Series III Stage 1 - Misfiring/Backfiring, lack of power

[jpalmer]

Hi All,

I am quite un-mechanically savy and just wanted a diagnosis on the problems I am having with my 1982 Series III Landy.

Currently she starts first pop fine and after she has warmed up she starts loosing power when you have the foot on the accelerator right down. It appears that perhaps all the cyclinders are not firing and a puffy sound comes from the engine. After you do this for a bit the truck will eventually backfire... The problem is quite inconsistant and often power returns to the engine and it runs well/as normal...

Can anybody help?

Kind regards,

Jordan

[Boston]

Any carb work done recently?
Pull the plugs. Colour?

[jpalmer]

Had a look at the plugs looking good ... No carb work done, was serviced before christmas however.

[greenmeanie]

I'd be thinking fuel issue too. As the loud pedal is all the way down I'd be looking at reasons for fuel starvation but you shoul also look at the exhaust and check for black smoke just to help eliminate overfuelling from the equation.

I'd start by disconnecting the fuel hoes at the carb (Fire ext handy is a good thing) and have someone turn the key and watch the fuel flow into a container. It should gush and not dribble. A second or two is all you need here. If the flow is at all suspect then go through your filters. After that pull the fuel pick up tube from the tank and check the end.

After that your into the carbs again.

[busboy]

The backfire leads me to think that a cylinder is not firing and when enough unburned fuel builds up, bang. Pull the plugs and look for a wet one then change it, if it still does it then change the lead, next the distributor cap.

[mearstrae]

Had a similar problem with my Hybrid, as it is set up like a Stage1, being a Range Rover engine and trans. It ended up being the Facett electric fuel pump was cutting out. This caused lean misses (back-fires through the intake) and loss of power. I replaced it with a Carter electric pump and all has been well for years.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 3500S

[REDrum]

Fuel starve is a good lead, try swapping easy stuff first: fuel filter, cap/rotor/point, wires. Good be "bad" gas too. Worst case is that you have jumped timing

[Wolf323i]

Does this thing have points? I had my points close up all the time on my BMW 320. A simple gaping adjustment with a match book as a feeler gauge always got me on the way.

[disco2hse]

No points on his. Electronic ignition (IIRC).

Might be fuel starvation but could also be sticking valves, worn cam lugs, hydraulic lifters need replacing, leaky high tension wires (more likely if it occurs more when warm).

The description sounds more like a timing issue to me. Split vacuum pipe or worn distributor cam?

Are you running the Mallory ignition system or Pertronix? The Mallory is known to fail, and so is the Pertronix (although it is more robust).