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Discussion Starter · #1 ·
My R/C keeps giving me 2 diff codes. Most of the time it says its running lean. But it smokes black and it smells very rich. I've changed the o2 sensor twice. Also changed the coolent temp sensor, map sensor, TPS sensor. The other code it has sometimes says the o2 sensor is not fluctuating. The fuel pressure is at 18psi and this is supose to be at 15 with the vacum hose on the regulator. 18 psi is right with the vacum hose off. There does not seem to be a lot of vacum at the hose. I have clean it out and can easily blow through the vacum port. The pressure never changes with the RPM's. I've check the cat for being clogged. It also has new plugs, fuel filter, cap and rotor.
Please can someone give any advice. I'm about to pull my hair out.
 

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First thing I would do is to get a vacuum gauge and see what kind of vacuum you have at the vaccum port on the manifold. The fuel pressure regulator is designed to run off proper manifold vacuum. 18 PSI seems a bit high as the spec is 14.5. Might also be a bad regulator or leaky injectors or o-rings. Check the vacuum first.
 

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Discussion Starter · #3 ·
Do you know how much vacuum should be there? I can't feel any. I have a vacuum pump with the vacuum gauge on it, but it starts at 3 inches. I hooked that up and it reads nothing.
 

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This is out of one service manual...At idling speed, an engine at sea level should show a steady vacuum reading between 14" and 22" HG. A quick opening and closing of the throttle should cause vacuum to drop below 5" then rebound to 23" or more.
Follow the vacuum hose from the fuel pressure regulator back the the source which is usually the intake manifold. Make sure the hose has not collapsed and that the port on the manifold is clean and open.
 

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Discussion Starter · #5 ·
The vacuum hose is connected to the throttle body. The port is above the butteryflys. My vacuum at the manifold is at 18". I have a Hanes book and its not to helpfull. If I connect the vacuum hose to the manifold the pressure drops to 7psi and starts to idle very rough. It did kick out another code for the air temp sensor. I changed that and the o2 sensor on Friday. So far so good but the last time it ran good for about 3 weeks before it started with the codes for running lean and couging out black smoke. Thank you for the help.
 
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