I'm having start problems with my 2001 V-10 w/120k miles. Intermittent problem, cranks, starts, shuts off within seconds. Will usually, so far, start and run normal after waiting varying amount of time. Replaced CPS, cleaned MAF, replaced air filter, and fuel filter and plugs have less than 10k on them. Proper oil level, and gas treatment added to de-ice fuel. When it does start, it runs with normal power.

Don't know if extreme cold, as low as 25 below zero @ nite, is adding to the problem. Have lived through past four years of this kind of weather and this is the first time I've had problems.

It shows no check engine lites, will a code reader detect issues that don't trigger warning lites? What should I do next? Any help will be greatly appreciated.

Charlie Doc

 

Hello and welcome, you have a commen problem. You have a IAC Valve(Idle Air Control) problem. The first thing to try is cleaning it and that usually works, but you might need to replace it. The valve gets carboned up and sticks. When you remove it take some carb cleaner to clean it. If that doesn't work then it needs replaced. You can do a search on IAC valve and will find many more posts on it.

Here is a thread that will show you where it is:https://www.ford-trucks.com/forums/5...rsion-v10.html

Here is one on how to remove it:2003 Ford F250 4x4 - V10 IAC

 

When your engine is about to stall, do you need to push down on the gas pedal to prevent it from stalling? If so, then most likely it is your IAC valve.

 

Thanks for the quick responses. I'll try cleaning the IAC next and will follow up with results.

 

So the IAC will keep the truck from starting and then let it start later?

 

It can.

To bypass the IAC, crack the throttle slightly (1/4) during starting. If that works reliably, it's pretty definite that the IAC is sludged up and is sticking.

 

Ever notice when you first start a car when it's cold out in the morning and the RPMs are high? The computer recognizes the engine being cold and opens up this valve to let more air flow into the intake...thus higher RPMs to warm up the engine faster and prevent it from stalling.

Once it warms up gradually, the valve closes and the idle slows down.

My guess is that when it's cold, the oil is more viscous and requires more work to keep the engine running; hence stalling. Once warmed up, oil flows easier and don't need as much gas to keep it idling.

 

I've been delayed by really cold weather, since I'm having to work outside on the truck. Daytime highs only in 20s. I've determined that inertia switch is only getting 6.4v on one pin, nothing on others. What is the most likely cause for this?

 

You should have the same voltage on BOTH sides of a closed switch, plus, the switch will only have battery voltage applied for about two seconds immediately after the ignition switch is turned to RUN from OFF. You must make your readings during this very brief interval.

 

Thanks to everyone that gave me suggestions to work on. It looks like I've finally got it fixed! Apparently an intermittent fuel pump problem. Replaced CPS, cleaned MAF and IAC, replaced air filter. Tested inertia switch and finally got pump to fail long enough to isolate it. Replaced fuel pump and so far so good. I'm afraid to get too excited until I've put a few more miles/days on it but it hasn't failed to start since pump replacement. It sure was a pain working on it in the driveway with snow and freezing weather ever since it started acting up!

 

Charlie is your truck still starting good sence the new pump was installed? Having the same problem here, had to have it towed home and about 3 hours later it started fine.
So will the IAC keep the pump from running, cant hear it run when it wont start.

 

Ridehd-I haven't had any problems since replacing the pump! :-)Thank goodness! It's been two weeks and it runs like it never had a problem. Mine was an intermittent problem and was really hard to pinpoint until it finally quit working altogether. Good luck!

 

Thanks for the reply, Im just dreading dropping the tank, but if it has to be done I will do it.

 

Thanks for the reply, every other fuel pump I've had quit on me never started working again. This is the first one that is intermittent problem, but thats what I think the problem is.

 

Dropping the tank is sort of a pain but fairly straight forward job. I was able to siphon the gas out and after jacking rear end up, sitting it back down on jackstands it was just a matter of lowering tank on to another jack and make all of the disconnections. Only special tool required is the gas line disconnect tool and I already had a set of them from previous jobs. Worst part of the whole job was working in really cold sub freezing weather outside!

I replaced my vapor hoses with slightly longer ones that made it easier to re-connect. The old ones cracked when I lowered tank. I lowered my spare tire and it made it much easier to work over top of rear axle to make connections. I had to use a hair drier to warm new hoses in order to slip onto fittings. Have fun!