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Car Wont Accelerate past ~4000 RPM Under Full Throttle


Utah02

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Rotor said R1. I will get new plugs that don't have resistance and gap them to 0.030" and that will hopefully help the bogging. When I sucked on the vacuum line it rotated counter clockwise and is plugged to the correct nipple.

Colby

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The stock mechanical fuel pump is more than adequate for all carbs including dual sidedrafts. A lot of these aftermarket electronic fuel pumps are junk. Given that your pump and filter is OK, your car sounds like it is suffering from a lean condition when the secondary opens up. Your fuel jets might be too small. You might want to try increasing their their sizes while decreasing the size of the air correction jets.

 

Slavs

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The stock mechanical fuel pump is more than adequate for all carbs including dual sidedrafts. A lot of these aftermarket electronic fuel pumps are junk. Given that your pump and filter is OK, your car sounds like it is suffering from a lean condition when the secondary opens up. Your fuel jets might be too small. You might want to try increasing their their sizes while decreasing the size of the air correction jets.

 

Slavs

I would consider this but my block in from an e21 so the mechanical fuel pump hasn't been ported (if that's the correct terminology)
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It is a little weird that you can achieve higher rpm as long as you do not give it full throttle.

That's what makes a few of us think fuel delivery's the problem.

But.

That pusher electric pump "ought" to do it.

Since I own the $20 fuel pressure gauge, I'd install that at the carb and... oh...

 

Did you know you have a filter IN your carb?  Yup, that big nut under where fuel goes in.

There's a brass strainer/ screen right there.  They can clog.  

 

So if you have 1.5+ psi at full wizzle when you have the problem, that little whatzigger can restrict fuel flow.

Easy to check- 19mm wrench, some comressed air, whallah.  If a bunch of debris comes out, that's my guess today.

 

Also, I agree with Mint,  the total high tension resistance is worth chasing- those plug wires have stranded me before, and I no longer use them.

But they also have high resistance, and you have a blue (high impedance) coil and resistor plugs- if you have any other resistance

in the high tension side, your spark will 'blow out' under large throttle openings and high load.

 

You win big points for keeping us updated and chasing things down.  Now check your damned fuel pressure! (grin)

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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That's what makes a few of us think fuel delivery's the problem.

But.

That pusher electric pump "ought" to do it.

Since I own the $20 fuel pressure gauge, I'd install that at the carb and... oh...

 

Did you know you have a filter IN your carb?  Yup, that big nut under where fuel goes in.

There's a brass strainer/ screen right there.  They can clog.  

 

So if you have 1.5+ psi at full wizzle when you have the problem, that little whatzigger can restrict fuel flow.

Easy to check- 19mm wrench, some comressed air, whallah.  If a bunch of debris comes out, that's my guess today.

 

Also, I agree with Mint,  the total high tension resistance is worth chasing- those plug wires have stranded me before, and I no longer use them.

But they also have high resistance, and you have a blue (high impedance) coil and resistor plugs- if you have any other resistance

in the high tension side, your spark will 'blow out' under large throttle openings and high load.

 

You win big points for keeping us updated and chasing things down.  Now check your damned fuel pressure! (grin)

 

t

Hey Toby

You'll be happy to here that I checked my fuel pressure today and I get 3 psi on the dot. So that's a good thing. I have recently cleaned the filter in my carb and it is... Ehh slightly discolored but not clogged at all. I also did advanced timing today as well. Tomorrow I will do valve adjustment but that doesn't seem like it'd be the problem. At this point I'm desperate to do anything.

One thing that came to mind was that I possibly have weak valve springs and right at 4000 they enter a harmonic vibration and can't keep up. But with a slightly depressed pedal that allows me to run passed that kinda cancels that out.

Thanks again

Colby

OH I also forgot to mention I went after the "fly in the fuel line" thing and sprayed compressed air through my line for about 5 minutes and no dead flies or confetti came out. So I can cross that off as well.

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Well,heck,

this is going to be harder than it sounded at first.

You got 3 psi under load, when it's doing it?

 

Try the non- resistor plugs, and also different wires, then, I guess.

At that point (pun intended) I would also put points back in,

only because there are almost no ways that

points can 'sometimes' misbehave.

 

My experiences with weak valve springs are always self- diagnosing:

the valves with the weak springs break their rockers.  And there's no getting past it-

as soon as the valves float, you lose that rocker.  For me, it's usually happened right around

7200 rpm. 

 

When you figure this one out, there are going to be more than a few forehead slaps...

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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I'll jump in...

 

I've read and re-read and watched the videos. Here's what I see:

 

All the plugs are sooty = poor spark, or over-rich fuel/air mix (Mint is correct about those Resistorized plugs.. ditch them for  NGK BP5ES to keep the same heat range)

 

Primary barrel of the carb is sooty black, while the secondary is clean. Choke butterflies are fully open in video, though.... curious.

 

Ballast Resistor not wired up on a black coil... I'd certainly check resistance on the coil (if it's about 1.8 ohms across + and - posts, you need to connect that ballast resistor, which should be about 1.2 ohms... check it too) If the coil is 1.8 ohms, you could have cooked the Pertronix by not running the ballast?

 

When you rebuilt your carb, did you replace the power valve? That part is not included in a lot of rebuild kits and its diaphragm is notorious for failure, especially with today's ethanol/blended gasolines... pew). Torn power valve diaphragm will cause your over-rich situation (black primary carb barrel and sooty plugs)...I don't think this all your problem, but certainly will cause bad symptoms.

 

Per Limey Steve's suggestion of fuel line leak... In the trunk... what size fuel line is that on the nipple of the gas tank sending unit? If that line doesn't fit snugly without clamping, it might leak a little bit of air and cause fuel starvation (ask me how I know). I recently solved what I think is a similar issue on my '75. The fuel line was big enough to fit on the clear plastic supply line, but too large for the sending unit nipple.  I bought an inline reducer (actually a vacuum line reducer available at the autoparts stores) that allowed me to use the proper fuel lines on both sides.

 

 I'm with Toby, you say you have 3 psi; but is that under load, when the problem occurs? 

 

Is the gas tank properly vented?

 

You've done a lot of trouble shooting and should be commended for the extra effort.  I hope we can get you sorted out soon...

 

Check coil resistance and insure that supply line on the gas tank is not leaking... that'd be a couple of easy things.  Change spark plugs and buy a new power valve from Pierce for the Weber.

 

You'll get it figured out :)

Ed

'69 Granada... long, long ago  

'71 Manila..such a great car

'67 Granada 2000CS...way cool

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Oh... and PROPERLY time the ignition. Pull the vacuum line off the dizzy and plug the line. Bring the engine speed up to 1400 rpm with the throttle speed screw and set your adjustable timing light to zero and look for the steel ball in the bell housing window while slowly rotating the dizzy. (it can be a challenge to see the steel ball, sometimes)  Remember, as you rotate the dizzy, the engine speed will change...so make sure when you get the ball lining up, that the engine is at the proper rpm.

 

post-42878-0-92219300-1452187003_thumb.j

 

and make sure the vacuum line is connected to the proper port on the Weber. 

 

dgxv_parts_labled.gif

 

 

'69 Granada... long, long ago  

'71 Manila..such a great car

'67 Granada 2000CS...way cool

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Hi, I saw the video and it sounds like you are having a fuel delivery issue.

If not too much trouble put old pump back in and put a return line with it. Use a smaller diameter line as a restriction. Also loose that other filter in their trunk. 6psi is a tad high but the return line should help that.

Been there done that.

Frank

FO 2573825

1971 2002, 5-OD, Recaro SE, BBK, 90Amp Alt, Turbines, VDO, Hellas, BD belts, LED Tails, 10 Foot DD

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Hi, I saw the video and it sounds like you are having a fuel delivery issue.

If not too much trouble put old pump back in and put a return line with it. Use a smaller diameter line as a restriction. Also loose that other filter in their trunk. 6psi is a tad high but the return line should help that.

Been there done that.

Frank

Watch the video again and you will notice the cylinder head is not set up for a bolt on mechanical pump.  ;)

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Hey everybody. All advice wages gone noticed and I'll be sure to check everything out. Just got new plugs and need to put the in and will do a proper timing tomorrow. Got rid of the filer taken out of the trunk I'm running 3 psi not 6 just letting you know. The only fuel pressure tester I he was not set up to test while running but I think I can get my hands on one tomorrow so the fuel pressure dropping is still a possibility Toby. That's my fault.

Thanks guys. It's greatly appreciated

Colby

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You are correct, but op said he had a electric 6psi pump at one time. So I suggest he put it back in with a return line.

Just noticed he is probably in a higher elevation than most and more psi may be the fix

FO 2573825

1971 2002, 5-OD, Recaro SE, BBK, 90Amp Alt, Turbines, VDO, Hellas, BD belts, LED Tails, 10 Foot DD

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Hi, I saw the video and it sounds like you are having a fuel delivery issue.

If not too much trouble put old pump back in and put a return line with it. Use a smaller diameter line as a restriction. Also loose that other filter in their trunk. 6psi is a tad high but the return line should help that.

Been there done that.

Frank

Use smaller diameter hose for return portion only!

FO 2573825

1971 2002, 5-OD, Recaro SE, BBK, 90Amp Alt, Turbines, VDO, Hellas, BD belts, LED Tails, 10 Foot DD

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Well Crap. Just checked the running fuel pressure and its 3 psi at idle and under acceleration drops to about 2.5 psi and stays there/slightly goes up during the bogging. So this leads me to believe it is not fuel related. 

 

Still need to put in the new plugs and do advanced timing. I'll get back when I've done that.

 

Thanks

 

Colby

 

https://youtu.be/w_xFMGOjjEI

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