So for a few months now my wife has been starting the 99½ by stomping on the gas pedal when starting. And not mentioning it. It's the only way it will start for her, apparently, but it's decided even that is too difficult these days. Obviously it's a 7.3L Diesel, crew cab long bed, silver.. totally relevant>

So I've been chasing down an electrical drain, not knowing how she was starting it so I'm certain it's not the batteries being down (however it does seem to drain them severely s.t. after three about attempts at starting there is not enough to continue). It also seemed to start fine for me after being trickle charged overnight. I think by the time she comes and tells me the truck won't start the batteries have been through the ringer.

So, that said, the tach bounces when starting, the wait light comes on double keying and plugging in the block heater makes no difference. The fuel pump runs.

Starting with the wait light just as it should catch normally, the sound switches down and starts resembling a low battery start. A moment before that my wife stomps the gas pedal down and it (usually) fires up.

So I have no idea where to begin. It hasn't been that cold (45ºF at night), months means many tanks of diesel have been through it, I replaced the engine fuel filter last year. 77K miles. Daily short trips (30-45 min one way)

Again, no idea where to begin...thoughts?

 

Just a note, but the wai to start light does NOT mean the plugs are on. The GPR could be bad. I have used a jumper wire over the GPR for 15-20 seconds before on mine and it would start. That's how I diagnosed mine.

Don't know how that ties into the pedal or the fact the block warmer was plugged in, but it may be worth a try.

 

How long was the block warmer plugged in? It will take a while to heat the block.

 

Why are you so certain it's not due to bad batteries? Based on your description, the batteries are the first thing I would suspect as a possible cause.

 

Because I just replaced them with new. How do I know the new aren't bad? I don't! They hold charge over night (12.92v) and there is no amp draw from the truck, but that doesn't mean they're not bad.

Days. We get cold snaps and could have feet of snow any week now, so once it gets cool the truck stays plugged in.

 

With 77k and new batteries I'm thinking glow plug relay behind the fuel bowl. It's probably original and they tend to go bad.

 

Any smoke while cranking?
What is the voltage inside the cab while cranking?

 

With new batteries and clean terminals, you could have a worn starter, causing a weak start condition. As stated I would also verify the GPR(Glow Plug Relay) is sending voltage to the GP's.

And the pedal stomp is a fluke, you(or anyone who wants to test it) can hold the pedal to the floor during cranking and after it's started the motor will do nothing but idle, after it's running the PCM must see the IVS change again in order to even use the TPS(throttle position sensor) information for engine control.

 

Are u running the correct size batteries for the truck or something different? With properly sized/rated new batteries at full charge, you should get more than 3 starting attempts.

 

This is not standing on the pedal. This is depressing it while cranking. It pushing down the pedal during the cranking causes it to rev immediately on firing, unlike holding the pedal to the floor. Does it do anything for starting? Who knows. The truck almost always starts for me.

Other questions:
Correct Batteries: yes DLG65 (65 Group)
No smoke while cranking, although apparently there is a huge puff of white/gray smoke every time my wife starts it.
It's 70º out today so the voltage when starting didn't drop below 12v
Slightly cold (40ºF) and the voltage was dropping below 11 when cranking (and not starting)

So I'm headed to Autozone right now to test these new batteries. Sigh.

 

White-ish grey smoke usually means glow plug issue. Like others stated the relay is probably bad. Start there

 

Get yourself a plug in volt meter from wally world that plugs into the cig port.

It should show.....

1) 12.5 v before you try to start truck.
2) when you turn the key on (WTS) the voltage will drop to 11.5 if GPR comes on.
3) Truck will not start if voltage drops below 10.5v.
4) when truck start (if) the voltage will slowly come up from 11.5 and 'jump' up when the GPR shuts off.
5) while truck is running the voltage will smooth out to 14.5v as output of Alt.

this will tell you a lot with what is going on with your truck.

 

Anything beyond idle would activate the IVS(Idle Validation Switch) so it doesn't have to be to the floor.

If the batteries and starter are both strong and connections are clean and tight,and you are having trouble turning the engine over, You could have a possible split injector nozzle filling the cylinder and partially hydrolocking the motor(Although I don't feel this is your issue because you would get white smoke all the time) You could have injector orings leaking oil down after sitting(Usually evident by oil in fuel condition, visible as a black fuel filter).

If this is just a slow or hard start condition, test the GPR, if it and the GP's are good, compression and injector testing would be my next move.

 

Batteries tested fine, together and individually. Came home, read thread:

Glow plug relay is bad. I didn't realize how easy it was to test (when I replaced it before I just replaced it because of symptoms).

Thanks everyone.

 

Have you bought a new one yet? Go to NAPA and ask for GPR109... Ask by part number not by the year of truck...cheaper...

This should be around 24.00. should have a 3year 36,000 mile warranty.