Hard start...only when warm??

[hilltopfarm]

Hi folks,

I got my project back together and running, only problem is that it has a hard time starting only after the first start (i.e. when warm). This makes me believe it is not the battery, but maybe the fuel system? By hard start I mean crank over 6-7 times before it fires up. When I put the reman engine in it, I also put professionally rebuilt injectors in there too.

I guess the next step would be to go and get a fuel pressure gauge and see that I'm getting adequate fuel pressure? But even that does not make sense since it only happens when warm

My truck specs are as follows:
2003 4.0L SOHC FX4

Thanks for any help, this one is really irritating.

 

[aaron88]

Check the filter as well. Put a fuel pressure gauge wouldent be a bad idea. My ohv was doing that when I first swapped it in ended up being a bad connection at the fuel pump it wasn't priming correctly.


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[hilltopfarm]

Thanks for the reply!!

What do you mean by 'bad connection at the fuel pump'? Bad electrical connection, or the fuel line was somehow not properly inserted? Replaced the fuel filter about 6 months ago, so I would guess that would be good to go.

Since my last post my truck has had hard time starting when cold , so I guess the 'hard starting only when warm' has been blown out of the water...

Also noticed that the battery has a drain on it when the truck is off. Put my dc amp clamp on there and it is anywhere from 2-.36 amps. Noticed that with the truck running the voltmeter in the instrument panel is slightly below the halfway mark, used to be quite a bit higher...
Charged the battery up last night and it was at 12.7V, this morning it was 12.47V. Guessing that that has something to do with it Guess it's time to start pulling fuses till the amp draw goes away to narrow it down.

 

[kimcrwbr1]

Maybe sniff the vacuum line to the fuel pressure regulator for fuel maybe a small leak in the diaphram causing a over rich condition. See if the fuel rail holds pressure after you turn the engine off? Three thing it could be if the pressure drops rapidly, leaking injector/s, bad regulator, or check valve in the fuel pump. Do you smell fuel out the exhaust whe it starts?

 

[RonD]

In '97 or '98 Ford dropped the fuel pressure regulator, switched to a pulse damper and no return line.
Fuel pressure is these is 60psi, vs the older 35psi with return line and FPR.

Yes, would be worth while to get a fuel pressure reading running and after 20-30 minutes of sitting, see if pressure is leaking out, so check valve in fuel pump if no visible/smellable gas leaking.
You can try to cycle the key on and off 3 times before starting, leave key on for 3 seconds, that will cause the computer to prime the fuel system 3 times, if engine starts quickly after this then there is a leak of pressure when engine is sitting.


I would disconnect battery, test voltage, then let it sit overnight and test in the morning before hooking it up again, just to get a baseline and to see if battery is starting to self drain, which happens when they get older, one cell starts to short and drains the others.

Not sure the 2004 Rangers had a Battery Saver relay, these were used to shutdown the GEM module after 20-30 minutes, so if a light was left on it wouldn't drain the battery.
These relays did fail so never shut off the power drain of the GEM, which was about .3amps.
After relay opens(20-30minutes after key off), drain would be .05-.07 which would be what it should be.

 

[hilltopfarm]

Talking about smelling fuel. I forgot to mention after running the new engine a little, I had to take the intake manifold off. It smelled strongly of fuel. Where could that be coming from? Might that have something to do with this whole problem?

 

[RonD]

The Fuel Pulse Dampener does have a vacuum line as a failsafe in case diaphragm should fail, if that happens unmetered fuel would be sucked into the intake(instead of spraying on hot manifolds ).

You could remove this vacuum line and check it for fuel smell, or fuel.

New injectors are great.......but..........new no longer means "it works", new now means "never tested".
Quality control for most parts has been moved to the consumer end, this makes parts cheaper but we are now the testers for failed new parts.
So with that in mind I wouldn't rule out a leaking injector, just because "it's new"

I know, it's a PITA but our buying habits forced this removal of Quality Control departments.
But warranties on these parts are usually better, lol.

 

[hilltopfarm]

Thanks for the info on that fuel dampener. I thought that it was the fuel pressure regulator, but like you said I guess the later models of the ranger did not have them. I'll go and pull that vacuum line today to check for the smell of fuel. If that dampener was leaking, would that explain my hard starts? I guess that a fuel pressure gauge would pick up a leaky dampener? Kind of weird that it would all of a sudden start when I put it all back together... What does the fuel dampener do???

As far as the injectors go...I put in rebuilt injectors that were rebuilt by a reputable company in Florida and tested on an ANSU machine. After being cleaned and having new seals, filters, etc. put in they were flow tested and checked under various rpm ranges to ensure that they work. So after all that testing I would assume that the injectors would not be at fault...but I could be wrong.

 

[simpler=better]

Jeep 4.0L engines have an issue similar to vapor locking when the fuel rail gets heat soaked (it's right above the exhaust manifold...well it's a jeep what did you expect). Is something like that occurring?

 

[hilltopfarm]

No I don't think that its getting 'heat soaked'. The fuel manifold should not get that hot. Never had a problem with it before it got a reman engine...

Thanks for the reply!

 

[hilltopfarm]

Yeah, I started getting the intake manifold off to check the vacuum line coming from the fuel pulse dampener (FPD) and noticed a very strong smell of fuel while taking it off, opened up the vacuum line and there was a smell of fuel in there as well.

Truck had a hard time starting to get into shop, was running really ruff...

I'm assuming I'll need another FPD. They are kinda spendy at $57 at the local O'reilly auto.

UPDATE: Got the thing off, and vacuum line did smell of fuel, had white residue on rubber connector. Intake manifold walls were lined with gasoline residue...Trying to test the FPD before getting another one, put it under 35 psi on the vacuum line side and it was holding. If there was a hole in the darn thing would it not leak down?? Or draw gasoline through into the vacuum pump tubing?

 

[hilltopfarm]

Ok, the FPD has been sitting for 45min with 35psi on it. Has not leaked. I guess that there is no hole in it, or it would most definitely leaked through. Is there any other way that fuel can get into the intake manifold. I need to get this figured out so I can get the truck back on the road.

Thanks for the help!

 

[RonD]

You would think it would leak at 35psi.
Fuel system runs at 60-70psi, but I would think 35 psi would be enough for test.
I am not sure of the diaphragm setup on the FPD, since it is a dampener it may need pressure on the fuel side to leak.
If there was fuel in the vacuum line that's the only place it could have come from, fuel from injectors couldn't be pushed into a vacuum hose, that would be bass akward of how thinks flow in an intake.

Not saying you should do this but you could do this,

Put a longer vacuum line on the FPD and place it so any fuel coming out will NOT get on the exhaust system.
Then plug up the intake vacuum for the FPD.
Go for a spin and see if it's starting is better

And cold engines can tolerate richer mixes(choked), which is why you noticed the issue first when engine is warm and wants leaner mix.

 

[kimcrwbr1]

Ok, the FPD has been sitting for 45min with 35psi on it. Has not leaked. I guess that there is no hole in it, or it would most definitely leaked through. Is there any other way that fuel can get into the intake manifold. I need to get this figured out so I can get the truck back on the road.

Thanks for the help!

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.

 

[hilltopfarm]

Thanks RonD & kimcrwbr1!

I guess that I do not properly understand how an intake manifold works. After reading around a bit, it sounds like the fuel is "atomized" in the intake manifold. So should there be fuel in the intake manifold??

I thought that the injectors sprayed fuel directly into the top of the cylinder where it was ignited by the spark plug. The area where the fuel smell is the strongest is in the intake manifold. I have never smelled fuel in an intake manifold before. That is why I am concerned.

Also I need to clarify: I took the FPD off of the fuel pressure rail when testing.

Whether it is leaking from the FPD is yet to be determined, but I did fill the thing with gas and apply air to the backside (only about 15psi) while maintaining the 30psi on the vacuum line connector. Maybe I should have tested it with 60psi instead. Any thoughts? Thanks for all the help!!