Having a cold start issue with the 91. After the grid heaters cycle, you have to give it throttle or it will not stay running. While it is running it surges randomly for about a minute, then it runs normally from there on. No other issues once it's warmed up.
Any ideas

 

I think the grid heaters are not working mine will do that to as I can not figure out my grid heater problem.

Mine will run okay after a minute too but mine anytime I fire it up when cold won't go past 1200 without pushing blue n couching till it's idled for a few minutes like it should when cold.

 

any gelling issues yet? bad fuel filter?

Could also very likely be an air leak in your line. Does it do this every time it gets cold, just recently, or every day it sits overnight?

 

Fuel filter is pretty recent. it's not cold enough for jelling and fuel isn't old enough for it.

Most times it will it doesn't act like air in the line it idles smooth it's just like the fuel is not burning fully till it runs for a few minutes. Umm I can leave it all day at fairly cool temps n see it happen. I replaced the lift pump also about 2 months ago it was draining back into the tank it's a carter so should be a good one.

 

does it haze white smoke?? if its cold and the heaters aren't working i'd say its incomplete burning. our tractor will do that when its cold it hazes white smoke and will have a lope enless we bring the engine up to around 1000-1200 rpm surging goes away but smokes there till its warm.

 

My grid heaters are working and I haven't noticed any change in how they cycle.
It is not cold enough for any gelling yet, but my "additive" includes an anti-gell. Got caught on that once before.
The fuel filter is recent and nothing odd drains out of it.
It happens first start of the morning after it has "cold soaked" all night. Doesn't do it later in the day after the sun has warmed thing up a bit.
As for hazing, It has been doing that for while after I put on the 4" exhaust a year ago.
If, like 9MM, I hold the RPM up like 1200 or more, it runs a little rough for a while but then smooths out and all is well.
I kinda have a sneaking suspicion my use of WMO may be the culprit. So it will be out of my fuel mix for a while and replaced with a high dose of Power Service Dieselklean.

 

Well, the power service and fresh from the pump fuel hasn't made any difference. Now that it is getting colder it is getting worse. Looks like I will be parking my truck for the winter.

 

I got mine figured out it was the intake temp sensor unplug it then turn on the key see the wait to start light comes on or put your finger on the heater grid case if it gets warm its working you will hear a click after the click the wts light should start flashing. Turn off the key n plug that sensor in till u get it fixed. Plug it in for the time being that's all I had to do with mine.

 

Put an IR thermometer on the grid heater block and it warmed up. With or without the sensor plugged in. My other truck had the same results, but it starts fine.

 

That's weird. Hows your lift pump might be draining fuel back into the tank. Mine did that n caused me problems when I let it sit for a few hours.

 

If it were the lift pump it would do it all the time. Not just when its cold outside. If the engine is warm, it doesn't happen even though it has not been run for a few days.

 

whats your timing at? Try to get initial timing close-ish to stock settings, these trucks start good in the cold with stock timing.

 

The timing is at the stock 1.25mm. I had it reset last fall when the front main seal had to be replaced. Prior to that, it had been 1 tooth advanced by the previous owner.

 

KSB work?

To test, warm the engine and take a small jumper wire from the + on the battery to the KSB. The idle note should change slightly. If it doesn't work, the cold start timing advance is not helping. If it works then, on a cold morning, tie it up before you start the engine. See if it starts easier or not. If it does, the IAT sensor is going/has gone out.

FWIW, I went 400 miles with my KSB switch on. No problems with the pump and netted 1mpg AVG more.

 

Yes it does work. The only thing I can think of at this point is that it has something to do with the M&H timing spacer considering the anomalies I've noted with and without it installed. I'm going to pull it back off and see what happens.