Won't Start When Below 45 Degrees?

10000degrees · **Joined:** Thu Apr 08, 2010 7:14 pm **Posts:** 30

Hey all,

I have a strange issue, my Libby won't start if it is below 45-50 or so after sitting for 6 or more hours. I have the in tank lift pump, pretty sure there is no air in the lines in the a.m. when I try to start, however I am about to junk that stupid filter head, will still get the air in lines CEL and limp, if I really goose it hard for an extended time... :evil:

So, that said there still may be an air issue at start up.. But, to start it when it fails, I just plug in the block heater for about 10-20 minutes and it fires right up, don't need to bleed, just a little block heat and it fires. I checked the glow plugs this weekend prior to installing the pump and found that all four read .4 ohms and the meter showed 3.5-3.6 volts at the relay on each plug. I believe that I read on here that the voltage doesn't show the whole 7 volts.. The only things I didn't do was to test direct at the plugs and pull one out and "light" it up. I'm just really frustrated with the cool temp no start without plug in.

Any thoughts appreciated!

Jerry

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

This issue could be caused by the PCV on the fuel rail. With air in fuel it might also have long term wear issues with the fuel metering valve on the CP3 pump. Could you measure the fuel return flow when the engine does and does not start?

805gregg · **Posted:** Mon Jan 24, 2011 11:46 pm

Does it turn over? Do you have a block heater? Plug it in, maybe it's a glow plug issue.

JL Rockies · **Posted:** Tue Jan 25, 2011 1:55 pm

805gregg wrote:

Does it turn over? Do you have a block heater? Plug it in, maybe it's a glow plug issue.

Welcome to the party.

10000degrees · **Joined:** Thu Apr 08, 2010 7:14 pm **Posts:** 30

Thanks for the replies.

It cranks just fine and I only have to apply block heat for about 10-20 min.

Keith, thanks for chiming in. Would I measure at the fuel return while cranking when its too cold and I know that it will not start? Measure also when warmed a bit? I have a 500ml graduated cylinder for accurate measurement too. Is the part on the ip replaceable? I am already leaning to that being an issue. It has always taken 3-6 full revolutions for the engine to fire when warmed. The original in line lift pump helped that and now the in tank has gotten it down to about two to three revs. Btw, the tune has been outstanding!

10000degrees · **Joined:** Thu Apr 08, 2010 7:14 pm **Posts:** 30

Ok, followed Keith's advice and checked the pcv valve on the back of the fuel rail.. No fuel ran out of it when I cranked it below the starting on-its-own temp (over 50.) I have an in tank lift pump and forgot about it, pumped fuel out of the disconnected hose from the pcv to return manifold, but otherwise no fuel from anywhere else. Put it all back together and plugged in the block heater for about 15 min and it fired right up.

Even if the glow plugs are shot, I would think that the Lib would fire at anything over 30-35 or so, uber high injection pressures and all...

I am starting to suspect the fuel metering valve on the cp3 now. Is there any way to test fuel pressure without a live data scan tool? Like maybe taking an ohm reading off of the pressure transducer on the fuel rail?

One trick left is to spoof the temp sensor into thinking the engine is warmer than it is... I will re-iterate that I measured .4 ohms on all four glow plugs on a 50-ish degree engine and also measured 3.6 volts during glow plug cycling. I will try this the next chance I get, probably not tomorrow morning, but on Friday. Should get down into the upper 30's Thursday night. I have the gut feeling that it will fire right up if the system thinks the block is warmer than it really is. <--- Hopefully not just wishful thinking!

Won't Start When Below 45 Degrees?

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