Intermittent starting problem

[cnsheets]

Hope someone has had a similar problem or can provide some knowledge...

2001 Explorer Sport, 4.0 V6

Few months ago after driving to get food, we came out of restaurant to leave. Went to start the car and it wouldn't start. Sounded like it tried to fire for a split second then nothing, just cranked over with no start. To me, it seemed like it wasn't getting fuel. Fuel tank read almost 1/4 tank. Just to be safe, we ran to the gas station and brought 2 gallons of fuel back, dumped it it, nothing....wouldn't start. Called AAA for a tow. We waited about 20 minutes, just before AAA showed up, I tried to give it another go......started right up, no hesitation.....huh? So we had AAA follow us home just to make sure, car ran perfectly fine. Just to be safe, I replaced the fuel filter that same night.... Cars been running fine for the past couple months.... Then, after returning home from a 20 mile drive, parked the car...went back out 10-15 minutes later, car wouldn't start. Same problem as before.... I nosed around, checked a few things, no OBD codes, nothing apparent... 20 minutes later, the car starts right up, no problem or hesitation. Funs perfectly normal.

Took it to the dealer .... they have had it for the past 24 hours and can not duplicate the problem. Starts every time for them. Had them drive it, warm it up, park it, wait, starts right back up. No codes for them either. They put a fuel pressure tester on the rail and shows about 30Lbs without the car running, turn the key on, and while running, it shows about 60lbs. They can't get it to not start. Its done it twice now to us and we are concerned that it may cut out while driving......Going to pick it up from dealer as it is pointless to pay them to keep periodically starting it to try and duplicate the problem.

What else can we check? Suggestions??

 

[cnsheets]

Hmmm. Guess my explorer is the only one ever that has had this problem.

 

[2000StreetRod]

low fuel pressure

When you say it doesn't start I assume it cranks every time but doesn't run. 30 psi is too low for a 2001 with a returnless fuel system. The pressure should be about 60 psi when the ignition key is turned to run. The next time it doesn't start turn the key off and on a couple times before cranking the engine. If it starts then it may be an intermittent fuel pump. Which V6 do you have?

 

[lorenzetti]

Same exact problem

We have a 2002 Ford Explorer 4.0 6 cylinder with the exact same problem.
I opened a thread for it yesterday.
We have been struggling with the same exact situation.
Starts then does not start but it does crank.
No codes, replaced fuel filter, fuel pressure at 60 constant.
Opened gas cap and can hear the fuel pump running on startup.
Cannot replicate the problem on demand.
It will always eventually start.
Noticed that when I hear it come close to starting I jam my foot on the excellerator and it starts and emits blue puff from tailpipe then runs fine.
Talked with Ford dealer service head yesterday and he thinks it is the upper air intake gasket that may be leaking air.
Don' t know what else to try so may go that route.
Keep me informed if you solve your problem and I wil do the same.
D

 

[lorenzetti]

Possible solution?

I have found that I have a leaking valve cover gasket and my mechanic claims this could be part of the problem? Thoughts?

 

[cnsheets]

I have found that I have a leaking valve cover gasket and my mechanic claims this could be part of the problem? Thoughts?

We also have a leaking valve cover gasket. Drivers side, right in the corner, drips onto the exhaust manifold and burns. Not a huge leak, been this way for many many months. I don't think the two problems are related, but could be wrong. I plan to replace the valve cover gaskets and upper intake manifold gaskets since the intake is part of the process to do the valve cover gaskets, but am more concerned about the starting issue first.

 

[koda2000]

i can't imagine how a leaky valve cover can cause this problem. it would have to be one hell of a leak to mess with the PCV system and even then i don't think it would cause this problem. the things that come to mind are intermittent fuel pump operation, due to the pump failing, or the fuel pump relay failing. i'd switch the relays around and see if that makes any difference. it might also be the crankshaft position sensor or its connection.

as far as the situation where someone stated his truck starts when he floors it and then puffs blue smoke, he might have a leaking fuel injector which is flooding his engine after turning it off when warm and trying to restart it shortly thereafter.

 

[cnsheets]

When you say it doesn't start I assume it cranks every time but doesn't run. 30 psi is too low for a 2001 with a returnless fuel system. The pressure should be about 60 psi when the ignition key is turned to run. The next time it doesn't start turn the key off and on a couple times before cranking the engine. If it starts then it may be an intermittent fuel pump. Which V6 do you have?

Stated above, 4.0L V6

30 psi was without the key on, key on and running was 60psi. I'm wondering if it is an intermittent fuel pump problem. Perhaps occasionally the pump seizes after being ran for a while, then doesn't run the couple times it wouldnt start, then after repeated attempts, it dislodges and starts running again..... is that possible? next time it happens, I'll check to see if the pump is running.

 

[cnsheets]

i can't imagine how a leaky valve cover can cause this problem. it would have to be one hell of a leak to mess with the PCV system and even then i don't think it would cause this problem. the things that come to mind are intermittent fuel pump operation, due to the pump failing, or the fuel pump relay failing. i'd switch the relays around and see if that makes any difference. it might also be the crankshaft position sensor or its connection.
.

I agree, I have ran engines before with the valve cover completely removed and they still ran. I don't think the oil leak is related. I tried to switch the fuel pump relay, however I'm not sure which one I should be switching. Looking at the info online for the layout of the control box and fuel pump relay location, it does not match up to the configuration of ours. So I just swapped a few around making sure to only swap like for like relays.

 

[lorenzetti]

I did just discovered a disconnected vacuum line on the Heater Control valve.
Think that might be the cause of the problem?

 

[2000StreetRod]

OHV or SOHC?

Stated above, 4.0L V6

30 psi was without the key on, key on and running was 60psi. I'm wondering if it is an intermittent fuel pump problem. Perhaps occasionally the pump seizes after being ran for a while, then doesn't run the couple times it wouldnt start, then after repeated attempts, it dislodges and starts running again..... is that possible? next time it happens, I'll check to see if the pump is running.

OK. I didn't know if the OHV 4.0L V6 was still being installed in the Sports in 2001. If you have the SOHC 4.0L V6 then this thread may give you some ideas: Engine No Start Procedure

I agree with others that the entry of unmetered air (vacuum leak) should not prevent the engine from running. Instead, it will cause it to idle fast. It might be a faulty crankshaft position sensor. Try disconnecting and reconnecting a few times to "clean" the contacts.

 

[cnsheets]

When I input the vehicle info into various parts website, it only gives me the engine option of SOHC. So I can only assume this is the type we have. I'll check out the crankshaft position sensor. Is there a way to electrically test the sensor? Looks like it is only a $15 part......I would much rather it be the problem than a fuel pump.....Wouldn't the sensor throw an ODB code if it were going bad?

 

[cnsheets]

2000StreetRod

Thats a lot of great info in those links. Thank you very much for linking me to those.

 

[2000StreetRod]

8th digit

If the 8th digit in your VIN is an X then you have the OHV V6. If the digit is an E then you have the SOHC V6.

It is very difficult for the PCM to determine that the crankshaft position (CKP) sensor is intermittently faulty. Some members have tapped on the CKP sensor when their vehicle did not start and that solved the problem.

 

[cnsheets]

Ok, so I wanted to bring this back to the table to see if anyone else has anything else to offer up.

I have not yet found the problem but I still suspect the fuel pump. I'm just procrastinating with it because of the cost, guess i hope it turns out to be something else.


Update to symptoms, the intermittent start problem is now more frequent..... here is what happens:

Cold, car starts up and drives no problem. After reaching operating temp, if I keep it running, it continues to run with no problems. If I shut it off after reaching operating temp and try to restart, it will not restart. It turns over and will give an initial stutter, but will not start. After 20-40 minutes, as everything cools down, it starts right up no problem. When it does not start, I think I can not hear the fuel pump prime, but then again, a few times I thought I could not hear it prime, it started, so maybe my hearing is bad or the beeping from putting the key in the ignition is drowning the pump prime sound out.....not sure....




I have kept trying to do searches on the problem, and others that have had similar problems, their final resolve has been many different things, ranging from loose inertia connections, bad relay, pump, ECT, etc., nothing definitive.

Anyway, I did replace the crank position sensor and the problem still exists, again, only when its up to operating temp it will not restart until cool down. I have no engine codes either..... Swapped the fuel relay with another one, problem still exists......

Someone mentioned the ECT being bad causing the computer to think its a cold start and giving the wrong fuel mixture and timing..... but wouldn't a bad ECT cause an engine code? And would a bad ECT cause drivability issues also if it always thinks its a cold start? I think the ECT is the next cheapest thing to try but not sure.....

Or, could the fuel pump still be the problem? Could the fuel pump be going bad, overheating and locking up after I shut it off thus cause the no start when hot? Then after cool down it loosens up and works again? Or could it be a bad ECT thats just not throwing an engine code? My concern with just going out and replacing the fuel pump is that it may not be the problem. I have read a few posts with people having similar problems that had already replaced the fuel pump previously, or just replaced it and their problem still exists.....

We just sold the car to my son, its his first car, and we feel really bad that its suddenly having this problem and am hoping to get a fix so he can learn to drive.....

It is the SOHC 4.0 V6 by the way.

 

[RomeovilleIL]

30 pounds before start-up is your key indicator here. The system should prime to the full 60. When the engine is warm it operates on closed loop, reducing the amount of fuel being allowed through the injectors. When cold and in open loop, it gives maximum gas. Since your pressure from priming is too low the engine is being starved if the engine temp is high enough for closed loop operation. More than likely when this is happening you could probably get it to fire and run with a shot of starter fluid. I would replace the pump.

 

[cnsheets]

I should clarify, the 30lbs is with the key off BEFORE pump priming. When the key is turned on, and the pump primes, it jumps to 60lbs.

Now that it no starts more frequently when its hot, I will see if I can put a fuel pressure gauge back on the rail and test pressure again. When we had the tester on before, they could not get the car to not start....now should be no problem getting it to not start since it happens every time it gets to operating temp.

 

[thedogzeus]

I would bet a significant amount you have an intermittant Crank Position Sensor.

When it next fails to start, immediately stick ur head under the front of the car and give the sensor a couple of light raps with a spanner. The sensor is located on the front of the engine near the crankshaft pulley and has a two wire cable connected to it. Unplug the cable, tap the sensor, refit the cable, try to start the truck. If it starts, you've found your issue.

This fault OFTEN DOES NOT GENERATE A DTC CODE, this makes it a bugger to actually diagnose.

 

[ptf18]

Any more input on this issue? My wife's S/T is doing about the same. It went the dealer today via tow truck

 

[keleko17]

Can someone dumb it down for me and tell me where the crank shaft position sensor is located?