No start when cool (not even cold yet)

Garbage_Mechanic · Apr 11, 2014

I have a 2002 F250 7.3 that has a cold start problem. I'm pretty sure I have a diagnostic plan but it can't hurt to see what you all might add to it!
The truck has about 260k on it. It is supposed to have had new injectors within a year (from where who knows) and new glow plugs recently. Then one new injector again. If it is below 40 degrees it will not start unless plugged in for 3-4 hours. Once started it seems to run pretty much how a a stock 7.3 should run. I got to see is do it for the first time today, but the laptop with Auto E was not available. It seemed to be trying to start on just one cylinder. People were in a hurry so, much to my dislike the tiniest whiff of either and it started just like there isn't a problem. I'll lay out my diagnostic plan in the next post....

Garbage_Mechanic · Apr 11, 2014

So here is what I'm thinking:

Verify cranking speed and batteries are ok. Sounded OK but double check.

Check build up of HPO pressure relavent to cranking and start up. Check with a gauge and with Auto E.

If there is an issue with HPO build up (500 psi minimum to start right?)
Check and be sure HPOP reservior is full. If res is full look for IPR or HPOP issue. I beleive the pump can be deadheaded and chcked for max psi buid up that way.

check fuel pressure, though I expect if it had low fuel PSI it wouldn't go down the road good.

check blowby with warm engine.

If it seems HPO is ok, then look for low compression or electrical / sensor issue.

Anthing I'm missing?

mustube · Apr 11, 2014

If you have AE, do a cold buzz test and cylinder contribution test. Check to make sure the glow plugs are working with a volt meter too. If your UVCHs are bad you might have a few not working. My truck was doing the same thing, and it was worn out injectors.

Garbage_Mechanic · Apr 11, 2014

Since the truck hasn't been in my fleet till now I really do have to check everything. I suspect something in the HPO system but have to check everything.

golfer · Apr 11, 2014

http://swampsdiesel.com/files/7.3LInjectorDiagnostic.pdf

Rideracelivemx7 · Apr 11, 2014

check your relay, even on a 40 to 45 degree day my truck will not start unless i let the glow plugs warm up for a few second. new injectors, twin hpops and key on fuel pressure. if i just go out and crank it with out the GPs it will just dump white smoke and fart at me. 5 second on the GPs and it will fire up like nothing was wrong.

You can go out and cross the 2 big terminal posts on the relay for 30 second with a screw driver or something. then crank it to see if it helps.

littleredstroker · Apr 11, 2014

Rideracelivemx7 said:
check your relay, even on a 40 to 45 degree day my truck will not start unless i let the glow plugs warm up for a few second. new injectors, twin hpops and key on fuel pressure. if i just go out and crank it with out the GPs it will just dump white smoke and fart at me. 5 second on the GPs and it will fire up like nothing was wrong.

You can go out and cross the 2 big terminal posts on the relay for 30 second with a screw driver or something. then crank it to see if it helps.

THIS