drtidmore

Thoughts on gas smell when engine first starts -- SOLVED!

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1 hour ago, drtidmore said:

there has not been ANY work on the rail connections that would have disturbed the 0-ring connection since that installation.

 

I suspect- that inadvertently raising the rail pressure by in installing the new pump pointed out the leak that was nearly happening anyway. I always lube any O-ring with either silicone paste or Permatex green synthetic grease.

 

I'm very glad you caught this in time:)

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2 hours ago, 89RedDarkGrey said:

 

I suspect- that inadvertently raising the rail pressure by in installing the new pump pointed out the leak that was nearly happening anyway. I always lube any O-ring with either silicone paste or Permatex green synthetic grease.

 

I'm very glad you caught this in time:)

The failing pump, when it was running was putting out 40 PSI which is in the same ball park as the new Bosch.  Could the new pump be related to the leak making its appearance, possibly, but the potential had to be there anyway as there can't be more than a couple of pounds of pressure difference if that between the two pumps.  Outside of my hypothesis of the lower bolt potentially not being snugged up completely, I can't explain why the leak occurred. 

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Old pump had a pulsator, which calms down the pump spikes. The new turbine is constant- no sine wave at all. Relative pressures are same, but delivered differently. Maybe total bs theory?

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1 hour ago, 89RedDarkGrey said:

Old pump had a pulsator, which calms down the pump spikes. The new turbine is constant- no sine wave at all. Relative pressures are same, but delivered differently. Maybe total bs theory?

Possibly, the new pump is obviously smoother as my fuel pressure gauge is rock steady where the old pump had some minor jitter.  I would think that the jitter would be more likely to pop a small leak than a constant pressure.  But I don't feel that the fuel pump was the root cause in any case, but rather the o-ring seal between the regulator and the fuel rail.  

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Another casualty of the intake cough? I would think that might affect the diaphragm but your exam didn't show any fuel in the vacuum line? That might cause a momentary spike if fuel pressure as they will increase pressure under boost automatically. Maybe a small piece of debris under the o-ring. Injectors use the same system under the same pressure and you can spin them in place with no leaks? Just spitballin'.

Edited by 2seater (see edit history)
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I had not thought about the regulator going to full pressure on the rail during the backfire, but I tested the rail at full pressure (i.e. using the green connector and the engine NOT running) after I installed the new fuel pump.  At that point, if there was an issue with the o-ring seal, it was not making itself apparent.  When I was getting ready to replace the fuel pump, I used the old pump to empty out the gas tank into 5 gallon gas containers and without thinking I did initially removed the return line from the regulator (as opposed to the feed line) and then I realized my mistake and reattached it.  If that back bolt was a tad loose, loosening and the retightening the return line  might have been enough to break the seal on the o-ring, but then again, I tested the fuel rail at full pressure of the new Bosch pump and I specifically ran my hand underneath the fuel pressure regulator to ensure that there was no sign of leakage.  I also did a fuel rail pressure leak down test and it held the full 40 PSI for well over 15 minutes, so that clearly says that there was no leakage at the regulator to rail connection. 

I just don't have a good explanation for this one.  Yesterday morning was a chilly one here (50) so I got out and fired up the engine to see if the cold might be a factor, but NO leaks all the thru the thermostat opening up completely.  Until my confidence in the regulator to rail seal is restored, I am going to keep a daily check for any signs of additional leakage.  

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It isn't that the regulator goes to full pressure, it can go well beyond. The fuel pump is capable of 100psi or so, if deadheaded, and if you apply positive pressure to the regulator, the fuel pressure will rise in a direct 1:1 relationship. For example, when I was trying more turbo boost, with 10psi in the intake, I would regularly see 55psi on the fuel pressure.

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2 minutes ago, 2seater said:

It isn't that the regulator goes to full pressure, it can go well beyond. The fuel pump is capable of 100psi or so, if deadheaded, and if you apply positive pressure to the regulator, the fuel pressure will rise in a direct 1:1 relationship. For example, when I was trying more turbo boost, with 10psi in the intake, I would regularly see 55psi on the fuel pressure.

Good to know.  I was not aware that the pressures could rise that high on the rail.  That being the case, such could be the causative factor in my situation.  

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This morning for the first time since my last post I smelled gas fumes immediately after starting and sure enough there was a good drip, drip, drip coming from fuel rail pressure regulator.  At this point, I decided to pull the fuel rail itself so that I could get a good look at the regulator to rail joint...BINGO!  Apparently when I replaced the original regulator a few years back, the o-ring stuck to the inside of the fuel rail and I did not catch the problem.  I had NO leaks until recently  Once I saw the old o-ring jammed up against the top of the fuel rail opening, I got my dog legged awl and popped it out.  This was the problem as it was keeping the regulator from inserting all the way into the fuel rail and over time, this led to the leaking.  

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Well, cold temperatures did cause catastrophic failure of fuel o-rings on space shuttle Challenger once upon a time...good eye there to catch the leak visually. Lucky you found it, as that could've  had a nasty end result.  

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I should make it clear that what I found was the OLD o-ring from the factory installed regulator lodged at the top of the fuel rail regulator fitting.  While the regulator did appear to insert into the fitting, the old o-ring was preventing it from seating properly. Yesterday, before I removed the fuel rail, after removing the regulator yet one more time, I used my cell cam to look up into the fitting to see if I could see a crack and what caught my eye was this green o-ring that appeared damaged.  That led me to remove the fuel rail so as to better inspect what I was seeing.  Once the old o-ring was removed the regulator seated into the fitting fully without ANY tension from the bolts which was very different that what I had been experiencing. 

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Oops! I wish I could claim nothing like that ever happened to me, but I can feel my nose getting longer just thinking about saying it :)

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