Not firing on 3 cylinders think it might be fuel related

[ol_skl_jp]

G'day all,

 

I recently put in a new manifold for the triples, but now i the engine is only running of 3 cylinders. Circled plugs are not firing.

Also when i press down the accelerator, fuel leaks out of one of the pump jet screw covers (circled in picture).

Close up view.

 

What im thinking there is no fuel going into cylinders 3 and 4 but dont know why number 6 doesnt fire because number 5 fires fine.

 

It could be ignition also, so im converting to electronic ignition. Still deciding on the Crane XR700 and the XR3000.

 

Thanks guys

Looking forward to hear you thoughts.

Sach 

[Enzo]

Hi Sach,

          The fuel leak will be from a blocked pump jet. Remove and blow through it. More info required as to what changes you made when fitting the manifold and over what period of time.Also check the plug leads and cap. What fuel pressure are you running. Should be about 2.5 psi. Regards David.

[Scoota G]

Hey dude,

 

Just a few questions that might help with diagnosis.

 

Were the carbs off the car for a period of time? 

 

Did you remove anything else?

 

Is there spark going to the plugs?

 

Have you tried swapping plugs around?

 

If you seperate the carbs from the manifold and disconnect the accelerator linkage and just give it a few pumps to see if the pump jets are squirting.

 

I think dave is right about the blocked jets as fuel can crystalize depending on conditions.

[ol_skl_jp]

Also check the plug leads and cap. What fuel pressure are you running. Should be about 2.5 psi

I have checked the firing order, i dont know how old the leads and cap are as i only bought the car a couple months ago. Still using stock mechanical pump and havent tested fuel pressure.

 

Were the carbs off the car for a period of time?

They were off for a couple of days, say took the off thursday and put them back on the following wednesday.

 

Did you remove anything else?

I did not chage any of the settings or mix up the carbs ie. put them back in the same order, front middle and rear. I did clean the carb body with crc carby clean, might have dislodged some dirt or something. Replaced the soft mounts as well

 

Is there spark going to the plugs?

I cant see the spark, but can hear the faint tick tick tick.

 

Have you tried swapping plugs around?

No i haven't, will try it

 

I will clean the jets.

 

Thanks guys

[ol_skl_jp]

Okay i swapped the plugs with the good cylinders but still nothing.

 

I tried removing the pump jets but its seems to be stuck and i dont want to pull too hard coz the powertune book says they are very easy to ruin.

 

and finally there is a spark on all cylinders although its an orange spark. Shouldn't it be blue?

 

 

[mick74]

Sach

 

I would be looking at the basics,

Rotor button for wear

Distributor cap for wear

Points - gap?

Condensor might be no good

Resistance on the coil , primary/secondary circuit. What voltage are you getting at the coil?

Leads - resistance, are they the same?

 

You might have to renew some or all the above.

 

Regards

 

Mick

[JP240z]

Have you replaced all the plugs?

Coz if it hasn't been tuned since I had it, it will definately foul plugs..

[Scoota G]

Connect a good plug to the leads when you test them and test the spark when it's darker.

 

Also the pump jets have an O Ring around them so they are a bit scary to take out the first time and you need a fair amount of pressure to get them out. They also only go in one way so don't try to twist them to extract them.

 

My pump jets were ok and then for no reason they just blocked up but it sounds like you have done everything else right so far.

[Zedman240®]

With the plugs that aren't firing, have you removed them and checked the plug itself? If they are covered with fuel, they wont be sparking at all, making the problem worse. Also, get a multimeter and check each lead for continuity. Each lead is around 3-6 Kohm. If you get one with no connection, theres your problem. Some people pull on the lead to remove them breaking the carbon wire in the lead making them useless. Just a worthwhile check...

[warrenz]

Hi

 

I had similar problems getting my triples to run properly. Even though I overhauled the carbies  before I put them on the car the pump jets still blocked up,

 

Take the air cleaners off and get a mirror and a light and then move the butterflies by hand and you can easily check if they are squirting fuel into the chokes.

 

If you pull the jets the top part will come off, which is OK then you need to squirt some WD40 into the bottom half to free it up. Don't twist just pull with a set of pointy nose pliers. You will probably find the O ring perished and corrosion residue. A good clean should do it.

 

Good luck

Warren

[ol_skl_jp]

Thanks for the input

 

I checked the resistance in the wires, they were around 9 for the short ones and 11 for the longer ones. These figures are apparently correct according to topgun's website.

I will have to clean out the jets tomorrow.

I will post some pics of my rotor and cap because i do not know what im looking for.

And will check the resistance in the coil and reset the gap if needed.

 

Cheers

Sach

[JP240z]

Are the plugs in the 3 cylinders that arnt firing wet?

[ol_skl_jp]

I went to see my mechanic today. And he fixed everything .

The issues:

- Not enough compression in 5 cylinders

- One of the plugs was wet

- The car has the wrong type of coil, not meant for points he said. Something about current and voltage being halved ???no idea. But its the correct coil for electronic ignition.

- re tuned the carbs but said he cant tune it properly, so he said to run kits through them and to clean them up a bit.

 

Thanks for all your help.

Sach