Fouling of plugs in '86 Volvo 240GL

  • Thread starter Thread starter Anton Sather
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Anton Sather

My 1986 Volvo 240GL has suddenly started fouling the plugs in a very short
time. I have brought it to the local mechanic, discovered it was getting
too much fuel and has replaced the fuel injection ECU, however it hasn't
solved the problem. He indicated the sensors were OK and I don't like to
disagree with him, but finding the actual problem is difficult for me.
Anyone have any suggestions?



I have recently replaced the high tension leads, distributor cap & rotor -
could this be a contributing factor?



Regards,

Anton
 
plug type cold or hot can make a difference I remember once I put a new set
of plugs in they were all faulty do you think that didnt confuse me
?Naturally I looked everwhere else that I had touched till disparate I found
the plugs klg were useless
 
how are your injectors as you cant get high octane fuel there?I used to use
spitfire and 95 octane to clean my injectors where as others used to take
them out and give them to the errr what they thought were mechanics and pay
through the nose .Try injector cleaner and remember Volvos love a hot rev
out to clean the engine .Use quality oil cheap oil gums up the engine .Hows
your muffler is it clogged up ?Hard up mount wellington might help all 1273
metres in a lower gear .Coming down with 100 octane but will have to settle
for 95 down there .Love the place .
 
Anton said:
My 1986 Volvo 240GL has suddenly started fouling the plugs in a very short
time. I have brought it to the local mechanic, discovered it was getting
too much fuel and has replaced the fuel injection ECU, however it hasn't
solved the problem. He indicated the sensors were OK and I don't like to
disagree with him, but finding the actual problem is difficult for me.
Anyone have any suggestions?



I have recently replaced the high tension leads, distributor cap & rotor -
could this be a contributing factor?



Regards,

Anton
Click to expand...


If the engine wiring harness has not been replaced it needs to be, these
always rot out and fail. I've never even heard of a 240 ECU failing,
that part is probably the most reliable component in the whole system.
 
My 1986 Volvo 240GL has suddenly started fouling the plugs in a very short
time. I have brought it to the local mechanic, discovered it was getting
too much fuel and has replaced the fuel injection ECU, however it hasn't
solved the problem. He indicated the sensors were OK and I don't like to
disagree with him, but finding the actual problem is difficult for me.
Anyone have any suggestions?



I have recently replaced the high tension leads, distributor cap & rotor -
could this be a contributing factor?



Regards,

Anton
Click to expand...
Check the vacuum hose from the fuel pressure regulator to the intake
manifold. If the diaphragm is ruptured or cracked, raw fuel is admitted
to the manifold and will ful the plugs in short order.

Bob
 
The car worked fine then suddenly started fouling plugs. The car worked
fine on the local fuel before, I think its in the injection system where
something (and it is driving me and the mechanic crazy trying to find out
exactly what!) isn't working and it defaults to a 'get home' mode. I've
used injector cleaner, use a quality oil withut going overboard and don't
scrimp on the routine maintenance/repairs. This happened suddenly, even tho
it took a bit to discover the plugs were actually fouling regularly - all
that needs to work out is why!

Thanks for the advice, if I find out what the problem was I'll certainly
post it on this group.
 
Anton said:
My 1986 Volvo 240GL has suddenly started fouling the plugs in a very short
time. I have brought it to the local mechanic, discovered it was getting
too much fuel and has replaced the fuel injection ECU, however it hasn't
solved the problem. He indicated the sensors were OK and I don't like to
disagree with him, but finding the actual problem is difficult for me.
Anyone have any suggestions?



I have recently replaced the high tension leads, distributor cap & rotor -
could this be a contributing factor?



Regards,

Anton
Click to expand...

In addition to the pressure regulator, you could also check the mass
air flow sensor.

It sounds as though your mechanic is replacing expensive parts and not
really diagnosing the problem. Try to avoid the temptation to start
pulling and replacing parts on your own as the suggestions roll in on
this forum. If there is not an obvious problem with the pressure
regulator you should consider switching to a mechanic who is familiar
with Volvo cars.
 
Anton said:
The car worked fine then suddenly started fouling plugs. The car worked
fine on the local fuel before, I think its in the injection system where
something (and it is driving me and the mechanic crazy trying to find out
exactly what!) isn't working and it defaults to a 'get home' mode. I've
used injector cleaner, use a quality oil withut going overboard and don't
scrimp on the routine maintenance/repairs. This happened suddenly, even tho
it took a bit to discover the plugs were actually fouling regularly - all
that needs to work out is why!
Click to expand...



I would bet money the problem is the engine wiring harness, these
*always* fail on Volvos made during this time period, if it has not been
replaced already with the upgraded harness I can assure you it is bad.
Look at it closly for insulation crumbling off the wires, if you see any
of that, it is deteriorating badly within the outer sheathing and it
will only get worse. Dave Barton sells replacement harnesses or you can
do what I did and rebuild the original. Fortunately replacement is quite
easy, hardest part is working with the crusty hardened original.
 
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