Help Needed 351W Wont Idle

[lone_star_dsl]

My plow truck is a 1994 F-250 with a fuel injected 351. I had problems with it not idling last winter and, unfortunately, I havent touched it all summer.

Sometimes I could plow for hours before the engine would finally idle. Sometimes it wouldnt idle at all. When driving down the highway, it felt as though another cylinder would fire up and I could instantly feel more power and the truck would idle fine after that.

I went out the other day and changed all the fluids and fired the truck up. I was pretty surprised at how quickly it started, but even at 70* outside, the engine wouldnt idle. It would fall off to roughly 200-300 rpms, hang on for a few seconds then quit.

Being a fuel injected engine, I dont know where to start looking for a problem.

Help me out guys, snow season is almost here!

 

[silverF250]

First place to start is plugs, wires, cap and rotor and fuel filter. I would also use some injector cleaner.

 

[94f450sd]

pull the IAC motor off and clean it out.clean out the passages for it in the throttle bottle.clean the throttle body and throttle blades.use a toothbrush and carb cleaner.

 

[94f450sd]

check the gap on the plugs or replace them and gap them.if the gap is not in the specified range a 351w will not run right.they will skip,idle like crap and get very poor fuel mileage.even when they are new they need to be gapped.

 

[F350DRW1]

And when your done doing all that, start the engine and spray some carb cleaner all around the hoses, intake, pcv, etc and see if you have a vacuum leak. The engine will speed up if you do. BTW, whats the fuel filter and fuel look like? Fuel stale? Filter full of rust?

 

[Zookie400]

my vote is for IAC, vac. leak, or TPS

 

[f100cleveland]

Check the fuel pressure regulator. Pull the vaccum hose off and if there is any fuel in it replace it. It could be alot of different things.

 

[JLDickmon]

And when your done doing all that, start the engine and spray some carb cleaner all around the hoses, intake, pcv, etc and see if you have a vacuum leak. The engine will speed up if you do. BTW, whats the fuel filter and fuel look like? Fuel stale? Filter full of rust?

x2
PCV hoses and the grommets on the back of the intake are notorious leakers on these engines..

 

[lone_star_dsl]

Thanks for all of the responses!

You guys are going to keep me busy this weekend. I will post back with either more questions or a final answer.

Thanks again!