My engine is running rich, flooding???? My truck is a 1986 F-150 302 EFI. The engine idles rough, black smoke and soot comes out the exhaust pipes, and black soot on spark plugs. Symptoms seem to disappear if I throttle the engine and hold it, but as soon as I release the throttle the symptoms reappear and in most case causes the engine to die. These symptoms have just started a week ago. I am unable to solve this problem and need help as to what the problem is.

Fuel injectors are cleaned and rebuilt. New plugs and wires. All new fuel pumps and filters. New air filters. New fuel pressure regulator. New dual function reservoir. New 3-piece timing set. New O2 sensor. New EGR Valve and sensor. New idle air control valve. New distributor, cap, and rotor. New ignition coil. New high volume oil pump. New alternator. New pcv valve. New knock sensor and air charge temp. sensor.

Any help or advice on this problem will be greatly appreciated.

 

It's unusual but if the MAP sensor goes out it'll do all kind of strange things to your injection, particularly at idle.

See if you can find one at a wrecking yard and switch it out. If that's the problem pony-up the money and buy a new one.

Jim

 

Does the check engine light come on when this happens? Are there any vacuum lines that may of come off?

 

Thank you for your replies. I will check the MAP sensor.

All vacuum lines are secure and free of cracks/holes. The truck does not have a check engine light. It has an 'emissions' system trouble light, but it is not lit.

 

The map sensor is good.

The truck is now in the shop and a ford whiz is looking at it. So far, he is scratching his head on this problem.

 

Please let me know what you find out. I work on these on occasion and I'm very curious what you find.

Thanks.

Jim

 

It's getting to much gas, the computer would never tell it to run that rich, Put a fuel presure gagde(spelling?) Should be between 30-35 i belive. If its not and in your case is high you have a bad regulator or fuel line. Dont have one take the Return line to the fuel tank off right after the Fuel regulator start the truck should be spitting gas out. MAKE SURE ITS working, if it is Check for kinked line it could be plugged.\

The efi in these trucks is really simple can only be a couple things i would supected regulator or return line.My truck did the same thing when the fuel regulator went the presure was around 45-50 pounds. Good luck
Oh yes and have lerned the hard way , just becuze somthing is new dosent mean it works

 

Ok, the ford mechanic has traced my problem to the fuel injectors. He says some or all (not sure how many) are stuck in open position and that is what is causing the engine to run rich.

Would anyone know an inexpensive place to buy new fuel injectors?

 

I had a Mustang do this once, turned out to the the ECM had a bad injector driver and kept the #3 injector wide open.

 

Check the injector harness with a noid light (not a test light, they draw too much current, and voltmeters can't read as fast as the injectors fire), and see if one injector is being held on. If none show constant ground, then the problem would be an injector. If any show constant ground, then the computer is bad.

 

Ok, here's the update.

The ford mechanic installed a new throttle position sensor (TPS) and new fuel injectors (I bought the injectors and dropped them off at the shop). In the process, it was discovered that bottom of the plenum was warped by .007" and had to be taken to a machine shop and machined for trueness. The ford mechanic put everthing back together.

He discovered that the truck would run fine after installing the new injectors and if the TPS was left unplugged. If the TPS was plugged in the truck would exhibit its rich running symptoms and the engine will throw a fit. Even with the good, new TPS installed, the truck would not run with it plugged up. Unplug the TPS, and will start up. He is baffled by this.

I have truck back now. I am baffled by the problem with TPS myself. As long as the the TPS is unplugged, the truck will run out fine. But the moment I plugg the TPS in, the engine throws a fit (starts coughing, sputtering, blowing black soot out the tailpipe, and very erratic idle) and eventually dies.

Can anyone shed some light on my TPS problem?

 

With the tps plugged in, the key on but the engine stopped, tap into the tps harness. You should be getting a 5v reference signal, and .5v at the idle position of one of the other wires, the third wire is a ground I believe. New parts can be bad, it could have a bad ground, or he didn't adjust it properly. If the tps is non-adjustable, adjust the throttle to get the correct voltage. There is an actual spec on the throttle position, I believe it was around five or six thousandths between the throttle plate and bore.

 

Ok, I've driven the truck some more since I have gotten back from the mechanic. With the TPS disconnected, the truck misses bad when its cold and emits rather foul exhaust fumes; however, when it warms up the missing goes away and so does the foul smelling exhaust fumes. The truck still won't run with the TPS connected.

I have checked the TPS and it appears to be good. There is .5 volts at idle and around 5 volts at wide open position.

Another ford mechanic advised me that if the distributor and/or ignition control module (ICM) is bad, that would throw off the TPS. My next to step is to determine whether the distributor and/or ICM is bad, and replace since both are still under warranty.

 

My father, who has been helping me with the truck wants to remove the efi and go back to a two-barrel carb. He is tired of messing with all the electronics on the truck and wants to go back to the basics. The truck has the eec-iv or tfi-iv ignition system and emissions stuff on it.

My father wants to know how difficult it would be to convert the efi back to a carb and will it be compatible with the tfi-iv ignition system?

 

The problem has been found. My father and I plugged in the tps sensor and started hearing a clicking noise. We traced the noise to the passenger side fender wall to a solenoid. It is next to an old coffee tin looking thing and there are four solenoids in a row. The specific solenoid is the one that is closest to the passenger fender wall. I think it is the EGR solenoid. The connector appeared to be corroded, so I cleaned the connector with a knife and used some vaseline cream. That has solved the problem. The truck will run with TPS plugged in.

Can anyone confirm for me that the solenoid closest to the passenger side fender wall next to the coffee tin is the EGR solenoid and can it be replaced?

Also, would anyone like to go out on a limb and offer an explanation as to why the engine would die as a result of this malfunctioning solenoid only when the TPS was plugged in?