Running too rich!

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Jan 29, 2004 | 09:30 PM

daddywx

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Running too rich!

I need some ideas. I have a 1990 F-150 FWD with a 302. It runs runs good and starts good. But the tail pipes are black and when you run up the throttle you get a puff of black smoke. I replaced the plugs (they were black), replaced the air filter, Ox censor. No change. Ran codes and get 32 EGR open/erratic or valve position open, 41 No Exhaust Gas Oxygen switching detected- always indicating lean, and 95 Fuel plump secondary circuit failure. I tried blocking the flow on the egr valve, no change. I would like to understand a little more before replacing the egr, fuel pump.

Jan 29, 2004 | 11:05 PM

EPNCSU2006

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From: Concord, NC

Check your fuel pressure regulator. It is probably leaking and causing the engine to run rich, and the computer can't make it go any leaner. Check it by pulling the vacuum line on the top of it, and if there is fuel there, it's time for a new regulator. The fuel pump code means that the fuel pump circuit failed intermittently at some point. Also make sure that the map sensor vacuum line has no leaks and wiring has no shorts.

Jan 30, 2004 | 12:18 PM

daddywx

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Thankyou for responding... I hate to sound too simple but what is the proceedure for checking the regulator? Also is the fact that the last owner redid the exhaust system w/o a catalytic converter likely to cause the computer any confusion. Thanks again for being willing to help. This computer stuff is great!!

Jan 30, 2004 | 12:19 PM

daddywx

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Jeez I just read the rest of your answer and you told me how. Sorry

Jan 30, 2004 | 01:12 PM

daddywx

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I'm a little akward with this system. I'm not sure what I am getting posted and whats not. I pulled the vacuum line of of the pressure reg and it was dry. I followed all vacuum lines and everything looks ok. I don't know what the map sensor is or where to find it. I assume its on the end of one of the vacuum hoses. Are there any other ways to check the pr reg? I really appreciate your help!!!

Jan 30, 2004 | 07:09 PM

EPNCSU2006

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From: Concord, NC

Did you pull it off with the engine running? It might need a vacuum to pull the fuel through. The map sensor is mounted on the firewall near the blower motor for the a/c on the passenger side of the truck. They don't usually go bad, and are quite expensive to replace, so check it well before going to buy a new one. Make sure the O2 sensor is in the exhaust and functioning properly. Check the computer to see if there are any codes too. Fuel pressure could also be too high, even if the regulator diaphragm was not punctured. You'll have to have a fuel pressure guage to test that. If you don't have one already, I recommend getting a Haynes manual for the truck. They have all kinds of tests and troubleshooting tips in there that can help you track down a problem. Good luck.

Feb 1, 2004 | 02:29 PM

daddywx

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No I didn't pull the vacuum hose while it was running. I'll try again. I will try to find a haynes tomorrow, and also get the fuel pressure checked. Something interesting happened this morning. I don't see how it can be related to running too rich but I'll run it by you anyway. When I got in (I drive truck) at three in the morning the truck would not start. It would crank good but would not hit at all. It was (Very) cold! After alot of starting fluid It started but it would run for a minute or two and then quit. After several cycles of this routine it would not even start. I assume there is water in the fuel filter and will change it first. If this experience might have anything to do with my original question please clue me in. Also one thing I thought of is that the engine temp is always in the lower quarter of the guage. I'm going to replace the thermostat tomorrow also. I assume that low temp could affect the fuel ratio at op temp but that would not account for the real rich running while it warms up. Thanks for all you are doing.