ksdaddy

I recently bought a 1990 F-150 4x4 to plow my yard this winter. It's a fuel injected 300 with a 5 speed. At first it idled horribly, wouldn't stay running, and yet would start right back up. It seemed to smooth out to some degree when it warmed up. I know it has last year's gas in it but it's not acting like old gas. The previous owner admitted it hadn't had plugs, etc, for 10 years or more. I put in new plugs, rotor, cap, wires, and fuel filter. It does run better, but still not right. When it's first started, it will jump right to life but stumble and die a couple seconds later. If it was my '82 F-150 with a carburetor I would just pull the choke out and problem solved! It acts exactly the same way. I re-start it at that point and it starts back up immediately and jumps to 2000 rpm for a few seconds, then is likely to die unless I tickle the gas pedal. Once it's running a minute or so it smooths out some. However when I go to move it, it will stumble and try to die and generally run like crap under light throttle. Stumble, buck, bark, fart, all that. Not good news when I'm going to use it as a snowplow and will be creeping a lot. I did replace some random short pieces of vaccuum hose here and there because they were obviously dry and cracked, and I did do a visual check of vaccuum lines and didn't see anything obvious. I may be jumping the gun but it does act like a vaccuum leak. I will use due diligence and perform the carb cleaner test but I was hoping someone may have experienced this same situation and might be able to give me a heads up as to what they found. Thanks for reading and possibly pointing me in the right direction.

mrgooden

Did you check out and clean the IAC and look to see if the EGR valve is stuck open. Just my 2 cents.

Richard

ksdaddy

I have not done either but I will now. If I'm able to manually move the EGR diaphram is that sufficient enough of a test?

mrgooden

That should be, in the old days, I just unplugged then and capped the line. If it was not stuck open that is.

Richard

MBR

Had a Similar problem turns out the throttle body base gasket was bad

ksdaddy

I cleaned the IAC and that helped a lot. Then I plugged the vaccuum line going to the EGR valve and now it runs very smoothly. I had intentions of making a plate under the EGR valve but just capping the line did what I wanted it to.

Motorhome1993

sorry, but what is the IAC?

candyspaw

the egr valve is actuated by a solenoid that is operated by the computer. the egr valve has a sensor fastened to it's top by two screws. the valve could have stuck, the vacuum lines could be leaking, there could be an electrical problem like a bad connection. The thing is, you won't know what you've got until you read YOUR CODES. Believe me it takes practice to read them. The problem is that as they tighten up on pollution controls, they'll catch you with the plugged egr valve. This information is for my 1992 f-150 with the 300 cu in six