Intermittent hard starting 2000 5.0.

[zorac311]

Hey everyone. I've read many old threads and haven't found conclusive answers. I have intermittent hardstarting on my 2000 5.0. Sometimes it cranks for 3-5 seconds like its starved for fuel, sometimes it doesn't. Doesn't matter if I prime the fuel pump by turning the key on a few times or not. Sometimes it fires right up and stalls unless I tap the gas. Sometimes it causes zero issues at all. I don't suspect leaking injectors or intake manifold at this point. It has newer plugs, coils, wires, battery and alternator. Fuel pressure test was ok. I'm leaning towards old fuel pump/in tank regulator if my simple ideas don't fix it. Egr valve, iac valve, clean MAF, ect sending unit, pcv. Not just throwing parts at it. I am just giving it the old tune up as I have time. It was my dad's explorer and it only hs 114k! Most things I've touched so far were all original parts. Just getting annoying and I'm trying to figure out if dropping the tank is in my near future or not!? Anything obvious I might be missing? Lol

 

[410Fortune]

What is fuel pressure at cold start?

2000 5.0 with only 114k is the stuff dreams are made of!

 

[zorac311]

What is fuel pressure at cold start?

2000 5.0 with only 114k is the stuff dreams are made of!

Heck yeah! Love this thing. Its about 10psi. While running its at 60 or so. So far today I've been turning the key 3-5 times to prime the system and no issues. It's definitely fuel related. Truck doesn't have codes, rough idle or issues at WOT. I'm thinking it has to be the pump going out, the sending unit, the sensor or the line that runs in between. Given thats all in the tank I'd just replace everything in one shot just because. Anything I might be missing here?

 

[Pete Deering]

Hey everyone. I've read many old threads and haven't found conclusive answers. I have intermittent hardstarting on my 2000 5.0. Sometimes it cranks for 3-5 seconds like its starved for fuel, sometimes it doesn't. Doesn't matter if I prime the fuel pump by turning the key on a few times or not. Sometimes it fires right up and stalls unless I tap the gas. Sometimes it causes zero issues at all. It has newer plugs, coils, wires, battery and alternator. Fuel pressure test was ok. I'm leaning towards old fuel pump/in tank regulator if my simple ideas don't fix it. IE, egr valve, iac valve, clean MAF, ect sending unit, pcv. Not just throwing parts at it. I am just giving it the old tune up as I have time. It was my dad's explorer and it only has 114k! Most things I've touched so far were all original parts. Just getting annoying and I'm trying to figure out if dropping the tank is in my near future or not!? Lol

Did you replace the fuel filter?
114K is new.
The 3-5 second start

 

[zorac311]

Did you replace the fuel filter?
114K is new.
The 3-5 second start

Yes it's new

 

[Mbrooks420]

If it always starts cold fine and is intermittent after the first start of the day I’d suspect the coolant temp sensor.

 

[zorac311]

If it always starts cold fine and is intermittent after the first start of the day I’d suspect the coolant temp sensor.

Just an update for everyone. Explorer has new: fuel pump assembly, pressure vent valve, pressure sensor, throttle position sensor, clean throttle plate, adjusted throttle cable, new MAF sensor, fuel filter, spark plugs, wires, coils, coolant temp sensor, air filter, egr valve and tubing. It doesn't feel starved for fuel anymore. Now the only issue is idling down and dying on warm start ups. Unless I tap the gas pedal it idles down and stalls. I'm at a loss here. Couple buddies/local shops can't figure it out either. Not a huge issue, just annoying!

 

[Pete Deering]

Just an update for everyone. Explorer has new: fuel pump assembly, pressure vent valve, pressure sensor, throttle position sensor, clean throttle plate, adjusted throttle cable, new MAF sensor, fuel filter, spark plugs, wires, coils, coolant temp sensor, air filter, egr valve and tubing. It doesn't feel starved for fuel anymore. Now the only issue is idling down and dying on warm start ups. Unless I tap the gas pedal it idles down and stalls. I'm at a loss here. Couple buddies/local shops can't figure it out either. Not a huge issue, just annoying!

? Where did you buy your replacement parts. Amazon, Ebay?
It sound like a coolant temp sensor.
Odb2- read the coolant temperature °F?
Unplug the MAF sensor and see if anything changes.

 

[Mbrooks420]

No codes, I assume?

 

[zorac311]

No codes, I assume?

Correct, no codes at all

 

[zorac311]

? Where did you buy your replacement parts. Amazon, Ebay?
It sound like a coolant temp sensor.
Odb2- read the coolant temperature °F?
Unplug the MAF sensor and see if anything changes.

Pretty much oem, ngk or delphi for everything.

 

[Mbrooks420]

How fast does the pressure bleed off after shutting it down?

Do the returnless systems have check valves in the sending unit?

 

[zorac311]

How fast does the pressure bleed off after shutting it down?

Do the returnless systems have check valves in the sending unit?

It still holds decent pressure. I think so, I replaced the entire assembly and the green tank vapor vent as well. I found a shop willing to check it out this week! I'll update everyone.

 

[Mesozoic]

Make sure it's not got a vacuum leak somewhere.

 

[zorac311]

Update for everyone. Finally got it to the shop. He ran a bunch of tests on it and will be driving it this week with computer hooked up and monitor what is going on. We're suspecting a leaking injector(s) at this point.

 

[zorac311]

Well no one can figure out the issue. After the explorer is warm and shut off (15-30) minutes the pressure drops to 40psi instead of 50-60. Once the engine is cold it starts fine again or immediately after shutoff. A few reputable mechanics in the area can't figure it out without REALLY digging in and dropping money into it. They all agree it's not a severe issue, more annoying than anything. It's NOT leaking injectors or intake gasket.

 

[Mesozoic]

Have you measured the vacuum at idle yet? Still sounds like a vacuum leak.

 

[zorac311]

Have you measured the vacuum at idle yet? Still sounds like a vacuum leak.

I'm not real great with vacuum lines and routing. I'm starting to think you might be on to something. Once I replaced the egr valve and tube I started getting a code for that now too. The shop said everything seemed fine but they were chasing a fuel issue.

 

[Mesozoic]

There's several vacuum lines that connect to the EGR system. It would be worthwhile to ensure that those are plumbed correctly and not leaking. At the age the vehicle is at now, it's very likely that the original vacuum tubing is probably due for replacement. An easy way to check the vacuum reading at idle would be to disconnect the heater bypass valve vacuum connection and connect it to a vacuum gauge. Should be an easy 15+ inHg reading, I would imagine. If it's lower than that, you've definitely got a vacuum leak. Someone else might be able to chime in and tell us what the stock cam has for vacuum at idle.

 

[zorac311]

There's several vacuum lines that connect to the EGR system. It would be worthwhile to ensure that those are plumbed correctly and not leaking. At the age the vehicle is at now, it's very likely that the original vacuum tubing is probably due for replacement. An easy way to check the vacuum reading at idle would be to disconnect the heater bypass valve vacuum connection and connect it to a vacuum gauge. Should be an easy 15+ inHg reading, I would imagine. If it's lower than that, you've definitely got a vacuum leak. Someone else might be able to chime in and tell us what the stock cam has for vacuum at idle.

There's several vacuum lines that connect to the EGR system. It would be worthwhile to ensure that those are plumbed correctly and not leaking. At the age the vehicle is at now, it's very likely that the original vacuum tubing is probably due for replacement. An easy way to check the vacuum reading at idle would be to disconnect the heater bypass valve vacuum connection and connect it to a vacuum gauge. Should be an easy 15+ inHg reading, I would imagine. If it's lower than that, you've definitely got a vacuum leak. Someone else might be able to chime in and tell us what the stock cam has for vacuum at idle.

I think that's a great place to start, I'm sure everything IS original. My EGR sensor is pretty crusty too, not sure why I didn't think to replace that as well as the lines to the egr tubing (facepalm)!