Intermittent Cranking

[dyoung4evr]

This past November my son's 2003 Explorer sport (SUV design) suddenly started experiencing problems cranking intermittently. Sometimes it would go 2 or 3 weeks between episodes. Usually the problem would be in the morning after it had sat all night, but sometimes during the day after it had only sat for a short time. Then, after letting it sit for a while, it would crank. He would drive it to the shop, but it wouldn’t act up on them while there. When it cranks, it runs well and never goes dead while driving. The shop replaced a stopped up fuel filter, and we thought that solved the problem. (Note: The Explorer failed to act up every time the shop had it. They had to diagnose based on symptoms.) After a few days, he experienced the same problem. I replaced the fuel pump relay, and the Explorer performed well for about a week, then same old problem. The shop was finally able to observe it in a “broken” state. They said they verified that it was the fuel pump. They replaced the fuel pump assembly, the vehicle cranked, and he drove off. That evening (last night) it wouldn’t crank. Any thoughts?

 

[ddrag]

If this is happening when it is raining or when it is moist out, check the spark plug wires. This was the problem on one of my other vehicles. I used an electrical grease around the problem wire and it worked for a little while but eventually it happened again. If this is the case just replace the wires. There is a ignition tester that is recommended by the haynes manual to test the wires but you should be able to just ground the plugs to the block when turning the key to see the sparks. The ignition coil could also cause this and it can be diagnosed at an auto parts store I believe. I have never had to mess with the ignition on my ST but have replaced just about all of the components on older cars. If you are certain these arn't the culprits your starter may have broken teeth on the gears and only intermittently jams up or you could have a phantom drain on the battery and just get lucky when it turns over. I hope this helps.

 

[dyoung4evr]

Thank you ddrag. There doesn't seem to be any correlation to weather. Also, seems if it was electrical it would turn on the Check Engine light. I was thinking that if the shop checked for voltage to the fuel pump under the hood and not at the pump, their tester could show the fuel pump bad even though it could be a bad connection between the relay and the fuel pump. I'm just grabbing at straws right now. My son is ready to trade it in, but I'm hoping it is something common that someone else may have experienced.

 

[ncranchero]

When it doesn't start can you hear the fuel pump "hummmm"? You may have to remove the filler cap and have someone turn it to ON while you hold your ear close to the filler neck.

 

[dyoung4evr]

ncranchero - Son says 'no'. The shop still insists it is the fuel pump, even though they installed a new one. They are saying that it is not unusual to get a bad one from the parts store. They say they have had situations where they have had to replace it 2 or 3 times before getting one that held up. Does this sound normal? Has anybody else had this experience?

 

[ncranchero]

ncranchero - Son says 'no'. The shop still insists it is the fuel pump, even though they installed a new one. They are saying that it is not unusual to get a bad one from the parts store. They say they have had situations where they have had to replace it 2 or 3 times before getting one that held up. Does this sound normal? Has anybody else had this experience?

The shop is full of it! No way a shop would continue to use parts that they had to change out 3 or 4 time to get a good one. If that's remotely true then you don't want their Chinese fuel pumps!

One thing to check is the inertia switch, inside on the firewall under the heater/AC unit on the passenger side. They can cause intermittent problems. Unplug it and see if the terminals have any heat evidence, like blue-ing.

 

[OffTrac]

I wouldn't use a shop that admittedly continuously and purposely uses inferior parts.

 

[01STrunner]

Spark plug wires don't always throw codes. My Chaparral boat with a 5.0L merc had these exact same symptoms and it was a burnt wire. It would run fine when it did fire up but if the engine was shut down in just the right firing sequence where that specific plug was needed most it wouldn't start. It was a very frustrating problem that had a simple remedy. Never hurts to check.

 

[dyoung4evr]

Thank you ncranchero, offTrac and 01sTrunner. Going to check inertia switch, spark plug wires, and........switch shops!

 

[dyoung4evr]

ncranchero - Shop replaced inertia switch and it appears the problem has been fixed. It has only been a week with no symptoms, but that is longer than he was normally going between no-starts - especially within the last month. Thanks everyone for taking the time to share your thoughts and experience!

 

[ncranchero]

Good deal! I guess time will tell. If that is the cure I'd be discussing some refunded moolah !