Car Dies after hard acceleration - Team Camaro Tech
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post #1 of 27 (permalink) Old Jan 1st, 06, 04:23 PM Thread Starter
 
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Car Dies after hard acceleration

I am experiencing problems with my car dying after a hard acceleration. It will start back up with a little hesitation. Here's what I have. 69 camaro, 496 stroker big block, holley mechanical fuel pump. I have a fuel pressure gauge right before the carburator. During an idle the gauge appears to rapidly spike and move around b/t 2 and 7 psi. I don't remember it ever doing that before. I thought it would be constant but I am not 100% sure. I should also mention that the car has a heavy lope. Also when I turn the motor off the pressure gauge is at 2-3 where as before it would be up at 6-7 and slowly reduce down to zero.

I am at a loss. I'm not sure if it's the iginition or the gas but obviously by the post, I'm leaning towards fuel problem. Anybody have any ideas.
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post #2 of 27 (permalink) Old Jan 1st, 06, 04:48 PM
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Re: Car Dies after hard acceleration

Fuel filter?

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post #3 of 27 (permalink) Old Jan 2nd, 06, 10:15 AM Thread Starter
 
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Re: Car Dies after hard acceleration

I replaced the fuel filter and the car works fine, for now. Didnt seem like the fuel filter though. Thanks.
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post #4 of 27 (permalink) Old Jan 3rd, 06, 12:41 PM
 
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Re: Car Dies after hard acceleration

I had a similar problem when I dropped a 427 into my 68 Camaro. It turned out that the hose from the gas tank and the fuel line (about 6") had a split in it. It didn't leak unless you shook the car back and forth causing the split to open on the flexing. I replaced the hose and problem went away.
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post #5 of 27 (permalink) Old Jan 11th, 06, 07:04 AM Thread Starter
 
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Re: Car Dies after hard acceleration

It's not the fuel filter. It died on me again and I'm still on the same tank of gas. This time it was not during a hard acceleration. I was driving around normally and the car started to spudder. I was having new problem with the gas gauge not reading correctly (it was buried on full) so I figured I was running out of gas. Luckily there was a gas station right in front of me so I pulled in and only put 14 gallons in a 18 gal tank. I figured it wasn't the gas. I started the motor, looked at my fuel pressure gauge and it read 0 psi. I turned the throttle and the car died. After that it would not start. I remember seeing an auto parts store up the road about 1/4 mile so I walked back, got a new filter, changed it out, and the thing started right up. The problem is when I cut open the fuel filter removed from this last change, there were no signs of a clog. There were no signs of any debris in it so it can't be the fuel filter. I should also mention that the tank looks new and the car is only a 5-6 yr old resto. I don't think it's the fuel pump because they either work or they don't. They won't cycle through a working and non working phase. So what the hell could it be?

I have my thoughts. I think that there is something inside the tank that is big enough to clog the intake of the fuel line. It's the only thing that makes sense to me. You know when your drinking an iced beverage and you suck up a piece of ice. Sometimes that ice won't dislodge until you relieve the pressure, i.e changing the fuel filter. Let me know your thoughts. I might be overlooking something. The fuel gauge is working correctly again, but that's another mystery.

I am going to disconnect all the fuel lines and blow them out with some air pressure and see if that helps. I might try to drop the tank as well to look inside and see if there's anything big in there.

Oh btw, the fuel lines are steel everywhere except right before and right after the fuel filter.
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post #6 of 27 (permalink) Old Jan 11th, 06, 08:30 AM
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Re: Car Dies after hard acceleration

Gas cap vent works?

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post #7 of 27 (permalink) Old Jan 12th, 06, 05:58 AM Thread Starter
 
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Re: Car Dies after hard acceleration

Is there a way to check? It new and it reads that its vented. I ordered it several weeks back.
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post #8 of 27 (permalink) Old Jan 12th, 06, 08:32 AM
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Re: Car Dies after hard acceleration

Remove gas cap, place lips upon the center item, or on the cap gasket, on the tank side of cap, suck with lungs.

If lungs fill with air, then cap is good. Blow out with air to check if vent seats.

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post #9 of 27 (permalink) Old Jan 12th, 06, 09:20 AM
 
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Lightbulb Re: Car Dies after hard acceleration

What size is the fuel line running from the tank to the carb ? Must be a 3/8's or larger all the way up. Check Screen sock on fuel sending unit in tank.
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post #10 of 27 (permalink) Old Jan 12th, 06, 10:57 AM Thread Starter
 
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Re: Car Dies after hard acceleration

Will check the cap. I expect it to be in proper working condition with it being brand new but then again, it's an OEM part. The connection point of the tank appears to nromal. No dents or irregularities.

The fuel line running to the front is definitely not stock. I noticed the stock line the other day and its half the size of the current one. I can measure the size but at a glance, 3/8 is probably correct. I thought about dropping the tank this weekend to take a look around inside since I am flushing all the lines anyway.

I spoke with friend that used to work on these cars (when they were new!)and he mentioned his buddy had the exact same scenerio I have with the sudden loss of fuel pressure and then it working fine again. He found out that the mechanical FP had a crack in the diaphram. They replaced it and never had that problem again. Does anybody fully understand the dynamics of a fuel pump and if a crack in the diaphram could cause this problem?
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post #11 of 27 (permalink) Old Jan 12th, 06, 12:31 PM
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Re: Car Dies after hard acceleration

Can't hurt to change a fuel pump, about 15 minutes.

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post #12 of 27 (permalink) Old Jan 12th, 06, 03:32 PM
 
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Re: Car Dies after hard acceleration

After re-reading your symptoms it does sound like the diaphragm in the fuel pump could be cracked.
If you had access to an electric pump you could place it in the system with the mechanical still in place. If the problem goes away the mech pump is bad for sure I'd say.
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post #13 of 27 (permalink) Old Jan 13th, 06, 06:11 AM Thread Starter
 
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Re: Car Dies after hard acceleration

I thought about going the electric pump route if I have to replace the fuel pump. There is an electric pump already in the back by the tank but it is not hooked up electrically or fuel wise. I actually do not know if it works but I will try it this weekend.

The gas cap is working properly. I think I will drop the tank and look around and also blow the lines out. I would rather spent a little time at this point exploring rather than just dropping 150-200 bucks on a new electric pump.

I appreciate all the info. I will post the results over the weekend.
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post #14 of 27 (permalink) Old Jan 13th, 06, 07:52 AM
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Re: Car Dies after hard acceleration

Dont bother w/electric the O.E pump is cheap and quik to change.
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post #15 of 27 (permalink) Old Jan 17th, 06, 05:42 AM Thread Starter
 
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Re: Car Dies after hard acceleration

I did not drop the tank or blow the lines. I thought about it more and when it would die and I changed the fuel filter there was always plenty of gas rushing out both ends of the lines. That to me should rule out a clogged tank. I figured I can blow out the lines when I change the mech FP which is what I ordered this weekend . I didn't feel like making the conversion from mechanical to electrical.

I don't think it is the filter at the carb if there is one. When the car dies, there is zero fuel pressure at the gauge which is right before the carb. This tells me that there is no gas in the line from the FP to the carb. If there was a clog in the carb filter, the pressure would still be up. So if there is fuel in the line to the FP (apparent when I change the fuel filter after dying) then it must be at or after the pump. That's why I decided to order a new one.

Have anyone ever changed a FP on a BBC? My friend told me that the pushrod can drop down and it is a pain to get it back up again (insert joke here). He recommended sticking something in the hole to prevent this from happening during the change out. The video I've seen of someone tearing down and rebuilding a small block chevy. This video has the rod just flying out when you take the cover plate off. Are big blocks different? I want to save the money and do it myself but I don't want to take on something I can't finish. BBC's don't leave much room to work around in there!

Oh, I did pick up some new hoses for the fuel lines. There just a couple of short runs of rubber hose back by the fuel filter. I will replace all of it this coming weekend. The line from the FP to the carb is steel braided and looks very new. I won't replace that right now.

Thanks for all the help.
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