Gentlemen:

I am new to the forum, but am a two-year owner of a 1997 Powerstroke 7.3 Turbo.

I have some questions regarding the electrical system to help me diagnose future ills, and if anyone could answer some or all I would appreciate it.

How long (seconds) should it crank before it fires, with glow plugs functioning properly? How long without glow plugs? I live in Florida.

How fast should it turn over when cranking?

A new CPS still does not show any tachometer reading when cranking. Is this a bad thing if it starts reliably?

How long should Motocraft batteries last, under good electrical conditions? For two years they load tested good.

I left loose terminals on one battery after replacing the glow plug relay yesterday because I am stupid and shallow and self-centered, then started it twice for short trips. Batteries dead this AM. Should I be surprised?

I know I have a failed glow plug, diagnosed with a test light. Would that cause the starting times to go from 1-2 cranking seconds to 2-5 cranking seconds?

Thanks!
cauchy

 

Well I'll try and answer some of your questions.

Cranking: Alot depends on the engine (wear, age, starter, batteries, injectors, HPOP system, injector wiring, etc.) you get the picture. But normally around 3 sec. on average. In Florida you don't need glow plugs. I live in southwest Ga. and I have a glow plug relay cut off switch. My glow plugs do not activate unless I turn them on with the switch. I never use my glow plugs unless its in the low 30's.

I don't know the exact RPM but it has to spin over fast enough for the HPOP to develop around 500 psi before the injectors will fire.

New CPS: If it cranks and runs O.K. but you do not have any tach movement, you have an interruption in either the signal to the tach or power to the tach. If the CPS is bad the truck will not start. The CPS is what tells the PCM the timing of the engine.

Most batteries will last approx. 3-4 yrs. (some longer) with good maintenance.

Your batteries should recharge. Use a slow rate 2-5 amp charger on them for best results. With the neg. cables loose, you were drawing power but not putting a charge back into them.

Glow plugs should be checked with an ohm meter. tgbeggs did a good post on checking the valve cover connectors and associated wiring (do a search for his post). It may not be a glow plug but a bad connector or bad under valve cover wiring harness. Extended cranking time could be bad connector or wiring for injectors, depleted oil (needs changing), clogged fuel filter (needs changing) clogged screen on the FPR (needs cleaning), low fuel pressure (possible weak fuel pump), loose connector on ICP or IPR, IPR going bad, etc. etc.

This is just general info. If you have a problem, give us as much info as possible and someone on here should be able to help.

 

Plowhand:


Thanks. Most informative. It may be that the batteries are showing good under load test (100 amps) , but not so good in the truck (200+ amps). Am having plugs replaced today. Could do it myself if I wasn't back at work. Will keep you posted. Come to think of it, I never timed the cranking, just estimated, but it was slower recently so I started replacing a few things that needed to be replaced.

Cauchy

 

another thing to concider .

If your engine is turning over slower lately you might have a starter that is dragging. Also a starter that is going out can draw a lot more current from your batteries that one in good shape. Just something else to check.

 

Yes, I replaced the starter in May 2005 with a newly rebuilt one. It was weak from day 1, but it always started the beast. Just put a new one in last week and it cranks faster, just takes longer now to fire, and I am pretty sure it is a glow plug or the wire to it.

cauchy