I have a 1987 5.0l efi and i got black smoke and terrible gas mileage

 

clogged air filter, fouled plugs, old plugs, dirty fuel filter, dirty throttle body would be good place to look

 

So it's running REALLY rich. Do you get any codes in the computer? That should be the first thing you check. Follow where that info leads you looking for damaged or broken sensor wires and/or vacuum lines before changing the sensor in question.

 

www.fordfuelinjection.com will show you how to retreive your codes

 

and i get no o2 sensor or running rich code i have replaced that could it be my egr it has new plugs and wires air filter fine the truck has good power still it just gets bad gas mileage and black smoke and doesnt idle worth a damm

 

check timing with spout out.

 

This is beginning to sound like a failed fuel pressure regulator or ECT sensor.

If the diaphram in the regulator fails, it'll pull raw fuel into the plenum. Pull the vacuum line on the fuel pressure regulator, and just turn on the switch to pressurize the rail. DO NOT START the engine, because if it's failed, it's going to leak fuel in the compartment. Some smelly fuel is a lot better than an under hood fire.

Plan B, if you don't see or smell any fuel coming out of the regulator vacuum line, get a vacuum pump, and a fuel pressure gauge and try the regulator out. Jumper pin 6 of the diagnostic plug to ground to run the pump. Check the pressure at the rail with no vacuum, and you should have around 45 PSI. Apply about 20 inches vacuum, and you should have about 35 PSI. 20 inches vacuum is idle vacuum, and zero vacuum is the same as WOT. Drop the vacuum quickly, and the pressure should rise just as quickly. If this passes, try Plan C. Oh, btw, jumpering pin 6 on the connector will generate a code that the relay's bad on the fuel pump. You just bypassed it with the jumper, so ignore that code.

Pressurize the fuel rail as above with the pressure gauge connected to the rail, and then just stop the pump. Watch the pressure. It should take a while to drop off. Mine still had about 10 PSI after nearly 10 minutes. If it drops quickly, you may have a leaking injector, or more. There's yet another test to run if the pressure doesn't hold as described.

Reconnect everything, and make sure you don't have any raw fuel in the engine bay. Get in, push the throttle to the floor, and try to start it. If it starts, that's definitely a leaky injector. The injectors should not fire at WOT during the Crank stage.

If it passes all these tests, the last resort is going to be that the ECT, or the wiring to it, has failed. If the ECM doesn't know the coolant temp, it'll never switch to closed loop control, which could explain why you're never getting an O2 sensor code. On top of this, it takes a while to get an O2 code, and it may not latch. I drove my '92 with the O2 disconnected nearly 8 miles before the CEL ever blinked at me. The KOEO test only looks to see if it's there, and reading somewhere between lean and rich with the engine not running.

The fuel delivery tests you can run without replacing any parts. The ECT can be checked for resistance, but you'll need to know the temperature of the engine as well. I think there's some info on fordfuelinjection.com about the appropriate readings, assuming you have an ohmmeter. The ECT costs about $12, and is relatively easy to get to.

All this is also assuming you have an appropriate thermostat installed, and the engine temperature is getting to at least 195 degrees. 195 degrees is where the ECM switches from open loop (MAP and ECT only) to closed loop (MAP, ACT, ECT and O2).

 

I'm with you there, Old Paint. When I read the title of this thread I knew thats probably what the problem was.

 

good post paint.

 

ive got the timing advance to 14 i have to run 93 so it wont rattle

 

that is too much advance.

try setting it at what it should be, 10 degrees with the spout out, and see how it runs.