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Discussion Starter · #1 ·
A little back story: I replaced my alternator about 2 weeks ago. When it died, I started and ran the truck 4 times with the volt meter reading low (indicating that the alternator was on it's way out). Finally the next morning, the truck would turn over, but not fast enough to start. I replaced the alternator, and ended up having to jump it from two jump packs (one on each batt). It took a lot, but finally it started and ran fine. My GP's are relitively new, and I tested my GPR. I'm fairly confident that my GP system is functioning correctly.

FF to yesterday morning. I noticed it the truck took longer than normal to start, but finally started. It ran rough for the first 1-2 seconds, and then perfectly. Once I drove it, it started perfectly the rest of the day. I noticed that after that first hard start, each subsequent start of the engine I noticed that it turned faster when starting. This morning, it started hard again. It took about 4-5 seconds of turning before it fired. After I drove it, it started up just fine, and again the engine turned faster when starting.

When I got home, I tested the batteries with a voltmeter. 12.2v on each with the truck off, and about 14.6v while running. I realize that the real test of the batteries will be tomorrow morning before attempting to start to see if they are draining. Here's the intersting thing, the batteries are mis-matched! Both motorcraft, but the passenger side batt is 650CCA/800CA, and the drivers side is 750CCA/950CA. So it appears that at least one has been replaced at some time. I don't think it's the starter, because it spins nicely once the truck's been started and run once.

So could my slightly hard starts be attributed to batteries which are on the way out? I know when alternators go, it's hard on the batteries and they often go too. Could having two different batteries harm my truck in any way?

Sorry for the long post, just want to make sure I didn't forget anything.

-MK
 

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Have your batteries tested seperatly and have the alt. tested again.
 

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Discussion Starter · #3 ·
The alt is 2 weeks old, and charges properly so I don't think that's it.

I'll have to get the batteries tested.

-MK
 

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I just put a new alt on my truck and I already dont trust it. It only makes 13.7 volts most of the time and at Idle only makes 42amps.
 

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Discussion Starter · #5 ·
Just got back from NAPA where both batteries tested 100%. Truck starts and runs just fine, but it seems that the past few mornings it's taken a bit longer to start, like I said ~5sec of cranking.

Thoughts?
 

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A little back story: I replaced my alternator about 2 weeks ago. When it died, I started and ran the truck 4 times with the volt meter reading low (indicating that the alternator was on it's way out). Finally the next morning, the truck would turn over, but not fast enough to start. I replaced the alternator, and ended up having to jump it from two jump packs (one on each batt). It took a lot, but finally it started and ran fine. My GP's are relitively new, and I tested my GPR. I'm fairly confident that my GP system is functioning correctly.

FF to yesterday morning. I noticed it the truck took longer than normal to start, but finally started. It ran rough for the first 1-2 seconds, and then perfectly. Once I drove it, it started perfectly the rest of the day. I noticed that after that first hard start, each subsequent start of the engine I noticed that it turned faster when starting. This morning, it started hard again. It took about 4-5 seconds of turning before it fired. After I drove it, it started up just fine, and again the engine turned faster when starting.

When I got home, I tested the batteries with a voltmeter. 12.2v on each with the truck off, and about 14.6v while running. I realize that the real test of the batteries will be tomorrow morning before attempting to start to see if they are draining. Here's the intersting thing, the batteries are mis-matched! Both motorcraft, but the passenger side batt is 650CCA/800CA, and the drivers side is 750CCA/950CA. So it appears that at least one has been replaced at some time. I don't think it's the starter, because it spins nicely once the truck's been started and run once.

So could my slightly hard starts be attributed to batteries which are on the way out? I know when alternators go, it's hard on the batteries and they often go too. Could having two different batteries harm my truck in any way?

Sorry for the long post, just want to make sure I didn't forget anything.

-MK
I would have both batteries tested separately and the starter motor. I don't like the mismatched batteries but that's just me. I am not sure that would cause a problem but it doesn't seem to make any sense to do that to me. You have two different capacity batteries hooked in series...I am not sure if the charging would be very affective...but I have no technical knowledge to fall back on to say it is a problem. :no:

Griz
 

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Discussion Starter · #7 ·
I think it's my GPR. It tested good 2 weeks ago when I replaced the alt. Here's my rational.

1. It's warm out (~50-60F), which explains the hard start, but start nonetheless.
2. It starts and runs fine after that first hard start
3. With the truck off, I see 14.4v between the two big posts on the GPR
With the key on and the WTS light on, I continue to see 14.4v (should read 0v or open no?)
With the engine just started and running, I still see 14.4v (again should be 0v or open correct?)

2 weeks ago, measuring across the 2 big posts on the GPR yielded 0v when running (within 2min of starting).

So with this rational, I think I need to buy a GPR.

Make sense?

-MK
 

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Check the starter. Had teh same problem this winter. Was turning over really slow in the mornings or after work but rest of the day was fine. Had batteries tested tested OK but i decided to change them as they were way to small and old. Truck still turned over the same. grabbed a new starer and all was good after that...
 

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When it does start the first time every day does it smoke like crazy or not? Cuz I know when my GPR failed my truck would smoke alot and wouldn't clean up till the motor had warmed up alittle
 

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Discussion Starter · #10 ·
My truck usually lets out a puff of bluish smoke when it first starts anyways. No difference that I've noticed.

Did I measure the GPR correctly?
 

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The proper way to test the GPR is to measure the voltage across the two large terminals while it is cycling. If the reading is higher than 0.3 volts, replace the relay.
To test the batteries they must be disconnected and tested separately.
 

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How old are your batteries? I'm assuming you have cleaned all of the connections everywhere. Reduced Cold cranking amps on an older battery is common. I use synthetic oil which turns over easier and faster. I'm guessing it's the batteries have weakened with age and the bad alternator weakened them more and the cold weather more yet but don't rule out all of the connections and grounds. They can and do have a major effect.
 

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Check your battery cables. Also charge your batteries to full charge with them disconnected. 12.2v is too low they should read at least 12.6.
 

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Discussion Starter · #14 ·
-Am I correct that when I first start the truck the reading between big posts on the GPR should be 0v (open)?

-I had the batteries tested with a handheld tester at NAPA and they said both were 100%

-I cleaned the terminals and cable connections when I changed the Alternator and sprayed the terminals with the red protective coating.

-How do I tell if my starter's bad or not?

-MK
 

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Check your GPR with key on engine off. Preferably with a cold engine. The circuit should be closed, not open. The voltage should be very low as you are testing the voltage drop between the two terminals.
 

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Discussion Starter · #16 ·
So how do I tell if it's bad then?
 

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So how do I tell if it's bad then?
Okay...the GPR is like most relays...this one will pass battery voltage to the GP's when energized. It sounds like you tested it correctly. But just in case...using a volt/ohm meter...put it on DC voltage and 20v scale. With the truck off...you should read battery voltage or close to it with one lead on one of the big posts and the other lead on the other big post. Now test it again with the truck in the Wait to Start position. With the same lead hook up you should only read .3 volts or less. If you read much more than that your relay is bad.

Griz
 

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Discussion Starter · #18 ·
Thanks Griz, reading battery voltage with truck off. After I got back from NAPA, I shut the truck off and and waited about 1/2 hour then went to get my multimeter. I came back and measured with the key on and WTS light on and read battery voltage. After letting the truck sit for another 3 or so hours, I tried it again, and measured about .6v with the key on and WTS light on.

I'm pretty sure it's the GPR at this point. I'm going to pick up the weatern plow one tomorrow (not paying $75 for the GPR-110 at NAPA).
 

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Thanks Griz, reading battery voltage with truck off. After I got back from NAPA, I shut the truck off and and waited about 1/2 hour then went to get my multimeter. I came back and measured with the key on and WTS light on and read battery voltage. After letting the truck sit for another 3 or so hours, I tried it again, and measured about .6v with the key on and WTS light on.

I'm pretty sure it's the GPR at this point. I'm going to pick up the weatern plow one tomorrow (not paying $75 for the GPR-110 at NAPA).
It is best to test the GPR when the engine is cold because the relay is controlled by the PCM which uses Engine Oil Temp, Barometric Pressure and Ambient Air Temperature to control the relay On/Off time. It could be during your first test the engine oil was still hot so the PCM didn't turn the relay on. But if you read .6 volts on your second test...then yes the relay is wearing out. There probably are bad internal contacts. Let us know if a new relay fixes it. :thumbsup:

Griz
 

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If it turns out that it is not the GPR, and if the batteries are over 4 years old, replace the batteries.

Our trucks need the power of strong batteries. Without them you will soon be replacing the starter. And, you will still have to replace the batteries.
 
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