2001 7.3L cold start/low power/bad mpg issues
 

I have a 2001 7.3L with 111,000 miles on it. In the last couple years it has gone from being my daily driver to a once in a while hauling truck so my issues haven't been urgent but now they ate getting irritating. The issues started as cold start issues. Anything less than 30F and it would not start at all. I also noticed a slight reduction in my fuel mileage. I am one of those who keeps religious records. Moved to a state that never got cold, lived close enough to walk to work, truck got parked and rarely driven for about a year, moved back to a state with ridiculously cold weather and problems started again. Long crank on start up, won't start when it's cold, blows white/blue for several minutes on cold start, blows white/blue for a few seconds on warm day starts, gets a consistent 10 mph empty or hauling, completely gutless as in can't hold 65 up a 4% grade with a 2 place sled trailer with one sled in it.

Some interesting facts, my husband calls it a Friday truck because of the litany of issues starting with a bad battery from the factory, which led to the replacement of the wiring harness, two alternators, a starter, clutch pin of sorts, crank position sensor (some debate as to what was actually replaced with the recall, done by a private shop before cam sensor recall) and several glow plug relays and some usual wear parts. I also had a bad mechanic for a while which resulted in the improper installation of the oil plug in where I lost ~4 gallons of oil on the highway doing 65, a mistake of the AC compressor for the alternator and subsequent bashing with a rock which cracked the housing, and loss of my fuel filter cap. I fired him. I'm sure the last two have nothing to do with my current issues, I just added them for smiles and spite.

So the question is, what would cause these symptoms? Husband wants to say injectors or something related. I'm thinking if I'm losing mileage due to injectors, say the tips are damaged and its dumping fuel into the cylinders wouldn't I see some smoking? My automotive knowledge is pretty basic. I know the difference between an AC compressor and an alternator. Anyway ideas theories and general comments are appreciated!

not that i am an expert, but sounds like your glow plugs might not be working

Nice long list of issues there...

First off I would bet your glow plug relay is shot. That would explain you cold start issues. That would be low hanging fruit, so to speak. Do some research here and tackle that one first.

And I would not have fired that mechanic. I would have taken him out back and beat him.:-X04

Maybe if a moderator could move this to the 99-03 7.3 forum . . .

Move to Texas, problem solved. :-X04

The quickest way to properly diagnose this issue, is to have someone with an AE or Ford NGS scan the truck for codes and perform a Cylinder Contribution Test to see what injectors may be failing or whatelse may be going on.

Hard starts in the cold definitely suggests that the glow plug relay needs to be replaced. There is a bigger and better version to replace it with that does an awesome job.

Welcome to guzzle's Stancor GPR replacement Mod Web Page

It also sounds like either the UVCH or Under Valve Cover Harness is loose and may need the 50 cent mod.

Ford Truck Enthusiasts Forums - View Single Post - 50 cent mod

If I lived closer, I'd lend a hand, but these should help you on your way...

I also think the glow plugs are not working. Since the truck was sitting most of the time and it being 11 years oid I would replace the injector o rings and also before you do that you might want to make sure the Under Valve Cover Harness is tight

I'm wondering if there may be a fueling issue on top of the GP relay.

Thanks guys, some great places to start, keep them coming ! Definitely not a glow plug relay, checked that. I've done so many relays I swear the truck says "relay" to me when as I'm cranking. Basically it won't start when it's 80 when a relay goes.

If thread needs moved, I would appreciate. Looked like the right place :).

Previous mechanic was my ex husband LOL!

Really? 80 degrees shouldn't require glow plugs. Does it smoke while cranking?

How old are the batteries?

Technically it's not in the wrong place.:)

I usually move the diesel threads to their corresponding diesel forums because that's generally where they get the best response and information. I'll be glad to move yours there if you'd like.....just say the word.:-X22

The glow plugs themselves may need replaced. They could be worn down to the point they are ineffective.

Codes and a contribution test are good ideas. Buzz test, too.

Look for places where you may be loosing boost pressure. Can you hear the turbo spooling up?

Shouldn't require glow plugs at 80 but it does. I live at high altitude and I noticed my husbands 7.3 does the same thing too since we moved. Doesn't smoke and the batteries are two years old. Put a trickle charger on it since it doesn't get driven often.


Tested the glow plugs and they are fine. I know there are some minor leaks with the turbo but you can hear it spooling. It's had maybe two check engine light come on, but never threw a code.

If the Check Engine Light came on there is a code or codes. Most parts houses don't have code readers that can read the codes off the 7.3's. Getting those codes should be the first place to start.

There is plenty of oil in it, right? My only thought/concern is perhaps due to the oil plug failing, there may or may not be damage to the High-Pressure-Oil-Pump (HPOP). A HPOP that isn't pumping well would lead to injector related symptoms because the pump itself pumps engine oil at a high pressure and volume like a hydraulic pump and holds the pressure against the injectors until needed. The high pressure oil is what actually powers the injectors. However normally this would be a problem at low RPM and get worse as RPMs rise since the injectors demand more volume/pressure than the pump can supply.

This doesn't sound like your problem thankfully, but just a thought to add.

Good luck and I hope you get to the bottom of it soon.