Hard starting even when engine is warm

matt.m

Well-known member
Joined
May 28, 2007
Location
VT
TDI
2003 NB
I got my car started this morning (about 2F). It started decently, drove down to the grocery store. The engine got up to operating temps. When I got back in the car to head home, the engine just turned over. It took 15 seconds of putting the accelerator to the floor and it finally started. Now, even if I stop the engine, let it sit for a minute, it will struggle to start when warm. I checked the EGR valve and it moves freely. No fault code. Any ideas?
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Pushing down on the accelerator won't do anything until after the engine starts.

Maybe your fuel is gelling?

If you have a clear fuel line (section of) going to your IP look to see if you're getting any significant amount of air in the lines.

My hunch is fuel gelling. Cross your fingers that that's it, otherwise your IP might be the culprit.

When was the last time the fuel filter was changed?
 

matt.m

Well-known member
Joined
May 28, 2007
Location
VT
TDI
2003 NB
Last fuel filter replaced 10k ago. It's due for a draining. I don't have clear lines. Fuel *could* be gelling, but when I started the engine this morning for the first time, it started normally. It ran normally when driving. My fuel source adds kerosene usually around November, unless...they didn't. Filled up the tank yesterday. I had a new IP installed because the original failed about 50K ago. I've been pretty good about making sure the fuel filter gets changed when needed. Yes, I hope it's fuel.
 

maxmoo

Veteran Member
Joined
Jan 19, 2011
Location
Lakefield, Ontario, Canada
TDI
2000 golf, 2001 golf, 2000 beetle, 2003 wagon, 2004 golf, 2004 jetta, all diesels
Your sending unit/fuel pick-up, that is in your fuel tank, has a very small orifice that can and often will bridge/plug with debris, ice, and/or gelled fuel.
When this happens the vacuum greated by the inj pump trying to suck fuel will cause air to be sucked into the fuel system at the weakest link, usualy the thermo T at the filter. This all happens more easily in cold temps.
See....
https://www.youtube.com/watch?v=yRMTEAKsScE
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
No clear line... Why oh why did VW ever decide to not do that on some cars? (daughter's wagon is that way and I've been cursing this for some time now- I think I may have one on a spare IP I have)

Blockages in the tank's fuel pick-up would, as maxmoo notes, result in sucking in air and that would be visible in the clear section of the fuel line to the IP. Disconnecting the fuel line from the filter and pulling vacuum (vacuum pump/tester is essential tool) can help identify if this is the source of the problem (clogging).

Also check that the fuel return lines aren't leaking, as this will also result in air in the fuel lines (air goes into the filter, if you have the stock filter setup [which uses the thermo-tee]).
 

matt.m

Well-known member
Joined
May 28, 2007
Location
VT
TDI
2003 NB
Huge thanks for the suggestions. I'll have to diagnose when I return from FL; I'm fleeing the frozen north for a while. 9F for the high today. Eesh.
 
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