Troubleshooting - Hard starting when hot

[Vagabound]

Hey Vagabound,  Several things came to mind when I read your symptoms.  I'm a former ASE Master Auto tech but without benefit of laying hands-on to diagnose I'm just sharing my raw thoughts... and my thoughts plus $1.65 will buy you a cup of coffee, as long as you don't forget your $1.65. 

...

Hi Doubleone,

Thanks for taking the time to provide so much good information on my mechanical challenges du jour.  A lot to chew on there.

I was glad to hear you say that you think it isn't the fuel pump.  All of the work and diagnostics that I've done to this point bring me to the same conclusion.  Despite that, I've replaced the fuel filter, fuel pressure regulator, and engine coolant temperature sensor all in the last month or so.  Symptoms persist.

As I home in on the cause of my "hard starting" problem, I'm beginning to suspect some involvement of my electrical system.  To be clear, the truck starts nearly ever single time.  The problem is that it drags or takes longer to start sometimes.  Never when cold.  Always when hot.  However, I've come to look at "hot" another way.  Hot can also be another way of saying "successive", meaning, second or third start in a row.  For example, start easily once when cold, short trip, stop, start again within 30 minutes, but not so easily that time, etc.  What I've noticed is that on the second or third start in a short time, the battery begins to act like it's worn down, struggling, not totally up to the task. Very seldom, I've even wondered if, on a third successive start, it was going to start at all ... but it always has ... eventually.

An interesting part of this mechanical mystery is that I've had the battery, starter, and alternator tested twice in the last six months.  Both times all components were fine.  A few days ago, I tested the battery myself with a multimeter.  Roughly 12.6v when engine is off, and 14.5v or so when the engine is running.  That supposedly is exactly what it should be.  And this battery has 850 cold cranking amps or thereabouts.

Then, I was fortunate enough to have someone share the following article with me regarding voltage drops.  I have yet to use it, but it seems quite similar to my situation:

http://www.aa1car.com/library/voltage_drop_testing.htm

Any experience with or thoughts about that?

Tom

 

[highdesertranger]

have you put an amp meter on the battery cable when the starter is dragging? just because a starter test good when cold doesn't mean it will test good hot. yes you need cables in good condition and the proper size especially when hot. also note the cables they sell at most auto parts stores are junk, so are the terminals. military terminals and heavy gauge cables work the best. highdesertranger

 

[Doubleone]

Hi Doubleone,

Thanks for taking the time to provide so much good information on my mechanical challenges du jour.  A lot to chew on there.

I was glad to hear you say that you think it isn't the fuel pump.  All of the work and diagnostics that I've done to this point bring me to the same conclusion.  Despite that, I've replaced the fuel filter, fuel pressure regulator, and engine coolant temperature sensor all in the last month or so.  Symptoms persist.

As I home in on the cause of my "hard starting" problem, I'm beginning to suspect some involvement of my electrical system.  To be clear, the truck starts nearly ever single time.  The problem is that it drags or takes longer to start sometimes.  Never when cold.  Always when hot.  However, I've come to look at "hot" another way.  Hot can also be another way of saying "successive", meaning, second or third start in a row.  For example, start easily once when cold, short trip, stop, start again within 30 minutes, but not so easily that time, etc.  What I've noticed is that on the second or third start in a short time, the battery begins to act like it's worn down, struggling, not totally up to the task. Very seldom, I've even wondered if, on a third successive start, it was going to start at all ... but it always has ... eventually.

An interesting part of this mechanical mystery is that I've had the battery, starter, and alternator tested twice in the last six months.  Both times all components were fine.  A few days ago, I tested the battery myself with a multimeter.  Roughly 12.6v when engine is off, and 14.5v or so when the engine is running.  That supposedly is exactly what it should be.  And this battery has 850 cold cranking amps or thereabouts.

Then, I was fortunate enough to have someone share the following article with me regarding voltage drops.  I have yet to use it, but it seems quite similar to my situation:

http://www.aa1car.com/library/voltage_drop_testing.htm

Any experience with or thoughts about that?

Tom

Computers run on electricity... Ignitions run on electricity... Fuel Injection runs on electricity... Starters run on electricity... Spouses run on electicity (JK)   So, if the starter is "dragging" and the engine is cranking slow we know you've got an electrical problem that needs to be resolved first before chasing any other symptoms.  If the battery load tested good, alternator output good, and starter draw within range then it's not likely those.  I also suspect the problem probably wasn't happening during testing...  Am I right?

I think Highdesertranger was right on target about checking the cables.  Replace any weak connections, or if corrosion is creeping back up into the wire strands, or if someone installed one of those cheap clamp type replacement connectors.  I hate those clamp style connectors because they'll work for about a year then get corroded and fail.  I learned early to wire my stuff totally bullet proof.  I use marine battery terminals with heavy wire, crimped and soldered copper eyelets, shrink-wrapped to the cables.  It's more time and labor up front but they'll never fail.  It always seems to happen that our RV's fail at the most inconvenient times, like when you're anxious to get somewhere, or out on the road in-between places... so it makes sense to do it right the first time.

You can certainly use a volt/ohm meter to check for voltage drops as the article states, the principles are sound, but I more tend to use the ohm scale to check resistance across connections.  Touch the leads together using the lower ohm scale and you'll see a baseline reading for a good connection, every meter is different but usually very close to zero.  More ohms than baseline means you have resistance.  When using a digital ohm meter it's normal for it to jump around a few numbers or flicker while testing.  A few ohms greater than baseline is within the range of error and is nothing to worry about.  You'll definitely find a large jump in ohms when there is significant resistance.  Start by checking the battery posts to battery terminal connections, then battery posts to the wire a few inches back from the terminal.  You can pierce through the cable insulation into the copper wire with a clean safety pin and touch the test lead to the safety pin.  Remove the pins when done.  You can also feel the cables and connections for localized hot spots when the problem manifests.  Cables will be uniformly warm but big resistance equals big heat, so an abnormally hot spot is where you'll find your defect...  I've also discovered mystery problems are frequently related to bad or missing ground connections.  Check and clean every ground connection at the engine block and intake manifold.  Make sure you still have a good connection at those braided ground straps, usually found at the firewall to intake or frame to block.  I added an extra ground cable to my rig as one of my first mods.  It goes from the negative battery terminal to an accessory bolt at the front of the block.  I run a smaller ground wire from that bolt up to the intake manifold ground bolt.  This type of grounding works good to eliminate alternator whine with audio systems.    I do this when wiring up racecars because hot high-compression engines crank slow and the ignitions need good grounds.  Speaking of ignitions, extremely advanced timing can also cause a hot engine to crank slow, but you already had the problem before messing with the distributor so it's not likely the issue.


While you're elbow-deep in the engine bay, just for preventive maintenance, be sure to check the plug-in terminal at the back of the alternator and make sure it's not burnt or melted.  NAPA and other part stores sell replacement pigtails if needed.  Starter solenoid contacts can also become burnt and pitted on the inside causing intermittent slow cranking but I think it would have shown as high starter amperage draw if the problem was happening during testing.  I don't like to throw parts at problems without first diagnosing and understanding the problem, but sometimes with frustrating problems, things like terminals, cables, solenoids, and cleaning the grounds are easy and cheap...

 

[gapper2]

Only a shadetree mechanic here, but I've had starters test good both in and out of the vehicle at places like O'Reillys and Autozone and got tired of the problem (hard starting) and replaced the starter and that solved the problem.  HDR has good advice. Measure the current when hard starting.

 

[Vagabound]

I continue to believe that one specific symptom, in this case, should be an important clue and also very Illuminating. That one symptom is great starting every day the first time, slower starting the second time, and poor starting the third time. Roughly every day. I'm generalizing and dropping exceptions and other details, but the fact that it's capable of a perfect _first start_ everyday, but so quickly goes bad on 2nd and 3rd starts should be indicative of a particular problem. I just don't know which at the moment.

To answer questions, no, I haven't yet done any electrical testing myself _during_ hard starting. I'll add that to the list, near the top. A complicating factor is that, not contrary to my description above, it is somewhat an intermittent problem. Not totally consistent, so a bit harder to catch. At least once though the auto parts store test was done because just prior to it I was having bad hard starting problems. As I recall, those tests were done both engine off and engine running.

Sometime in the last year I cleaned and reconnected every ground that I could find. Sanded the contact points, added dielectric grease, the works. As I recall, there weren't many; maybe three. Don't recall any other details about that.

After all the input, I think my next step is to check and clean all of the key electrical connections. I'll let you know if I find anything interesting.

Thanks for everything so far,

Tom

 

[Doubleone]

I continue to believe that one specific symptom, in this case, should be an important clue and also very Illuminating. That one symptom is great starting every day the first time, slower starting the second time, and poor starting the third time. Roughly every day. I'm generalizing and dropping exceptions and other details, but the fact that it's capable of a perfect _first start_ everyday, but so quickly goes bad on 2nd and 3rd starts should be indicative of a particular problem. I just don't know which at the moment.

To answer questions, no, I haven't yet done any electrical testing myself _during_ hard starting. I'll add that to the list, near the top. A complicating factor is that, not contrary to my description above, it is somewhat an intermittent problem. Not totally consistent, so a bit harder to catch. At least once though the auto parts store test was done because just prior to it I was having bad hard starting problems. As I recall, those tests were done both engine off and engine running.

Sometime in the last year I cleaned and reconnected every ground that I could find. Sanded the contact points, added dielectric grease, the works. As I recall, there weren't many; maybe three. Don't recall any other details about that.

After all the input, I think my next step is to check and clean all of the key electrical connections. I'll let you know if I find anything interesting.

Thanks for everything so far,

Tom

I doubt it will be the keyed ignition switch because that supplies voltage only to the starter solenoid, and it works or doesn't.  Since the starter is cranking that means you have adequate voltage to actuate the solenoid. Low voltage from the key switch typically manifests as a complete no start (solenoid won't engage) or solenoid buzzing (drops out) while starting.  The solenoid is just a big relay, it doesn't take much voltage to pull in the contacts, but the contacts do get burnt and pitted over time.  You can check the complete key switch and transmission lock-out circuit to the solenoid by measuring voltage at the solenoid "S" terminal when the problem happens.  You can audibly hear the solenoid will have a solid clack when it engages.  You could also jumper across the "B" and "S" terminal and that will connect the circuit and crank the engine directly from the solenoid, bypassing the key switch circuit.  Be careful when using a metal object that you don't burn your hand because it may arc.   You can also disable the ignition and measure voltage drop across the "B" and "M" terminals while cranking, should be less than .5 volt drop.    ...But the way you describe the symptoms the key switch circuit is not likely the issue.

Gapper2 got me to thinking... I had a customer who neglected an engine oil leak from a valve cover and oil dripped down over the starter for a long time and eventually got inside on the brushes.  I've also had starters on boats that corroded from water in the bilge.  Starters are a very basic brushed motor.  The brushes wear and the starters can go bad on one or more stator windings.   Intermittent problems can happen when the starter stops with a brush on the bad spot.  A bad winding or brush could definitely cause a slow cranking but the starter testing should have shown that.

The two problems as I understand are 1.) progressively deteriorating starter performance with each successive cranking and 2.) intermittent rough idle.  First things first, we have to resolve the starter issue, then we'll see how it runs.  Progressively slower cranking makes me think bad battery, resistance somewhere in the circuit, solenoid, or starter in that order.  Since the battery load test found the battery was good, and you already ruled out cables, and connections, I'd say to replace the solenoid since that's cheap and easy, next would be a starter.   If you need to buy a starter I wouldn't get it from O'Reilly's or Autozone since those are mass re-builders and quality is hit and miss.  I have all of my alternators and starters custom built at a shop in Bloomington, CA (Alex Auto Electric).  I like that I can shake the man's hand and look him in the eye, he's also a nitpicker when it comes to details, and I like that.  Otherwise, I'd go to NAPA or buy a new starter.  Amazon shows a 4+ rated Premier Gear PG-3268 Professional Grade New Starter for $64.




One last thought in the spirit of trying to help; I'm certainly not meaning to aggravate or annoy... you are using an automotive starting battery and not a deep cycle, right??  Construction and chemistry of a deep cycle works for low amperage sustained loads (≤100a) but they can't supply large amperage for starting (300-500a) as rapidly as a starting battery.