Volvo 740 running problems...

I've skimmed Google for suggestions, but none of the symptoms others had
described seemed to fit the bill, so here goes.

Ok, I have a 1990 model Volvo 740 estate, powered by a pierburg carburettor
fed 2.3 inline 4.

The car will always start straight away from cold without any problems what
so ever, indeed it started first turn of the key having been stood for over
two months when I collected it a few weeks ago.

Anyway, it will always run fine for at least two miles, and then it gives a
hint of hesitation on low throttle settings, before finally coming to a
halt - flooring it at any stage brings this all about much quicker.

If you take it for a short spin and the above doesn't happen before you get
back, the car will sit on the drive ticking over quite happily all day.

If once it has cut out, you leave it a few minutes, it will start again and
continue on its way once you've floored it to clear its throat, so to speak.

I've had the carburettor and fuel filters changed, as these were my
mechanics initial diagnosis, and these haven't made any difference.

The mechanic is adamant that spark is present at all times, even when it
falters.

So... the mechanic seems unwilling to try anything else, and I'm at the end
of my tether - I'd like to keep the car, as its a very comfy smooth ride,
and I have occasion to need a seven seater from time to time, but I'm
unwilling to keep throwing more and more money at it if it isn't diagnosible
without buying and replacing all the bits on it one by one until we hit
gold.

Can anyone recommend a specialist in Kent or London UK, who'd be able to
sort it with the minimum of fuss and guess work?

TIA

 

From a point at sea, to the circles of your mind, this is JackH:

This isn't answering your specific question, but I am thinking:

Fuel pump
Fuel pump relay
Fuel pump fuse
Carb. icing
Vapour lock
Blocked fuel tank vent

I suggest these without any confidence whatsoever, since I've only
ever owned injected Volvos.




--

Stewart Hargrave

A lot faster than Royal Mail


For email, replace 'SpamOnlyToHere' with my name

 

Well for an engine to run you need fuel, air, and spark, so if the spark is
always there that eliminates that, the air is probably not the problem
because an issue with that is rarely intermittant, so it's very likely a
fuel problem. I've never seen a carbureted Volvo up close but from
experience with lawnmowers it sounds like the carb has a fuel bowl that's
occasionally not being replentished, these usually have a float that
operates a needle valve to regulate fuel in the bowl and it sounds like that
may be sticking or getting clogged, but you say the carburetor has been
changed, hmm is there a fuel pump? Perhaps air is getting into the system
somewhere, or maybe the return vent to the tank is clogged, does it still
have this problem if you remove the fuel filler cap?

 

A few of these can be eliminated because IIRC the carbureted Volvos lack an
electric fuel pump. Seems silly that a company like Volvo used carbs on such
recently produced cars.

 

hello Jack

i suspect your EGR valve is stuck open
the easiest way to deal with this is to simply close the tube from the
valve to the inlet manifold permanently with some exhaustsealer or
silicone(let it dry out long enough so it will not be sucked into the
cylinders)
this metal tube is visible under the carb,it is fastened to the manifold
with 2 bolts
also eliminate all the vacuum tubing related to the EGR and Pulsair
systems,a colourfull bunch of tubes only there to anoy people
an older volvomechanic who knows carburetted volvo's shoud be able to
disconnect EGR AND pulsair and leave the necessary vacuumlines in place

i hope this will cure your problem


Marc Brack

4x 960
1x 740 16v
1x tatra 613-4

 

Hi James... yes, fuel cap was one of the first things I thought to try, and
it made no difference whatsoever!

Fuel pump wise, I've been led to believe it has a mechanical one under the
bonnet, *and* an electronic one in the tank... I've looked at the fuel
filter at times, just after it's stopped running yet again, and this always
seems quite well stocked with fuel.

It's just so bloody frustrating - the car is in too good a nick to scrap,
yet it's too old to justify spending a stack of cash on in order to *maybe*
find out what is up with it!

ARGH!!!!

 

Hi Mark.

The above sounds like a fairly easy and, if necessary, reversible
suggestion.

I'll give that a try next... paging any Volvo mechanic who knows his onions
and knows which pipe to unhook from what etc.

 

Fuel filter seems well stocked, even when the car has died.

That was one of my initial thoughts actually, but it doesn't seem to be
that; I do know from past experience with other makes that Pierburgs tend to
suffer with this, mind.

Don't think so, as no rush of air if you undo the filler cap after its
stalled.

Cheers

 

I know you said earlier in the thread that you had replaced the carb, but
have you checked the diaphragm for a split? They are well known for
splitting, and the symptoms you have are the same on one of my mates Volvos,
a 745 2.3 with carb. Was the replacement carb second hand?
I fixed his problem with a small dab of bicycle tube puncture repair kit
glue on the split on the diaphagm.

Stuart.

 

Afterthough..... have you filled the damper on top of the carb with oil?
Engine oil will do. A dry damper doesn't usually have the great effects you
are having, but it is necessary for the carb to function properly.

Stuart.

Stuart

 

I don't think it has that sort of carb - this one looks like a conventional
weber'esque twin choke special.

 

I thought you had the Pierburg carb? Solex(Zenith) and Pierburg used on
Volvos have a diaphragm and oil damper, SU carbs have only the damper. The
Solex Cisac is a twin choke type. As far as I know the carbed engines only
have a mechanical fuel pump on the engine, no electrical pump in the tank.
Have you tried a new mechanical fuel pump?

Stuart

 

Hi Jack. ; )

I too have a 740 with running problems and really do not wish to part with
it.
I am not as clued up with the Volvo as most people in this group but I have
had a similar problem as you are experiencing with an Audi 100

You say if you floor it you can clear it's throat?
I don't wish to deter from the trend others have followed and I don't wish
to undermine your mechanic BUT.

Try the distributor. Remove the cap and see if there is oil present.
The oil seal on the rear of the distributor had perished slightly on my old
car causing the odd drip of oil to creep through and foul on the contacts of
the cap. "Flooring" used to clear it and then it would be okay. If I stopped
the car for an hour or so then went back 7 out 10 times the problem had
returned. A new seal cured it.

I know your mechanic said there is a spark at all times, he however did not
say if it was erratic or weak.

Just another simple thing for you to check.

Carbs:

Pre 1987 models were fitted with the Pierburg 2b5
1987 on Were fitted with Pierburg 2B7

Both are twin BARREL, fixed jet, downdraught. Auto choke.

Twin Barrel but not twin choke.

Two fuel pumps are fitted electric fuel tank pump and mechanical main pump.
Apparently.

The Pierburg 2B7 does not have a fuel return connection.

 

You could always try a company called "Braydon Motor Company" - they have
been good to me in the past.

http://www.volvocarparts.co.uk/

They're in East London, and they specialise in Volvos though as they aren't
Volvo dealers they can replace with secondhand parts if you want. They're
usually cheaper than the others - you could give them a call and see if they
have an idea. They can't be bad - I've got a 1990 740GLE Estate 2.3 with
over 230,000 miles on the clock and it's still going strong!

Mark

 

Hello all: I suspect the problem is with the "hall sensor" inside the
distributor that seems to act up when the Volvo motor is about 12 years old.
This happened to me with a 1985 B230F when the car was 12 years old. Worth
a try... Cam

--
Cameron Price Newington, Ontario, Canada

http://cvolvo.com

1960 P 120 Amazon #046279 100,370 miles
1980 262C #6618 244,004 km
2001 V70 AWD XC 35,285 km

F2000SL 3,862.2 km Cannondale Volvo Team Replica
R600 2,708.5 km Cannondale road bike
Jekyll 3000 3,629.0 km Cannondale Volvo Team Replica

TACX i-Magic Indoor Virtual Trainer 768.7 km

 

I have... a 2B of some description, which has no diaphragms as such, other
that ones on the vacuum side of things (and which have tested as being ok),
and which is of a conventional Weber style twin choke design.

 

'ow do.

Same here, but I'm not re taxing this one unless I can get it to run
properly, and I absolutely *loathe* these problems that no-one seems to be
able to just say 'ah yes, it's that'!!!

Basically, if I floor it whilst I'm driving, it will make it cut out that
little bit quicker from cold, than if I keep it on low throttle settings.

Once it has cut out, you have to leave it alone for a couple of minutes, and
then it will eventually fire... once it starts to splutter, you have to
floor it to get it to catch properly, and once you've done this, it will
idle fine.

It will then drive a little further before doing it all again... heavier
application of the throttle will accelerate it towards cutting out that much
quicker.

The more I think about it, the more it seems to be something electrical
messing about when under duress or once it has got to a certain temperature.

Many thanks, I will check that out later this week.

Indeed... and tbh, I'm beginning to think that this was one of his 'don't
know, can't be arsed', specials.

Yup, that's the kiddy.

Ah, ok... I'm not exactly a carb expert, but that sounds about right.

Ok... well I'm getting to the point where I can't be arsed with it any
more... I'd like to think that somewhere based in Kent or SE London knows
their onions on these, so if anyone can recommend me a place that won't piss
me around or savage my wallet without good justified reason, and who will
know what they are looking at, rather than changing parts willy nilly in the
hope of hitting the jackpot, I'd be grateful; I've already spent around £100
on parts etc., on the recommendation of others, and to no avail.

 

It sounds very much like the fuel filter is becoming blocked. Some of these
filters are very small and IIRC you have an in-tank pump unit which can get
pick-up blockage.

Cheers, Peter.

:
: : > Hi Jack. ; )
:
: 'ow do.
:
: > I too have a 740 with running problems and really do not wish to part with
: > it.
:
: Same here, but I'm not re taxing this one unless I can get it to run
: properly, and I absolutely *loathe* these problems that no-one seems to be
: able to just say 'ah yes, it's that'!!!
:
: > I am not as clued up with the Volvo as most people in this group but I
: have
: > had a similar problem as you are experiencing with an Audi 100
:
: > You say if you floor it you can clear it's throat?
:
: Basically, if I floor it whilst I'm driving, it will make it cut out that
: little bit quicker from cold, than if I keep it on low throttle settings.
:
: Once it has cut out, you have to leave it alone for a couple of minutes, and
: then it will eventually fire... once it starts to splutter, you have to
: floor it to get it to catch properly, and once you've done this, it will
: idle fine.
:
: It will then drive a little further before doing it all again... heavier
: application of the throttle will accelerate it towards cutting out that much
: quicker.
:
: The more I think about it, the more it seems to be something electrical
: messing about when under duress or once it has got to a certain temperature.
:
: > I don't wish to deter from the trend others have followed and I don't wish
: > to undermine your mechanic BUT.
:
: > Try the distributor. Remove the cap and see if there is oil present.
: > The oil seal on the rear of the distributor had perished slightly on my
: old
: > car causing the odd drip of oil to creep through and foul on the contacts
: of
: > the cap. "Flooring" used to clear it and then it would be okay. If I
: stopped
: > the car for an hour or so then went back 7 out 10 times the problem had
: > returned. A new seal cured it.
:
: Many thanks, I will check that out later this week.
:
: > I know your mechanic said there is a spark at all times, he however did
: not
: > say if it was erratic or weak.
:
: Indeed... and tbh, I'm beginning to think that this was one of his 'don't
: know, can't be arsed', specials.
:
:
: > Just another simple thing for you to check.
:
: > Carbs:
:
: > Pre 1987 models were fitted with the Pierburg 2b5
: > 1987 on Were fitted with Pierburg 2B7
:
: > Both are twin BARREL, fixed jet, downdraught. Auto choke.
:
: Yup, that's the kiddy.
:
: > Twin Barrel but not twin choke.
:
: Ah, ok... I'm not exactly a carb expert, but that sounds about right.
:
: > Two fuel pumps are fitted electric fuel tank pump and mechanical main
: pump.
: > Apparently.
:
: > The Pierburg 2B7 does not have a fuel return connection.
:
: Ok... well I'm getting to the point where I can't be arsed with it any
: more... I'd like to think that somewhere based in Kent or SE London knows
: their onions on these, so if anyone can recommend me a place that won't piss
: me around or savage my wallet without good justified reason, and who will
: know what they are looking at, rather than changing parts willy nilly in the
: hope of hitting the jackpot, I'd be grateful; I've already spent around £100
: on parts etc., on the recommendation of others, and to no avail.
:
: --
: JackH
:
:

 

Have you checked the fuel lines and filters for blockages (all fuel filters that
is).

Cheers, Peter.


:
: : > Hi Jack. ; )
:
: 'ow do.
:
: > I too have a 740 with running problems and really do not wish to part with
: > it.
:
: Same here, but I'm not re taxing this one unless I can get it to run
: properly, and I absolutely *loathe* these problems that no-one seems to be
: able to just say 'ah yes, it's that'!!!
:
: > I am not as clued up with the Volvo as most people in this group but I
: have
: > had a similar problem as you are experiencing with an Audi 100
:
: > You say if you floor it you can clear it's throat?
:
: Basically, if I floor it whilst I'm driving, it will make it cut out that
: little bit quicker from cold, than if I keep it on low throttle settings.
:
: Once it has cut out, you have to leave it alone for a couple of minutes, and
: then it will eventually fire... once it starts to splutter, you have to
: floor it to get it to catch properly, and once you've done this, it will
: idle fine.
:
: It will then drive a little further before doing it all again... heavier
: application of the throttle will accelerate it towards cutting out that much
: quicker.
:
: The more I think about it, the more it seems to be something electrical
: messing about when under duress or once it has got to a certain temperature.
:
: > I don't wish to deter from the trend others have followed and I don't wish
: > to undermine your mechanic BUT.
:
: > Try the distributor. Remove the cap and see if there is oil present.
: > The oil seal on the rear of the distributor had perished slightly on my
: old
: > car causing the odd drip of oil to creep through and foul on the contacts
: of
: > the cap. "Flooring" used to clear it and then it would be okay. If I
: stopped
: > the car for an hour or so then went back 7 out 10 times the problem had
: > returned. A new seal cured it.
:
: Many thanks, I will check that out later this week.
:
: > I know your mechanic said there is a spark at all times, he however did
: not
: > say if it was erratic or weak.
:
: Indeed... and tbh, I'm beginning to think that this was one of his 'don't
: know, can't be arsed', specials.
:
:
: > Just another simple thing for you to check.
:
: > Carbs:
:
: > Pre 1987 models were fitted with the Pierburg 2b5
: > 1987 on Were fitted with Pierburg 2B7
:
: > Both are twin BARREL, fixed jet, downdraught. Auto choke.
:
: Yup, that's the kiddy.
:
: > Twin Barrel but not twin choke.
:
: Ah, ok... I'm not exactly a carb expert, but that sounds about right.
:
: > Two fuel pumps are fitted electric fuel tank pump and mechanical main
: pump.
: > Apparently.
:
: > The Pierburg 2B7 does not have a fuel return connection.
:
: Ok... well I'm getting to the point where I can't be arsed with it any
: more... I'd like to think that somewhere based in Kent or SE London knows
: their onions on these, so if anyone can recommend me a place that won't piss
: me around or savage my wallet without good justified reason, and who will
: know what they are looking at, rather than changing parts willy nilly in the
: hope of hitting the jackpot, I'd be grateful; I've already spent around £100
: on parts etc., on the recommendation of others, and to no avail.
:
: --
: JackH
:
:

 

You could try attaching a hose to the fuel pump input and sticking it in a
small cup of fuel, saw that trick once when we were trying to get an old
truck with contaminated gas tanks half full of 7 year old gasoline running.
If the rest of the car is in decent shape how hard could it be to get going?
Worst case you could drop in a whole new motor from a junkyard.