mj1pate

Yes, plenty of threads on this topic. Forgive if I've missed something in them.

I'm getting long cranks to start lately.

If the car has sat for any length, I can pretty much depend on a long crank, maybe 5-6 seconds before it turns over. When the engine starts, it immediately settles into a smooth idle, without any hunting. It runs great and never dies.

During the last year, the fuel dampeners and regulators were all replaced with OEM. The fuel pump, filter and one-way valve have also been replaced. Before I replaced the fuel pressure regulator, the leak into the vacuum hose caused the car to jump into an erratic idle, sometimes dying and requiring a second start. That situation has improved completely since replacing the regulator/dampeners. The long cranks began 4 months after replacing the last of the dampeners and 7 months since replacing the fuel pump/filter/valve. The injectors were serviced by WitchHunter about 15k miles ago.

Persistence with long cranking pays off so far and it starts. I attempted to connect a fuel pressure gauge to the fuel rail this evening and removed the screw cap. I expected fuel to come squirting out, since I thought the fuel line stayed pressurized. Only a drop of fuel came out of the end of the fuel rail, when I unscrewed the cap.
This is an indication of loosing pressure after the pump is off, correct?
If so, is there a best way to isolate the pressure loss between the one-way valve and the injectors?

James Bailey

You might want to TEMPORARILY attach a fuel pressure gauge to the fuel rail to see how long it holds pressure after shut off....or run a jumper to the fuel pump relay so you can turn on the pump pressurize the system BEFORE cranking. That way you know what the problem is

mj1pate

How long should the line hold pressure?

James Bailey

it is in the tech spec books but I do not have one....the CIS cars with the accumulator it was several hours but the later cars it is maybe an hour...???

Mrmerlin

check the dampers and the FPR vacuum lines for fuel smells , any fuel smells means a leaking part
add A bottle of techron to the fuel also add some MMO 6oz, do short drives

littleball_s4

Hey,

I would park the car in a place with good natural light. Let it cool down completely (better overnight). Remove everything on the way to have good access to fuel lines (I think MAF housing at least). Have somebody jump the fuel pump relay for 5 or 6 seconds and look/hear/sniff for leaks, moving pipes and unplugging things (vacuum lines) as you do so. Don't be gentle.

It is uncommon, but not unheard of, that the leak takes place only with little pressure and then sorts of seals itself with pressure. It will do so only for a while before bursting completely, it's a time bomb. That's why it could be a good idea to look for leaks as you jump the relay. You can open the rail cap and repeat a couple of times if needed.

Remember leaks take place at the places with limited access, like the flex hoses of the dampers/regulators in the back of the engine. Also injectors could leak in the connector to the rail.

Taking too long to start is frustrating, but catching a fire is more, that would be my first priority. Short of the check valve or FPR, any other fail can and will start a fire.

Also, keep in mind the whole FPR + dampers thing is a bit messy, there are several combos which are similar but not the same and several items which look remarkably alike. Double check that you are using the right combo for your car.

Good luck!

littleball_s4

Also, I would change all flex fuel lines if you didn't already. I think they have the biggest failure cost / replacement cost ratio of all parts in the car. And they look good up until the moment they burn your car.

Sorry to worry you, surely nothing bad has to happen, but better safe than sorry.

mj1pate

Merlin; what us MMO? Yes, I have just put in a bottle of Techron.
Thing is, all the flex lines up front have been replaced. The bad startup symptoms (sudden hunting and then dying) quit with replacing the regulator/dampeners. And those symptoms were caused by leaking back thru vacuum hoses towards the throttle body. Now, I'm kind if wondering if maybe the new regulator just isn't doing its job correctly. I'm also cautious about ripping things apart (been a busy year). I wonder if there is a systematic way of isolating internal problems between the regulator, check valve (all fairly new) and fuel injector (internal) leaks. I don't smell any fuel, the injectors were serviced and reinstalled less than 20k miles ago.

I will try and determine a more exact "trend" concerning how long I have to crank under what circumstances. And then under the "worst case " circumstances I'll put the jumper in for the relay, pause a few minutes and see if it starts right up. .... And then go from there. and thanks. ideas are hugely appreciated.

rbrtmchl

I'm pretty sure that Stan is referring to Marvel Mystery Oil.

mj1pate

Wow... I thought marvel mystery oil was good for fuel line moving parts (CIS, or ISV). Is it good for other fuel line functions? My ISV is also fairly new.

jpitman2

Pump relay not priming at turn on ? Poor connections to pump reducing its volts while cranking? Pump relay gets hot in use ?
jp 83 Euro S AT 55k

Mrmerlin

What Robert said
I'm pretty sure that Stan is referring to Marvel Mystery Oil.


MMO is used in the fuel tank with the techron it will keep the injectors lubed,

mj1pate

Interesting, Merlin. So, the method is to use them at the same time?

BTW: (probably the n'th time for this question) Do you fly Merlin powered machines?

Mrmerlin

^^^ Oh I Wish I did,
still looking for my first ride in a Mustang