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Discussion Starter #1
ok i don't think it's the timing here's the problem

in the morning if i pump it and turn it over varrrrrooomm starts great and quick but if i drive it and it warms up good then shut it off for 5+ minutes the thing turns over and over and over (turns fast) until it starts

i noticed that the gas is draining back down the line (i have a clear filter near the carb) when it sits those few minutes. i also have headers and the temps get high under the hood but engine is at 160 or so mosta the time 180 at most.

the carb is an edelbrock 600cfm w/ performer intake, could it be just getting too hot and boiling the gas out or does the fuel pump have something to do with it? \

oh i also smell gas when it sits and i get back in after 5-10 minutes or so but none if it sits overnight kinda weird

getting crappy mpg now too

UPDATE: i installed an edelbrock heat gasket $15 and checked all lines for leaks which there were 2 at the connections gas smell is gone but hard starting still exists


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John Krenn
1970 malibu SS look-a-like well kinda
307/200-4r (soon to be 355 or 383)

Ft.Worth, Tx



[This message has been edited by chev-hell (edited 11-22-99).]
 

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probably torn diaphragm in fuel pump, or cracked hose or line from the fuel pump to the carb. Fuel should stay pressurized to carb after shutdown, and obviously yours is not..if you smell gas you will probably see where the leak is unless it is internal to the fuel pump.

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70 chevelle ss396 conv
66 chevelle ss396 hdp/conv
55 chevy prostreet
 

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I would think that even if your gas is draining back, there should still be enough in the bowl to get it started. One thing I would check is see if when you go to start it, pop the hood, remove the breather and work the throttle linkage. Look down into the primaries and see if your accelerator pump is squirting. If it is, then I don't think drain back is your problem, and would look at is as a possible flooding problem. Also, I don't see how the fuel in the bowl could evaporate that fast. If your pump isn't squirting,and you smell gas, I would look for a leak at the carb, rather its leaking on the outside, or internally into the manifold. BTW, once it does start, is there black smoke ( from flooding) at the exhaust?
 

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Discussion Starter #5
just oil smoke usually from what i can tell since i have to keep pumping for a few seconds to get it to start running right, i rebuilt the carb 3 mos. ago and once started it runs perfect, just that hot start problem. it may be a combo of under hood temps w/a bad fuel pump ya think??

gunna wrap the headers soon

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John Krenn
1970 malibu SS look-a-like well kinda
307/200-4r (soon to be 355 or 383)

Ft.Worth, Tx
 

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I am having the same problem with my edelbrocks. Cold, coupla pumps, fires right up, but hot and has set for more than a few minutes crank, crank, crank. it's caused by fuel getting into the manifold (flooding). I don't know if it's boiling or just leaking. I am solving the problem by going back to Hollys on everything except the truck. One of these days I am going to try setting the floats a little lower.

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Harley
69 461 El Camino Nitrous Model, 69 Chevelle coupe
70 El Camino,71 SS Camaro
79 Corvette
Kerrville,Tx.
 

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If fuel is boiling in the carb and flooding; holding the accelerator wide open, without pumping, while you crank should make it clean out and start a little faster. If that's the problem, what about blocking or restricting the heat riser passages on the intake?
One more thought.Is your resister bypass wire hooked up and functional? you know, the purple one that goes from the inside(?) post of the starter solenoid to the coil? If it's disconnected or burnt thru by headers, you won't get a full shot to the coil while cranking. I know this is elementary, but checking it has cured more than one starting problem for me.
Bryan

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'65 Malibu frame-off project(slow going!)
'70 C-20 Longhorn p/u (daily driver)
 

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Discussion Starter #8
no heat riser and it has an hei dist on it?? i may just check out the carb seals and re-tighten all the bolts in it.
 

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I'm having the same issue. It's not so much the hard start, but the drain back. Also, fuel seems to be sitting in the lines (new clear view fuel filter gets filled all the way up as the car runs for a little bit). This caused a very noticable loss of power (2.5 seconds at the strip). If you do find a problem with the fuel pump or the carb, please email me and tell me what it is. I have the same setup, edelbrock performer 600cfm, stock mechanical fuel pump, all on a 350. What is a heat riser and how does it work?

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Another poor college student trying
to keep a hot Chevelle on the streets.

--70 Malibu--
350/300hp (more than that now)
and a decaying TH350
 

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i am having the same problem with a holley EVERYTHING is new from gas tank to carb i was told it might be a slight vapor lock problem i can't cure the problem
 

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Just swapped in a fuel pump today. It sisn't make things go away, but only slightly better. What's the fuel pressure going to the carb? Edelbrock says it's got to be 6psi or less. Check that out.

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Another poor college student trying
to keep a hot Chevelle on the streets.

--70 Malibu--
350/300hp (more than that now)
and a decaying TH350
 

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On an edelbrock or carter afb the large vent on the passenger side of the carb on the top must be open. Do not plug this. The instructions are vague and most people will plug it. It will cause problems if you do. It could be the problem
 

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i did the same thing you just explained on a nova that i had. i cuoldnt figure it out. i put a holley carb on and it fixed it. then i found out how to fix the edelbrock problem and it ran great...even raced it afterwards..
 

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There is a problem Carter and Edelbrock carbs sometimes have on hot start, the butterflys are sitting in the proper position, not open too far or too little, and the engine does start with just a little throttle opening past curb idle.

This problem is caused by the engine wanting more air, not fuel. If your engine starts better hot by opening the throttle and holding it there while cranking, not pumping the throttle, then the idle fuel system is not set correctly or the fuel levels in the bowls are too high.

If the fuel screws cannot make the engine run properly at idle when they are between 1-1/2 to 2 turns out, the set fuel jets that control the idle screw feeds and the off idle transition need work.

First thing to do is confirm the float levels are correct and there isn't a leak in the needle/seat assembly or a sunk float. Usually, the float level will make the carb work like crud if it isn't right, and can make the fuel smell some people encounter.

If there is a hot starting problem, set the fuel screws to between 1-1/2 to 2 turns out from gently bottomed out, and reset the idle speed with the stop screw. If the problem still exhists, and the performance is down at idle to about 1/4 throttle, look into the oriface size on the idle jet tubes on the primary boosters (these brass tubes are on the botton=m of each booster venturi, and have a drilled oriface). The oriface is the idle and low speed transition jet size. Changing it will alter the fuel screw settings and the overall off-idle transition.

I just did a small block 350 with an Edelbrock 625 carb, and the engine was stock except for an edelbrock mild cam. To cure the off-idle stumble and get the screws within the proper settings, I had to increase the orifaces .002, then raise the mainjet one size. This doesn't mean your carb needs to be rejetted.

Another thing to remember is if the timing is retarded, the vacuum in the engine will suffer, and will affect the power piston springs and will allow the needles to stay in their up positions and will make the engine run rich. This condition is rare in stock engines, but is more prevelant in ones with increased duration cams. A rich mixture will also affect the idle vacuum adversely, and can make the springs appear to be wrong.

Confirm proper float level first, then set the idle mixture screws and curb idle speed, and go from there.
 

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I just installed a 1406 tonight on my K5 (350) and I have to hold the pedal to the floor to get it started. It doesn't matter if it is cold or warmed up. After it is running the engine idles smooth as glass. If I turn it off, even for a second, I have to hold the pedal to the floor a crank on the starter for a few seconds before it will start.

When it was running at idle I had to set the mixture screws to 1.5 turns from the seat to get max vacuum of 16". Off idle throttle response is great, runs like a champ when running.

I had a Q-Jet on it and it ran fine except I need an electric choke because my wife can't keep it running for anything when cold. I'll buy another Q-Jet in the future, but in the meantime I need to fix this thing ASAP.

Could the electric choke or linkage cause any problems like these? Ideas?

Thanks guys.
 
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