Edelbrock Performer 600 losing prime ???

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PhillH

PhillH

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Hi,
had some issues that I thought were related to tuning my new 360, well I've pretty well got it worked out in no small part from help here. As part of the process I rebuilt the carb, the engine used to fire up immediately after hitting the key, then it took longer and longer cranking for it to start. I thought the fuel pump was going but, this is what I have discovered.
The engine now takes about 10 seconds of cranking, then a bunch of shots on the pedal, then another 10 seconds of cranking, then another bunch of shots on the pedal and it will start with no throttle. So I learned that the primary injectors have no fuel visually till all this cranking pumping, then once fuel starts to come out of the primary injectors it fires right up. It will fire up just reaching in and turning the key after all this. Then if it sits for 30 minutes or more I have to pump the fuel up again, same thing it will start fine after this.
Now I don't know where the fuel is going but it's definitely losing it's prime some where.
 
FYI- I rebuilt the carb because I discovered the oil was getting diluted with fuel.
 
The carb doesn't loose prime, it is one or a few things that are the issue.

1; Fuel leaking from carb, possibly the throttle shafts.

2; Fuel evaporates from the carb bowls.

3; Fuel pump loosing prime/failure to hold fuel in line.

To solve this issue myself, I installed a Edelbrock electric fuel pump at the rear of the car. Very very quick to surpply fuel and mostly, I have to say, pretty quite. NOTHING like the old Holley fuel pumps. Easy to wire in and NO REGULATOR needed. The pump needs a relay kit which I also used the Edelbrock stuff.
 
Ok,
1. Do the throttle shafts run through the float bowl?
2. Will the fuel evaporate in 30 minutes?
3. Does the fuel pump hold the prime for the primary injectors or does the fuel bowl?
 
PhillH said:
Ok,
1. Do the throttle shafts run through the float bowl?
2. Will the fuel evaporate in 30 minutes?
3. Does the fuel pump hold the prime for the primary injectors or does the fuel bowl?
Click to expand...

1. no
2. no
3. primary injector or accelerator pump? the Accelerator pump use fuel from the fuel bowl...there is no primary or secondary fuel bowl on the eddy carb...they share the same...

fuel bowls are small compared the a holley....take a couple days to evaporate from fuel pump then there is no gas for accelerator pump to prime engine...engine must be cranked to fill bowl....
 
Rusty that may work for me thanks, but I'm thinking this is a new issue that shouldn't be there, so I'd like to fix it if possible.
70aar, thanks, I'm not real familiar with all the proper terms, but it is the accelerator pump that is dry, somehow that is leaking down to dry in 30 mins. There is no external leaking, sooooo. Are we thinking fuel pump, which I don't mind replacing but don't think thats the issue. Or is the fuel going down my intake? Which is totally unacceptable, but I don't know how to determine that except to wait and see if my oil fills with fuel. ????
 
Quote from INERTIA in another post=
For those that have the long cranking problem,, that's caused by empty fuel bowls and lines,, perhaps this'll help,,

The mechanical pumps use a spring to keep even pressure/suction in the line,, and maintains that suction/pressure with the engine not cranking/running.. (Ever change a fuel filter a while after the engines been running and get a shot of gas?)

What I do, and suggest you do, when you know it's "crank" time,, is crank the engine 3 or 4 revolutions,, and wait,, what's happening is the fuel is now being moved by the residual pressure supplied by the pump,, wait maybe the count of 5,, then crank 3 or 4 times and wait again, count of five,, now try pumping the gas slowly while continuing to crank,, and it'll catch ..

Cranking and cranking, doesn't increase suction cuz the pump's spring is already compressed as far as it can,, so waiting in such a manner will save battery,, with the same results,, this really helps when you got a low battery to start with..

hope that makes sense and hope it helps..



So this morning the engine completely cool, I gave a tiny tiny push on the throttle to see if the accelorator pump had fuel in it, it did so I did above from Inertia in another post, it worked exactly like he said. So I shut it down inside 30 seconds, there is no way it could be hot enough foor any boil off. Now I'm waiting 30 minutes to see if it has lost something, it should fire right up, but won't.
I did note that the fuel filter was only half full, after the start it was full again.
Eddy Performer 600, mid 70s 360, electronic ignition.
 
Si it's been a little over 30 min and I go to start it and nothing, just cranks. I cranked 5 sec, waited5, cranked 5, waited 5, cranked again and she fired up.
 
IMO you have multiple problems.
1) the bowl is going dry, and
2) the pump is "losing its prime", or
3) the pump is sucking air

Once the fuel get's into the bowl, it cannot return. It can only escape by evaporation or gravity. So, what I would do, is remove the carb to the bench.I would put it over a catch basin, and support it so that I can see under it. Then I would pop the top and fill the bowl. Then mark the fuel level, and walk away for an hour. Come back and check the level. Repeat about 3 or 4 times. This will prove the bowl is or is not leaking by gravity.If you see it leaking from at or above the liquid line,right at the start of the test, as in out the nozzles, you have put too much liquid in the bowl.

Fuel pumps seem to last forever, but not so. The arm return spring can break,pop out, or loose tension. When that happens it can seem like it takes forever to fill the bowl, or it may not fill it at all.There are check valves in the pump that direct the flow in a forward, to-the-carb, direction, They can and do go bad, or debris gets stuck in them.Sometimes, rarely, this allows the fuel to siphon back to the tank.But more often than that, the pump will suck air somewhere. Usually I find it right at the little rubber jumper from the gauge unit in the tank to the hard-line. I always double clamp those with gear clamps with the heads 180* apart. Of course it can suck air elsewhere, but that spot is hard to detect because it is high enough to not actually leak.
So if the carb proves to not be leaking, I would perform a fuel pressure test. If it passes, about the only other possibility is evaporation/boiling. In Florida,at this time of year,I can't really see evaporation, to the extent that you describe, in less than a week. So that leaves boiling.Boiling requires the intake, and/or underhood temperature to be pretty warm.
However, there is one wild card. At about this time of year, in Canada, fuel suppliers begin blending gas as "winter fuel". This gas has a higher vapor pressure designed to help cold starting.It does evaporate much faster than "summer gas". I have no idea if they do that down South.
And finally is the tank-vent. If the tank is under a vacuum it will make it easier for the fuel to siphon back;IF, and only IF, the pump checkvalves are bad.
Rusty's pump will solve your issues, unless it pumps it out at that jumper hose I mentioned,cuz under pressure loose clamps will allow it to leak.
 
Before & After running the engine/driving the car, have you opened the carb up to see the fuel level?
 
That check valve is also available in 3/8" part#800-196
800-196-007.jpg
 
Sounds like you guys are on the right track, I was checking timing, while I was there I held it about 2k revs and looked at the clear filter, it was definately sucking air somewhere, I could see the bubbles. Lots of little tiny bubbles.
 
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