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Old 10-12-2018, 12:18 AM   #1
jriviera
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Default Kjet help needed new pumps, still low pressure

Hi there everyone. As the title states I need some Kjet advice. My 79 242 was having issues on acceleration, so I had checked fuel pressure and found it to be 27-30 psi. I also found the in-tank pump to not be working. Well, I just replaced both pumps and my pressure is.....27-30! This is my first k-jet car, and any advice for the next thing to check would be greatly appreciated.

Thanks,

John
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Old 10-12-2018, 01:51 AM   #2
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filter
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Old 10-12-2018, 07:58 AM   #3
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Thanks for the reply! Guess I shoulda mentioned new filter. But having worked in the automotive world before I know that people often start throwing parts at something before checking basics.

My next thought was checking actual voltage at pump. If I were only getting , say 11.5v, would that be enough to see that big a drop in pressure?
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Old 10-12-2018, 02:36 PM   #4
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Where / how are you checking fuel pressure?
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Old 10-12-2018, 03:03 PM   #5
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^ This. It sounds like you're measuring return pressure, not pump pressure.
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Old 10-12-2018, 03:08 PM   #6
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OP...I went through some Kjet fuel pressure issues a while ago...here's the thread for reference. Not saying you have the exact same problem, but I did some basic Kjet fuel pressure and flow testing (starting at post #19).

http://www.forums.tbforums.com/showthread.php?t=170882

Last edited by oldschoolvolvo; 10-12-2018 at 03:16 PM..
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Old 10-12-2018, 08:16 PM   #7
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I will check the link oldschoolvolvo. Thanks!

I'm checking pressure as per the way the "Kjet tester kit" instructions showed. Pulled line from regulator to fuel distributor, installed gauge setup with the two lines and shutoff valve between

below is a link to a pic of how I have it

http://oi61.tinypic.com/2v9tfeu.jpg
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Old 10-12-2018, 08:56 PM   #8
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Linky no worky.
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Old 10-13-2018, 08:19 AM   #9
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Hmmm it seems my computer prowess is almost as good as my Kjet abilities

Last edited by jriviera; 10-13-2018 at 08:23 AM.. Reason: Didn’t use good link
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Old 10-13-2018, 08:25 AM   #10
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Old 10-13-2018, 11:24 AM   #11
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I see the pic. With that arrangement, when the valve is open the gauge will read control pressure. With the valve closed, the gauge will read system pressure. Is that how you are checking it? When you see a 30 lb reading, is the valve closed?
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Old 10-14-2018, 01:19 PM   #12
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No, valve open, I will close valve and report back. The instructions with the tester were vague at best.
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Old 10-14-2018, 01:37 PM   #13
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OK well to go over how you test. Valve open so fuel flows to gauge and through the hose back to the fuel distributor is control pressure. You should see this start low and rise as the engine warms up. it rises as the fuel mixture is adjusted to warm vs cold engine.

valve closed is for system pressure check. Only hold it closed long enough to get a good solid reading and then open the valve. This measures system pressure but it also leans out the engine so you only do this test for a few seconds while the engine is running. You can also do this test before the engine is running but I like to see what it is while running.

Valve closed engine off after being fully warmed up is the rest pressure test. You should see a slow decay of the system pressure in a specified time after running. This tests the fuel check valve in the fuel pump.
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