Slow cranking

Friday

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#1
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MAKE: GMC
MODEL:Sierra
YEAR: 1994
MILES: 194K
ENGINE: 350
DESCRIBE ISSUE....Just bought this truck. It had been sitting for a while, and not being driven. When I test drove it on Tuesday, it cranked pretty slow, but started. Test drive was fine. Drove it home (60 miles) yesterday. Figured the battery just needed to charge up while driving it. When I got home, it still cranked slow before starting. The battery reads 12.48V with key off, 14.06V with engine running, and 13.77V with a load (blower on high, lights on). Alternator reads 14.19V with engine running and 14.09V with a load. Are these readings good or is something amiss?
 
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#2
You need to load test for a sulfated battery, (that won't get any stronger, no matter how long you charge it). If you don't have a proper load tester and only a DVOM, you could measure voltage while cranking. I don't have exact value for this test, but 11 volts while cranking would probably be OK, 9 volts would be too low. Another good test would be to disable fuel or spark and then crank. If the engine will only crank for about 5 seconds before it runs out of battery, the battery may need to be replaced. A good battery will crank way longer. A worn out starter is another possibility.
 

Friday

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#3
You need to load test for a sulfated battery, (that won't get any stronger, no matter how long you charge it). If you don't have a proper load tester and only a DVOM, you could measure voltage while cranking. I don't have exact value for this test, but 11 volts while cranking would probably be OK, 9 volts would be too low. Another good test would be to disable fuel or spark and then crank. If the engine will only crank for about 5 seconds before it runs out of battery, the battery may need to be replaced. A good battery will crank way longer. A worn out starter is another possibility.
Thanks, Dan. Starter was next on the list if battery and alternator prove okay. I'll try the cranking test tomorrow.
 

billr

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#4
If the battery voltage is OK while cranking (and 10-11V would be my guess, too), then check voltage right at the big power terminal on the starter; again, while cranking. There may be a problem in the big cable from the battery to the starter.

If you do check voltage down at the starter, then put the meter ground lead on the starter housing, not just some handy chassis part or the engine. That way you will be checking both the power and ground "cables" to the starter.
 
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#5
these are good trucks - pretty basic, loads of parts and easy to work... this is a can do.

Battery and truck been sitting for awhile ? MIght be a new battery on the shopping list.
 

jd

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#6
If you end up needing a starter, it seems the classic "Delco" and the newer PMGR (Permanent Magnet Gear Reduction) starters were both fitted to your Make/Year/Model/Engine. I'd been a big fan of "Delco" because they were so easy to fix. If I had a few junkers I could always get a couple working ones out of the parts. Brushes were easy to change and bushings, drive, solenoid, all available as repair parts.

But recently, I got to really like the PMGR starters! There aren't as many parts out there for them, but they seem to go longer before they NEED work, and they're inexpensive. That, and much easier to install! A fraction the weight to hold in place trying to start that first bolt.
 

billr

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#7
For a PMGR starter, I suggest <dbelectrical.com> They have new units for $44.95, with free shipping to you. When I have ordered, delivery was two days. Yeah, they are "made in China", but many of us on a Saturn forum have had good service from them. Also, keep in mind that "Jap crap" was once much derided, now we lap it up as being "premium". There is no rational reason for avoiding Chinese products because of quality concerns.
 

Friday

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#8
For a PMGR starter, I suggest <dbelectrical.com> They have new units for $44.95, with free shipping to you. When I have ordered, delivery was two days. Yeah, they are "made in China", but many of us on a Saturn forum have had good service from them. Also, keep in mind that "Jap crap" was once much derided, now we lap it up as being "premium". There is no rational reason for avoiding Chinese products because of quality concerns.
Bill, I had looked at those. I was surprised at the price. Even the normal reman units at Advance Auto are far cheaper for this truck than they were for my 2000 Jeep Cherokee. I guess volume does make a difference.
 

Friday

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#9
You need to load test for a sulfated battery, (that won't get any stronger, no matter how long you charge it). If you don't have a proper load tester and only a DVOM, you could measure voltage while cranking. I don't have exact value for this test, but 11 volts while cranking would probably be OK, 9 volts would be too low. Another good test would be to disable fuel or spark and then crank. If the engine will only crank for about 5 seconds before it runs out of battery, the battery may need to be replaced. A good battery will crank way longer. A worn out starter is another possibility.
Battery drops to 9.8 when cranking.
 

billr

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#10
That seems low, time to take for a (free) load-test. I assume you aren't doing this test in sub-freezing weather...
 

Friday

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#11
That seems low, time to take for a (free) load-test. I assume you aren't doing this test in sub-freezing weather...
No. Pretty warm here (kansas). I pulled the fuel pump relay and it kept cranking, so maybe the whole thing is my imagination.
 

nickb2

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#14
There is no rational reason for avoiding Chinese products because of quality concerns.
I agree do a degree. There are many good chinese products out there, I just don't agree on them dumping so aggressively around the world without regards to their workers and environment and to ethical trade. Also, seems like what Japan did back in the 70's and 80's, another form of economical/trade warfare but on a way bigger scale. But that is for another debate.
If the battery voltage is OK while cranking (and 10-11V would be my guess, too), then check voltage right at the big power terminal on the starter; again, while cranking. There may be a problem in the big cable from the battery to the starter.
Correct me if I'm wrong, but Friday has not yet done any resistance or voltage checks apart from telling us it drops to 9.8v while cranking.

I would definitely start with checking for ground tightness and corrosion. I hardly ever see corrosion on the positive side, but checking there also is a start. However, if you are getting 9.8v after 15sec on cranking, that is a normal reading to me. If it is going below 9.5v, a load test is in order on the battery. Negative lead from batt to block is often an issue on these trucks.
 

Friday

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#15
Any news? Hoping the battery is all that's needed - so far.
I'm going to clean the terminals, ground, etc. Then check the connection at the starter. I'll post back. Been rainy here, and it's that time of year when you mow every other day. Getting back to the truck today hopefully, although there is rain in the forecast. . .