Strange Fuel Starvation Problem.

Oct 18th, 2003, 20:33

Hi guys,

I've got a real strange problem with my 1986 240 GLE estate. It's a CISAC carb model with a mechanical fuel pump. The problem seems to be located between the fuel pump, a odd fuel economiser thingy and the CISAC Carb. The car will perform fine for days and then without warning going up hill or at 50+MPH she'll suddenly begin to backfire, cough and drop her speed down until I have to get off the road where she'll cut out. However if I turn the key immiedatly after she'll start up and settle back into a steady Idle. I'll pull away and mabe she'll be fine, or more likely, I'll travel a few hundred yards and begin coughing and spluttering again. Three time this has happened this week. The last time the RAC got her running again by bypassing the black economiser thingy and putting the fuel line direct to the carb. They reommended I change the fuel pump as it was probably weak and unable to supply both the carb and tank return pipe from the black thing. I Did change the pump but the problem reappeared today. Any ideas?

Peter Milnes · Oct 19th, 2003, 00:44

Check and change all fuel filters. One on the pick-up in the tank, one on inlet side of fuel pump, one on inlet side of carburretor and possibly one associated with the fuel economy module. The tank one can usually be cleared by undoing the connection to the fuel pump and blowing back down the line with a garage air line to clear the filter. Then add some fuel cleaner to the fuel in the tank. The other ones are generally of the small gauze type and are easy to clean but check the valves chambers in the pump as well. I have had this happen on a variety of cars.

All the best, Peter

Clifford Pope · Oct 20th, 2003, 08:27

Does it tend to do it on cold mornings? I have had this problem.
There is a small heating element, on all the time, in the base of the carb, to counteract the known tendency to icing on this carburettor. Check for continuity. The element can be removed, and a common fault is simply a poor earth contact.

Oct 21st, 2003, 23:49

Nope it's not the heating element. In fact the fault seems to turn up only after a long run when the cars' warmed up nicely. I've got a spare pierburg carb from a 740 I may try, Mainly due to the return tank output. The Car runs on Shell Optimax. I hoped that if there's dirt in the tank that the detergents in the petrol sould have cleared it!

Peter Milnes · Oct 22nd, 2003, 02:09

You are better off using a proprietary fuel cleaner such as Redex from Halfords etc. This will also clean the injectors.

All the best, Peter

Oct 18th, 2003, 20:33	#1
Ianpearce112 Guest Location:	Strange Fuel Starvation Problem. Hi guys, I've got a real strange problem with my 1986 240 GLE estate. It's a CISAC carb model with a mechanical fuel pump. The problem seems to be located between the fuel pump, a odd fuel economiser thingy and the CISAC Carb. The car will perform fine for days and then without warning going up hill or at 50+MPH she'll suddenly begin to backfire, cough and drop her speed down until I have to get off the road where she'll cut out. However if I turn the key immiedatly after she'll start up and settle back into a steady Idle. I'll pull away and mabe she'll be fine, or more likely, I'll travel a few hundred yards and begin coughing and spluttering again. Three time this has happened this week. The last time the RAC got her running again by bypassing the black economiser thingy and putting the fuel line direct to the carb. They reommended I change the fuel pump as it was probably weak and unable to supply both the carb and tank return pipe from the black thing. I Did change the pump but the problem reappeared today. Any ideas?

Oct 19th, 2003, 00:44	#2
Peter Milnes Premier Member Last Online: Apr 10th, 2014 00:01 Join Date: Feb 2002 Location: Tonyrefail	RE: Strange Fuel Starvation Problem. Check and change all fuel filters. One on the pick-up in the tank, one on inlet side of fuel pump, one on inlet side of carburretor and possibly one associated with the fuel economy module. The tank one can usually be cleared by undoing the connection to the fuel pump and blowing back down the line with a garage air line to clear the filter. Then add some fuel cleaner to the fuel in the tank. The other ones are generally of the small gauze type and are easy to clean but check the valves chambers in the pump as well. I have had this happen on a variety of cars. All the best, Peter

Oct 20th, 2003, 08:27	#3
Clifford Pope Not an expert but ... Last Online: Today 09:44 Join Date: Dec 2001 Location: Boncath	RE: Strange Fuel Starvation Problem. Does it tend to do it on cold mornings? I have had this problem. There is a small heating element, on all the time, in the base of the carb, to counteract the known tendency to icing on this carburettor. Check for continuity. The element can be removed, and a common fault is simply a poor earth contact.

Oct 21st, 2003, 23:49	#4
Ianpearce112 Guest Location:	RE: Strange Fuel Starvation Problem. Nope it's not the heating element. In fact the fault seems to turn up only after a long run when the cars' warmed up nicely. I've got a spare pierburg carb from a 740 I may try, Mainly due to the return tank output. The Car runs on Shell Optimax. I hoped that if there's dirt in the tank that the detergents in the petrol sould have cleared it!

Oct 22nd, 2003, 02:09	#5
Peter Milnes Premier Member Last Online: Apr 10th, 2014 00:01 Join Date: Feb 2002 Location: Tonyrefail	RE: Strange Fuel Starvation Problem. You are better off using a proprietary fuel cleaner such as Redex from Halfords etc. This will also clean the injectors. All the best, Peter

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