other Hard overnight starting - SOLVED

[Healey3000]

Hi,

 

I have always had an issue with extended cranking if the car sits for a couple of days or even overnight at times.  Starting on the same day is never a problem, leading me to believe that fuel is draining back into the tank.  Although, I'm confused why the fuel in the float bowl isn't enough to get things going.  The check valve that prevents drain-back is missing (underhood).

 

For those of you who have the check valve installed, where exactly is it plumbed?  Between the fuel filter and the pump inlet or between the pump outlet and carb?  Probably makes no difference but best to check (pun intended).

 

Thanks!

Edited August 24, 2016 by Healey3000

[jplips]

I have a valve between pump and fuel line that comes out of firewall. Still have hard overnight starting issues despite the valve on my Solex PHH40 set up

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[jplips]

Correction: between fuel filter and line coming out the firewall. After fuel filter is the Pierburg pump

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[roadhog0]

I've been tempted to put one back by the tank so that the fuel doesn't drain all the way back.

 

Things I have found to be extremely important for starting after sitting overnight is setting the float level correctly and having a good float needle. A new one seams to alleviate this problem for some time (ethanol in gas making it hard?).

 

Also, don't forget that a carburetor is at the simplest an open fuel bowl and gas evaporates at room temperature, therefore the gas in the fuel bowl goes away over time.

[Healey3000]

Thank you, both.

 

Will start with a check valve and then consider an electric pump.

Edited June 30, 2016 by Healey3000

[zinz]

I solved my problems... I'm convinced the new Pierburg was providing too much pressure...and I think it had an internal leak that allowed fuel to return back to the tank.  (Long crank times after sitting to prime the carb and long crank times after it was hot)

 

I actually bought an in-line check valve I had planned on installing near the tank, but that became unnecessary when I installed an electric pump and regulator set at 2 pounds.  Absolutely no more problems.  It bump-starts now, every time, hot or cold, sitting or not.

 

I fought this problem for years... believe me, I'm happy to have finally solved this problem!

 

Now... JP... your 90 degree Pierburg is a different beast. Try putting the filter after the pump. Then go to installing a pressure gauge between the pump and your Solexes and see how much pressure your pump is delivering.  If it's more than 3 pounds, then put a regulator between the pump and carbs and dial it back to more like 2 pounds.  I was amazed how much difference that made in my car...but that was on the Weber car.  My dual Solex car with the 90 degree pump never gives me this trouble.

 

Ed

[jimk]

The carb bowl filling is designed the SAME way as your toilet.  Fuel will not be sucked back out of the carb bowl., there is an air gap that prevents drainback, just like the toilet.  It wouldn't be nice to draw water back into the city system if the system lost pressure.  Fuel drips/sprays/runs out of the float fill valve (commonly called the float needle valve) into the bowl.

 

[Healey3000]

1 minute ago, jimk said:

The carb bowl filling is designed the SAME way as your toilet.  Fuel will not be sucked back out of the carb bowl., there is an air gap that prevents drainback, just like the toilet.  It wouldn't be nice to draw water back into the city system if the system lost pressure.  Fuel drips/sprays/runs out of the float fill valve (commonly called the float needle valve) into the bowl.

 

Exactly.  Which is why I can't figure out why there isn't enough to get the engine running, which will then prime the system rapidly.  Perhaps the bowl is leaking?  I've looked closely but can't see any signs of leaks.

 

I have one of those plastic in-line filters and it is essentially empty after the car sits.  I assume that some amount of air would be expected but this thing just has a few drops at the end proximal to the tank.  That's why I assume I have a drain-back problem (but not from the bowl).

[Healey3000]

Hi Ed,

 

Interesting experience (pretty scary too!).

 

I don't think I have an over-pressure issue as the car runs fine and starts fine hot or cold on the same day.  What do you mean by a 90 degree Pierburg?  My pump is stock, as far as I know.  Is that a 90-degree unit?

 

Thanks.

[zinz]

EXACTLY the same issues I fought for a long time.  After you shut it down, do you have fuel weeping from the fuel line that attaches to the carb?  That was the clue I ignored that I had too much fuel pressure... I had blamed it on hot fuel boiling.  Nope.

 

Get a regulator and if that doesn't solve it, also get an electric pump in the trunk.  

 

 

[Healey3000]

1 minute ago, zinz said:

EXACTLY the same issues I fought for a long time.  After you shut it down, do you have fuel weeping from the fuel line that attaches to the carb?  That was the clue I ignored that I had too much fuel pressure... I had blamed it on hot fuel boiling.  Nope.

 

Get a regulator and if that doesn't solve it, also get an electric pump in the trunk.  

 

 

Hmm, I'll have to look again.  Perhaps, because I see signs of something on the manifold between the runner castings.

 

What brand of pump and regulator did you use?  Kind of a shame because I do plan to go EFI; I'm just not ready to stop driving the darned thing to do the conversion :-)

 

Thanks.

[zinz]

If you have fuel on the webbing of the intake between the carb and the head (front, right corner of the carb), I'd bet your accelerator pump is leaking... If so, then you are dealing with a few more issues... probably need to rebuild the carb.  

 

I had similar issues when resurrecting this '75 and rebuilt the carb, but continued to have these long cranking times to restart it... despite all-new ignition and rebuilt carb.  It was the newer Pierburg that was causing my problems...

 

If you are going EFI, spending $125-$150 to rebuild the carb and add an electric pump and regulator may not fit your budget/plans.  

 

I used an electric pump and regulator out of the parts stash... I think they were both Mr. Gasket brand.  About $35-$40 each. Carb rebuild kit with power valve is about $65-$70...without power valve is about $15 cheaper.  The cheaper kit will have the accelerator pump, anyways.

 

I only know that it completely solved my hard starting problems.

 

Ed

 

[jimk]

On one of those days that you believe it will be hard starting, remove the air cleaner and looking down the throat, watch for the pump shot as you stroke the throttle.  That should tell a lot about a dry bowl, bad pump etc.

[Healey3000]

Sure would be nice if the e30 318is pump could be PWM'd down to 2 psi.  I suspect that may be difficult, considering it likes running around 50 psi.  It may be possible to compromise by running it near 10 and letting the regulator do the rest.

[Healey3000]

1 hour ago, jimk said:

On one of those days that you believe it will be hard starting, remove the air cleaner and looking down the throat, watch for the pump shot as you stroke the throttle.  That should tell a lot about a dry bowl, bad pump etc.

Good idea!