Tahoe Cranks But Won't Start

[Stratosurfer]

All,
Tahoe cranks and acts like some firing but no start.
Checked:
PMD: new backup plugged in: no joy.
Fuel Pressure: Plenty of fuel pressure with boost pump out the top of the Racor and the drain in startup sequence.
Relay: Verified all relays in relay box seated properly.
IP is new in last 20K miles from GM.
NO CODES
It has been really cold and the truck was hard to crank when it was down around 15F even with block heater. Thought it was the cold.
I put in anti-gel in the Tahoe and Sub before the blast hit early last week. Suburban has been starting and is starting fine.
I installed a Heath Max E Tork Saturday before last along with Turbo Master. After installed Tahoe started right up.
I got out Heath's manual and even followed the procedure to reset the timing.
Cranks but no start.
Any thoughts.
Thanks

[racer55]

A bit lost with your explanation,you said it started right up and no no start?
Was the no start after the timing relearn or has it run fine for a week and now has quit?

[Stratosurfer]

A bit lost with your explanation,you said it started right up and no no start?
Was the no start after the timing relearn or has it run fine for a week and now has quit?

It has run for a week and now won't start. This week has been on block heat all week as we had few days above 20F, records for Central Texas.

After an hour on the charger and block heat (its 40F and dropping) the Tahoe started. I drove and put in 10 gals fresh diesel in case any issues from the freezing weather last week. Could my ECU have been on a learning curve during a crazy time (very sub freezing weather), and this cause a problem?
Thanks

[twaddle]

Have you checked the operation of the glow plugs and any associated circuitry?
If it will fire up OK with the batteries fully charged and the block heater keeping things cosy it can point to a faulty glow plug system.

What make of PMD do you have plugged in?

Good luck

Jim

[Stratosurfer]

Have you checked the operation of the glow plugs and any associated circuitry?
If it will fire up OK with the batteries fully charged and the block heater keeping things cosy it can point to a faulty glow plug system.

What make of PMD do you have plugged in?

Jim,
I have very little (none?) knowledge of the glow plug system. Where should I start looking?
I have the Dipaco PMD and have Plugged in my backup (new gray Stanadyne) to confirm that PMD is not the issue.

[racer55]

You can check the glow cicuit out with a test light to see if power is going to each glow plug,then use an ohm meter to see if the glows themselves are burnt out.
And there can also be a situation where the glow plug relay will allow voltage to pass through but not current when its contacts get burnt.

So you will want voltage and current to flow to the glows(the volt meter in the dash is a good indication of current flow-it will fall and rise when the glow cycle starts/stops).providing your glow controller is working.
And you want glow plugs capable of glowing,the ohm test should yield readings of around 1-2 ohms from each plug,anything else would need replacement.

The coolant sensor in the t-stat housing tells the ecm to cycle the glows so that could be a place to look also.

A call to Heath might be in order as well.

[DaveBr]

My truck was very hard to start untill I changed glow plugs. They don't last forever.

[tommac95]

A 6.5L in decent condition starts very well -- mine started with no glows at 35*F.

I concur that you want check into glowplug system.

If you have a meter which handles 20Amps DC , a good measure is to put that in series with each plug-- it will peg initially , then moderate as the element heats , and resistance increases.
The plugs die regularly {get good ones from Kennedy-- they last longer} ;
the GloPlugRelay dies occasionally ; the wires feeding power to the Plugs are FusibleLinks... and they occasionally fail "Open".

The battery cabling to the alternator and/or starter may have expired as well (if it cranks the starter cable is fine).


You can check the FIP output by 'cracking' loose one fuel injector line before cranking over the engine. Some fuel should leak/spray from the loose connection.

The anti-gel will take a while to circulate .... But the engine should Start and Run for a while before the filter clogs with wax crystals precipitating out of the fuel (even if the frigidity persists).

I had an old VW (50HP) diesel that leaked fuel at the FIP whenever ambient temp dropped below about 14*F.

The cold may have deranged some mechanical ... or electrical connections. Spring beckons ;
good luck with it.