hello, i am having problems with my 97 having very hard starts with the first start of the day.it does start easy when it is plugged in but in the morning if not plugged in or after a 10 hour day at work i have to turn it over at least twice and sometimes 3 or more. the batteries are fresh and charged and put in new glowplugs and new relay thinking that would help but did not???anything else i should check replace before i give up?

 

Have you verified the new relay is actually working?

Next thing I would try is open the hood, turn the key to the run position, take a screwdriver and short across the 2 big posts on the glow plug relay for 20 or 30 seconds, then quickly get in the cab and crank it over. If it starts good then your new relay is probably bad.

 

I'll be happy to hear that it is your new GPR. That means its not the Poppets ...

 

Have you tried simply leaving the key in RUN an extra 10-15 seconds before cranking it?

 

i did check the relay afer install and it was good and i have tried leaving the key on for longer AND turning key off and on the refire GP relay.

 

That's what I was thinking too. Hopefully that means there's a big could of white smoke when he cranks and it won't start, instead of faint smoke.

Probably not though.

 

The truck only has 95000 miles on it could the injectors gone bad already?and there is a big cloud of white smoke when I first fire it up cold and puts out a lot of white smoke until it warms up???

 

White smoke means you're fueling, but still cold and not igniting much of the fuel. If the smoke clears pretty quickly before the truck is good and warm, your issue may be slow cranking until first fire. Oh, and dont' try to give it throttle to start- that basically floods it. If it takes a while for the smoke to clear, you may still have issues in the glow plug system.

Do you see the volt gage drop significantly when you're waiting to start? That means current is going to the glow plugs. But gage will still drop even if only a few glow plugs are drawing current.

Have you confirmed that you have +12V on the relay output when waiting to start? If not, then it's the relay or the control circuit.

Have you checked the wiring harnesses, both relay-to-valve-cover and under-valve-cover? Get an ohmmeter, and with no power to the relay, check the resistance of the harnesses. Should be near zero, maybe 1 ohm if your probe isn't making good contact. If several ohms or higher, you have a problem. You have four plugs, two to each valve cover, with 5 pins in each. I recollect that the outer pins on each plug are glow plugs, middle pins are injector positive, and center pin is injector ground. On the relay-to-valve-cover, you should see near-zero resistance between the controlled output terminal of the relay, and the plug.

For the UVC harness, you should see very low resistance between the glowplug pin and any good ground... head is probably best checkpoint. If resistance is more than an ohm or so on any of these wires, they need replacing. This won't differentiate between bad harness or bad glow plug, but if the plugs are new, odds are on the harness.

Theoretically, resistance should be near zero, but I almost always find some resistance with the probes.



My $0.02.

 

I did not think about the harness I will check that next.thanks

 

Under-valvecover-harnesses are one of those "do it while you're in there" jobs... the major headache is getting to them.

I did my plugs this fall (5 of 8 weren't working, and cold start on anything but a warm day was dicey), and just figured on replacing both plugs and harnesses.

If you DO pull the valvecover to get at the harnesses, wouldn't be a bad idea just to double-check continuity on the glowplugs themselves. Top of plug to ground should be very low resistance.

 

everything checks our from relay down to the harness plugs. i do notice it is a very slow cranking... could all this just be due to a drained battery. when i am waiting for the glow plugs to heat i notice the gauge for the batteries go to past a quarter of the gauge and then cranks real slow after i they warm up

 

Have you _load_ tested the batteries, in isolation?

 

by isolation do you mean while heating the plugs one battery at a time?

 

No. He means unhooking the truck's batteries and testing them with a quality tester. You must unhook them or the other battery may conceal the battery in question's badness.

(Badness is a technical term)