head scratcher

[mrbrian200]

I had wondered if the evap code could possibly be related. I will look into what it would take to replace this but at this point I am leary of throwing more money at it. I have had the eval code for almost 4 years now but the time dependent hard start has only appeared in the last few months.

Is there a thread anywhere that can help me determine which configuration my 98 is? I don't much relish attempting to locate it in these temps, -18ºC this morning!

On a '98 it's entirely possible you have multiple issues. Such as a weak spark having trouble igniting a rich fuel mix due to a failed failed purge valve at startup. Starting fine at -18C supports the idea of a purge valve issue as the fuel is more stable/less evaporation the colder it gets. But at those temperatures atmospheric humidity drops and you're less likely to have trouble with a failing ignition coil due to moisture intrusion that would be more of a problem at higher/above freezing temperatures. I think we're getting close- it's going to be one or a combination of these potential issues giving you trouble.
Richhaleparker wisely brought attention to the ignition coil/igniter-IDM, I would start there first. But if you make progress after addressing the ignition system you still want to know the cause of the EVAP system DTC. As problems in the evap can result in the enging running either rich or lean at different times. A lean condition can damage exhaust valves especially on a turbo engine. You don't want to go there.

[shegarty]

Okay, finally got some fuel pressure data and from what I can tell everything appears to be normal. The car had sat for about 15hours before collecting this data

Initial pressure - 0psi
Key Pos II - 10psi
Crank - approx 38-39psi (started right away)
Idle - 36psi
Small load - 38psi
Shut off - 40psi
2nd start
Key pois II - spikes to ~43psi then drops to ~40psi (starts right away)
drops back to 36psi
fulled warmed up 34psi
Shut off - 40psi

This is what I have so far - just doing a leak down test now - will report back what I find.

[abscate]

Dont worry about the leak down test too much. The key thing is when you get the no-start, what is the fuel pressure doing then?

[shegarty]

Dont worry about the leak down test too much. The key thing is when you get the no-start, what is the fuel pressure doing then?

That is the biggest part of the problem right now. Based on what it has been doing in the past today should have been a no/hard start. Up until now anything past the 15-18 hour mark was giving me trouble, irrespective of the ambient temperature.

I did two other things since the last no start - clean up the contacts on the coil from the IDM and swapped the MAF for a know good one (the one the car came to me with that I swapped out for a spare two years ago while chasing this issue) simply because the first was easy and I had a spare of the second. Maybe I found my problem?

[abscate]

It is even more important to have those diagnostics ready when the problems are intermittant, as opposed to a hard no-start.

The era when cars could be diagnosed by symptom ended in about 1985

[shegarty]

Leak-down test:

shutoff - 40 psi
5 mins - 42 psi
10 mins - 41 psi
20 mins - 41 psi

It would appear the the new regulator is holding vacuum and doing it's job.

[shegarty]

The key thing is when you get the no-start, what is the fuel pressure doing then?

Finally got some data from a hard start scenario. Sitting for about 22hours, ambient temp around -4ºC:
initial fuel pressure at the rail 0psi
key pos II - slow build to about 4psi
key pos III - slow build of pressure, engine cranks for 4-5 seconds but doesn't start until pressure reaches about 38psi

I then shut off engine before it warmed up and bled the remaining pressure from the rail:
initial pressure 0psi
key pos II - quick build to 10psi
key pos III - quick build to 38psi and fires up after minimal cranking

So, despite replacing both the fuel pump and pressure regulator it would appear that there is still a loss of fuel pressure in the system that bleeds down over time. The only question is, where the heck could it be bleeding? There are no outward signs of leaking, no residual fuel smells and I have already down a leak-down test on the injectors which came back negative. Should I just cut my losses and attempt to install a check valve somewhere to prevent the pressure loss? If so where would be the best place to do that?

[RickHaleParker]

Perhaps one is asking the wrong question.
Is the correct question, why is pressure bleeding off or why does it take so long to build up pressure?
A debris surge can clog a fuel filter real fast.

[erikv11]

I agree, the unusual thing seems to be how long it takes to build pressure. That slow build to 4 psi is not normal at all. Should be a quick jump to 35+ psi.

I haven't followed all details of this long and well documeted story, but when was the fuel filter replaced? Are the fuel line connections good at the fuel pump?

[shegarty]

Perhaps one is asking the wrong question.
Is the correct question, why is pressure bleeding off or why does it take so long to build up pressure?
A debris surge can clog a fuel filter real fast.

I agree that a clogged filter could have the same effect, but it would not explain the time sensitive nature of this problem. A clogged filter would result in a long buildup of pressure on a consistent basis, would it not? I suppose you would also expect some fuel starvation under heavy load. At present I am not experiencing any other symptoms aside from the hard start. The fuel filter was replaced in 2015 and I've only done about 45k km since then.