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Cannot Diagnose This Problem...


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#1 mingy

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Posted 20 March 2017 - 09:07 PM

Hi folks, a while back i asked the question as to why after encountering an incline does my engine start to lose power, it only occurs when going uphill after a while.

It feels as though it is misfiring or running on three cylinders but once i am back on the flat it slowly picks up and is ok again. I have since replaced the facet fuel pump and the coil but it still persists.

The engine size is 1380 fuelled by the usual HIF44 which had been partially rebuilt during the engine rebuild, it was setup and run in as per usual  and then rolling roaded to fine tune it.

It achieved 100bhp and managed 112mph on the RR but,all this was on the flat, i just cannot seem to get to the bottom of it and as i am putting it back on the road for spring i would like to erase this problem once and for all.

Any thoughts would be great.

 

Cheers. 



#2 minihobbymini

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Posted 20 March 2017 - 09:11 PM

Could be due to increased combustion chamber heat due to loading. Do you have decent quality spark plugs? Have you checked for vacuum leak on the timing control?

#3 sonikk4

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Posted 20 March 2017 - 09:12 PM

Have you got a fuel pressure regulator fitted?? Is the inside of the tank clean??



#4 carbon

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Posted 20 March 2017 - 09:13 PM

Quite a few years ago I had a similar problem with a '76 Mini Estate. This would get about half way up a long hill and then really lose power and was struggle to keep going.

 

Long story short, the vented fuel cap had been replaced by non-vented type.

 

I drilled a 1/8 hole in it, problem solved.



#5 mingy

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Posted 20 March 2017 - 09:30 PM

I have a Sytec fuel pressure regulator set at 2-3psi located as close to the carb as possible mounted under the front scuttle, the ignition is electronic so no vac take off and the plugs are NGK. The fuel cap is a standard lockable one but there is a breather pipe off the fuel tank neck that exits from the back valance. How can i determine if the fuel cap is of the vented type ?



#6 cal844

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Posted 20 March 2017 - 09:45 PM

Change the coil, had this on our 998, also the module on the dizzy(our 65D(factory fitted to 89 on carb cars) have the module and vacuum advance) they go well.

Had an issue when we changed the clutch, the coil had failed(was knocked about a bit) we changed the carb, needle, dizzy, etc etc but it was the coil... Fitted a new one and it went perfect

Edited by cal844, 20 March 2017 - 09:47 PM.


#7 mingy

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Posted 20 March 2017 - 09:56 PM

I changed the coil first, thinking this was the problem but even with the new one fitted the problems still there, it seems to be a " load " problem as minihobbymini has stated.

Should i check the rocker gaps ?, i will also change the plugs asap and might even renew the leads with 8mm type ( if it will make any difference ).

 

 

Keep the thoughts coming folks........



#8 carbon

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Posted 20 March 2017 - 09:57 PM

I have a Sytec fuel pressure regulator set at 2-3psi located as close to the carb as possible mounted under the front scuttle, the ignition is electronic so no vac take off and the plugs are NGK. The fuel cap is a standard lockable one but there is a breather pipe off the fuel tank neck that exits from the back valance. How can i determine if the fuel cap is of the vented type ?

If the breather pipe is working properly then you don't need a vented fuel cap.

 

Easily checked, take the filler cap off and drive up a long hill.



#9 mingy

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Posted 20 March 2017 - 10:01 PM

Never thought about doing that carbon, will give it a go.... ta.



#10 Dusky

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Posted 20 March 2017 - 10:12 PM

What fuel pump are you using?

#11 mingy

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Posted 20 March 2017 - 10:14 PM

What fuel pump are you using?

 A Facet red top.



#12 Allrounder

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Posted 20 March 2017 - 10:19 PM

Could try and find a local hill that you can get the fault to rescuer, ideally with a safe area to pull over giving you the opportunity to check what the spark plugs look like as these will give you a insight to what's happening in the cylinder.

#13 Magneto

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Posted 20 March 2017 - 11:10 PM

Have you checked your float level in the carb?

#14 Moke Spider

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Posted 20 March 2017 - 11:16 PM

It does sound to me like a fuel delivery issue.

 

I had one once that was a little tricky to track down, in the end, I temporarily fitted a Tee Piece in the fuel line, right before the Carb and then ran a Fuel Pressure Gauge from that, which, being temporary, I just ran a hose back inside the car so I could monitor the fuel pressure while driving.

 

In my case, it was an intermittent problem with a few fuel pumps.

 

It could also be a blocked strainer. Not widely known, but there is a strainer over the pick up pipe inside the fuel tank. Difficult to even see! If you suspect this is causing the issue, I'd suggest knocking it off (punch down the outlet does the trick) and running a fuel filter, which you're likely doing in any case.



#15 minimans

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Posted 20 March 2017 - 11:35 PM

As suggested check the float level on the carb.........






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