some 4 weeks ago I posted on problems with my 740 estate 1987 B230K BiFuel (mainly LPG driven, carburettor type here in the Old World!): intermittent ticking noise, not from inside the engine, to be heard clearly inside the car, significantly less outside, fix relation to engine rpm, no difference when driving or static, no difference wheteher clutch depressed or not. The experiments done, combined with "listening sessions":

* take away all belts to ancillaries,take away crank pulley,

* renew timing belt with tensioner,

* release all emission control activations

* hint from this board: renewed 3 engine rubber blocks

* hint from this board: replaced the exhaust (now SS type.I imported from Sweden: RakaRor. Excellent fit, all SS incl. first pipe up to brackets bolts etc for about USD400 including fast shipping. See www.rakaror.o.se),

* removed the two exhaust heat shields

* checked all engine sensors etc, cabling

* checked all relais inside the car for ticking(!!??)

* created clearance from the inlet duct to the hood, due to the gas mixing device on the carburettor,

* read extensively Steve Ringlee's FAQ from beginning to end....

* .......and still the ticking noise remained intermittently present.

I thought to have done everything, but finally after staring at the block........

I NOTICED THAT I FORGOT ABOUT THE MECHANICAL FUEL PUMP!

This, together with the Pierburg carburettor is apparently not present in any US model 700, so does not show up in any publication on this board. Well, taking the pump away (I can drive on the "second fuel") and putting a plate on the hole in the block, cleared the issue fully. Throughout its life this car may have driven only 1000mls on regular gas and the rest on Liquified Petrol Gas, so the pump may have sufferred in some way; or an issue may be in the fuel tank (hose rotten)causing "standing waves" in the fuel lines, which generate contact noise to the car body. For understanding and finally clearing this issue, I will separately post on this board.

Anyhow, long story, but hopeful interesting for those with mechanical pumps; maybe a chapter on such pumps and on carbs can be added to FAQ....?

Thanks for support from the board!

Jaap.