7.3L Powerstroke glow plug relay?

My 01 F350 w/7.3L has been getting harder to start in cold weather. Yesterday I started it for the first time in a week and it had been below freezing for a couple of days. Took 7-8 attempts before it would run. Restarted fine after warmed up a few mins. This morn I used a digital volt meter to check some things out.

At first both the battery and hot side of the glow plug relay were at 12.3V. A little low due to truck's lack of use. Turned key on to activate the glow plug relay and plugs. Voltage on the output side was 10.2V, losing a little over 2.1V through the relay.

I have read that anything over .3 V (3 tenths) means bad relay.

I hooked up my large wheeled battery charger for a couple hours and the batteries now read 13.5V.
Hot side of the relay was the same at 13.5. Turn key on and the output side was as 11.5V, but the kicker is that the input side also read 11.5V

So....is the GPR bad (I think so) but why would the input side also drop that far (11.5v) with glow plugs on and fully charged batteries at 13.5V

Batteries bad also?

Batteries are about 3 years old. Motorcraft Gold (middle range of the Ford batteries, silver, gold, platinum)

Bad relay - no. Both sides reading the same = no voltage drop. Check the supply from the battery to the relay for a drop. I just went through changing my batteries recently - had good voltage, but no amps when called upon.

David, I have the exact same problem. When it's stone cold it's a bear to start and runs a little rough for a minute or two. Yesterday it was in the teens here. Earlier this week it was in the 30's, so I plug in the heater for about an hour and it started pretty easy. I haven't tested the relay on mine yet, but after doing a ton of searching about the problem I found the same thing you did. More than .3V drop and it's no good. I'll test mine tomorrow and see what I get.

David Cole wrote:...Turn key on and the output side was as 11.5V, but the kicker is that the input side also read 11.5V

Doug Rahn wrote:...More than .3V drop and it's no good. I'll test mine tomorrow and see what I get.

Read carefully - no voltage drop..

I just changed my GPR out on my 99.Before I changed it, the guage on the dash would not flinch when I turned the switch on for pre heat.After I switched GPR,the guage instantly reads in the minus even after the light goes out.Then it starts coming back to normal position as the glow plugs heats up.Fixed mine. Do not buy a autolite relay,get the motorcraft oem one.

I bought this setup for mine I put the relay on but have not converted it over manual yet

hit read full details


http://www.ebay.com/itm/Ford-diesel-glow-plug-relay-Manual-controller-solenoid-/270485301931?pt=Motors_Car_Truck_Parts_Accessories&hash=item3efa2e2aab

DFI429 wrote:

David Cole wrote:...Turn key on and the output side was as 11.5V, but the kicker is that the input side also read 11.5V

Doug Rahn wrote:...More than .3V drop and it's no good. I'll test mine tomorrow and see what I get.

Read carefully - no voltage drop..

The first time I checked it before topping the battery off there was a voltage drop. After I charged the battery there wasn'r one across the GPR. Intermittent, perhaps the contacts in the GPR are sticking.
'

David Cole wrote:

DFI429 wrote:

David Cole wrote:...Turn key on and the output side was as 11.5V, but the kicker is that the input side also read 11.5V

Doug Rahn wrote:...More than .3V drop and it's no good. I'll test mine tomorrow and see what I get.

Read carefully - no voltage drop..

The first time I checked it before topping the battery off there was a voltage drop.  After I charged the battery there wasn'r one across the GPR.  Intermittent, perhaps the contacts in the GPR are sticking.
'

David that what mine did before it finally went out, one time it check good then it wouldn't.

DFI429 wrote:

David Cole wrote:...Turn key on and the output side was as 11.5V, but the kicker is that the input side also read 11.5V

Doug Rahn wrote:I haven't tested the relay on mine yet, but after doing a ton of searching about the problem I found the same thing you did. More than .3V drop and it's no good.

Read carefully - no voltage drop..

Read carefully. I added in the previous sentence you had omitted. I was merely stating that I had read the same thing he did about voltage drop.

update:

Installed the new Motorcraft GPR. That was the ticket.  Starts much easier now when cold.  

http://www.amazon.com/Motorcraft-DY861-Glow-Plug-Switch/dp/B000C5DJDI/ref=sr_1_1?ie=UTF8&qid=1425582030&sr=8-1&keywords=motorcraft+DY861

Hmm, does my 96 f-450 wrecker have one of these? Where is this problem relay located? when i got it several years ago i put new GP's in because it didn't start good but they didn't help. Also put on the solenoid look'n piece on top of the engine with no change,still pia to start if its under 40*!

cool40 wrote:Hmm, does my 96 f-450 wrecker have one of these? Where is this problem relay located? when i got it several years ago i put new GP's in because it didn't start good but they didn't help. Also put on the solenoid look'n piece on top of the engine with no change,still pia to start if its under 40*!

The solenoid look'n piece is what they call the relay buy the kit I posted and convert it to manual it by passes the timer and you can heat the gp longer if needed

Thanks Jim,i may check the voltage on mine and see if it's been the problem all along. I like the old truck but always hated cold weather starting this thing. I can plug it up for an hour and it'll kick right off.

cool40 wrote:Thanks Jim,i may check the voltage on mine and see if it's been the problem all along. I like the old truck but always hated cold weather starting this thing. I can plug it up for an hour and it'll kick right off.

The relay looks just like a ford starter solenoid but it is different the starter solenoid will not work  the glow plugs. I had one that was marked on the box for glow plugs that was behind the seat of my old 93 f250 when I bought it. I put it on my 95 and it would not work looked up the number on the box and it was a starter solenoid.

I know i bought this one for glow plugs as I recall it was pretty expensive. It's a carquest so it could be a pos! I'll be happy if it is and i can fix this thing where it'll start.

I ordered a GPR from this guy today,   monster . Then this morning when I walked out of Autozone I saw a puddle under the truck, Diesel   . Sweated bullets driving back home   . With Mike's help I found out where it was coming from, diesel all down in the valley, the O rings on the Fuel Bowl Drain Valve. He had those on his web site so I ordered those also.

http://www.dieselorings.com/16-009-white-rodgers-stancor-586-902-monster-glow-plug-relay.html

I had installed the new GPR and that didn't fix my hard start on cold days. I ended up taking it to a dealer and let them run the diagnostics to pin point the problem. I just got it back today and as it turned out it was bad "O" rings on the injectors and bad under valve cover injector harnesses. Boy, did that cost me an arm and a leg Even though it was running good before, I can definitely tell a difference now, but I'll have to wait until next winter to see if that took care of the starts on cold days. It should from what I've been reading on the web.

Last thing to get working correctly on this truck is the A/C, warm weather is here.