Hard start...only when warm??

[hilltopfarm]

That tells us the check valve and the injectors are good it has to be the FPD pull the fitting off of the brake booster and smell for fuel it is common for fuel to destroy the booster from the older FPR leaking, if you smell fuel there dont even question the cost of the new FPD.

What did I do to tell you that the check valve and injectors are ok? Also if the FPD was bad would the leakdown test not have shown it?? Just trying to figure this one out...Thanks for your help!

 

[RonD]

There is should be no fuel in the upper intake, where vacuum hoses are connected.
Injectors spray fuel near the head and intake valve, and because they only spray when engine is turning the fuel can only travel one way, towards the head, the direction of the air flow.

I would rinse off the FPD vacuum line, make it REAL CLEAN inside and out, then smell it for fuel smell, should be none.
Reinstall FPD and vacuum line.
Drive around for a day and see if vacuum line gets fuel in it.

I think it will.

 

[kimcrwbr1]

Do you smell fuel in the vacuum hose where else can it be coming from? Did you check fuel pressure when running? You can allways try brazing two nipples on a jar lid and then pull a vacuum through the jar to the FPD and see if fuel drips into the jar?

 

[hilltopfarm]

I think what I shall do is assemble everything. Hook up my hand operated vacuum pump to the FPD routed through a catch container, pump it up to 30psi and drive for a while. If the thing is leaking, it should accumulate in the catch container, and not be drawn into the intake manifold. Sound like a good idea? Basically what kimcrwbr1 was saying to do.

Like Mr. RonD said, I do not see why there would be a smell of fuel in the intake manifold except for it being drawn in through the vacuum lines. In any case there should not be the smell of fuel in the intake manifold, correct?

Oh, and I have not checked the fuel pressure while running. Would that be advisable? I guess all that would tell me is if the pump is working correctly...

 

[hilltopfarm]

Sorry for the belated response.

First the good news:
I got the catch can in the vacuum line for the FPD and no fuel or fuel smell coming from the FPD.

The bad:
Noticed while driving down the freeway the engine has a vibration to it anything past 2K RPM. Does not matter whether it is in neutral or being driven it still makes the same vibration. I checked all the things that I could think of: Engine mounts grounding out, exhaust grounding, took off the accessory belt...
Also the hard starts, sometimes it has to turn over 5-8 times before it finally gets going. Others it starts, but has a kind of lag to it after the first ignition. Kind of ruff for the first couple of seconds.

Wondering what I should do next?? Even the engine remanufacturer seems puzzled by this one... Any suggestions???

Thanks!

 

[RonD]

I had similar vibration and it was the Fan Clutch going out.

When engine is cold start it and test for vibration, when you know where it vibrates, RPM wise, shut off engine and remove(disengage serpentine belt), restart engine and test for vibration, battery light will come on maybe even CEL, but it won't hurt anything to run engine without water pump for a minute.
If vibration is gone then my guess would be fan clutch.
If it only vibrates when warm then I would bet money on the Fan Clutch, but your money not mine, lol.


Back to the slow start, you have sequential injectors, all will have power(12v) when the key is on, but none will have a ground.
Computer grounds each injector to open it.
If one of these six Ground wires had a short to ground then injector would open on it's own.
You could use a test light or meter with key on and test if any injectors have a ground.
On a cold engine it would start but not quite as fast, cold engines like Rich mixes.
Warm engine doesn't like rich mix, would take some time to start.

Pressure test should show this, pressure would have a steady drop with engine off key on as fuel leaked out via the open injector.

Have you tried the Key on/Key off test to prime the fuel system?
Turn key on count to 3
Turn key off
Repeat 3 times, then try to start, this cause fuel pump to prime system 3 times.
If it starts right up then I would thing fuel pump issue, might not be the pump but a leak in the delivery system in the tank.

 

[hilltopfarm]

Thanks for the reply RonD.

I did remove the serpentine belt and the vibration is still there so that's not it (unfortunately). As far as the injector goes, I will check those sometime this week and let you know what I find. I don't suppose that would be the cause of my vibration issue? Or maybe a spark plug not firing??? (I did check the wires before installing them with an ohm meter)

One other thing I thought of... Would the harmonic balancer have anything to do with it? Or the flywheel? When I installed the harmonic balancer, I torqued everything down and of course made sure that the key was installed. Flywheel was not resurfaced, but only had about 7K miles on it since it was resurfaced and clutch replaced.

Thanks again!

 

[hilltopfarm]

It's been a while since I last posted, but here is an update: After taking the truck to a well respected shop in the area per engine manufacturers (Promar) request, I found out that the vibration is internal. They also checked the fuel pressure and it was normal and did not leak down after sitting all night. I still have the hard start issue though! After more conversations with the manufacturer they think that it is the balance shaft in the engine. He told me that there is an outside chance that it is a bent connecting rod, which he said would not be there fault. As far as the balance shaft goes, he said that they would only pay $45 p/h to fix it IF the problem was deemed to be theirs. Really SUCKS!!!

So, since I am only employed part-time right now, I guess I'll tear into it myself. I want to do it without removing the engine. Was thinking of removing the front axle/diff in order to get the oil pan of to get access to the balance shaft. First before doing anything, I'm going to check compression on the engine just in case it was a bent connecting rod.

Any thoughts on if it is likely for the balance shaft to be the source of my vibration? If so what would be the easiest way to get to the shaft without removing the engine??

Thanks for all the help!!!

 

[RonD]

The 4x4 4.0l SOHC engines had balance shafts the 2WD 4.0l SOHC engines didn't, so I would think it was a harmonic vibration issue with the front drive shaft, not an engine specific vibration.
So in 2WD mode there would be no vibration unless balancer was mis-timed, it is chain driven and has a tensioner.
http://www.jasperengines.com/pdf/Ford4.0BalanceShaftTB.pdf

Anyway, I have never pulled a 4.0l SOHC apart but from what I have read the timing chains often loosen up and cause issues, so if these have never been changed then I would pull the engine and do all of it at the same time.
The balancer is driven from the rear of the crankshaft so not certain you could service it with engine in the vehicle.

Yes, check compression for sure, bent connecting rod, on a currently running engine, could only come from a hydro lock, maybe from a leaking injector but if system is tight(holding pressure), then how would it happen?
Unless it had a blown head gasket in the past?

 

[hilltopfarm]

Thank you Ron for the response!

This is a new remanufactured engine with approx. 260 miles on it. That is part of what has me upset. Guess I should have been clear about that in my post.

Anyway, I know it is not the front drive shaft, since it makes the vibration in both neutral or on the road, most noticeable at 2-2.3K and pretty steady up from there. As far as I have noticed it has made the vib since putting it in.

I was thinking that I could remove the front end to get at the upper oil pan/engine cradle where the balance shaft is. Anyhow, not sure how that would be the problem unless like you said it was not timed correctly at the factory... I guess I'll find out when I tear into it tomorrow...Not looking forward to it

 

[hilltopfarm]

Update: Got the front differential pulled today. Tried to check compression, but valve in my tester was bad. Will get a new valve tomorrow. Looks like there should be enough room to pull the engine cradle with the front diff out. May have to jack the engine up a bit...

 

[RonD]

Watch for firewall clearance when raising the engine, i.e. the distributor

 

[hilltopfarm]

Good tip! Thanks