i have a 97 f-350 psd, when the weather gets below 30 i plug the truck in and when i go to start it, it still has a very rought start to the point where it kills the batterys. any suggestions ??

thanks,
tyler

 

First, unless you are cranking on it for an awfully long time it should not kill your batteries, I would suggest having them load tested seperately (disconnect the battery cables and test each one "load test not just voltage") just about any parts place will do this for free. It takes alot of juice to crank and fire the injectors at the same time and if your batteries are weak it will (1.) not spin over fast enough, (2.) will not have enough juice to fire the injectors.

Second, check your GPR (glow plug relay) and make sure it's working properly.

Third, make sure your getting tach movement while cranking. If not then change your CPS (Cam Position Senor).

Let us know what you find.

 

To do a quick test of your glow plug system locate the glow plug relay under the engine cover (plastic hood looking thing on top of the fuel filter, draw a line from center of filter to right headlight and the relay is about 6” from the filter housing under that line). When the truck is having a hard time starting use a jumper cable and jump between the two large terminals for 90 seconds or so. This bypasses the relay - the glowplugs draw a bit of current so be ready for a spark or two. Disconnect the jumper and try to start the truck. If it starts fine then your problem is either the relay or what controls it.

To diagnose the relay further you will need a digital voltmeter. With key off you should have battery voltage to one large terminal and nothing to the other large or either of the small terminals.
With key on for the first two minutes or so you should have battery voltage to both large and one small terminal. The other small terminal should show ground. This shows the relay active.
With the key on and after the glow plug cycle has finished you should have battery voltage to one large and both small terminals. The computer activates the relay by grounding the second small terminal thus activating the relay.

It is possible to have battery voltage to both large terminals when the relay is active and still have a bad relay. If the contacts inside are pitted or corroded you may have enough voltage passing through it to light a test light but not enough to actually run the glow plugs. Generally you will lose voltage across the relay if this has happened. This is why you need a meter (preferably digital so you can test the glow plugs if you need to) rather than a test light to check the relay. With the glow plugs on (first minute or so after turning the key on in cooler weather) and the engine not running check the voltage at both of the large posts on the relay. There should be no more than .3 volts difference (less is better) and the one from the batteries (always hot) should have 12.5 volts or so at the relay post.
If you determine the glow plug relay is operating as it should, check the information on the glow plug system.

If you decide the relay is OK and you need to get into the glow plug system I have an excellent article by Carpentractor with a couple updates and comments saved in MS Word format I can send you along with the glow plug relay info above and a copy of the thread I started when my UVC harness shorted out while I was out of town. If you need the information send me an email at Believer45@gmail.com with GLOW PLUG INFORMATION in the subject line, let me know what site you saw this on and what email to use and I will reply with three attachments.

Dave / Believer45

 

How long do you have it plugged in before you attempt to start it?
It takes 3-4 hours to get the engine warm enough to start OK.

Does it start OK after you had it running for a while..2-3 minutes or so?

If it's been plugged in 3-4 hours and still has a hard start condition then either the block heater isn't working or you have a fuel or HPO system problem.
Check the HPOP oil level on your next cold start CLICK HERE
Check the fuel pressure while cranking...should be more than 30 psi. You might want to change the fuel filter.

 

i have the truck plugged in for at least 8 or 9 hours, from the time i get home until i go to school. it will start just fine after a few minutes of running.

tyler

 

Are you sure the block heater is working?

 

is than an easy way to check this?

 

2 ways that I know of:
Ohm it out from one prong of the AC plug to the other. Resistance should be around 12 - 14 ohms or so. When I plug mine in and it's quiet, I can hear the coolant start to boil about 10 - 15 seconds after plugging it in, then it gets quiet. If your resistance is too high but not infinity it's probably bad. If it reads infinity, it could be blown or you could just have a broken cord or AC plug.