Hi All.
This is my first thread and i would really appreciate help from enthuiasts!
I have searched the internet for advice on this problem and can't get anywhere.
The Car is a 1990 740 2.3 with i believe a K jet Intection although im not certain (It has Bosch 0 438 120 203 stamped on the injection)
The car has overall been very reliable but gradually started to have starting and chugging problems. Recently it gave up starting at all unless i sprayed quick start into the air intake then it would start immediatly and run like a dream all day long but then this stopped working so i had to take it off the road.
I thought i would have a look at it yesterday and started by removing the big black rubber bellow that links the lower injection unit with the throttle body on the inlet manifold. Underneath this i found a large round plate that lifts up and down as you accelerate (excuse the vague descriptions but im not experienced with injection systems) just infront of the fuel distributer. This plate was stuck down so i freed it up but as soon as it closed again it would jamb again so i adjusted it slightly so it stayed open a little. I put the Rubber bellow back on tightened the jubilee clips and spun it over. After about 10 seconds of cranking it fired up and ticks over ok but slightly uneven. When you rev it up it chuggs until about 1500rpm then it clears and is fairly crisp. Upon driving the car it is immediatly obvious that it is chugging quite badly as you pull away but as you get going it clears and drives fine but when you ease off and then put your foot back down no matter from what speed, the engine chuggs and struggles to pick up.

So what im asking is if anybody can advise me what to look for and what might be causing this. Im so close to getting it running right and don't want to have to surrender and take it to a garage to be looked at.

Many Thanks
Ben

 

I have just started it up now and it is hunting on tickover. Its chuggs down low until its about to stall then picks up again then repeats this cylce continuously.
Looks like im going to need to find out what this is too!

 

Sounds like the car is starving for air. I think you are talking about a throttle body plate. They are supposed to be cleaned as part of normal maintenance. I use to remove and clean mine every 5k. Fuel injection cars are pretty sensitive with their vacuum system, you have to keep them in good shape, hoses clear and cracked and torn parts replaced. That car also has a flame trap that should be replaced.

Take the throttle body off and spray it down real good with throttle body cleaner (not carb cleaner).

 

Thankyou very much for your advice.
I will check this out when the rain stops and let you know how it went.
If you see this before i report back, could you tell me what the flame trap is and where it is located.

Thankyou
Ben

 

Not really. My 740 was a '87 model and I know they move that stuff around a little all the time. It's likely in a tube end that connects close to the motor. Usually in a casing about the size of a soda bottle cap. Usually you will have to pull a hose off and turn the housing a little for it to unlatch. If you go to www.fcpeuro.com or some parts website you can see what it looks like. Should be close to the throttle body. There is a small honeycomb white piece in there that can get clogged. Should be replaced every 5 to 10k.

 

A US model 1990 would most certainly be LH2.4 or Regina injection. K-Jet was abandoned by Volvo in the early 80s, like I think 83 or 84 was the last year. afaik, NO US model 740 was K-jet.

now, if you're in another country, well, then its harder to say. on the front of your engine, should be a paper sticker with some bar codes and the engine type, like my 1987 240 is a B230F, and my 1992 740 turbo is a B230FT.... What is yours ?

see...


for mine.