Warm start issue

[Backwoods_BC]

Having a starting issue with my 91 6.2. GP relay is on the way out the door, just wired up a manual override. Getting a tiny bit of air in the return line if I leave it sit for a few hours, but dont notice any while running. It starts good when cold, it starts when its hot, but anywhere in between it seems to cough and sputter but not catch and fire. I am getting anywhere from none to ALOT of white smoke out the exhaust, the glows all work. My fast idle solenoid seems to be staying on, so I have disconnect it, and my GP relay. I get 12v at the advance solenoid, and I can hear it and the fuel shutoff click when I apply power to them. Oh, and it does it even if its just barely warm, I can put my hand on the engine and it is barely noticable. Im wondering if my timing is out, or if the idle speed is set wrong? any ideas?

[Alaska9076.2L]

I am newbie myself, but i just had a lot of help from DmaxMaverick and Robyn and they helped me with a starting issue that i had. DmaxMaverick explained to me how there can still be a lot of air present in fuel system and still allow for fuel smoke and IP pump operation, all is discussed in my last thread above yours. It seems odd to me that it only happens when your engine is in between temp thresholds, i have experience the no start when hot because of tolerances in the IP pump my only cure for that was either time or pack snow or ice around the IP pump to cool it, therefore tightening up the tolerances in the IP pump. Although mine is 85 6.2L it maybe like yours, the temp sensor in the engine head i believe feeds the cold advance and high idle. If ambient temp outside allows for it try operating vehicle throughout the day without using that portion of the system by disconnecting all electrical connection from IP pump except the fuel shut of course. This should eliminate your concern of IP pump timing. It sounded like you have already disconnect the high idle, and for all i know that works in conjuction with the timing advance:confused:. Your issue sounds a lot like the one i had. You may just be getting air in fuel system, which could cause the erratic fuel smoke from exhaust. Check out my last thread DmaxMaverick helped it make sense to me.
Dave

[Alaska9076.2L]

Where about in BC are you located?

[Robyn]

A warm "no start" with the engine just barely warm and the glow plugs
"offline" can be the result of several things.

As the injectors wear they do two things, loose POP pressure (the point at which the nozzle opens and admits fuel into the precup to start combustion.

The second thing that can happen to the injector is that the nozzle starts PEEING a stream instead of spraying a fine cone of fuel mist.

Large droplets or streams will not ignite and when the engine finally starts, will cough out a lot of white smoke

Another thing that can happen is that the injection pump can be worn enough that at low speed with the very thin fuel the plungers can't produce enough pressure to pop the injectors.

If the engine starts OK when COLD with the glows working and runs OK otherwise, I am suspect of the injectors first off and the IP second.

The injectors must be removed to have them tested but you can do a simple trick to test the IP for Heat failure.'

Dump a couple quarts of motor oil into a gallon of diesel, shake it well to mix and then dump this into the fule tank.

If the hot starting improves noticeably then the issue is a worn out IP.

If no improvement is noted then the injectors are likely the culprit.

A fresh set (have yours rebuilt is my prefered method) of injectors will likely rectify the situation.


Many times when the injectors get to the end of their lifespan these symptoms apear.

Usually an engine with poor injectors will also show whitish/blue smoke at idle even after running for a bit (warm)


If the oil trick helps then a freshen up on the IP is in order.

If you do the IP, do the injectors too.

How many miles on the rig since any injector/IP work has been done???

Once there is some heat in these engines, the glow plugs should not be needed to start.

Engine temps above 100F (coolant temp) should allow for a clean, no smoke startup.

Keep us posted


Missy

[Backwoods_BC]

Sorry for the delay in follow up. So far the truck seems to be starting fine with just the manual glow switch. 6 or 7 seconds of glow and she fires right up. Thanks for the replies.

[Robyn]

If you need to use glow in order to get the engine fired when its still slightly warm, the issue is probably that the injectors are at the end of the road.

Once the injectors reach a point that the POP pressure is too low, they also start to slobber (Pee a stream) rather than spray a fine mist.

This sort of condition makes starting difficult and smokey even when the engine is warm.

A fresh set of squirts will likely improve the overal starting and running of the engine and maybe even return some lost MPG.

On a hot day, even if the engine has not been run overnight, these engines if in good shape can in many cases be started without wating for the glow plugs.

Missy