98 Explorer doesnt start...sometimes

[jl102284]

Most of the time my 98 Explorer,4.0 OHV, starts up and runs great but sometimes in the morning (only in mornings) it will not start, it just cranks and doesnt fire. I cant figure out what the problem is.

First I thought it was a fuel problem and replaced the fuel filter. It ran great for a few days then one morning it wouldnt start again. It seemed like it was on wet damp mornings when it wouldnt start so I changed the spark plugs and wires. Ran great for a few days then wouldnt start again. I realized all the mornings it wouldnt start it was cold out, so I thought it wouldnt start because of the cold. I replaced the ETC (engine temperature control) sensor, temperature sender, thermostat, and coolant. It ran great for about a week. Now this morning which was warmer and drier than days earlier this week when it started fine, it wouldnt start. It did the same thing it did before I did any of this work. This afternoon it started right up no problem.

Does anyone have any idea what the problem could be?

 

[swetrid]

You probably have fuel pump problem. You will have to ck fuel pressure when it won't start to make sure.

 

[Wrench]

Another issue has to do with the CPS or the CMP sensor. The CPS sensor is most likely if you have proper fuel pressure for startup. I have found that most of the OHV engines will idle with 10 psi fuel pressure but won't start unless they have 60 psi. Prompt the ignition key twice in a row if you have a no start problem. This will tell you if you have a fuel pressure problem if it starts after the second prompt. It's still a good idea to check your fuel pressure so you can rule that out as well as the check valve function.

 

[ZacFields]

This is the same frustrating problem I've got right now. Scared to take it to a mechanic because if I can't replicate the problem (since it's not every morning, regardless of how cold it is outside), I'm concerned that they'll just start grasping at straws and I'll end up paying for several things to be fixed.

Let me know if you find out what your problem was. I've got a 2001 explorer with a very similar issue.

 

[herringdan]

Have a 97 v8 exployer runs good when gets hot run and cuts right off and after it cools it runs fine anybody know whats going on

 

[jl102284]

The truck went a couple weeks with no problems then last week when the temperatures were below freezing for a couple days it wouldnt start. Over the weekend temperatures warmed up to the 40's and it started and ran good. I checked the fuel pressure then and came up with these numbers: while idling it was about 30 psi., while holding pedal at 2000-3000 rpm. it would go down to about 28 psi. and when I turned the key to start the engine and it turned the pump on the pressure would go up a few psi.
Today the temperature outside is back in the 20's and no start. I checked the fuel pressure while trying to start the engine and it went up almost to 40 psi. I think these pressures are normal for this engine. I am pretty sure it has something to do with the freezing temps. I put a can of dry gas in the tank while it was running over the weekend.
Does anyone know what this problem could be.

 

[jl102284]

Today I did what I should have done in the first place.
Bought a spark checker and determined my Explorer is not getting spark in the cold temperatures.
I ran an extention cord to a heat gun under the hood to warm the engine for an hour and then the truck started right up and the had good spark.
What would cause it to not spark in the cold?

 

[jah81592]

I would replace the crank position sensor. I have seen this in my shop and repairs it every time. Buy a Ford sensor.-j

 

[b-gangl]

im having same issue. Ive replaced the crank sensor and did nothing i got the truck up into my heated garage and still nothing. So frustraing

 

[bladescape]

I am having a similar problem, however mine won't start when the engine heats up, as soon as the engine cools down it will fire right up. It seems to like the cold start but not a hot start. I changed all the same things except for the thermostat.

 

[jl102284]

I would replace the crank position sensor. I have seen this in my shop and repairs it every time. Buy a Ford sensor.-j

I think you were right, thanks for the advice. I replaced the crankshaft position sensor a few days ago. So far it has started everytime. Half the time it starts right up like normal. Half the time it takes a bunch more cranks than normal before it fires, so it seems like something still isnt right, but it starts which it wouldnt do before.

 

[jl102284]

I think you were right, thanks for the advice. I replaced the crankshaft position sensor a few days ago. So far it has started everytime. Half the time it starts right up like normal. Half the time it takes a bunch more cranks than normal before it fires, so it seems like something still isnt right, but it starts which it wouldnt do before.

I guess the crank sensor wasnt the problem. I am back to where I was before with the truck not starting in the cold. I can run an extention cord to a heat gun placed on the top of the engine, close the hood, then after about 15 minutes of heating it will start right up. The heat gun was pointed towards the coil. Next time I get a chance my plan is to remove the coil bring it in the warm house for a few hours, re-install it, and see if that can help me determine if its the problem or not.

 

[Sabe]

Have you checked the wiring for the position sensor circuit?
What about the plug - Was there oily grit all over it?

 

[shaysrevenge]

I happen to have the answer to everyone's prayers! Listen closely...

I have a 1998 Ford Explorer 4.0L SOHC, and spent years trying to figure out why it wouldn't start correctly in cold weather. After a lot of research I finally discovered that it wasn't the fuel filter, fuel pump, IAC, or any other component. The problem was with the Air Intake gaskets (upper and lower). That's right a couple of stupid rubber bands have been the cause of your troubles. Here's how: In the cold weather, the old gaskets shrink thus causing a vaccum leak in the engine. The excess amounts of oxygen will usually be interpreted as lack of fuel (but the fuel is usually not the problem at all). Then, once the temperature increases the gaskets expand, thus sealing the vaccum leak. This is why the engine usually starts better in warmer weather, and only then gives you problems after it has cooled overnight.

The gaskets can be replaced for about $350 at a dealership, take it in there and tell them what the problem is, and don't let them sell you some $200 part that won't fix the problem.

***Obviously there is still a chance this may not fix your specific problem, so take the advice with a grain of salt.*** Enjoy, and send all gifts of appreciation to my Paypal account (just kidding).