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- Is it possible that these readings are not correct from this obd2 app ? Shouldn't they drop a bit and stay for 1-2 hrs?
sure it's possible the readings are incorrect but do you know what Hyundai says they should be, it's a ecm calculation that will vary based on engine requirements, it sounds like the pump may be operating correctly but it possibly could be showing signs of wear on the piston , albeit slight and intermittent.
-What regulates pressure AFTER car is off ? Gas tank press.regulator (one that sits on top of the tank, inside vehicle under carpet/back seat) bad?
nothing regulates pressure when off - the hpp has a one way value that prevents backflow so pressure can rise upon engine shutoff as one stroke of the piston can produce high psi and once power is cut the injectors close as does the power to the hpp control solenoid, the system is designed to hold high pressure in the rail, so if the pump is leaky or an injector pressure could drop - causing longer crank cycle.
I could not reproduce longer cranking times this morning while this obd2 reader was hooked up
check this vid out on scanning/interpreting pump readings, car with long crank but also loss of power at higher rpms - if you are not expereincing that I wouldn't replace the hpp.

 

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Discussion Starter #22
Thx for a reply and video link. So far I have not experienced anything like this with looong cranking time AND loss of power. Pretty cool the way diagnostics are on modern engines...
Looked at diff.options buying HPFP and oem are 500$+ ,some aftermarket are 400$+ but there are chinese made ( ebay/amazon) that can be bought for as low as 110$(?). Anyone have experience with these ultra cheap ones? I know that it is you get what you paid for...
Any good sources on geting these pump here in US or Canada (oem or brand name aftermarket ones)?
 

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the dealer replaced my high pressure fuel pump and the long start problem is still there. No loss of power. just the long start.
 

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the dealer replaced my high pressure fuel pump and the long start problem is still there. No loss of power. just the long start.
And did the dealer run diagnostics that indicated the pump needed replacement and that replacement would rectify the crank time issue.? Unless covered by some sort of warranty it seems to be expensive ($1k) to replace at the dealership , a diy job is ~ $350 for a quality pump and it's maybe a 45 minute job. In any event hope you kept the oem pump in case you ever need it , the pump like most any pump is a wear item.
 

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the dealer replaced my high pressure fuel pump and the long start problem is still there. No loss of power. just the long start.
BTW one of the possible causes of longer crank cycles is carbon buildup on the valves, but often you might experience some other symptoms like rougher idle at startup . But some gdi engines are prone to building deposits on the intake valves.
 

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BTW one of the possible causes of longer crank cycles is carbon buildup on the valves, but often you might experience some other symptoms like rougher idle at startup . But some gdi engines are prone to building deposits on the intake valves.
Theta II is no exception.

Had it on my Sonata and probably had it on the first Santa Fe Sport engine.

Got the best cleaning ever...replacement via the recall!!

Sent from my SM-G965U1 using Tapatalk
 

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Discussion Starter #27
Decided to change that high press.fuel pump. Looking at videos everyone has fuel line quick disconnect with orange/red tab that pops out. My looks different ( see photo in 1st post). How do you disconnect that style?
 

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Discussion Starter #29
So just a push on black plastic "sleeve" in and silver/metal quick connect plug slides out?
 

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Discussion Starter #31
Any suggestions on which tool will fit? Do I remove black plastic sleeve 1st and THEN slip on fuel disconnect tool? Or tool goes over this black sleeve and gets pushed in order to disconnect it?
See my 1st post how this looks like on my car
Thx for any tips
 

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I have one similar to this, there should be u tube videos showing how to use it.

 

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Discussion Starter #35 (Edited)
Replaced that HP fuel pump with a new oem pump. Cars started ok and no CEL/MIL lights...
Now lets see if longer crank time will be back...:unsure:
UPDATE:
Its back:mad:
Long(er) cranking time, but...
I think I narrowed it down to if it sits for 1-2 hrs outside (after running OK!) it will crank a bit longer. Losing pressure in fuel line somehow while sitting?
Leaky fuel injector(s)? Any way to determine which one is culprit? Any good deals on these injectors lately? Rockauto had some rebuild ones (around 80 US$ minus core charges)
 

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Fuel line pressure from the tank is supplied by the in tank pump to the DI pump on the head. The in tank also has a fuel filter.

Had to replace the sending unit on my Sonata and decided to do the filter as well since it's all together. Fuel that drained out was black. That car also had long crank but the throttle body was the culprit. Sounds like you did that and no change

I dont have the service manual open but I think you need to see what pressures are called for at the rail and compare to what is shown on the scan tool. If they are lower than spec I'd suspect either the in tank pump or the in tank filter.

Quick check is turn on the ignition but dont start the vehicle. The pump should whine loudly as it primes and builds line pressure. Then after engine starts, the whine quieter but always there.

Also are you 100% sure its fuel related? If possible look at the scan tool data for the MAF those can get dirty and mess with starting and drivability

Sent from my SM-G965U1 using Tapatalk
 

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Fuel line pressure from the tank is supplied by the in tank pump to the DI pump on the head. The in tank also has a fuel filter.

Had to replace the sending unit on my Sonata and decided to do the filter as well since it's all together. Fuel that drained out was black. That car also had long crank but the throttle body was the culprit. Sounds like you did that and no change

I dont have the service manual open but I think you need to see what pressures are called for at the rail and compare to what is shown on the scan tool. If they are lower than spec I'd suspect either the in tank pump or the in tank filter.

Quick check is turn on the ignition but dont start the vehicle. The pump should whine loudly as it primes and builds line pressure. Then after engine starts, the whine quieter but always there.

Also are you 100% sure its fuel related? If possible look at the scan tool data for the MAF those can get dirty and mess with starting and drivability

Sent from my SM-G965U1 using Tapatalk
No MAF, it's a speed/density system so map is the main sensor. A leak down test of the fuel rail can sometimes identify whether it's a leaking fuel injector, but one likely needs specialized equipment to do that, but they can leak.
 

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Replaced that HP fuel pump with a new oem pump. Cars started ok and no CEL/MIL lights...
Now lets see if longer crank time will be back...:unsure:
UPDATE:
Its back:mad:
Long(er) cranking time, but...
I think I narrowed it down to if it sits for 1-2 hrs outside (after running OK!) it will crank a bit longer. Losing pressure in fuel line somehow while sitting?
Leaky fuel injector(s)? Any way to determine which one is culprit? Any good deals on these injectors lately? Rockauto had some rebuild ones (around 80 US$ minus core charges)
how many miles on this car ? did you take a fuel pressure reading from you scan tool 1 and then 2 hrs after hot engine shutdown ? If the fuel rail pressure is too low the fuel can percolate(vaporize) from the engine heat and create a longer crank situation but personally I wouldn't throw more parts at it unless you can pinpoint the cause.
 

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Discussion Starter #39 (Edited)
Thanks for all replies!

This SFS 2.0t has about 65000 kms (40000 mi)

Very frustrating chasing this...still no CEL (no DTC code displayed or pending).

Using my little bluetooth obd2 reader I can trend fuel rail pressure after engine is off and it does drops fairly quickly from 500-550psi (running at idle) to 450,430,380...300..250...200..
all the way to 20-30psi (?) Maybe 15-20 min it takes to drop in fuel rail pressure (according to obd2 reader).
One think I've noticed is that evap pressure is 1940psi and drops to 448ps then back to 1900psi (roughly) then after 15-20sec goes down to 400 and back up (!?). What controls this evap pressure? That (evap pressure) is one of the options on my obd2 car scanner app
Vaporizing fuel in fuel line? I heard about that. That how it started this summer (+30c = 85F) for me when car was hot/running it would crank a bit longer after short break and restart (coffe/pitt stop for us).
One friend recommended liqui moly brand of fuel injector cleaner (jetclean version I think!). He swears by it. It may help in unclogging injector(s) so they properly set back/seal fuel line (he thinks!)
Any help is much appreciated!
 

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Thanks for all replies!

This SFS 2.0t has about 65000 kms (40000 mi)

Very frustrating chasing this...still no CEL (no DTC code displayed or pending).

Using my little bluetooth obd2 reader I can trend fuel rail pressure after engine is off and it does drops fairly quickly from 500-550psi (running at idle) to 450,430,380...300..250...200..
all the way to 20-30psi (?) Maybe 15-20 min it takes to drop in fuel rail pressure (according to obd2 reader).
One think I've noticed is that evap pressure is 1940psi and drops to 448ps then back to 1900psi (roughly) then after 15-20sec goes down to 400 and back up (!?). What controls this evap pressure? That (evap pressure) is one of the options on my obd2 car scanner app
Vaporizing fuel in fuel line? I heard about that. That how it started this summer (+30c = 85F) for me when car was hot/running it would crank a bit longer after short break and restart (coffe/pitt stop for us).
One friend recommended liquid moly brand of fuel injector cleaner (jetclean version I think!). He swears by it. It may help in unclogging injector(s) so they properly set back/seal fuel line (he thinks!)
Any help is much appreciated!
were you using any fuel injector cleaner in the past ? Can't hurt to try a dose, I've not been a big proponent but I know many people who swear it has fixed issues. I don't think the evap system has anything to do with the crank issue, it uses engine vacuum I believe to remove vapor from the tank but the evap system operates under specific parameters , some use pulses of vacuum switched on and off by the ecu but I'm not familair how the HYundai evap system works.
 
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