240 K-Jet POS!!!

branmcw · 11-23-2009, 11:56 AM

81 245 K-Jet
starts hard and misses until it warms up then it runs fine any ideas what could be wrong?

tiredoldtommy · 11-23-2009, 12:08 PM

Cold start injector or thermal timer? Or wiring to either or both.

branmcw · 11-23-2009, 12:38 PM

ways to check?

tiredoldtommy · 11-23-2009, 01:11 PM

Do you have a manual? The Bentley manual is the best, but a Haynes would work too.

Also, the factory Volvo green books are available for download at K-jet.org. I think they have a troubleshooting file as well.

sho_shane · 11-23-2009, 01:17 PM

Mine does the same think and in my case its the thermal timer.

gsellstr · 11-24-2009, 02:56 AM

CPR is plugged and running either line pressure for control pressure, or it's running full control pressure when cold instead of dropping it. Check your control pressure cold and warm. It should be somewhere in the 35-ish psi range when cold, 55-ish psi range warm. If it's 65+ psi you're running at or near line pressure.

moxy123 · 11-24-2009, 03:30 AM

CPR as above.

If I remember right the thermal only works while cranking and then does nothing over 80F or so, but you may want to check.

dl242gt · 11-24-2009, 03:27 PM

There is the thermal time switch. It controls how long the cold start injector will spray while cranking. The cold start injector only sprays while cranking.

Then there is the thermal cutout switch which is used on the late model kjet and the kjet 240 turbos. This is an open/close contact switch at the rear of the left side of the block. It grounds out when the block temperature is below 60F IIRC. It is connected to the lambda ecu terminal 7 providing extra fuel for the engine while it's really cold. As the engine block temp goes above 60F the switch opens because that is a ton of fuel and isn't need as the engine gets warmer.

Lastly and very importantly above was mentioned the control pressure regulator. The control pressure is a feedback fuel pressure used against the plunger in the fuel distributor. In cold conditions the warmup regulator aka control pressure regulator lowers the fuel feedback pressure so the plunger will travel higher making the fuel mixture richer for warmup. As the temperature in the unit heats up with it's heater inside and the engine temp rises the control pressure is increased until the fuel feedback pressure is at a setting where it provides the warmed up engine fuel mixture.

You need to check the injector seals too. For checking the thermal time switch and thermal cut out switch you need a multi meter set for ohms and a cold engine to see if they are conducting. For the control pressure testing you need the kjet fuel pressure gauge setup which will let you test system presssure, control pressure, and rest pressure. Check out the Volvo manuals on k-jet.org. Download and readup how kjet warmup works and how to troubleshoot it.

BrickBaller · 11-24-2009, 04:13 PM

Read the sig.

RP80242GT+T · 11-24-2009, 04:26 PM

+1 for CPR. Did you check injector seals?

John242Ti · 11-24-2009, 05:04 PM

The 1981 240 Turbos don't have the thermal cutoff switch, btw. But, I'm thinking it's probably the CPR, or it may be a gummed up fuel distributor, which is likely as well. Especially if the car has been sitting for a while.

-J

dl242gt · 11-24-2009, 05:48 PM

Yeah, I always forget that first year doesn't have that thermal cutout switch. I agree it's probably the control pressure regulator. When I bought my 82 turbo it had the same symptoms and it was a combination of bad injector seals and the control pressure regulator clogged.

It took about 8 tries before it would start and idle. Then after the injector seals but before the cpr it took about 4-5 tries. Then after the cpr was replaced it started easily and ran great.

moxy123 · 11-24-2009, 06:08 PM

Fill the fuel filter with Seafoam and run it through the injectors slowly, a few minutes between pulses, with the fuel pumps bypassed and moving the air plate.

11-23-2009, 11:56 AM	#1
branmcw Board Member Join Date: Jun 2008 Location: Largo Fl	K-Jet POS!!! 81 245 K-Jet starts hard and misses until it warms up then it runs fine any ideas what could be wrong?

11-23-2009, 12:08 PM	#2
tiredoldtommy Board Member Join Date: Mar 2008 Location: Antlers, OK	Cold start injector or thermal timer? Or wiring to either or both. __________________ ---------------------------------------------- When you're a tired old gimp², you get easy to please. ---------------------------------------------- '03 C70 HPT drop top 95k (stylin cruiser) '83 242 turbo, 305k (ridge runner) '84 245 NA, 248k (hauler/tractor) '66 New Yorker, 440 4bbl (needs a new home) '84 244tic (project or parts? definitely parts)

11-23-2009, 01:17 PM	#5
sho_shane Board Member Join Date: Nov 2009 Location: Greenville,TX	Mine does the same think and in my case its the thermal timer. __________________

11-24-2009, 02:56 AM	#6
gsellstr Vintage anti-ricer Join Date: Oct 2004 Location: Somewhere in a northern California smog bank	CPR is plugged and running either line pressure for control pressure, or it's running full control pressure when cold instead of dropping it. Check your control pressure cold and warm. It should be somewhere in the 35-ish psi range when cold, 55-ish psi range warm. If it's 65+ psi you're running at or near line pressure. __________________ RIP Doug Williams "Mr. Doug" 4/15/2009 Pete Fluitman "fivehundred" 7/14/2013 Mick Starkey "TrickMick" 1/10/14 Mark Baldwin "blue850t5" 7/19/18 Nick Fengler "fengler" 8/6/18 Thomas Fritz "stealthfti" 10/11/18 Bob Davi "bob davi" 10/2021 74 144 B20 http://forums.turbobricks.com/showthread.php?t=224983 90 745Ti http://forums.turbobricks.com/showthread.php?t=334698 If you need Superpro bushings PM me for price and availability!

11-24-2009, 03:27 PM	#8
dl242gt Old and boxy but good. Join Date: Jun 2002 Location: S NJ, a suburb of Phila.	There is the thermal time switch. It controls how long the cold start injector will spray while cranking. The cold start injector only sprays while cranking. Then there is the thermal cutout switch which is used on the late model kjet and the kjet 240 turbos. This is an open/close contact switch at the rear of the left side of the block. It grounds out when the block temperature is below 60F IIRC. It is connected to the lambda ecu terminal 7 providing extra fuel for the engine while it's really cold. As the engine block temp goes above 60F the switch opens because that is a ton of fuel and isn't need as the engine gets warmer. Lastly and very importantly above was mentioned the control pressure regulator. The control pressure is a feedback fuel pressure used against the plunger in the fuel distributor. In cold conditions the warmup regulator aka control pressure regulator lowers the fuel feedback pressure so the plunger will travel higher making the fuel mixture richer for warmup. As the temperature in the unit heats up with it's heater inside and the engine temp rises the control pressure is increased until the fuel feedback pressure is at a setting where it provides the warmed up engine fuel mixture. You need to check the injector seals too. For checking the thermal time switch and thermal cut out switch you need a multi meter set for ohms and a cold engine to see if they are conducting. For the control pressure testing you need the kjet fuel pressure gauge setup which will let you test system presssure, control pressure, and rest pressure. Check out the Volvo manuals on k-jet.org. Download and readup how kjet warmup works and how to troubleshoot it. __________________ Dave, 1982 242 turbo. 338k miles. MVP coilovers and 3" exhaust. Flowed 405 with a V15. Cossie turbine housing with upgraded compressor housing. 90+, IPD remote oil filter. Some other goodness, too. Been lots of fun over 25 years. Restored in 2k. Now ready for a 2nd restoration. 1993 245 Classic, 435k miles, enem V15. IPD bars and chassis braces. Simons sport exhaust from Scandix. sbabbs ezk chip. Been a good road warrior. Genuine Volvo rebuilt leaky M47.

11-23-2009, 12:38 PM	#3
branmcw Board Member Join Date: Jun 2008 Location: Largo Fl	ways to check?

11-23-2009, 01:11 PM	#4
tiredoldtommy Board Member Join Date: Mar 2008 Location: Antlers, OK	Do you have a manual? The Bentley manual is the best, but a Haynes would work too. Also, the factory Volvo green books are available for download at K-jet.org. I think they have a troubleshooting file as well.

11-24-2009, 03:30 AM	#7
moxy123 Board Member Join Date: Feb 2007 Location: Phoenix, AZ USA	CPR as above. If I remember right the thermal only works while cranking and then does nothing over 80F or so, but you may want to check.

11-24-2009, 04:26 PM	#10
RP80242GT+T R-Sport Cluster Guy Join Date: Apr 2003 Location: Cape Coral, FL	+1 for CPR. Did you check injector seals? __________________ RP R-Sport and OEM Stock Instrument Cluster Restorations, Sales, parts, service, and customizing. LED Conversion Services Volvo GT Stripe Kits. 1980 242 GT Turbo 2006 Mini Cooper S GP number 1148 1989 240 Wagon " The Beast" Daily Driver

11-24-2009, 05:04 PM	#11
John242Ti LH-Jet & Carb Free Zone Join Date: May 2003 Location: Duvall, WA	The 1981 240 Turbos don't have the thermal cutoff switch, btw. But, I'm thinking it's probably the CPR, or it may be a gummed up fuel distributor, which is likely as well. Especially if the car has been sitting for a while. -J __________________ 1982 242Ti - black, B23FT/M46 combo. @john242ti on IG

11-24-2009, 05:48 PM	#12
dl242gt Old and boxy but good. Join Date: Jun 2002 Location: S NJ, a suburb of Phila.	Yeah, I always forget that first year doesn't have that thermal cutout switch. I agree it's probably the control pressure regulator. When I bought my 82 turbo it had the same symptoms and it was a combination of bad injector seals and the control pressure regulator clogged. It took about 8 tries before it would start and idle. Then after the injector seals but before the cpr it took about 4-5 tries. Then after the cpr was replaced it started easily and ran great.

11-24-2009, 06:08 PM	#13
moxy123 Board Member Join Date: Feb 2007 Location: Phoenix, AZ USA	Fill the fuel filter with Seafoam and run it through the injectors slowly, a few minutes between pulses, with the fuel pumps bypassed and moving the air plate.

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