Cold Start Fuel System Questions

[FEF]

All,

I have a question about cold starting, glow plugs, the fuel system system, and how it's all supposed to work when cold (about 30F).

I've replaced the glow plugs with G60s on the right bank. I still need to do the left bank, but I assume they are working as I show current going through the connections. I've taken out most everything out of the glow circuit except the sensor in the head and the stock relay (near teh vacume pump). A clear filter is put before the firewall filter, hoping to see if I have stuff coming from the tank. Many of the return lines have been replaced, and the system burped at the injector fittings.

Once warm, the engine runs pretty darn well, but it's really tough to start cold. I've noticed that when the engine's running, the clear filter (down stream from the fuel pump) is mostly full. When it not running, the filter is empty. Should the filter that's just before the firewall filter drain?

I admit I have only 4 new glow plugs. Is it unreasonable to expect 4 known good plugs, on the same bank, start at about 30F? Is that the main issue, if guessing?

Having not seen what these engines should do, I'm at a disadvantage.

I am running B100, but I have the same issue with dino oil.

I suppose it could be compression, but I have virtually no blow-by.

Injectors? Sure. Is having them tested the only way to rule it out?

IP timing? I have reason to believe timing may be retarded. It's just a gut feeling really. I guess I'll have to look into how to check it. With Mercedes diesels, we do a drip test. Is there a drip procedure, or do I have to spend $200 for a timing rig.

Thanks in advance for the help.

[allformike]

well i would finish putting in the other glow plugs and that will help with the starting. the filter should not be having fuel drain back out of the filter, there could be a fuel leak. mine was doing the same thing a few months ago and i found a leak on top of the tank so i didn't see any fuel on the ground. mine still ran with the leak, but it was not up to par like i thought it should be. if i'm correct, i think that glow plugs are supposed to have a negative voltage going through them. are you sure that they are working, do you if that the glow controller is functioning properly? and if you are not, i as well as everyone here would say that you should be useing POWER SERVICE FUEL ADDITIVE-THE WHITE BOTTLE IS FOR WINTER AND HELP WITH LUBRICATION AND PROTECTION FROM FUEL GELLING.

my answers are basic and everyone else can give you more details. hope this help:)

[HammerWerf]

THe glow plugs are connected to the positive side of the battery. If you connect the GP's to the negative side of the battery, nothing should happen. The engine block is the ground for the GP's.

Your engine should be capable of starting on four GP's. Start-up will be a bit rough, with the other four cylinders puffing white smoke till they warm up a bit and start firing. Ran my '83 in that configuration last winter. This winter, I was able to get the '99 to start on one GP at low 30's for about a week before I got too checking GP's. Found 5 of 6 I tested dead. Replaced all six. Still have to get behind the turbo.

HammerWerf

[FEF]

So Clearly, there's something not right.

It's either fuel, timing, or compression. I guess I'll have to dig deeper.

[arveetek]

How long is your glow time? The 60G's require a longer glow cycle than the stock controller is designed for. At 30 degrees, the 60G's should glow for at least 10 seconds before trying to start.

I would disagree with others and say that 4 good plugs is not enough to start a 6.2L at 30 degrees. My personal experience has been that even 2 or 3 bad plugs cause a really hard start at that temperature, and that 4 bad plugs might result in a no start condition.

I would first get all 8 plugs up to par, and then adjust the glow time if necessary, and then see what happens.

Casey

[93GMCSierra]

I would be sure your lift pump is running, and pressurizing correctly, as the drain back is indication of fuel problem.

[Peter J. Bierman]

My TTD has lowered compression and denifetly let me know when one or two plugs are dead, very rough idle for like 30 seconds and lots of white smoke, but it start at 5 plugs when freezing a little.

If you are not able to find a leak or other couse for the drainback, you can put in an electric liftpump and hook it to the glow relais so you have always fuel at start up, the pump stops when the glowplugs go off, so no safety isues.
The lift pump lets the fuel right through when the engineis running.

I made this setup in my truck and it's an exeptionaly good starter.:)

Peter