Fuel Pressure Reg. Issue?

Facesnatcher

Registered User
When my car a 89'SC at idle it has 38psi of fuel pressure with the vacuum hose on and 40psi with it off and my stock Vacuum gauge in the car says 8 to 9.inc. It also has a missfire, and run rougher the warmer it gets. The rough running tho is more noticeable at idle or when you put it in a high gear like 5th and floor it you can watch the Vac. gauge twitch. I found out that when I give it gass my fuel pressure goes up to like 50 or so but then tanks to like 28psi with my throttle still open. When it idles back down it goes back to 38psi. Also once the car warms up it stalls out when at idle and is then really hard to start, the engine turns over but it doesn't want to start up unless i pump the gas peddle over and over. Also, there is no smoke of any kind coming out of my exhaust, and no gas in the oil or anything like that. When I pulled the plugs they did have black carbon on them like it was running rich, and one plug had fuel still on it. Replaced the fuel injector on that but it didn't help.


Things I've tried so far- New fuel filter, new spark plugs and wires, new coil pack, new TPS and Idle motor, new MAF, new Computer, new Coolant temp sensor, new crankshaft sensor and new cam sensor. Tried D/C ing the O2 sensors just to see if anything changed, it did not. I've checked and checked for vacuum leaks and can find none, also new EGR valve.
 
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I know it's a somewhat different system. But my 95 f150 had the same problem and it was the temp sensor. It was reading that it was way colder than it actually was.
 
I found out that when I give it gass my fuel pressure goes up to like 50 or so but then tanks to like 28psi with my throttle still open.

Well, you have a fueling problem then. Either the regulator, or the pump itself, or the wiring.
 
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