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Car Wont Rev Past 2,000 Rpm

L26

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#1 bbqjackson

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Posted 26 April 2016 - 04:57 PM

Hi Guys,

 

Looking for a bit of advice / help with my l26

 

My car was running quite well for a period of time, and after a drive up to the shops the following problem ensued.

 

Car struggles to start when previously it didn't. Once started, it is able to rev freely and drives up until it reaches operating temperature. Once there it seems to hit a flat spot and won't rev past 2,000 rpm

 

Done the following,

 

* Replaced the points

* Distributor cap and rotor

* New spark plugs (one was fouled) 

* New fuel filter

* Tank has been flushed

 

It has been to 3 different shops (not sw motorsport yet) and still no luck. The last shop said there was a bit of dirt/rubbish in one of the carbies and charged $300 for a clean. 

 

Has anyone had this problem before (i'm not too mechanically savy).

 

Cheers



#2 gav240z

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Posted 26 April 2016 - 05:14 PM

What condition is your distributor in? Any major vacuum leaks?

#3 bbqjackson

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Posted 26 April 2016 - 05:23 PM

What condition is your distributor in? Any major vacuum leaks?

 

Distributor look to be in good condition, the button appeared to have abit of wear and the contact point on the rotor was a bit black.



#4 WA240Z

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Posted 26 April 2016 - 05:41 PM

A couple of possibilities to check,
 

1. Spark plug leads, particularly coil to distributor, but if the car is missing it may be down on one spark plug lead. Not uncommon that the issue will only show up under load. You mentioned one spark plug was fouled, this may be because that spark plug lead is shot.

2. Fuel pump, might deliver enough fuel to idle and rev with no load but not under load. If mechanical the diaphragm may be shot.

 

When you have issues like this always change one thing at a time, check to see if the issue is rectified then move onto the next. Don't make 6 changes then test. For one you wont know what the problem was, and secondly you may end up chasing your tail.



#5 hmd

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Posted 26 April 2016 - 05:43 PM

if all else fails go to swmotorsport in Mulgrave or MIA engine in Dee Why.



#6 PB260Z

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Posted 26 April 2016 - 06:22 PM

I would also look for inlet manifold leaks.

If all else fails do a compression test, well two of them actually - One when cold and the second when hot.

#7 Retro Z

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Posted 26 April 2016 - 07:13 PM

Float level height shutting fuel off under load?

#8 George

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Posted 26 April 2016 - 09:36 PM

Float level height shutting fuel off under load?


Last mechanic cleaned the carb so I'm assuming they checked that.

It sounds like a fuel delivery issue though. Check out fuel pump as Billy (WA240Z) mentioned. Not sure whether this explains the starting issue... Hmm. Fun and games.

#9 scott

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Posted 26 April 2016 - 10:18 PM

fuel or vacuum. i had a lot of leaks when i put mine back together. my dizzy is also worn and wont rev part 4k but runs fine under that.



#10 bbqjackson

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Posted 27 April 2016 - 08:56 AM

Thanks alot for the feedback so far fella's

 

 

fuel or vacuum. i had a lot of leaks when i put mine back together. my dizzy is also worn and wont rev part 4k but runs fine under that.

 

This one is interesting as the car is fine under 2,000 rpm ... hmmmm

 

Going to start with the fuel pump and as wa240z said, knock them off 1 by 1.



#11 PB260Z

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Posted 27 April 2016 - 12:02 PM

Hi Mate

If the fuel system checks out I would be looking at things that are effected by heat or expand when hot.

Gaskets, coil and leads for starters

Love these more challenging ones.

Cheers

PB

#12 George

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Posted 27 April 2016 - 03:11 PM

Hi Mate

If the fuel system checks out I would be looking at things that are effected by heat or expand when hot.

Gaskets, coil and leads for starters

Love these more challenging ones.

Cheers

PB

 

He said:

 

"Car struggles to start when previously it didn't."

 

Do you think that's a separate issue then?



#13 PB260Z

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Posted 27 April 2016 - 03:21 PM

I overlooked that comment :-\

 

Sounds more and more like a intake vacuum leak to me.

What impact does the choke have on the engine when it is hot ?

 

But without having the car in front of me I am only guessing


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#14 George

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Posted 27 April 2016 - 08:00 PM

 
But without having the car in front of me I am only guessing


It's hard enough with the car in front of you isn't it? Haha.

On that note, and sorry to go off topic slightly, have you heard of the podcast Car Talk? Couple of ex-mechanics who happen to be a riot to listen to take calls from car owners with issues and they try to diagnose them. They have a really high success rate at both solving the issues and making you laugh. Very entertaining and educational.

#15 nat0_240_chevZ

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Posted 27 April 2016 - 11:17 PM

Is the clutch fan seized? Doesn't explain the hard starting but.
Is it noisy when revving? Like a hovercraft? Had almost identical problem on an old 2+2, way back.
Check it out.
Nat0

#16 bbqjackson

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Posted 28 April 2016 - 01:11 PM

Sorry fellas, havent been able to respond to many questions as i won't get to check out/ try some of the above until Saturday. 

 

PB - The choke has no effect / funny enough, Im not too sure its doing much on cold start either but cant confirm. My apologies as i'm not to mechanical and any work is normally handled by Steve at quickfit

 

Nat0 - Clutch fan still working normally and no noise until it hits 2,000rpm which then feels like it just bottoms out. soundwise, like it is sputtering 

 

George - Been abit of a learning exercise, first carbie vehicle. May revist the fuel pump as i believe they have a filter inside (correct me if im wrong)?



#17 George

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Posted 28 April 2016 - 01:36 PM

George - Been abit of a learning exercise, first carbie vehicle. May revist the fuel pump as i believe they have a filter inside (correct me if im wrong)?

 

All you need is a Phillips #2 screwdriver. Give it a go, it's dead easy.

 

Check for cracks as per photo #2 and other gunk. Clean everything and replace filters/diaphragm if necessary. Careful with the filters though as some types are secured to the cast making it impossible to replace. You most likely will not need to replace them - just a good clean with an air compressor.

 

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#18 PB260Z

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Posted 28 April 2016 - 01:43 PM

It's hard enough with the car in front of you isn't it? Haha.
On that note, and sorry to go off topic slightly, have you heard of the podcast Car Talk? Couple of ex-mechanics who happen to be a riot to listen to take calls from car owners with issues and they try to diagnose them. They have a really high success rate at both solving the issues and making you laugh. Very entertaining and educational.

Never heard of them, will have to check it out.
Thanks

#19 pauly_adams

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Posted 30 April 2016 - 02:27 PM

change your condensor and if that doesnt fix it, look at your coil 



#20 1600dave

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Posted 30 April 2016 - 04:17 PM

Sound to me like its running overly rich - hole in float / sunken float / needle & seat faulty / dirt in needle & seat / etc.

 

You would think a mechanic would have picked it up if its been to a couple, but perhaps not.

 

Is either carb leaking fuel out of the overflow on top of the float chamber ?







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