loosing power

[learner]

hi all
i have a problem when my mav is towing or extra weight on it that it looses power. i have a brand new head on it and it is petrol/gas 4.2lt. timing set at 12 at present. it has new plugs/leads and petronix iginition. it is auto and i only get 4klms to a litre of fuel any ideas of what to do to fix
thank you

[Parksy]

Pull out a spark plug and check its colour. White or very dark is no good which would indicate bad fuel mixture. Listen to the exhaust while its idling and see if it makes a consistent puff, puff puff noise in time with the engine. Alternatively, hold your hand about 30 cm from the exhaust and you should only feel abit of warmth and gentle air movement. If you feel alot of pressure, this is a good indication of a vacuum leak somewhere on the intake side of the engine. Use a can of wd40 or similar and spray it around seams and gaskets and hose connections and listen for a rise/drop in engine rpm. This will be a good indication of an unwanted air intake.
Don't know much about autos, but I'm sure an experienced person in the drivers seat could tell you if the auto is slipping or not which could be causing your bad mileage. Maybe a fluid/filter change on the auto is in order.

[GQ TANK]

If you are getting 4km l of LPG - then its running about normal - ie 25 per 100k. Im getting 24 l (LPG) per 100 with my manual gq 4.2

What do you mean when you say you are loosing power?

Ie you go up a big hill slow then when you had no weight on the back or you can hardly move the truck with the weight on the back.

have yopu considered it could be your auto slipping? - can you smell anything after you have towed?

[learner]

hi parksy
thanks for the info i will give them a try
learner

[learner]

hi gq tank
i lose all my top end speed when i place about 200kg in it even on a slight incline. with no load i can sit on 100k in top but with that little weight top end around 80k
thanks learner

[learner]

hi parksy
thanks for the info i will give them a try
thanks learner

[threedogs]

Grab some Vacuum guages and hook them up,
They'll tell you straight off whats wrong

[learner]

i will follow up on this
learner