Ford Explorer

[bigcountrysg]

My buddy has a ford explorer. Well the past couple days it has been starting when it feels like it. Engine cranks but will not start. Just had a tune up not to long ago, the shop that did the tune up did the following.
Plugs, wires, oil change, fuel filter change, trans flush, coolant flush, airfilter change, front diff fluid change, rear diff fluid change, greased all grease points. Now the vehicle is ready for winter. Um no now it does not start all the time. Being the tune up was done a month ago and ran great up till this week I am thinking fuel pump. I am going to check it out this evening when he gets off work. But I was wondering if any techs on here could give me there opinion on this. Also I am thinking maybe the cam position sensor is gone bad. I say this because his explorer does not have a distributor. It is a 1999 model 4x4 with 160,000 miles on it. Never had a problem like this before and the vehicle is well maintained. I offered to buy it off him because I know how well the vehicle is maintained. That brings me back to the fuel pump took a crap. I already know that the pump is in the tank.

[alabamafrog]

My old Bronco ii had an intermittent no start problem, found that the fuel pump relay was flaky. It had a Schrader valve that was very easy to check fuel pressure with the key on. Also a free code scan from a parts store might help.

[bigcountrysg]

I have a code scanner and will be taking it with me to my buddy's house. I have a fuel pressure gauge to hook up at the shrader valve and will be taking it as well.

[bigcountrysg]

Ok fuel pressure tested at 65 psi off the shrader valve, I got one code with the scanner P0303 cylinder 3 misfire detected. I am thinking this was stored before he did the tune up. I say this because after doing a few tests that all came back negative. We went for a road test after I cleared the one code. Went back home and rescanned and got no codes detected. I talked to a guy and he was talking about a coolant sensor that tells the pcm what the engine temp is at start up. He said if this sensor was bad that the cold start setting from the pcm would not be used and the engine would attempt to start like it was at normal operating temp.

The engine starts in the afternoon even after sitting all day. But it will not start in the morning, this problem began on Tuesday. Any one have any ideas. I went through the trouble shooting guide in the repair manual. But I am thinking that a diagnostic computer needs to be hooked up to the vehicle as the code reader can not run diagnostic tests.

[mrnecsteve]

I have owned 2 explorers and a girlfriend owned a third. You NEED to check the plug wiring install thoroughly. I have seen some funcky things on this ignition setup where
a shorted wire/bent plug tip can take out a whole bank intermittantly. Pull each plug and examine it carefully. Check to be sure a wire hasnt gotten damaged. Hopefully this will be the cure.
If not....do not throw parts at it until you verify that the timing chain is in order.You may not be able to verify yourself. At 160k,this is a consideration.

[bigcountrysg]

Originally Posted by mrnecsteve

I have owned 2 explorers and a girlfriend owned a third. You NEED to check the plug wiring install thoroughly. I have seen some funcky things on this ignition setup where
a shorted wire/bent plug tip can take out a whole bank intermittantly. Pull each plug and examine it carefully. Check to be sure a wire hasnt gotten damaged. Hopefully this will be the cure.
If not....do not throw parts at it until you verify that the timing chain is in order.You may not be able to verify yourself. At 160k,this is a consideration.

Timing is not off at all. The plugs and wires are fine they are new a month ago. The vehicle starts in the warmer temps in the afternoon but after sitting all night it will not start in the morning when it is cold out side. So after the tests that I have equipment to perform came back all negative. I am lost and I know it is something simple. We are not throwing parts at this truck. No parts have been purchased yet.

[mschn99]

is it a pushrod motor or a double overhead cam motor (OHV or SOHC)

There is a good chance its the Idle Air Controll Valve (IAC)....if its a pushrod motor it could be a bad fuel pressure regulator causign it to flood in the morning when its cold and the extra fuel wont burn.....

Check for spark....if you have spark and fuel its pretty much gotta be electronic with very few exceptions.

[bigcountrysg]

Originally Posted by Marc

is it a pushrod motor or a double overhead cam motor (OHV or SOHC)

There is a good chance its the Idle Air Controll Valve (IAC)....if its a pushrod motor it could be a bad fuel pressure regulator causign it to flood in the morning when its cold and the extra fuel wont burn.....

Check for spark....if you have spark and fuel its pretty much gotta be electronic with very few exceptions.

Thanks marc I will check that out.

[jwiger]

also, if you suspect flooding, i would pull and clean a spark plug (or two) before cranking. then crank it for a bit and look at them again (if it cranks with out firing that is) if it's wet and stinks of raw fuel then you either have too much fuel, or no spark. spark is easy to determine, and if the ECT (engine coolant temp) sensor was bad then you would get a code for sure, but you might not get a code if the IAT (intake air temp) sensor is dirty.... i've seen vehicles refuse to run if this is dirty, or if the air filter is not installed, the turbulance of the air upsets the MAF. just some stuff to think about.

[bigcountrysg]

Originally Posted by jwiger

also, if you suspect flooding, i would pull and clean a spark plug (or two) before cranking. then crank it for a bit and look at them again (if it cranks with out firing that is) if it's wet and stinks of raw fuel then you either have too much fuel, or no spark. spark is easy to determine, and if the ECT (engine coolant temp) sensor was bad then you would get a code for sure, but you might not get a code if the IAT (intake air temp) sensor is dirty.... i've seen vehicles refuse to run if this is dirty, or if the air filter is not installed, the turbulance of the air upsets the MAF. just some stuff to think about.

The guy I talked to said the Oppisite about the ECT. He said it won't throw a code. That I would have to test it for ohms. He said it would be either wide open or closed.