[SOLVED] 4.0 SOHC is long cranking when hot

[koda2000]

Unless you always buy your gasoline at the same crappy place, I doubt bad fuel is your problem. Other than Amoco/BP premium grade, all gasoline is pretty much exactly the same, other than a tiny (and I mean tiny) amount of a proprietary additive, it's all pretty much the same. If you want to test, try a tank full of Amoco/BP premium. No ethanol, and it's non-fungible (meaning nothing can be substituted for it).

 

[slisman]

I meant quality of gas cap (at the top of fuel filler neck). Should be it air-tight to keep pressure intank or not? But still I am not sure if it could cause such problem.

Today I will have new 100% MAF. And then I will try to diagnose somehow this evap system (fuel tank vent lines), thats my only idea for now.

 

[donalds]

Smoke test?

 

[koda2000]

I meant quality of gas cap (at the top of fuel filler neck). Should be it air-tight to keep pressure intank or not? But still I am not sure if it could cause such problem.

Today I will have new 100% MAF. And then I will try to diagnose somehow this evap system (fuel tank vent lines), thats my only idea for now.

Yes, the gas cap should have an air tight seal, but I don't see how a bad gas cap could be your issue. It usually will turn on the CEL.

 

[Tech By Trade]

Its not your gas cap, it will run fine with a loose cap, it will just throw a code.

 

[slisman]

Thanks for all new responses
1) My MAF is definitely good - tried to replace with 100% sure one and no changes
2) Smoke test is about to be done - I'm finishing my DIY smoke machine. It can tell us a lot
3) Today I will also check wiring of PCM, as written above (2nd page)
4) VSS can be related to this? I think not and new trouble code can be caused by long cranking. But maybe I am not right?

 

[koda2000]

No, not VSS.

 

[slisman]

PCM wiring checked and cleaned - still same long crankin.
I'm finishing smoke machine, hope it will show me direction

 

[koda2000]

For what it's worth, I don't think a smoke test will tell you anything about your issue. A smoke test is helpful in finding vacuum leaks. Vacuum leaks will typically cause starting problems on a cold start (not a hot/warm start) on the 4.0L SOHC and will usually set the CEL with P0171/P0174 ODB II codes.

 

[slisman]

Seems logical.

I have new suspect - fuel injection damper (this one o firewall). I have returnless system. I've found similar problem caused by this damper.

But there is problem with this part availabiity here in Europe.

 

[donalds]

This problem happened to me this probably was covered but how long did your fuel pressure hold after you shut down the car when I upgraded my fuel pump the high performance pump the new pump had no check valve in it fine start when cold but not hot and no amount of cycling the key helped I am ended up installing a one way check valve in the tank of your pressure drops like a brick when you shut her down then look there more closely
Like I said this may have been covered just a thought

 

[slisman]

I have no resolution yet but it is clear that enigine is being flooded after shuting down due to pressure kept in fuel system.
Today used and 100% sure fuel injection damper arrived (again - I can check it without buying new part). Should I take off coil pack to replace this damper? Access is not very good

And maybe should I try one more time with diagnosing injectors? @koda2000 proposed good&simply way to diagnose it (take off fuel pump fuse and burn all fuel from lines - after it next idle should be smooth without cranking) but maybe I should make next try? Maybe after shutting down I should decrease fuel pressure by shrader valve? Then I will be sure that engine is not flooded.

To sum up:
-FPR intank is good and when engine is cranking long fuel pressure is correct - so that we can exclude this part
-Engine is somehow flooded - what parts can cause it? Injectors and damper?

 

[donalds]

Injector

 

[koda2000]

I have no resolution yet but it is clear that enigine is being flooded after shuting down due to pressure kept in fuel system.
Today used and 100% sure fuel injection damper arrived (again - I can check it without buying new part). Should I take off coil pack to replace this damper? Access is not very good

And maybe should I try one more time with diagnosing injectors? @koda2000 proposed good&simply way to diagnose it (take off fuel pump fuse and burn all fuel from lines - after it next idle should be smooth without cranking) but maybe I should make next try? Maybe after shutting down I should decrease fuel pressure by shrader valve? Then I will be sure that engine is not flooded.

To sum up:
-FPR intank is good and when engine is cranking long fuel pressure is correct - so that we can exclude this part
-Engine is somehow flooded - what parts can cause it? Injectors and damper?

I thought you'd tried pulling the fuel pump relay and letting the engine run out of fuel before letting it sit hot (to try to eliminate the possibility of flooding due to a leaking injectors). If not I'd starter there. I don't recommend releasing pressure via the schrader valve on a hot engine.

On a 2000 model, the fuel pressure damper is just there to moderate the pressure for the injectors. I don't recall if it is vacuum controlled (like on the older models, which had the FPR on the fuel rail). The problem with the older models was that the FPR's vacuum diaphragm could leak and then fuel could go where it wasn't supposed to go, getting into the engine. IDK what issue the fuel damper could cause if bad. Perhaps it could cause flooding... ?

Edit:
I just looked up the 2000 FP damper on RA and it appears that it is vacuum controlled, so it is possible for fuel to to get sucked/pushed in the engine via the vacuum line if the diaphragm is ruptured. Do you have a vacuum pump to test it with? It should hold vacuum. At $250 I'd want to be damn sure that the damper was bad before installing a new one.

 

[slisman]

Hey, thanks for another response!

1) I've done your test. Engine was running and due to lack of fuel (relay taken off) it shut down. After one hour it was cranking long again - despite the fact that there was no fuel in system. As I wrote it again - it seems that there is no possibility to be caused by leaking injectors or this damn damper.

2) Yep, damper is vacuum driven.

3) Hmmm maybe ECT again? It so no first time that new part (good quality) can be broken. I should take a look on this again I think. Good diagnosis with voltage meter etc.

 

[slisman]

I have new observations. Everything checked with voltometer (ECT, IAT) and is good.
But now I am 100% that there is problem with fuel system. But not with fuel pump or intank FPR or pressure - this part seems to be good. There is problem with flooding (injectors or this damper?).

In the morning I've primed fuel system twice but with no idling and go home. After one hour I've tried to start engine and long cranking was present. So definitely it is not connected with temperature or electrical stuff or vacuum, but with fuel leaking into engine

I will start with this damper (have used one to replace). Any ideas how to change?
Or maybe there is any possibility to test injectors via forscan?

 

[slisman]

Guys, problem finally solved!
Thanks for all your help.
It turned out that one injector was extremely leaky.
And now - Explorer idles right away!

 

[donalds]

Guys, problem finally solved!
Thanks for all your help.
It turned out that one injector was extremely leaky.
And now - Explorer idles right away!

Sweet thanks for the update and Mark this thread as solved

 

[slisman]

Done.
Still don't have idea why injector test by @koda2000 did not idicate injectors (i.e. take off fuel pump relay, burn all pumped fuel till engine shuts off and then try to idle after hour) - injector was one of first suspects with ECT.

But all in all I'am satisfied with ending

 

[koda2000]

So glad you finally figured this out. I don't know why removing the fuel pump relay and running the engine out of gas didn't show a leaky injector sooner, but that finally makes sense.

Congrats! Another one in the books.