misfire and lack of power

[soulman309]

Hi,

 

I'm new to this forum, but I’ve only just found it.

 

I have a misfiring problem on my TR4. I've done a search around this topic and can only find spark plugs and ignition coil as possible related problems.

 

I've been restoring my TR4 for too long and have been pottering up and down a farm track before I get it MOT'd.

 

All was going well. The car has been driving fine for hours, up until now.

At some point today it simply decided it had had enough.

 

The symptoms are this:

- It will start and idle for upto 1-2 minutes, misfiring or not before deciding to uncontrollably stall.

- When revving, it misfires on what feels like one cylinder.

- Occasionally everything clears up long enough to drive the car 50 meters before its power dissipates and the car stalls.

- I got stuck trying to get it up a hill, I could excessively rev it to get it moving and then half way up the hill the revs would die and it would either just idle or completely stall.

- The problem is intermittent and it feels like its electrical.

- When revving and trying to drive the car, the revs don't seem to have anything behind them (no oomph), which is why it needs to be revved so hard.

 

What have I done?

- I have removed the spark plugs and checked for sparks. They all spark. They all seem fairly consistent but I'm not sure what else to look for.

- I have changed the ignition coil for a spare one I had lying around - no change noticed.

- I've checked the fuel glass and it's always full, so I can't see a problem drawing fuel from the tank.

- I've checked and copper-greased most of the ignition electrics.

 

What I am confused by is that it was all working fine, and now it is very temperamental.

 

Any light anyone could shed on this would be most appreciated.

If there's anything that you think I should check that I haven't please let me know and explain how to check it.

 

Thanks.

[MikeF]

In this situation I would start with electricla as that is the probably most likely and easiest to quickly fix. It could be the condenser, [as you already done the coil], these are two thigns than can fade as you describe.

 

For electricxla I would make sure all the HT is clean [including inside of dizzzy head and plug ceramics] and all gaps are clean and correct, and that nothing is loose. You probably hav done all that.

 

If that doesn't do it, myself in this situation (long time off road) I would forgo the intellectual satisfaction of finding out the specific ignition fault. I would jsut just chnage points, rotor arm and condensor. All these things are quick and cheap to do, and likely to serially pop their clogs anyway after years of sitting about.

If the electricls are now right and the problem still exists then you have a fuel problem and for concise timesaving advise you will ahve to wait till a genuine brain comes on line!

 

Mike

[RogerH]

It could still be electrical (dizzy capacitor etc) however it could be a build up off muck in the fuel tank.

Very carefully have a look in the fuel tank to see if there are any masses of algae !!! it happens.

Although the fuel pump glass looks full it may not be flowing through.

Possibly disconnect fuel pipe from tank and allow to drain and see if flow is interupted.

Check the carb float chambers for excessive muck build up.

 

Best of luck

Roger

[unclepete]

Soulman

Have you fitted an aftermarket fuel filter or is one fitted?

The internal fuel filter mesh can breakdown and cause severe flow restriction. Take the plugs out, disconnect the fuel pipe and stick it in a bottle. Spin her over and you should see big spurts of fuel filling the bottle very quickly!

Very similar symptoms were experienced by a group member in France last year and after various atempts at roadside repairs ended up with a recovery vehicle back to the UK, a head removal and various carb strip downs with what ended up as a £2 filter!

 

Check the simple bits first!

 

Good luck

Unc

[Dale Moore]

Hi There

Are you running Stromberg carbs on your Tr4? If so check the daiphragms A small hole in one of them will cause the problems you are experiencing

 

Regards

Dale

[tony-qld]

I had pretty much the same sort of problem as well. The problem started shortly after fitting new plugs, points, condenser, coil and leads. After messing around with everything I hadnt replaced it ended up being the brand new condenser. I have had the same thing happen with new plugs as well. Sometimes you get a dodgy one straight out of the box.

[PJM]

I would go along with the advice so far, but have two questions. You say you have copper greased the ignition electrics, what have you greased and was it done before this problem arose?

[Ade-TR4]

Have you checked the timing?

 

If it's out, then any adjustments you make to the mixture will not be very effective.

 

Use a strobe to set it to 8-10* BTDC (if it'll run long enough to do it), otherwise, do it statically.

 

I'd definately replace the rotor arm. It's very likely to be the problem.

 

Good luck!

Ade

[soulman309]

Hmm, found what the problem was.

Bit embarresed to say, but not enough fuel in the tank!

 

I had checked and could see fuel in there, but I think it might use gravity as an aid to flow fuel through easier.

This is why it coughed and spluttered and misfired.

 

As it's not on the road yet I just top it up with a petrol can.

It's never really very full as you can only get so much in a can.

 

Topped it up and off we go.

 

Thanks very much for all your advice though.

 

Lesson learnt - Always check the simplest things fisrt!!!!