1989 740GL throttle body

Difficulty starting, especially in the cold. Replaced plugs, wires,
cap and rotor, but still have issues. When car does start, it will
run rough for the first 4 or 5 minutes, then will run fine. Tried
starting this AM, car sputtered for a couple seconds and died . I
pulled the plugs, and they were wet (gas). They also had a carbon
build up on them. I cleaned the plugs and tried again. Car almost
started, but it didn't quite catch.

Researching the group, sounds like the throttle body needs a cleaning
along with the flame trap. Should I look at anything else while I'm
in there? Thanks in advance, pretty sure I wouldn't have 199k miles
without this group!

John

 

Yes - under the throttle body is the small cylindrical Idle Air Control
Valve. That also gets its share of glop. Between the throttle body and the
IACV you can expect to go through a pint or so of carburetor cleaner
spray... no kidding!

The throttle body is best cleaned by removing it so you can "shoot" through
it, but it can be cleaned on the car. Pay special attention to the small
passage on the lower part of the TB that connects each side of the throttle
area to the knurled idle adjustment screw at the bottom. I prefer to count
the number of turns and 1/4 turns the screw is open, then remove the screw
for cleaning the passages. Squirt lots of cleaner through there, then
reinstall the screw as far open as it was. BTW, the idle speed is actually
set by the ECU, so the screw merely adjusts the range of the IACV operation.

Be careful with the hoses on the IACV. If they have hardened they can be
brittle.

Mike

 

Thanks Michael. I'm betting the hoses will need to be replaced. Is
the retro-fit for the flame trap the way to go?

 

The flame trap can be cleaned, but most people prefer to replace or remove
the screen altogether.

Mike

 

I think it's worth it, the kit was only ~$25 last time I bought one and
it makes servicing the all-important flame trap so much easier. I have
no idea why Volvo chose to hide such a critical but otherwise simple to
deal with part so well.

 

Thanks James, have a nice Easter. You too Mike-

 

Well, I spent the beter part of Saturday cleaning the throttle body
and IACV. Also replaced the flame trap. On the first try, the car
ran rough for 5 seconds, peaking at 1000 RPM, and died. Tried to
restart, but it wouldn't catch. Pulled the plugs, they were gassy.
Dried and replaced. Car did the same thing. I'll continue to
research the newsgroup to see what else I should look at. Thanks
again for your help-

John
1989 740GL
199,902 miles

 

How's the wiring harness? '89 may be updated or it may have the
crumbling engine wiring.

 

I was hoping the wiring harness wasn't the issue, guess that's the
next step. And so close to 200,000 miles...Only scrap yard with a
Volvo in my area does the pulling for you. $150 still a good price?
Thanks again for the reply.

 

I dunno, the harness is only $15 around here, but you have to pull it
yourself. Might check and see what Dave Barton has, he sells good
harnesses but they're in the $150-$250 range IIRC.

You'll want to check your harness first though, the one you have might
be fine, '89 is the transition year.

 

Since you have no other suspect, run a test to rule out a failing fuel
pressure regulator.

http://brickboard.com/FAQ/700-900/FuelSystem.htm#Fuel_Pressure_Regulator

 

So after all the cleaning and non starts, I went out of town for a
couple weeks. When I got home this weekend, guess what started right
up. Idles very high, ~2300, but I found a couple other posts in the
group explaining the fix after cleaning the throttle body,trap,etc.

I can't thank you guys enough for all the help!! Now on to the 200k
medallion. Thanks again-