Missfire Big Time

[peter-qen00]

I think iv got a big prob ! Chimeara started to missfire and started to fill the exhaust with fuel. I have got no oil pressure from the oil light switch port and ignition switched on only shows oil pressure 30psi on gauge. Help !

[Smokey Boyer]

before you panic, check the obvious things like ignition leads and spark plugs.

I had a misfire on mine which was an ignition lead that had split where the cable goes in to the spark plug boot. I must have looked at it three times before I realised it had split just inside the boot, and only noticed the problem when the weight of the spark plug extension pulled the cable apart.

[jojackson4]

Run it in the dark you will see easy if it's a lead / extender that's shorting out

[QBee]

Where are you? Location I mean? One of us could pop over and help you find the problem if we knew where you are.

[peter-qen00]

Ringmer Nr Lewes Sussex

[QBee]

Identify in which cylinder(s) the plugs aren't firing.
Get a cable tie, start the engine, and as soon as it is warm test the exhaust manifold temperature at each exhaust port (2 inches from the gasket), by just dabbing the end of the cable tie onto the pipe. Any cylinder with a good spark, the exhaust will melt the cable tie immediately, a non-firing one(s) won't.

Then you can narrow your search to those specific plugs/extenders/leads

[sparkythecat]

Top tip QBee. I'll use that one in future

[Colin RedGriff]

peter-qen00 said:

I have got no oil pressure from the oil light switch port and ignition switched on only shows oil pressure 30psi on gauge. Help !

Can you provide more detail on this?

When you say you have no pressure from the oil light switch port - do you mean the oil pressure light is lit on the dashboard or have you measured it with something? Is this with the engine running or not?

When you say the gauge shows oil pressure with the ignition on - is this with or without the engine running? If it is without the engine running then your problem may be an issue with the earth from the engine block. To test run a new thick earth cable from somewhere like the starter motor to the chassis. If it is with the engine running then that sounds like normal behaviour.

I would check all the earth connections are tight and clean.

[QBee]

sparkythecat said:

Top tip QBee. I'll use that one in future

Well, you could spend a tenner on EBay on a digital laser thermometer (get one that goes over 400 C), but if he doesn't have one to hand, the cable tie is just as good for this job, as the difference in temperature between firing and non-firing is well over 100 degrees C and the melting point of plastic is in between. A top engine builder from the wilds of South Lincs showed me the cabe tie dagnostic tip.

[peter-qen00]

Yea measured with a gauge with engine being turned over not running. Any ideas on why fuel pouring out of the exhaust when running ! highly dangerous. thank you for all your help