Big hesitation.
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Big hesitation.
Looking to hear if anyone can give me advice on what to check out on the 1.6 laser. The engine starts good, but on pressing the accelerator there is a big hesitation, do it slowly and it will rev ok. Out on the road i can drive it but if there is a hill it gets quite hard to get to the top. Timing is right, electronic ign, carb seems in tune but smells rich going up a hill. New filters all round. Going for the MOT saturday 2nd april, hopefully will pass even if not running properly.
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Re: Big hesitation.
What carb is fitted? If the weber dgav from the 2.0l, then it could be float valve not sealing, or dodgey power valve diaphram making rich mixture...
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Re: Big hesitation.
It sounds like it could be an ignition or timing issue, are you sure that the vacuum advance is free and working? Was it timed static or running with vacuum detached? What is it set to BTC? I assume all the ignition components are in good order, dizzy cap and rotor arm and plugs still need to be in good nick with electronic ignition.
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Re: Big hesitation.
Gaps in plugs ? Leads ? But as they say what carb are you running ?
Ford Capri 2.0 Laser 1987 Mercury Grey .......
Re: Big hesitation.
I think the rich fuel smell is the giveaway here.
Too much fuel getting into the carb so when you accelerate and it adds even more then its moving the mixture outside of a combustible range.
However, if the above answers don't cure it then this is also a classic symptom of a failing accelerator pump diaphragm.
When you push the throttle down, the flap opens which suddenly dumps the low pressure by reducing the venturi effect (Check out Bernoulli's Theorem). Therefore the carb temporarily cannot suck the fuel through the jet.
The accelerator pump exists to cover this temporary loss of low pressure by firing fuel straight into the carb mouth.
If you open the throttle slowly the engine is able to keep up and keep pulling the air through fast enough to create a low pressure area in the carb, thus sucking in fuel.
The accelerator pump is basically a diaphragm with a big spring behind it. The spring forces the diaphragm across to allow room for a small reservoir of fuel to accumulate behind it.
When you push the accelerator open a long way, the linkage acts on a plunger on the other side of the diaphragm, overcoming the spring and pushing the diaphragm across, forcing the accumulated fuel out through a jet into the carb mouth.
If the diaphragm splits the fuel just nips to the other side of it and doesn't squirt in.
Simple check. Take of the air filter, look down the carb and open the throttle right up. Don't need the engine running. You should see a squirt of fuel.
On the assumption that you have a 32/36 DGAV fitted then there is a Y-shaped nozzle below the choke flaps. If the carb came off a lower spec (GL or similar, you may well only see fuel squirt into one barrel as the other side is blanked off. On a 'S' model, it should squirt into both barrels.
You may also have a blocked Y-nozzle. Simply remove the top of the carb, undo the screw in the middle and lift it out to clean it. Beware there is a very small ball bearing underneath the nozzle body, which acts as a valve to stop the carb sucking fuel through in normal operation.
Probably not your issue, but always handy to know a bit more about how the carb works.
Too much fuel getting into the carb so when you accelerate and it adds even more then its moving the mixture outside of a combustible range.
However, if the above answers don't cure it then this is also a classic symptom of a failing accelerator pump diaphragm.
When you push the throttle down, the flap opens which suddenly dumps the low pressure by reducing the venturi effect (Check out Bernoulli's Theorem). Therefore the carb temporarily cannot suck the fuel through the jet.
The accelerator pump exists to cover this temporary loss of low pressure by firing fuel straight into the carb mouth.
If you open the throttle slowly the engine is able to keep up and keep pulling the air through fast enough to create a low pressure area in the carb, thus sucking in fuel.
The accelerator pump is basically a diaphragm with a big spring behind it. The spring forces the diaphragm across to allow room for a small reservoir of fuel to accumulate behind it.
When you push the accelerator open a long way, the linkage acts on a plunger on the other side of the diaphragm, overcoming the spring and pushing the diaphragm across, forcing the accumulated fuel out through a jet into the carb mouth.
If the diaphragm splits the fuel just nips to the other side of it and doesn't squirt in.
Simple check. Take of the air filter, look down the carb and open the throttle right up. Don't need the engine running. You should see a squirt of fuel.
On the assumption that you have a 32/36 DGAV fitted then there is a Y-shaped nozzle below the choke flaps. If the carb came off a lower spec (GL or similar, you may well only see fuel squirt into one barrel as the other side is blanked off. On a 'S' model, it should squirt into both barrels.
You may also have a blocked Y-nozzle. Simply remove the top of the carb, undo the screw in the middle and lift it out to clean it. Beware there is a very small ball bearing underneath the nozzle body, which acts as a valve to stop the carb sucking fuel through in normal operation.
Probably not your issue, but always handy to know a bit more about how the carb works.
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Re: Big hesitation.
If yours still has the standard single barrel VV type carb as fitted to most non S 1.6 Capris then this isnt worth fixing. An opportunity to swap to a good used 32/36 Weber & manifold. Better reliability and bhp for very little money.
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Re: Big hesitation.
Second this swap!Not_Anumber wrote: ↑Mon Mar 28, 2022 3:58 pm If yours still has the standard single barrel VV type carb as fitted to most non S 1.6 Capris then this isnt worth fixing. An opportunity to swap to a good used 32/36 Weber & manifold. Better reliability and bhp for very little money.
A wise man once said... "you can never have too many capris - buy another"
It's me, I'm the wise man.
It's me, I'm the wise man.
Re: Big hesitation.
If yours still has the standard single barrel VV type carb as fitted to most non S 1.6 Capris then this isnt worth fixing. An opportunity to swap to a good used 32/36 Weber & manifold. Better reliability and bhp for very little money.
This sounds like a good fix to me.
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Re: Big hesitation.
Bug wrote: ↑Mon Mar 28, 2022 12:13 pm I think the rich fuel smell is the giveaway here.
Too much fuel getting into the carb so when you accelerate and it adds even more then its moving the mixture outside of a combustible range.
However, if the above answers don't cure it then this is also a classic symptom of a failing accelerator pump diaphragm.
When you push the throttle down, the flap opens which suddenly dumps the low pressure by reducing the venturi effect (Check out Bernoulli's Theorem). Therefore the carb temporarily cannot suck the fuel through the jet.
The accelerator pump exists to cover this temporary loss of low pressure by firing fuel straight into the carb mouth.
If you open the throttle slowly the engine is able to keep up and keep pulling the air through fast enough to create a low pressure area in the carb, thus sucking in fuel.
The accelerator pump is basically a diaphragm with a big spring behind it. The spring forces the diaphragm across to allow room for a small reservoir of fuel to accumulate behind it.
When you push the accelerator open a long way, the linkage acts on a plunger on the other side of the diaphragm, overcoming the spring and pushing the diaphragm across, forcing the accumulated fuel out through a jet into the carb mouth.
If the diaphragm splits the fuel just nips to the other side of it and doesn't squirt in.
Simple check. Take of the air filter, look down the carb and open the throttle right up. Don't need the engine running. You should see a squirt of fuel.
On the assumption that you have a 32/36 DGAV fitted then there is a Y-shaped nozzle below the choke flaps. If the carb came off a lower spec (GL or similar, you may well only see fuel squirt into one barrel as the other side is blanked off. On a 'S' model, it should squirt into both barrels.
You may also have a blocked Y-nozzle. Simply remove the top of the carb, undo the screw in the middle and lift it out to clean it. Beware there is a very small ball bearing underneath the nozzle body, which acts as a valve to stop the carb sucking fuel through in normal operation.
Probably not your issue, but always handy to know a bit more about how the carb works.
That's a super post.
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Re: Big hesitation.
Martin, tips like that are pure gold dust. I mean, how would anyone know about that, unless you hear it from someone who was there back then doing all these things.
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Re: Big hesitation.
Thanks to every one that replied to my question last sunday. I work away from home, came home early with cover, just got round to checking reply. So, its 32 weber manual choke. Timing was done running, vacuum disconnected and block off. New cap, rotor and leads. Timing set at 6 % btdc. Not outside yet but will check the suggestions by you all. Thanks again.
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Re: Big hesitation.
Should have read COVID.
Re: Big hesitation.
Are you getting anywhere with this?
Or still hesitating?
Or still hesitating?
Re: Big hesitation.
C'mon now. That's another month gone by.
The biggest hesitation seems to be fixing it.
The biggest hesitation seems to be fixing it.
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Re: Big hesitation.
If it helps Bug I had a big hesitation as well, set the points again and problem solved!
Only thing is that I also seem to have fiddled with the timing as the auto now changed up gears way too early and I can't seem to sort it again
Only thing is that I also seem to have fiddled with the timing as the auto now changed up gears way too early and I can't seem to sort it again
A wise man once said... "you can never have too many capris - buy another"
It's me, I'm the wise man.
It's me, I'm the wise man.
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Re: Big hesitation.
I think your spot on here Bug, had the same problem with a 390 Holley carb, on the the Holley you can adjust when the accelerator pump does it's thing, on mine I had it set too late, crack the throttle, big rush of air into engine, no fuel to go with it = big hesitation until it catches up with itself.Bug wrote: ↑Mon Mar 28, 2022 12:13 pm I think the rich fuel smell is the giveaway here.
Too much fuel getting into the carb so when you accelerate and it adds even more then its moving the mixture outside of a combustible range.
However, if the above answers don't cure it then this is also a classic symptom of a failing accelerator pump diaphragm.
When you push the throttle down, the flap opens which suddenly dumps the low pressure by reducing the venturi effect (Check out Bernoulli's Theorem). Therefore the carb temporarily cannot suck the fuel through the jet.
The accelerator pump exists to cover this temporary loss of low pressure by firing fuel straight into the carb mouth.
If you open the throttle slowly the engine is able to keep up and keep pulling the air through fast enough to create a low pressure area in the carb, thus sucking in fuel.
The accelerator pump is basically a diaphragm with a big spring behind it. The spring forces the diaphragm across to allow room for a small reservoir of fuel to accumulate behind it.
When you push the accelerator open a long way, the linkage acts on a plunger on the other side of the diaphragm, overcoming the spring and pushing the diaphragm across, forcing the accumulated fuel out through a jet into the carb mouth.
If the diaphragm splits the fuel just nips to the other side of it and doesn't squirt in.
Simple check. Take of the air filter, look down the carb and open the throttle right up. Don't need the engine running. You should see a squirt of fuel.
On the assumption that you have a 32/36 DGAV fitted then there is a Y-shaped nozzle below the choke flaps. If the carb came off a lower spec (GL or similar, you may well only see fuel squirt into one barrel as the other side is blanked off. On a 'S' model, it should squirt into both barrels.
You may also have a blocked Y-nozzle. Simply remove the top of the carb, undo the screw in the middle and lift it out to clean it. Beware there is a very small ball bearing underneath the nozzle body, which acts as a valve to stop the carb sucking fuel through in normal operation.
Probably not your issue, but always handy to know a bit more about how the carb works.
Great Post explaining how it all works, wish you had wrote this about 2 years ago!
Wayne
If an honest man is wrong and after demonstrating that he is wrong he either stops being wrong or stops being honest
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Re: Big hesitation.
I have found 3 holley 390's now that have had the wrong accelerator pump diaphragm assy fitted. The difference being the length of the linkage rod . These may have been part of an incorrect overhaul kit but whatever it sure gave problems getting the thing to run right.
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Re: Big hesitation.
Good call, got a Holley on a V6 Essex, took a lot of fucking about to get it dialled in - as you know there are loads of options for tuning it to your application which can be a headache but once it's done it certainly let's the Essex breathe and along with big valve heads it ain't far behind triple webbers and no where near the price of the triple carb set up.Mc Tool wrote: ↑Wed May 04, 2022 10:04 am I have found 3 holley 390's now that have had the wrong accelerator pump diaphragm assy fitted. The difference being the length of the linkage rod . These may have been part of an incorrect overhaul kit but whatever it sure gave problems getting the thing to run right.
Wayne
If an honest man is wrong and after demonstrating that he is wrong he either stops being wrong or stops being honest
Re: Big hesitation.
Cheers Wayne,Mr B wrote: ↑Wed May 04, 2022 9:26 amI think your spot on here Bug, had the same problem with a 390 Holley carb, on the the Holley you can adjust when the accelerator pump does it's thing, on mine I had it set too late, crack the throttle, big rush of air into engine, no fuel to go with it = big hesitation until it catches up with itself.Bug wrote: ↑Mon Mar 28, 2022 12:13 pm I think the rich fuel smell is the giveaway here.
Too much fuel getting into the carb so when you accelerate and it adds even more then its moving the mixture outside of a combustible range.
However, if the above answers don't cure it then this is also a classic symptom of a failing accelerator pump diaphragm.
When you push the throttle down, the flap opens which suddenly dumps the low pressure by reducing the venturi effect (Check out Bernoulli's Theorem). Therefore the carb temporarily cannot suck the fuel through the jet.
The accelerator pump exists to cover this temporary loss of low pressure by firing fuel straight into the carb mouth.
If you open the throttle slowly the engine is able to keep up and keep pulling the air through fast enough to create a low pressure area in the carb, thus sucking in fuel.
The accelerator pump is basically a diaphragm with a big spring behind it. The spring forces the diaphragm across to allow room for a small reservoir of fuel to accumulate behind it.
When you push the accelerator open a long way, the linkage acts on a plunger on the other side of the diaphragm, overcoming the spring and pushing the diaphragm across, forcing the accumulated fuel out through a jet into the carb mouth.
If the diaphragm splits the fuel just nips to the other side of it and doesn't squirt in.
Simple check. Take of the air filter, look down the carb and open the throttle right up. Don't need the engine running. You should see a squirt of fuel.
On the assumption that you have a 32/36 DGAV fitted then there is a Y-shaped nozzle below the choke flaps. If the carb came off a lower spec (GL or similar, you may well only see fuel squirt into one barrel as the other side is blanked off. On a 'S' model, it should squirt into both barrels.
You may also have a blocked Y-nozzle. Simply remove the top of the carb, undo the screw in the middle and lift it out to clean it. Beware there is a very small ball bearing underneath the nozzle body, which acts as a valve to stop the carb sucking fuel through in normal operation.
Probably not your issue, but always handy to know a bit more about how the carb works.
Great Post explaining how it all works, wish you had wrote this about 2 years ago!
Wayne
I just did it to prove I can still remember, not having had a Capri for quite a while now.
Reckon I could still set up an auto choke though.