Confused 740GL owner

Hi all new member here. I have a 1988 740GL saloon Auto which has a few issues.
Ok ive been reading thru old posts to see if i could work out what it is from previous votes, but now seem to have 20 different possibilities.

Basically, I purchased a 740GL for my brother in law off ebay which was pretty local to me. Went to pick it up and noticed it didnt have much fuel, but i did have about 5 litres of unleaded i bought along with me, though the car is i presume Leaded as it has a red cap i was sure it would be fine to get me home (20miles) Driving home i was obviously taking it easy doing 60 on the motorway with light acceleration and all was fine, with my brother in law driving behind me in my Carlton. Anyway came off 1 motorway M5 and onto the M32 near my home, i though id give her a quick burst to see how she went, and was suprised to notice she felt faster than my carlton. Thats when things went wrong as suddenly the car started stuttering like it had sucked something thru the fuel lines and when i pulled over she conked out. restarted and off i went again everything seemed ok though idle was then a bit eratic. Drove onto the dual carridgeway toward mt house taking it easy but as soon as the revs went to 3000 she started dying again, so pulled over restarted and drove the rest of the final mile as a steady pace not going above 3000 rpm. Now my search has thown up, speed sensor, AAM, Vacuum Lines, Fuel Pump etc etc and now im confused. What i did notice is that for no reason the orange arrow showed up now and again on my dashboard (Overdrive relay?) and when the car clunked out the temp was reading 1/4 on the guage, but when i restarted 3 seconds later it showed back on cold?

Sorry for the novel, any idea's?

[LankyTim]

The arrow is the top gear lock out for the auto box, it stops it from going into top gear, say if your towing a caravan. as for the temp gauge, 740s are famous for having erratic instruments, especially the fuel gague!


Im assuming your car is injection?

If it were my car, id suspect clogged fuel lines or fuel filter, try running some redex though the tank to clean the fuel line and injectors.


Is the fuel pump noisy? If it is youll hear a funny whirring from the rear of the car. When theres enough fuel in the tank, the fuel pump doesnt have to work too hard, as the syphoning effect of the fuel means that its easily sucked out and to the engine, when the car is nearly out of fuel though the pump has to work much harder, and a weak pump sometimes cant supply enough fuel to the engine and on high revs splutters or cuts out.

TBH i dont know if its a carb or inj, ill have a look at the engine plate when i get home. As for fuel pump noise, there was nothing from back of car but, did notice when i switched off the heaters it sounded like they were still whirring away (passenger side of car somewhere)i was driving at the time so could not investigate more, but when i started her this morning the sound wasnt there, car idled fine untill i reved it a bit then it died again.

[GrahamB]

I have a 1988 740GL Estate, B200E engine, which uses unleaded petrol (at least it has for the past 14 years!). I would be surprised if your engine is for leaded petrol. The fuel pump looks like a good starting point for your problem.

>I have a 1988 740GL Estate, B200E engine, which uses unleaded
>petrol (at least it has for the past 14 years!). I would be
>surprised if your engine is for leaded petrol. The fuel pump
>looks like a good starting point for your problem.


It seems to have pretty much every bit of paper for work carried out on it since new including all MOT's and there is nothing in there about it being converted to un-leaded and when i got the car there was a bottle of lead substitute that came with it. Im only the 4th owner, 1st had it for 3 years 2nd then had it untill a month ago, the 3rd had it for a month and now me (well my brother in law). And they guy i bought it off is the son on the man who had the car from near new and said he's sure it was never converted to unleaded.

Thanks for the fuel pump advice, which one would it be, im sure i read on here there are 2?

Thanks for the help Marcus.

[Mike_Brace]

These engines are fine on unleaded without conversion.

Mike

[LankyTim]

Yes there are 2, one in tank pump called the lift pump, and the main high pressure one under the car, where the rear seat is called the main pump. This is the high pressure pump for the injection system. Try filling the tank full and empty a bottle of redex injector cleaner into it, might work. If the main pump is weak the full tank will put less pressure on it and it may run as normal. If it does thats your problem!

Hi again. Ive got the car running better but it still cuts out sometimes after she warms up and i blip the throttle. ive sprayed the majority of a can of carb cleaner into it, put in redex and changed the fuel filter. I was told that an idea was to blow air back thru the fuel system incase its clogged somewhere. Any suggestions?

Ohh the engine is a B230K.

I had a 740 with a B230K, lovely engine, loads of character and surprisingly good performance.
Check that the hot air trunking which runs from the exhaust downpipe into the airbox is intact (it's a silver, foil looking hose, about two inches across). The Carb NEEDS a warm air supply when the temp gets low, unlike injected engines which are fine without it.
This pipe often gets removed when it deteriorates, because it's expensive to replace, but without it my carb used to ice up at motorway speeds, and I would loose all power and have to pull over. After a few minutes it was fine again (because it had warmed up). Took me ages to figure out.
The other possible fault is the mechanical fuel pump on the side of the engine block, these occasionally fail, but are cheap (www.eurocarparts.com) and easy to replace.
In addition check the fuel filter is clean (these are VERY cheap to replace).
Also, it may be worth making sure the mixture and idle speed on the carb are correctly adjusted, and that the choke is working. These make a huge difference.
The carb also has an accelerator pump, which enriches the fuel mixture when you blip the throttle (which is why carbs give such nice throttle response). That may be faulty.
I think that covers most of the things specific to that engine. The other things to check (ignition components etc.) are common to most modern engines.
Also, I would make sure the thermostat is working if you're noticing that the engine doesn't warm up properly. Coolant heats the choke on the carb and releases it. If the engine doesn't warm up, the choke will stay on.
Sorry, I've gone on a bit here!! You certainly don't need to worry about AMM's high pressure fuel pumps etc, as your engine doesn't have them. It's nice and simple.
Best of luck!!
Jim

The 2.0 litre injected 740s were unleaded ready. Volvo had already made the 740 series unleaded ready when they had the 2.3 carb engine in from late 86. They had a sticker on the back window saying "Follow my lead, remove the lead"

They still had red fuel caps on some of the unleaded ready cars to aid confusion.

I was 9 years old then.