Check Valve & Hot Start Issues ***Split From Incentives..DMC***

[rothsean]

...
I started to have rest-pressure problems with the pump causing hot-start issues. ...

I had the same problem. I just installed a check valve that cost $7. It works great, at two hours I am at 1.8 BAR?

[Silverbullet]

I had the same problem. I just installed a check valve that cost $7. It works great, at two hours I am at 1.8 BAR?

Can you explain what check valve you used, where you got it, where you put... May come in handy. I got my combo unit in July 2012, so far no issues... but for $7 it seems it may be a good idea to do...

Craig

[rothsean]

Can you explain what check valve you used, where you got it, where you put... May come in handy. I got my combo unit in July 2012, so far no issues... but for $7 it seems it may be a good idea to do...

Craig

Yes, eBay. It is $14 for 2. Search for "inline fuel check valve"

[rothsean]

Here is the link

http://www.ebay.com/itm/5-16-8mm-Inline-Check-Valve-Fuel-Diesel-Gas-Pump-Liquid-One-Way-Non-Return-/221021777223?pt=Motors_Car_Truck_Parts_Accessories&hash=item3375ecad47&vxp=mtr

[Silverbullet]

Here is the link

http://www.ebay.com/itm/5-16-8mm-Inline-Check-Valve-Fuel-Diesel-Gas-Pump-Liquid-One-Way-Non-Return-/221021777223?pt=Motors_Car_Truck_Parts_Accessories&hash=item3375ecad47&vxp=mtr

Ok.... Where did you put it? On the Pressure output by the pump?

Craig

[Silverbullet]

First, it's *six* month warranty - not three - it's printed on the line item for every invoice (along with the disclaimer about fuel tank contamination voiding the warranty). If someone told you three, they were mistaken.

Next, since you haven't contacted us about the second failure I encourage you to do so - with this product we have been very liberal with replacements for failed check valves, and here's why:

We tested three units on three different cars for nearly a year in three separate parts of the country. As you recall, we first showed this unit at our open house in the summer of 2011 - and production units didn't really start to ship until May/June of 2012. We had zero problems with any of the test units. We've had about an 8% failure rate on the first batch of about 250 or so units, and SOME of the those were swapped out with later units FROM THAT SAME BATCH which in a few more cases exhibited the same check valve failure.
Based on this, we went back to our supplier and as of February of this year they have been supplying units with a different pump. These pumps have performed well and the only failures (3 to date) on those were ALL due to fuel tank contamination upon inspection of the failed pumps/filters. Units with the later pumps can be identified by the letter "A" at the end of the serial number affixed to the controller box. As of June, we are also hot stamping the letter "T" on the fuel modules with the later pump or that have had the pumps replaced under warranty.

Now that we've been about six months on these new units, with the aforementioned good results, we've determined that we will extend the warranty on each unit that was originally sold prior to February 2013 by an additional 12 months. This is done on an exchange basis, simply contact your selling dealer to have this exchanged. As always, units that exhibit fuel tank contamination are not covered under warranty, but *may* be able to be repaired by the dealer for a nominal parts & labor charge. Letters to the this effect are going out early next week, once we are sure that we have identified all the purchasers of this part. The majority of them were sold by our dealers (not DMCH) so we're working with them to get this list as correct as possible.

We're also working with our supplier to develop a "user -installable" replacement pump, and have actually sent a couple of these out to a few users to test - this will mean that the user can replace the pump down (or on the side) of the road should they experience a failure in the future.

Chris, I sent you a PM - please call/reply when you can and we'll get you sorted out.

So, with the "Normal" leak down failures, does the $7 Check Valve fix the problem? If it does, it seems it would cost way less than shipping out a new pump... Have you tested a in-line Check Valve?

Thanks,
Craig

[rothsean]

So, with the "Normal" leak down failures, does the $7 Check Valve fix the problem? If it does, it seems it would cost way less than shipping out a new pump... Have you tested a in-line Check Valve?

Thanks,
Craig

I have tested it. I installed it on the pressure side line coming out of the fuel pump.

Before installing the check valve last Monday I tested fuel rest pressure. A 22 minutes I was at 0psi. After installing the check valve I tested pressure. At 2 hours I was at 27psi.

[cybercusp]

I have the latest version of the new fuel pump combo and am starting to have hot start issues as of yesterday. I'm suspecting it's the check valve again. The latest version of the fuel pump was installed last month and has less than 1,000 miles on it. If I do the plug swap it starts right up. Also starts no problem when cold.

I'm thinking I'm going to install the inline check valve and see what happens.

There's the fancier version available..

http://www.ebay.com/itm/S-U-R-R-5-16-In-Line-Fuel-Check-Valve-/161087766917?pt=Motors_Automotive_Tools&hash=item2581944185&vxp=mtr

Can anyone see an advantage from one check valve over the other?

[DMC5180]

Ok.... Where did you put it? On the Pressure output by the pump?

Craig

That IS where you would have too put it too work as intended.

[refugeefromcalif]

I have the latest version of the new fuel pump combo and am starting to have hot start issues as of yesterday. If I do the plug swap it starts right up. Also starts no problem when cold.

Does anybody have a picture that shows which plugs to swap?

George

[Delorean Industries]

George,
on the drivers side of the engine compartment there is a gray plug attached to the warm up reg on your valve cover at the rear. There is a blue plug on top of the brass tube for the cold start valve. With the car off key off unplug the blue plug and install the gray plug in its place. This will force the cold start injector to fire even if the engine is hot. This is a tell tail sign of a ppr o ring issue, fuel pump check valve issue or accumulator failure. Immediately once the engine fires remove the gray plug and reinstall the blue/gray plugs to their original locations.

[refugeefromcalif]

Thanks Josh!

George

[djdogbone]

This looks like a wonderful alternative to replacing the accumulator. I wonset what is the lifespan of the plastic vs metal versions of the check valve.

[Rich]

I have tested it.....After installing the check valve I tested pressure. At 2 hours I was at 27psi.

Good info.

Do you also know what the fuel rest pressure was just after engine shutdown for comparison to the 2hr pressure?

[DMC5180]

This looks like a wonderful alternative to replacing the accumulator. I wonset what is the lifespan of the plastic vs metal versions of the check valve.

I would expect the metal valve to hold up longer than the plastic one. It really depends on the precision quality of the internal components though.

[DSNW Toby]

This looks like a wonderful alternative to replacing the accumulator. I wonset what is the lifespan of the plastic vs metal versions of the check valve.

The addition of an inline check valve is an alternative if the existing check valve in the fuel pump has failed. It will not help you if your accumulator has failed. If a failed accumulator is the cause of a hot start problem, replacing the accumulator is the only solution in a Bosch CIS system. It is important to avoid mixing and matching causes for a particular symptom. Just sayin' ...

[rothsean]

Good info.

Do you also know what the fuel rest pressure was just after engine shutdown for comparison to the 2hr pressure?

Yes, immediately after shutdown it was 40psi.

[Bitsyncmaster]

Yes, immediately after shutdown it was 40psi.

That sounds normal. My car is 43 or 44 PSI immediately after shutdown.

[Ryan S.]

I have the fancy metal valve and it works great. I installed it about a month ago and have been driving it almost everyday. No more hot start. :nana1:

[NightFlyer]

There's also a middle-of-the-road metal check valve for $14:

http://i.ebayimg.com/t/5-16-Check-Valve-Diesel-or-Gas-8mm-One-Way-Fuel-Flow-/00/s/NjQwWDYxNg==/$(KGrHqJ,!jQE9Nl0y-tIBPlHwcGRlg~~60_12.JPG

http://www.ebay.com/itm/5-16-Check-Valve-Diesel-or-Gas-8mm-One-Way-Fuel-Flow/281150456580?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%2 6asc%3D16682%26meid%3D865901471822890807%26pid%3D1 00005%26prg%3D7845%26rk%3D3%26rkt%3D5%26sd%3D17111 4869030%26

[refugeefromcalif]

That sounds normal. My car is 43 or 44 PSI immediately after shutdown.

My car has 54 PSI while running. (Is this Good)?
After shutting it off it drops to 0 in about 45 seconds.
My new Fuel Accumulator gets installed tomorrow morning.

We'll recheck the new pressure numbers after.

George

[Bitsyncmaster]

My car has 54 PSI while running. (Is this Good)?
After shutting it off it drops to 0 in about 45 seconds.
My new Fuel Accumulator gets installed tomorrow morning.

We'll recheck the new pressure numbers after.

George

Control pressure is dependent on engine temp. From memory mine is 50 PSI running hot. As soon as you shut the engine off it should drop to 40 to 45 PSI which is now called the rest pressure.

0 PSI in 45 seconds is WAY BAD:hmm:

[NightFlyer]

Control pressure is dependent on engine temp. From memory mine is 50 PSI running hot. As soon as you shut the engine off it should drop to 40 to 45 PSI which is now called the rest pressure.

0 PSI in 45 seconds is WAY BAD:hmm:

One would think that you should have a visible fuel leak somewhere in the system if you're losing rest pressure that quickly!

Either that or the air metering plate isn't fully returning to its rest/closed position upon shutting off the engine.

[Delorean Industries]

One would think that you should have a visible fuel leak somewhere in the system if you're losing rest pressure that quickly!

Either that or the air metering plate isn't fully returning to its rest/closed position upon shutting off the engine.

Mots likely along the lines of a check valve or ppr/accumulator failure internally. External leaks normally mean it wasn't running to start with.

[Rich]

One would think that you should have a visible fuel leak somewhere in the system if you're losing rest pressure that quickly!

+1 on Josh's statement. Rest pressure leaks can go a few places where you won't see them.

These are just two of them:

Fuel pump check valve leaks cause the pressurized fuel to leak back to the fuel tank.
Accumulator diaphragm leaks cause the pressurized fuel to leak into the safety return line that leads to the fuel tank.

[Bitsyncmaster]

+1 on Josh's statement. Rest pressure leaks can go a few places where you won't see them.

These are just two of them:

Fuel pump check valve leaks cause the pressurized fuel to leak back to the fuel tank.
Accumulator diaphragm leaks cause the pressurized fuel to leak into the safety return line that leads to the fuel tank.


Also the PPR O-ring failure could send the fuel back to the tank via return line.

[refugeefromcalif]

Fuel pump check valve leaks cause the pressurized fuel to leak back to the fuel tank.
Accumulator diaphragm leaks cause the pressurized fuel to leak into the safety return line that leads to the fuel tank.
[/INDENT]


Also the PPR O-ring failure could send the fuel back to the tank via return line.

Thanks for the other items to check. I haven't found any external leaks.

New accumulator was installed today. Pressure when running was 52 PSI. Shutting the engine down it dropped to 40 within 15 or so seconds. It slowly fell to 0 after 4 minutes.
Funny thing though, (Maybe I'm missing something), 5 minutes later the car started right up.?
So it's time to move onto the other checks. :cry:
I Do have the new fuel pump/sender unit but, my car was doing this before it was installed so,,, I'll have to see if I have one of the bad units I've read about or, it's got to be something else.

I'm trying to figure/find how to check a PPR o-ring problem. Anybody have pictures on how/where to start? I'm also going to search the forum.

Thanks again! And Sorry for Highjacking this thread.

George

[Rich]

Pressure when running was 52 PSI. Shutting the engine down it dropped to 40 within 15 or so seconds. It slowly fell to 0 after 4 minutes.
Funny thing though, (Maybe I'm missing something), 5 minutes later the car started right up.?
So it's time to move onto the other checks.

A note about the funny thing.

Losing all of the fuel rest pressure 4 minutes after shutdown means you most likely DO have a hot start problem. If you did not have the engine completely warmed up AND if you did not leave it off long enough when you ran this test then the fuel may not have had a chance to heat up, then vaporize at that low pressure and create a hot start problem.

With the stated leakdown time you can expect to get stuck next time you refuel or need to restart the car after a hot soak.

Congrats on getting your rest pressure loss time up from 45sec to 4min.

And, yes, time to move on to the other checks - assuming the replacement accumulator isn't leaking at all.

[Ryan S.]

George,
I would check the fuel pressure for your fuel pump combo unit first, if you haven't done this already. Connect your pressure gauge to the fuel pump line directly and measure. This will rule out the fuel pump. Then try the o-ring.