Will not start when cold!!!!!

[jhnlennon]

I have a mysterious starting situation with my 91 in my sig. and I have done everything I can think of to solve it. The first thing I have done is install brand new motorcraft plugs( I ohm'ed them before I installed them too). Then I replaced the glow plug relay and cleaned out the connector that supplys power to the relay and made sure both fuseable links were good. Then I did the manual glow plug conversion and replaced all the fuel return lines. Next came a new starter and tested the power cable to it for resistance. After doing all this it still will not start if it is below 30 degrees. If I plug it in it will fire right off. I know my glow plugs are working because my volt gauge goes way down when I activate them manually. I can glow them for 15 seconds 2 times in a row and it wont even attempt to fire. Plug it in for 2 hrs and bam fires on the first crank! The injectors have been replaced recently and I just timed the engine to about 8 degrees and my advance mech. seems to be working. The cold advance and fast idle is working too. I did a compression check and I have over 400 psi on all cylinders after about 4 or 5 revolutions. I doubt I have a fuel drain-off issue because when I plug it in it fires right off without a hitch. What gives? I am starting to get very frustrated

 

[RLDSL]

How old is your injection pump? is the high idle solenoid kicking in when you set the throttle before starting it? do you depress the throttle at least halfway and hold it there while cranking ( if below 30 to the floor ) till it catches then quickly release the throttle?

 

[jhnlennon]

No idea how old the injection pump is, and yes I have it floored when I am cranking, and nothing. If I plug it in for a couple hrs it will fire right off. If its cold I can crank forever it seems and it wont even pop off at all.

 

[Al_E]

Where you at in Wi? I am in Waupun and might be able to give ya a hand.

 

[jhnlennon]

Where you at in Wi? I am in Waupun and might be able to give ya a hand.

Near the fox cities

 

[david85]

There is a 6 wire connector near the dipstick of the engine. The biggest wire that goes through that connector should be orange. Thats the wire for the glow plugs. This connector is underdesigned for the amount of amp draw and can sometimes burn if even the slightest corrosion of other imperfection sets in.

Take the connector apart and see if there are any signs of a weak contact in there. A falt at this connector can cause enough resistance to still put draw on the battery but not enough power to properly heat up the glow plugs.

 

[suv7734]

There is a 6 wire connector near the dipstick of the engine. The biggest wire that goes through that connector should be orange. Thats the wire for the glow plugs. This connector is underdesigned for the amount of amp draw and can sometimes burn if even the slightest corrosion of other imperfection sets in.

Take the connector apart and see if there are any signs of a weak contact in there. A falt at this connector can cause enough resistance to still put draw on the battery but not enough power to properly heat up the glow plugs.

+1

On mine there were actually two wires running through that connector. The connector is not rated for enough amperage to carry the current necessary for the glow plugs and the connector started to melt (any resistance from corrosion etc. will cause this). My cure was to cut the wires out of the connector, clean them up, splice them together and seal the connection. It's been that way for 10+ years and no problem... so far.

 

[LCAM-01XA]

How about entirely replacing the two main power wires with a single 4-gauge hi-current cable wired to the battery through a 250A megafuse?

 

[jhnlennon]

Thats the connector I talked about in my first post that I pulled apart and cleaned. It wasnt melted or even dirty. I am starting to think my pump is weak although I have no other problems with the truck other than the cold start thing. It will start fine if plugged in and runs great otherwise.

 

[Andylad13]

if it starts great when plugged in then its a glow plug problem. maybe the controller isnt functioning properly.

 

[jhnlennon]

As I stated in the first post, I bypassed the controller and went manually with the glow plugs. I can glow them for 15 sec. 2 times in a row and nothing. My volt gauge is swinging way down too. Even with resistance in the circuit you would think that glowing them twice in a row would be enough to get the truck going.

 

[Andylad13]

oh oh i thought you had the switch in addition with the manual override. well then something is definatly wrong. you might have a break in the actual plug wires that go from plug to plug and only some are getting it. pull out the plugs and connect them to the wires, i think you'll have to ground them too, dont know how, but try it. then have someone hold the push button and see if everything is working as it should. chances are, i think you wont be seeing much "glowing", even though the volt meter goes down.

 

[Agnem]

I can glow them for 15 sec. 2 times in a row and nothing. ....

And how many times in a row have you done that? If your not waiting at least a minute between those 15 seconds, you could very well burn them out. However, it doesn't sound to me like they are working, so you may be safe. Sort of. Take a voltage measurement at the #2 glow plug (you'll have to get creative to make contact). You should see around 6 volts when the glow cycle starts, and slowly rise towards battery voltage by 15 seconds. If it isn't doing that, you've got a bad contactor, wiring, or plugs.

 

[jhnlennon]

I just checked them all again with a test light and they are all good. With the motor running, when I activate the plugs manually there is definately a draw, the volt gauge goes way down and you can hear the load on the motor. I checked each individual wire going to the glow plugs with my dvom by hooking one lead to the glow plug end and the other to where it hooks up to the controller and I have no resistance issues there. And like I said the relay was replaced and the controller still works. When its cold I get about a 12 second glow time. I am ALMOST positive my plugs are working.

 

[LCAM-01XA]

12 seconds is too short - I see near 20 seconds of initial glow time, no afterglow tho, I use ZD-9s that are only few months old, and I never really used my manual override switch for them (I only have it in case one or more plugs go out), it's all automatic controller action.