90 model 740GL auto, B230F w/220,000+ miles

Guys,
I've got a problem with the motor bogging down upon acceleration. If
you back off the pedal just a little it takes off sometimes and will run up
to speed and run normal until slowing for traffic. When pulling a hill it
lugs until it shifts in lower gear and then it usually takes off and will
get up to speed. If your climbing a real hill (very steep) it just slows to
a stop chugging all the while. I pulled the distributor and cleaned up the
cap as it had some oil in it and slightly filed the contacts, reassembled
and it did seem to help as I was able to drive 150 miles home but it's not
fixed by any means.
I would appreciate any and all help with diagnosing this problem.
Bruce

 

There are a few possibilities that spring to mind:
When was the timing belt last replaced? This sounds like what happens
if it hops a tooth, poor low rpm response and picks up dramatically
around 3500rpm. Spark plugs in need of replacement will also sometimes
behave this way.
Another possibility is that your loss of power is the knock sensor
backing off the timing. That could be caused by an overly lean mixture
(low fuel pressure from a clogged fuel filter or failing fuel pump).
Oddly enough you might also be running too rich of a mixture and at
partial throttle the oxygen sensor is leaning it out, and at full
throttle enrichment the engine is going far too rich.
Just as a general rule when diagnosing any problem, check all the
vacuum lines for cracks, being loose, or popping off

 

I had a bad fuel pressure regulator cause similar symptoms, found a
junkyard part for a few bucks and popped it in, been fine ever since.

 

Bill, I did check the vacuum lines first thing even before cleaning the
rotor cap and bug. I checked the mileage on this timing belt and it shows
about 50,000 on it. It sounds like it might be time for new plugs and a fuel
filter to start with. I'll let ya'll know what I find out after that and
I'll keep the fuel pressure regulator as the next step James. I do
appreciate this information and will get the parts tomorrow. Thanks
again,
Bruce

 

OK, Bill and James,,,
It would seem that one of the suggestions was infact the salution as
a quick drive around the block shows that the problem has been resolved. I
installed new plugs, air filter and the fuel filter. I'll drive it in to
work and let you know again how it does.
Thank you both very much, Bruce

 

Well, I spoke too soon as it ran just great/normal for about 40 to 50
miles then it began sputtering again and I didn't think I was going to get
back home this evening. I stopped at an auto parts store and picked up a
small bottle of injector cleaner/water treatment stuff, put it in the full
tank and it took right off again. So far, so good! I guess they're not
getting enough for gasoline these days so they're adding water? Anyway, it
does seem to be doing much better now.
Thanks again for your information, Bruce

 

This has the Bosch fuel system with an air mass meter right? Sometimes
the AMM fails intermittent at first, also could be oxidized contacts on
the connector.

 

No it's the Regina System James

 

I did try an new (used) fuel pressure regulator this morning from a local
salvage because this thing is still crapping out on me everyone and a while.
It didn't help. I left it at the shop for a diagnostic to find the problem.
They said this afternoon that they wouldn't be able to look at it till
Monday. Anyway, that's my update on the continuing saga.
Bruce

 

Well the word is "Fuel Pump" is weak Ordered one this evening and will get
it installed a.s.a.p.
Bruce

 

Let us know what happens. Usually the pumps either work or they don't,
anything is possible though.

 

James,
I got the new fuel pump in last evening and drove it all around town
today. It didn't miss a beat. I guess the guys at my local independent Volvo
shop were right on wit their diagnostics. Week fuel pump. I'm just glad
she's back running good again! Thanks for the input it's always appreciated
very much.
Bruce

 

Well I spoke too soon on this new fuel pump installation. I had to pull
it again to re-soder one of the leads cause I didn't do the job right the
first time.
;? ( Bruce