How's yours run

[poolsexpo]

I'm a little unsure on how this truck is acting. I do alot of research on the Explorer, and most of it comes from here which is a huge help. I have a 99 Explorer, 6cyl ohv, 2wd auto with about 153,000 miles. The issues I'm having are lately when I go to start it, it is cranking for about 10-15 seconds before it fires, in which once it fires, it's stumbly like it's lacking air or fuel. It stumbles for 5 seconds than goes to idle like it should. I recently have also been dealing with a electric issue about same time this started. When turning key to start, starter goes real slow like weak battery. I bought new battery and had it charged. Then I removed starter and cleaned it up, sanded all contact's and grounds then put it back on, pulled ground cable and supply cable and cleaned the ends. Put new terminals on battery and had alternator checked at 3 separate places. Same slow turn over. Once started the battery gauge is in normal place. Besides those two minor issues, the truck seems to have a very very slight misfire or shudder every I'd say 30 seconds. I am meticulous about my vehicles, I keep up with everything. For what it's worth, since the possible misfire, I have done new Motorcraft plugs gapped to I believe. 58? Whatever the minimum gap is recommended I went a few above it. New wires, filter, seasoned, Trans fluid and filter change, upper and lower intake gaskets about 8,000 miles ago. New pcv valve, iac valve, dpfe sensor went out and blew a hole through intake so the hole has been filled and patched.

 

[2000StreetRod]

check voltages

Since you have a new battery and have cleaned the terminals I suggest that you measure the voltage across the battery terminals with the engine off and again with the engine running. The gauge on the instrument cluster is not accurate. Maybe your alternator is not charging the battery. Low voltage can affect numerous things (i.e. fuel injectors, fuel pressure, ignition, MAF sensor, IACV). If you don't have a multi-meter you can buy an adequate one at Harbor Freight for about $6. The alternator testers available at discount auto parts stores only check the output voltage with almost no load on the alternator. If they tested it in the vehicle then I suspect your starter solenoid, brushes or bearings are shot.

 

[poolsexpo]

Thanks for the suggested help. I did have my buddy do a voltage test, which he said was ok with engine running, however when engine was off and key in on position, the voltage would alternate between 12.6 and 11.4. This kinda leads me to think the cables themselves do have more corrosion on the interior. I will check into this more when I have a minute. As far as the motor at startup, I was having a stumble issue. I did the intake gaskets several months ago, which I did go through a great deal of research to see what gasket brand everyone had the best success with, which I ended up buying from O'Reilly. (when purchasing your gaskets if you are replacing, specify several times which motor you have and which gaskets) I was given wrong gasket at two stores since cell that's the only one they carried. Anyways, the other day I decided to check all the bolts. Intake has studs, with a very small star head and then a nut over the stud. I loosened the nuts in the reverse torque pattern used during installation. When I put a wrench on studs, which tighten the fuel rail to the lower intake gasket, I got almost 2 full turns out of each stud before even snugging up?????.hlw did they get so loose? Is this where I have been loosing small amounts of coolant each month? I tightened them all then tightened the nuts. It runs so much smoother, and I am super thrilled to say it actually nearly stopped the valve chatter I had.

 

[gatzdon]

Your startup issues sound just like mine.

At the moment, I'm convinced I have a small cylinder head crack on cylinder 3 that seals up once the engine is running. When the vehicle is cold, coolant can seep into the cylinder and hinder startup.

For now, I would get an OBDII reader and get the pending codes. You may not have a check engine light on yet, but if you are getting misfires on startup, you should have a pending code telling you which cylinder. Changing the spark plug on the afflicted cylinder may improve startup, but if there's a leak/crack, it will eventually foul up again. (note, you cannot cleanup platinum plugs. Once they are shot, they are done).

I have been driving mine like this for nearly 75,000 miles, changing the spark plug on cylinder 3 every 5,000 to 10,000 miles.

Don't know if this is your issue, just relaying my experience with my 2000 6cyl OHV 4WD Explorer.

 

[Mike65]

I have the same problem with my 2000 Ranger 4.0 OHV. I have to replace the spark plug also about every 8-10K miles in #-4 cylinder & top off the coolant reservoir. I re-torqued the lower intake but it did not help. Mine has been like that since I bought it almost 2 years ago & about 20K miles.

 

[jester1023]

Check the fuel pressure. I don't have access as I'm typing this to the spec needed, but it shouldn't be hard to find. Maybe someone will chime in for the specification. This behavior is very classic to the fuel pump bleeding off pressure and then struggling to keep up. Eventually, it will get weaker and weaker...resulting in stranding you somewhere with a tow bill. There is a vast theory that claims a pump is either bad or good. There is truth to that in the sense that a properly working pump is "good" and anything less than that is "bad". Not all pumps just quit...the ones with electrical problems typically do, but not mechanical issues.

On the electrical possibility...a new battery doesn't equal a good battery, but my thought would lean a little more toward starter drag. There are always other possibilities with mechanical objects.

 

[pcam13]

I had this issue when I first bought mine too.. Only 25,30 psi fuel pressure. Replaced the Pump, regulator, and filter. Still cranks for a while at random times but runs decently. Have to replace spark plugs and wires. One rubbed through and makes it shake at idle... 273kms and leaks from the rack, diff and valve covers... typical Canadian rust but the 5.0 wont quit.

 

[jester1023]

I had this issue when I first bought mine too.. Only 25,30 psi fuel pressure. Replaced the Pump, regulator, and filter. Still cranks for a while at random times but runs decently. Have to replace spark plugs and wires. One rubbed through and makes it shake at idle... 273kms and leaks from the rack, diff and valve covers... typical Canadian rust but the 5.0 wont quit.

With all those miles, yours may just be a little low on compression or has slack in the timing chain.