Thread: Lack of Power

Hi,
hopefully someone knows the answer to this issue. The other day i was sitting at the lights running on LPG when the motor backfired. This blew off the connection between the Plenum chamber and the LPG mixer. I re-attached everything and managed to limp home. I'm now finding that although the motor starts and runs fine it seems that there is a lack of power. I cant get above 40km/hr When I depress the accelerator the revs increase up to a point but then plateau and don't increase any further. I'm thinking there is a sensor problem somewhere. I've had the MAF off and the flap moves freely and does not appear to be bent. All vacuum hoses appear to be in place. I'm going to try running on petrol this afternoon to see if it is maybe LPG related, perhaps the mixer was damaged by the backfire.
Any hints as to where to start looking?

Also any thoughts on the likely cause of the backfire, it is not a regularly occurring problem? I've replaced the plug leads being careful to route them correctly and she now runs a whole lot smoother. I'm also looking at replacing some of the vacuum hoses as they look a little sad. The backfire has not been repeated.

thanks for your assistance

Gareth

1987 Range Rover Classic. 3.5EFI. LPG/Petrol

1. You cannot 100% prevent backfires on gas. Every ignition component must be top notch to reduce the chance of a backfire to a very low level. This includes timing settings (run 6 to 10 deg advance at idle) plug gaps (0.6 to 0.7mm max.) , lead resistance and type, rotor button to cap clearance, coil and amplifier weakness. Replacing parts without checking gaps, resistance etc can often make the problem worse.

2. Take the cover plate off the end of the mixer and check the cover for warping and the diaphragm for tears.

3, Make sure the maf flap opens fully.

4. Do not run a flapper system without a backfire flap installed downstream of it.

5. Make sure all leads are firmly connected at both ends. Just the other day someone came in with their '89 RRC with every lead left loose at the cap, only the boots held the leads on. It was serviced by a local mechanic who shall of course remain nameless as per the rules of the forum.