Long crank, no faults

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jlglr4

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A small leak in the check valve (maybe only in one of the pumps) that‘s draining pressure off while turned off might not make much difference in the performance of the pump when running. Wondering if you’ve compared fuel pressure before a normal start to fuel pressure before it does the long crank. If there are situations when you’re pretty sure the engine will start quickly, like maybe setting for only 30 minutes or an hour, you could compare the pre-crank fuel pressure with what you see after sitting overnight. Might give you some clue about whether fuel pressure is really the issue. If it’s 50 psi after setting for 2 hours, but still starts up quickly - maybe its not a fuel pressure issue.

You might also do a little research and see if there is a way to crack the fuel lines and pressurize them - see if they hold pressure. Maybe test the right rail, left rail, and then feed line back to the pump separately. Perhaps a garage would have a way to test for injector leak without having to pull the injectors.
 

Jimmy Brooks

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A small leak in the check valve (maybe only in one of the pumps) that‘s draining pressure off while turned off might not make much difference in the performance of the pump when running. Wondering if you’ve compared fuel pressure before a normal start to fuel pressure before it does the long crank. If there are situations when you’re pretty sure the engine will start quickly, like maybe setting for only 30 minutes or an hour, you could compare the pre-crank fuel pressure with what you see after sitting overnight. Might give you some clue about whether fuel pressure is really the issue. If it’s 50 psi after setting for 2 hours, but still starts up quickly - maybe its not a fuel pressure issue.

You might also do a little research and see if there is a way to crack the fuel lines and pressurize them - see if they hold pressure. Maybe test the right rail, left rail, and then feed line back to the pump separately. Perhaps a garage would have a way to test for injector leak without having to pull the injectors.

To be honest with you I’m not quite convinced that pressure building is the issue. I say this because I’ve watched the car crank on cold starts to where it would turn over at 350 psi or crank it’ll 1000psi or even 1400psi and still not turn over. The issue has definitely progressed as well, it doesn’t even have to be cold starts. I watch the rail pressure build after turning off the car and then it tends to hit a peak and go back down to 45-56 psi. I’ve also seen it crank when there is only 50ish pressure in the rail and turn over as if nothing was wrong with it. Genuinely doesn’t make sense to me at this point. I’ll do the little guide for diagnosing the fuel pump but I’m also about ready to turn it over to the shop. Just wish I could know for sure what’s wrong with it so I didn’t have to pay for a diagnosis phase or even could just fix it myself. It’s just really tough without any fault codes.
 

greiswig

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To be honest with you I’m not quite convinced that pressure building is the issue. I say this because I’ve watched the car crank on cold starts to where it would turn over at 350 psi or crank it’ll 1000psi or even 1400psi and still not turn over. The issue has definitely progressed as well, it doesn’t even have to be cold starts. I watch the rail pressure build after turning off the car and then it tends to hit a peak and go back down to 45-56 psi. I’ve also seen it crank when there is only 50ish pressure in the rail and turn over as if nothing was wrong with it. Genuinely doesn’t make sense to me at this point. I’ll do the little guide for diagnosing the fuel pump but I’m also about ready to turn it over to the shop. Just wish I could know for sure what’s wrong with it so I didn’t have to pay for a diagnosis phase or even could just fix it myself. It’s just really tough without any fault codes.
Is all this assuming that the readings you're citing are actual pressures? IOW, if the sensor is bad, trusting the reading on it and looking for the correlation between fuel pressure and whether or not it is firing might be a bit like measuring a dead person's temperature with a thermometer that only reports temperatures between 98F and 99F, and pronouncing the victim "healthy."
 

Jimmy Brooks

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Is all this assuming that the readings you're citing are actual pressures? IOW, if the sensor is bad, trusting the reading on it and looking for the correlation between fuel pressure and whether or not it is firing might be a bit like measuring a dead person's temperature with a thermometer that only reports temperatures between 98F and 99F, and pronouncing the victim "healthy."
I agree with this but the sensor seems to be reading fine when the car is at idle and when accelerating. Plus the car seems to run great after it’s started. Another thing I notice is that the longer it cranks the slower it turns over when it finally starts firing almost as if the engine was flooded with fuel. The best way I can put this is a normal start as soon as it starts firing the engine goes to 2000 for a second then goes down into high idle at around 1300 rpm where as when it starts after cranking for a while the rpms will go up much slower and it I wouldn’t see it touch anything over high idle on its own. It’s almost seems as if I’m dealing with an ignition issue but again no misfire codes. Sometimes when the car is trying to start I’ll hear sputters so I know it’s misfiring a little bit as soon as the car actually starts and is idling there are no misfires. If it still sounds like a sensor issue then I’ll buy a new sensor I just don’t like spending money till I’m sure of the issue but it looks like I’m kinda out of options at this point.

(Edit, the voltage is also normal and moves up with engine revs when cold)
 
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jlglr4

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Yep, this is a tough one. You could try pulling the plugs and see if you can identify any one cylinder that might have a problem - fouled plug or wet cylinder. Maybe start it cold to get the pressure up, then shut it down immediately (before it gets hot) and let it set for 30 minutes or an hour. Look in the cylinders to see if you have a wet one which would point to a leaking injector flooding the engine while it sets. If you're going to go through the trouble, might just replace the plugs while you're in there. Or just take it to the shop and see what they say.
 

Jimmy Brooks

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Yep, this is a tough one. You could try pulling the plugs and see if you can identify any one cylinder that might have a problem - fouled plug or wet cylinder. Maybe start it cold to get the pressure up, then shut it down immediately (before it gets hot) and let it set for 30 minutes or an hour. Look in the cylinders to see if you have a wet one which would point to a leaking injector flooding the engine while it sets. If you're going to go through the trouble, might just replace the plugs while you're in there. Or just take it to the shop and see what they say.
Ya I just replaced the plugs last year. I had the shop do it because I was in a hurry so I think the coils are still original. Maybe I’ll pull them this weekend and see if I see any fuel residue in the cylinders. The one thing that just doesn’t quite sit right with me is the fact that the car will build nearly 1800 psi of fuel pressure but won’t turn over but when it does will run fine. It’s almost as if it won’t fire ignition. Almost makes me want to think it’s an ECU issue but I don’t get miscellaneous faults from it. I do tend to get weird random ABS codes (U0415-00 (28) (headlamp module) U0121-00 (68) (instrument pack)) they have always been miscellaneous and never set off my abs light. Abs works fine, so does traction control so I’ve never worried abt them. At this point I’m very stumped. I just don’t understand how it could be high pressure fuel pumps if they are able to make 1800 psi of pressure under cranking conditions, run perfectly fine under normal conditions with almost perfect fuel trims, and get 2150 psi of pressure at high idle. I also just don’t understand how it could be injectors either if Im able to go flat out from 0-80 mph without any type of power bog or misfire codes. It just doesn’t make sense to me at this point. Again, considering that most of the fuel system in this car is mechanical (and the fact that it seems to turn on at different fuel pressures each time) it really makes me want to think that it’s just not running the ignition when it should be while cranking. Would that even make sense on this truck without having a bad ecu?
 

jlglr4

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I don’t think you can rule out leaking injector or check valve based on good performance when fired up. Slight leakdown might be enough to give you a starting problem, but not running problem.

Looking at spark, a failing crank position sensor or maybe camshaft position sensor might cause no spark until it gives a good signal, but i would expect more codes/problems at least intermittently. Possible though.
 

steevo

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Intermittent Crank pos sensor issues usually occur when warm. I wouldn't change the cps without looking at the signal with a scan tool or a scope to confirm an issue. I tend to lean toward a minor injector leak based on the info in the thread.

Unfortunately the best way to check for a leaking injector is to pull & test under pressure, which is not easy on these vehicles. Next best is the leak down test, which you have kinda already done by monitoring pressure at the rail. Of course as jlglr4 points out, that doesn't isolate the injector, it could be the check valve. Because the leak is likely small and the vehicle runs well once started, you probably won't find a wet plug.

Try slightly pressing the throttle when you try to start. The leaking injector causes a momentary rich condition that can cause a long crank. Had this problem on another vehicle and opening the throttle would shorten the crank time, I presume because it would help lean it out. I pulled and tested the injectors and indeed one was leaking. Different car but similar symptoms.
 

Jimmy Brooks

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been busy over The Last week so the LR4 has just been sitting. Been driving my 5 series instead and noticed that after sitting for a week there was a drop of oil on the ground coming from the driver side valve cover back corner which makes its way from the exhaust manifold to the differential mount. I was planning on pulling injectors myself and getting them tested but now I’m questioning that since pulling injectors is already half of the way to do a valve cover. However I’m hesitant to pull the trigger on a valve cover just to have it replaced again whenever the timing chain in this car starts rattling. (Would also be my first time doing an open engine job and not sure if I’m completely confident in doing that.) i let it sit again for another 5 days and never saw another drop of oil on the cardboard I put under it, however the differential mount is coated in it so im sure the leak isn’t as present with normal daily use but that could also just be because the oil burns on the exhaust manifold and never made its way down there till now.

as for the symptoms of the truck, it likes to crank and then the starter will stop the car will fire a couple of times then die. Second time it’ll crank for a bit then start and idle and drive normal. I’ll get a distinct rich smell after starting it (not sure if it’s oil burning on the manifold or gas from the tail pipe) no codes still. Also doesn’t have to be a cold start anymore to get a long crank, simply leaving it for over 10ish minutes will do it now. Correct me if I’m wrong but I feel like injectors makes The most sense considering my HPFP doesn’t seem to have an issue climbing up to 2100 psi and I only have issues on start ups.

my question is what is the best route to go down? Since I don’t have a specific code replacing all the injectors would probably make the most sense unless they all get tested and non of them are bad. But is the valve cover even worth doing? I just don’t have the spare cash laying around to do a whole timing chain overhaul but I don’t necessarily plan on doing one any time soon (don’t really get any chain noise from my engine) and I would hate to see a brand new valve cover gasket go if I end up doing the chain in the next 10k miles if fate leads me there.
 
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ftillier

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Is the valve cover gasket single use, or is it an age thing that cause it to harden up and then leak?

In any case, a set of valve cover gaskets is $100 at fcpeuro, you could buy that, then return it when you get a replacement for the timing chain work.
 

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