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Old 04-30-2021, 11:40 PM   #1
Jsegura525@aol.com
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Default 1982 240 turbo starting issue

Greetings - just acquired a 82 240 k-jet turbo that has a starting problem. It will eventually start up if I pump the fuel pedal quite a bit, then I have to play with the pedal for about a minute then it idles fine. Then it will restart with no problem, but after being off for about 1.5 hours it's difficult to start again. It needed plugs, plug wires, distributor/rotor, valve cover gasket. Any ideas to why it has an issue starting if it is off for over about 1.5 hours. The engine also backfires back into the fuel distributor upon rough startup and while rough idling when it does start up, then backfires go away when idle is good. All advice is appreciated.

Last edited by Jsegura525@aol.com; 05-01-2021 at 07:47 AM..
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Old 05-01-2021, 01:16 AM   #2
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K-jet is a strange beast if you’re not used to it. From what you’ve described — the 1.5 hour restart window, specifically — I’d probably start with the fuel accumulator. I’d check the neighboring parts (main pump and check valve) while I was at it. Good luck.
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Old 05-01-2021, 08:19 AM   #3
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Brontes II - Would a good way to test the accumulator and check valve be to jumper the two pumps for at least 10-15 seconds before turning the key to start, this way I'll be building up fuel pressure and if the car still refuses to quickly start then I can overrule those two items since I then know pressure is there? I'll still check the two fuel pumps, the intank pump to confirm that it is working correctly and not wired in backwards. The main pump seems to be working fine since when the car does start there is no fuel issue. What task does the fuel accumulator actually preform? At first I thought the accumulator was an older version of the check valve. My fuel filter is up in the engine compartment, if after sitting overnight can I unscrew the filter up front to check if I have good pressure up there still?

Last edited by Jsegura525@aol.com; 05-01-2021 at 08:35 AM..
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Old 05-01-2021, 12:58 PM   #4
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Small world affect. When I bought my 82 turbo in 1995. It had exactly that starting problem. The issue was the control pressure was too high. This causes a lean engine which takes many tries to start but then when warm seems ok. The hard starting after sitting is probably the combination of the lean fuel mixture from the high control pressure and the bad accumulator next to the fuel pump. Control pressure regulator is also called the warmup regulator. You'll need to get yourself a kjet fuel pressure testing rig so you can test system pressure, control pressure, and fuel pressure decay after shutdown. I think you can rent the fuel tester from hiperfauto a member here on the board.
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Old 05-01-2021, 02:13 PM   #5
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Before tearing into the fuel system verify that the cold start system is working.

Dave is correct. You need a fuel pressure gauge to properly diagnose K-Jet. You can build your own gauge as outlined in this thread or you can rent my OE Volvo gauge and adapters.

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Old 05-01-2021, 02:52 PM   #6
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Default No fuel pressure at filter

Hello fellas - this morning when I went out to tinker on the 82 244 turbo again I was thinking that it was a vacuum problem at the coolant temperature pressure switch and that maybe it was not turning on the Warm up/control pressure regulator. I was able to blow through coolant temperature pressure switch, so this led me to assume it is at least allowing the Warm up pressure regulator to activate. Then I though I would check my fuel pressure by removing one of the fuel lines at the fuel filter. Upon doing so there was no fuel pressure in the system. This is probably why I have to pump the fuel pedal to get her to start. Now how do I determine if the loss of fuel pressure is at the injectors or at the check valve?
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Old 05-01-2021, 03:28 PM   #7
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The thermal vacuum switch is for cold running boost enrichment only. It doesn't turn the WUR on or off.

A lack of fuel at the filter could be one of many issues. A bad accumulator, fuel pump check valve, leaky injectors or fuel lines all come to mind.

The accumulator has a vent that will leak fuel if the diaphragm is bad. Early cars have a hose barb with a hose that goes back to the fuel sender in the event of a leak. Later cars have a screw with slits on either side that the fuel will leak out of.

To see if the injectors are leaking you'll have to pull them out of the head and place them in small bottles or shot glasses to collect the fuel. Pressurize the system by bypassing the fuel pump relay and check to see if the bottles are collecting fuel.

If there are no external signs of a leak it's probably the fuel pump check valve. The best way to see it is with a fuel pressure gauge.

Pumping the gas pedal has no effect on a K-Jet car.

You should probably read up on the K-Jet fuel system. Here's a link to the greenbook.

http://www.240.se/litteratur/tp30454.pdf
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Old 05-01-2021, 03:48 PM   #8
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I'm with Ian on the fuel pump check valve being a very likely candidate. When those fail the symptoms you describe are common.
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Old 05-01-2021, 04:57 PM   #9
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Thanks to you both... I'm sure I have an extra check valve in the parts bin.
Hopefully it will fit the pump. I report back in a day or two. Thanks again.
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Old 05-01-2021, 05:00 PM   #10
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That sn though
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Old 05-01-2021, 05:41 PM   #11
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What is a sn ?
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Old 05-02-2021, 01:27 PM   #12
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Quote:
Originally Posted by Jsegura525@aol.com View Post
Brontes II - Would a good way to test the accumulator and check valve be to jumper the two pumps for at least 10-15 seconds before turning the key to start, this way I'll be building up fuel pressure and if the car still refuses to quickly start then I can overrule those two items since I then know pressure is there? I'll still check the two fuel pumps, the intank pump to confirm that it is working correctly and not wired in backwards. The main pump seems to be working fine since when the car does start there is no fuel issue. What task does the fuel accumulator actually preform? At first I thought the accumulator was an older version of the check valve. My fuel filter is up in the engine compartment, if after sitting overnight can I unscrew the filter up front to check if I have good pressure up there still?
I strongly second the advice that you need a K-Jet/CIS compatible fuel pressure tester and some good reference literature to properly troubleshoot this system. You really, really need them both. K-jet components can die slow deaths and it's not always as simple as "it works or it doesn't."

IF you did have a pressure tester, I would recommend attaching it at the fuel filter and then priming the system (either using a fuse panel jumper or just cranking the key). The basic idea is to see how much pressure is being produced, how quickly and smoothly it rises, how long it remains constant, and how smoothly it subsides. The check valve is responsible for holding the initial system pressure and the accumulator smooths the pulses. The target value ranges and significantly better explanations can be found in the Volvo Greenbooks or Bosch technical manuals. This would at least tell you which side of the fuel system to focus your efforts. (Assuming that it's just one problem.)

The check valve could be failing and not holding pressure as it should. The accumulator could be sticking due to varnish, etc. creating a pressure pocket, or it could be the cold start valve, or a leaky injector, or an imbalanced fuel pressure regulator. It's almost impossible to say without more detailed data.

An appropriate test gauge isn't that expensive. It's definitely cheaper than throwing parts at the problem trying to fix it. Plus you're almost certain to need it again if you hang on to the car for any length of time. That said, if you do determine that there's a problem with the accumulator, the check valve, or the even main pump, then I'd recommend that you just go ahead replace the whole lot of them at once; as well as clean up any old wiring, connectors or tubing. It's not the most difficult job in the world, but it is a messy, under the car, pain-in-the ass kind of job. If possible, it's better to do it all and be done with it.

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Old 05-03-2021, 08:56 AM   #13
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Thank you Brontes II - I'll be borrowing a fuel pressure tester and checking the pressure at various locations to see where the fuel pressures is escaping from. I do admit I need to read up on K-Jet, my reading comprehension is not my best asset (due to ADHD). Yesterday when starting her up I jumped both fuel pumps for about 15 seconds (prior to turning the key and kept the jumper on until she started, ) to get the fuel line primed and pressured but still had to turn the key about 6 to 8 times and sometimes holding the key on until she started and stayed idling, the
whole time with my foot pumping the fuel pedal (reminded me of the carburetor days) or else she would not stay running. The car backfires at the air filter rubber cover (turbo) during this whole start up process. But she does eventually start and idles rough, but I'm still needing to pump/play with the fuel pedal and then as if fuel broke through she idles fine. It's as if fuel breaks through eventually after struggling. I will also be inspecting the intank pump either today or tomorrow to confirm its condition and if pumping in the correct direction. Thanks again for all your advice.
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Old 05-03-2021, 03:47 PM   #14
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Although kjet is old and mostly mechanical it's not simple or cheap. Think of an antique grand father clock. A set of factory manuals is highly recommended.
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Old 05-03-2021, 03:52 PM   #15
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PM replied. I disagree, Kjet is very simple but as you say not cheap for components anymore. A good set of manuals and you'll understand how it all works. Not many places are rebuilding this stuff anymore which is a shame.
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Old 05-04-2021, 08:59 AM   #16
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Why does the Warm Up Regulator/Control Pressure Regulator have both a vacuum going to it AS WELL AS wiring ?
I'm getting the plunger in the air filter popping up and down (sounds like backfire) only while having difficulty starting, is that probably caused by the WUR not sending a correct message?
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Old 05-04-2021, 11:13 AM   #17
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This might help:
https://tasteslikepetrol.net/2020/02...tronic-basics/

It’s a basic guide to k-jet components and operation. There’s a section about CPRs including an animated gif.
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Old 05-04-2021, 05:11 PM   #18
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SHE IS FIXED : I replaced the Warm Up Regulator/Fuel Pressure Regulator with one from the Pull & Pay and now she starts up on the first try. The car was losing fuel pressure at the WUR, because the fuel lines were not snug as they should have been. THANK YOU ALL FOR ALL YOUR ADVICE AND KNOWLEDGE. MUCH APPRECIATED.
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Old 05-04-2021, 08:24 PM   #19
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Always happy to try and help. Glad to hear you’ve got it fixed.
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Old 05-05-2021, 01:45 PM   #20
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Just curious, where did you find a turbo kjet in a pnp?
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Old 05-05-2021, 01:49 PM   #21
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Early turbos use the same WUR as the NA cars.
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Old 05-05-2021, 08:01 PM   #22
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Quote:
Originally Posted by hiperfauto View Post
Early turbos use the same WUR as the NA cars.
Yup. And certain units for others makes (VW/Audi/Porsche, some Mercedes, etc.) are close enough to “work” even if they aren’t perfectly to spec. It’s all Bosch. I had to make due with some junkyard Audi and and VW parts in my ‘84.5 TIC the last few years I owned it.

What I’m curious about is where he found ANY k-jet parts at a pull yard. Period. They’ve all been like hen’s teeth in my neck of the woods for years.
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