

This morning, it was slow-starting again. I had some errands to run, so I didn't get a chance to do any troubleshooting until this evening.

I disconnected both batteries and put them on charge. I wanted to see how dead they really were. Both batteries took a charge really quickly.. Since the thing was having trouble cranking again today, I figured they were cooked. After charging them, I had 13.28 volts on the passenger side and 13.02 on the driver's side.

There's a solenoid mounted to the right fender, that has a positive wire from the battery connected to it. I unhooked the positive wire and all the others on that terminal, to start looking for a possible short. With the positive terminal of the passenger side battery connected, I ran a test light lead from the negative terminal of the same battery to each of the disconnected wires.

None of them made the light come on, nor did they register any voltage on my volt meter. When I tried the test light on the black wire, which is on the opposite solenoid terminal, it flashed. The black wire is piggy-backed with the large red cable, leading to the starter. I put the volt meter on that wire and got 12.56 volts. With the volt meter still there, I tried the test light again. It flashed again and the volt meter dropped to zero, then slowly rose back to 12.56 volts.

My best un-educated guess, is that there is a problem with the starter mounted solenoid. With everything else on the vehicle eliminated, That's all that is left.

If there's anything else I can do, please let me know. If it is the starter mounted solenoid, is there any way to fix it, without buying a new starter?

Thanks in advance,
Gary

 

[sassyrel]

you can buy just the solenoid---your diode bridge in the alt might be bad--disconnect the batts for the night after charging--if they are up in the morning--alt bad---could have a small short in solenoid--though ive never seen it---

 

[EMD_DRIVER]

Isn't the alternator wire one of the wires, going to that post on the solenoid. I took everything off of that terminal and still had the gremlin.

Gary

 

[Agnem]

Yes the fender starter solenoid is where the alternator is attached. after you think you've disconnected it, you can probe the B+ on the alternator for voltage with your test light. Shouldn't be any.

 

[BigRigTech]

Check your cab to engine ground strap - I just fixed my co-workers truck last week for the same issue. His engine/cab ground strap had broken and the starter was using the small ground cable from the fender to the negative battery post for a ground. Obviously it was too small and the truck would crank over very slow if at all. 300 six in that one. I would also do a voltage drop test on both the positive and negative systems while cranking the engine. I suspect you have a voltage drop issue on a connection somewhere.

I worked on a Freightshaker M2 last week for 2-1/2 days chasing a voltage drop issue like this. The engine would crank for 2-3 seconds and stop even with the key still in the crank position. Turns out the grounds to the Bulkhead module (central computer for all the ECM's) were poor and it was cycling during cranking just like you took the ignition power away from it because it was loosing battery power due to the poor grounds. Some dummy grounded the batteries to one frame rail and the ECM's to the other with no negative jumper strap in between.

Put one mutlimeter lead on the positive battery post and then on every other positive battery connection leading to the starter - checking both sides of each connection will show you the voltage not flowing through that connection. Do the same for the negative side. You should see .2V or less of voltage drop accross each connection but cummulative they can add up to a lot.

 

[EMD_DRIVER]

I looked at it again this morning and both negative battery cables are mounted to the engine block. Both are on the front of the block, with one on each side. I also tried Mel's suggestion and found that I have 12.65 volts coming from the lead on the alternator. I have an old alternator that came with the truck. It makes a lot of noise when I spin it, so I figured the bearings had gone out of it.

Could I try swapping parts between the two alternators?

Gary

 

[EMD_DRIVER]

Check your cab to engine ground strap

Where is it located?

Put one mutlimeter lead on the positive battery post and then on every other positive battery connection leading to the starter

There are only two wires leading to the starter. One is the main positive battery cable and the other one is the black wire from the fender mounted solenoid. Where would the other positive battery connections be, that lead to the starter? I did fix the positive battery terminal connector, that goes to the driver's side battery.

Gary

 

[EMD_DRIVER]

I went ahead and pulled the alternator... If I need to replace it, it'll already be out. NTM the fact that I should be able to have it tested... Do you think they'd find a problem with the internals, or do they just want to see if they're charging?

Anyway, I tested for voltage between the negative battery post and and it's disconnected connector. After removing the alternator, I get 0.49 volts. That's a far cry from 12.65! Still makes me wonder where that .49 is coming from...

 

[sassyrel]

emd--put the year of your truck in your avatar--helps with diagnostics--if your truck is new enough to have the 130 amp alt--and ive rebuilt a few!!!--their a b@#$%^ to get apart--not like the old 85 amp units---

 

[EMD_DRIVER]

Guess I need to quit using the quick reply feature. It doesn't put my sig at the bottom of the posts..

There is a tag on the one that I pulled. It states that the alternator is a 90AMP. It is a reman unit.

Gary

87 F250 Ext. cab 155"WB 6.9 NA

 

[BigRigTech]

If the connection is tight between a cable and a post or stud there should be almost no voltage seen on the meter when it's neg/neg or pos/pos. Voltage drop testing is very good - shows a lot of bad or loose connections. An easy test would have been to unhook the alternator wires and let it sit overnight. If it still cranked hard the next morning then you didn't find your problem.

 

[EMD_DRIVER]

I can still do that.. It won't take 5 minutes for me to get the alternator back in it's spot (For the belts) and try cranking it in the morning.

Thanks for the tip!
Gary

 

[BigRigTech]

It may be your alternator draining the batteries - it's a cheap way to find out. Most Ford's have a small metal ground strap from the firewall of the cab to the rear of the engine....Having said that I've never noticed if they put them on the diesel's too. I do know that on a gasser having that strap off can make for some real gremlins.

 

[EMD_DRIVER]

Perhaps I should make sure that I do have one..

If not, I can make one!

Gary

 

[EMD_DRIVER]

Took my alternator to AZ this evening and had it tested. It failed miserably!

Guess I found the gremlin..

Gary