Hey guys. I'm trying to help my dad figure out his F350's non start issue. Lemme start with the known.

Yesterday, didn't want to start. With a jump, started and ran just like normal.

Today, doesn't want to start again. Try jumping the batteries again... Nothing. (I had my 7.3, running, hooked up to it for about 10 minutes).

Just cranks. No attempt to fire, and no white smoke from the tailpipe, however, with shot of ether (I know, I know, I wasn't there for that. Local mechanic) it fired, but wouldn't stay running.

When I came over, checked fuel delivery to the filter bowl, has good delivery.

Resting voltage on batteries -12.0 on one, and 12.5 on the other.

Rpms while cranking are SLOW, according to Torque pro, it didn't top 80 rpm whilst cranking.

It has had a lackadaisical starting crank for awhile, I believe it to be starter motor wearing out, however, not sure if this is the current problem.

Checked IPR plug, not oily at all, looks good. Didn't start with IPR unplugged either.


I'm leaning towards bad starter just not spinning fast enough to start, but the ether fired at a much lower compression, making it want to start then.


Thoughts? Anything else to check to point towards or away from starter without dropping starter and bench testing? The batteries and alternator are relatively new (within last year I believe).



Thanks everyone, Stephen.

 

Starter is a possibility. You should also check voltage while cranking at each battery. A bad battery can pull voltage down far enough it won't start even with a jump.

Of course if you have a 7.3, you could always swap parts to be sure before spending money.

 

Did you just test the battery voltage or did you do a load test the batteries? Make sure you test both individually. What voltage do you have as you're cranking the engine over?

 

Did you unplug the IPR or the ICP? It won't start with IPR unplugged. I'd check health of batteries, quality of connections then starter. 80 RPM's won't get it running. Does the tach move while cranking? Could be the CPS.

 

I just tested the voltage on the batteries, I didn't think a multimeter could do a load test. Now after some googling, I guess it can, didn't know that. Also, I didn't get voltage while cranking, I didn't have a second person to crank for me then.


​​​​​I did unplug the IPR, not the ICP, I guess I got confused. I thought I saw somewhere that if the IPR was bad, it should start with it unplugged. Is that the ICP that does that?


I did see the tach moving while trying to crank, but not much. Thats why I hooked up torque pro to get a value. However my dad was looking at it last night and said that it didn't seem like it was cranking slow at all when he had his suv jumping it.
Still no fire though.

 

Yes, the ICP is the one to unplug to test if it's the problem. I have a voltage meter that I can plug into my cigarette lighter. I got two for cheap off of Amazon or fleabay. Tach moving while cranking should rule that out as the problem. I didn't know about load testing with a voltage meter either but I would expect that some type of running the headlights for a short period of time and checking the batteries should sort of do it.

 

Regarding doing a load test, I don't believe a MM can do that unless you have a special one, it has to be able to apply a load to the battery (individually/out of truck). Getting your cranking voltage can be done with a little creativity, set up meter, set phone up to record a video, crank engine watch video. .
I suppose you could check that the CPS connections are tight. Good luck.

 

Stephen, your problem is similar to not enough coal in the forge, but different. 80 rpm is your problem, so start following the battery, cable corrosion, loose connection, bad starter, low voltage problem.

Larry

 

Well, I'm on mandatory overtime at work, and didn't have time to work on the diagnosis, so my dad had it taken to a local shop that has done all the work on this truck before. We'll see what they find out I suppose.


Thanks everyone, Stephen.

​​​

 

12 volts on that one battery is a problem 12.06 volts is 25% charged,the 12.5 volts on other battery is near 90% charged,i would get good hot batteries on board first.

 

12 volts is nearly dead, 12.5 is about 60% charge.

Modern sealed batteries are 100% charged at 12.8 (not 12.6 like the old standard batts), a tenth or two doesn't sound like much but a big difference in terms of percentage.

http://jgdarden.com/batteryfaq/SoC.xls

A jump start is an emergency thing, as soon as possible an external charger is used to fully charge the battery back up. This is important. The vehicle charging system will not do this unless you drive to Montana or something like that and may be damaged.

 

I live in Montana so my batteries are good.

 

A load test is really nothing more than measuring the battery voltage while under load. I have TorquePro running when I crank, and battery voltage typically drops to around 11Vdc, even below 11Vdc, while cranking. But it's been doing that for years.

I believe there are a few minimums the PCM wants to see before telling the injectors to fire: 100 rpm; 500psi ICP; ~10Vdc; FIPW is 0.6ms while cranking until ICP>500psi, then 1-6ms. If there's no smoke at all then one or more of these is missing.

 

Another thing to think about that cropduster and Tedster are talking about. Power = Current x Voltage. Power is what the starter is using to spin the engine. The lower the battery voltage drops, the more current needed by the starter to spin it at the same speed. Also, Power = Current squared x Resistance, and some of that power is wasted by the starter as heat. So as current goes up, the heat due to internal resistance goes up even faster. That's why low batteries can kill a good starter, and why a failing starter, once it starts failing, will go quickly and possibly take out any or everything between it and the batteries, including the batteries.

 

Actually, the 10Vdc is just a general rule of thumb. I've seen trucks start lower than that while cranking. They were weak battery conditions and we waited for the GPR to cycle the glow plugs off before attempting to crank to avoid excessive draw, but I've seen trucks start down in the 8.6 Vdc range.