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L98 will not hold fuel presure

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Old 09-02-2017, 12:35 AM   #1
Bangkok Dean
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Default L98 will not hold fuel presure

My 1990, L98 when turning the key on won't show pressure but with several tries to start it will and the pressure goes up to 40 lbs and runs ok. then when I turn the motor off the fuel pressure drops right away to 0. Then it takes several tries to restart?

Last week I changed the in tank pump and inline fuel filter due to low running fuel pressure. That helped it run ok. now this new problem?
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Old 09-02-2017, 04:51 AM   #2
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Please check for a leaking fuel pressure regulator. Pull vacuum hose, that runs from the fpr to the manifold and check for fuel dripping or a strong fuel smell at the hose end.

Otherwise it could be a leaking injector. I believe your 1990 has no cold start injector. That was the leaking one at my 1985.
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Old 09-02-2017, 04:15 PM   #3
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Crimp off the return line and turn the key so it pressurizes. See if it holds pressure then.
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Old 09-03-2017, 02:32 PM   #4
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I would also check for a ruptured pulsation dampener in the tank. Remove and replace with a short piece of fuel line. That was one of the causes of my pressure loss on my 85.
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Old 09-03-2017, 05:19 PM   #5
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Quote:
Originally Posted by viii View Post
I would also check for a ruptured pulsation dampener in the tank. Remove and replace with a short piece of fuel line. That was one of the causes of my pressure loss on my 85.
It will need to be a hose rated for submersion. I really recommend that you get the install kit from. Racetronix
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Old 09-03-2017, 05:45 PM   #6
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Quote:
Originally Posted by aklim View Post
It will need to be a hose rated for submersion. I really recommend that you get the install kit from. Racetronix
I agree. For submersible applications use SAE 30R10 fuel hose . Regular hose will turn to mush from the outside in.
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Old 09-03-2017, 09:10 PM   #7
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Old 09-13-2017, 04:56 AM   #8
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Finally fixed the problem. The in tank fuel pump had a leak in the fuel line in the tank itself. Now it holds 45 lbs pressure and actually starts right away and runs better than it had in the past.
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