CIS gurus: Warm starting problems with the GTI.
02-22-2009, 06:02 PM
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CIS gurus: Warm starting problems with the GTI.
So now that the GTI has good wheels/tires and is tagged/titled/insured, I'm having an issue after driving it. It warms up just fine, drives around fine, no problems. But once it's warmed up if I turn it off and leave it for 5+ minutes it won't start for about 30 minutes. No matter if I start it with or without my foot on the gas. It just cranks and cranks and cranks but never fires. If I start it right back up it's okay.
I swapped out fuel pump relays on a whim, but that didn't make a difference. I also unplugged the cold start valve and control pressure regulator one at a time to no avail (as per some old CIS diagnostic literature on warm-starting problems). The only other thing mentioned is that there's a leak in the system, but I don't see any.
Fuel tank, pump and filter are all new. While cranking there's no pops or anything, actually seems like it's out of gas, but there's 1/4 tank in it.
I swapped out fuel pump relays on a whim, but that didn't make a difference. I also unplugged the cold start valve and control pressure regulator one at a time to no avail (as per some old CIS diagnostic literature on warm-starting problems). The only other thing mentioned is that there's a leak in the system, but I don't see any.
Fuel tank, pump and filter are all new. While cranking there's no pops or anything, actually seems like it's out of gas, but there's 1/4 tank in it.
02-22-2009, 08:25 PM
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Only when the engine's warm though? As per the Audi CIS book...
"Its function is to delay the initial pressure surge when the pump starts. This delay is necessary to prevent the control plunger from being forced up before sufficient control pressure has been allowed to build up. It also serves as a reservoir to keep the system under sufficient pressure (1.5 - 2.5 bar) for a short period of time when the engine is turned off thereby preventing vapor lock."
It was only in the low 50s today...hardly the ideal conditions for vapor lock.
It was only in the low 50s today...hardly the ideal conditions for vapor lock.
02-22-2009, 08:41 PM
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Alright, it's worth a shot...but when it does start it's not acting like it's flooded...
...at least compared to a flooded carburetor vehicle. No backfiring, no drama...just cranks for a second or two and starts.
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02-23-2009, 04:27 AM
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Re: Alright, it's worth a shot...but when it does start it's not acting like it's flooded...
you need to put gauge on it and check warm rest pressure, if it leaks down then start isolating which part of system,it can be fuel pump check valve, fuel dist check valve or warm up regulator, or injectors.and yes you car get vapor lock on 50 degree day.trying to fix cis without a gauge is pissing into the wind
02-23-2009, 10:16 AM
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Amen to CIS guages here!
Put guages on it, ck for residual pressure. Vapor lock can happen at any temp, and the vw's were famous for it (btdt 2 A1 Sciroccos). You can also add the hot start pulse relay if it's not already there, found on all audi CIS turbo cars.
Vaccuum leaks are next... You can ck this by having someone crank the car as you lift the CIS flap thru the CO adjuster with a 3mm Allen. If car starts this way, look hard for vacuum leaks. The valve that controls Fuel tank Vapors is a known problem on most VW/Audi CIS cars.
HTH
Scott J
Vaccuum leaks are next... You can ck this by having someone crank the car as you lift the CIS flap thru the CO adjuster with a 3mm Allen. If car starts this way, look hard for vacuum leaks. The valve that controls Fuel tank Vapors is a known problem on most VW/Audi CIS cars.
HTH
Scott J
02-23-2009, 10:42 AM
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Alright, will invest in a fuel gauge set...any recommendations?
Harbor Freight has <A HREF="http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97706">This</A> kit, which according to the manual has CIS adapters.
I'm assuming (hoping?) it's not the fuel pump as that was just replaced when the GTI got a new fuel tank AND filter.
Does K-Jetronic have a dist. check valve or warm up regulator? When I get home I'll have to go over my CIS book/Bentley manual again...
The only reason I questioned vapor lock is that I've never had it happen on a CIS car...actually the only time I've experienced it was on really hot days on a carb'd vehicle.
I'm assuming (hoping?) it's not the fuel pump as that was just replaced when the GTI got a new fuel tank AND filter.
Does K-Jetronic have a dist. check valve or warm up regulator? When I get home I'll have to go over my CIS book/Bentley manual again...
The only reason I questioned vapor lock is that I've never had it happen on a CIS car...actually the only time I've experienced it was on really hot days on a carb'd vehicle.