Hi all, im new the the forum, and I was hoping u could give me some help with my 95 f150. I have the 4.9L straight 6 and it has trouble starting after it has been sitting for several hours. It usually sputters and coughs to life. Once it is running, there are absolutely no problems, at any speed(idle or driving down the road) what so ever. I have already checked the fuel pressure and bleed-off, and every thing checks out. My thought is that it is a air related issue, as it starts fine when the engine is hot. Im planning to look at the idle speed motor tonight, am I on the Right track? It is as if the engine is starting with too much air because the idle control motor is not choking it enough?? Any thoughts or advice are appriciated.

 

IAC would be a good guess, but if it would not move (controled by the ECM) then you would be getting a code.

When was the last time it got a tune up? 10 years old 120-150,000 miles???
I'd change Plugs, wires, fuel filter, air filter etc....??

This sounds like a simple fix. Check fuel pressure too with a gauge. It could also be a weak fuel pump. Check the pressure before and after you change the filter. If the pressure get higher after the filter, obviously it was just a clogged filter.

Good luck......

 

thanks for the advice. I have already checked the fuel pressure, and all is well ( at the engine). it has 107k miles on it, and has had new fuel filters installed almost every year. The idle motor moves, as it reduces idle speed after being started and running for about 30seconds. The reason i am so puzzled is that the truck runs and idles perfectly. It just doesn't wanna start. Sombody has told me that it could be the coolent temp sensor (not the sending unit for the guage) located on the thermostat housing.

Does anyone know what the correct resistance for the sensor is when the engine is hot or cold?? Thanks

 

My 1989 F150 4.9L came with what Ford called an "after-run blower" system, in the hopes to prevent excess heat from the exhaust and head (which incidentally, are only about an inch away from the fuel rail) away from the rail and injectors, for a period of about 10 minutes. This was thermostatically controlled with a sensor on or near the rail. Only ever kicked on twice on mine. I suspect this is what's causing your problem, fuel boiling in the rail and creating air pockets. Here's what I'd try ....
1. Open your hood immediately after every ride for a while to see if it stops. The extra air will evacuate heat more quickly, hopefully preventing fuel boil.
2. Bypass your fuel pump relay with a jumper wire to engage the pump full time for a while after shutoff, causing constant fuel flow to keep the fuel in the rail cool. Fuel won't boil if it's not near the exhaust for a short period of time.

Don't kid yourself, fuel can boil easily. My dad was a lumberjack many years ago, and told me that he fueled his chain saw while it was running, because if it was shut off the centrifugal fan wouldn't cool the engine and fuel would boil in the carb. Instant air lock !

Hope you get it figured out.
Denis.

 

My '93 5.0 has had problems w/ the idle air control valve before. You can get a new one at advance auto parts for 1/2 the price of ford, but supposedly the quality on some parts like that is inferior to oem. Easy to install, about 10 mins. w/ a screwdriver.

 

I am haveing the same problem. Did you ever figure it out?

 

if the fuel pressure and bleed down is good, then i'd run a check for codes. a coolant temp sensor can cause that symptom.