Yet another 88 240 wont start (sometimes)

This is a great forum and Ive been reading for tips and tricks, your
opinions will be appreciated. Ive Googled this list for hours and see
similiar problems, but not this specific one.

1988 240 GL USA model. About 2 months ago, wont start - cranks good
but wont turn over. Tow to the Volvo independent and left overnight.
He goes out and it starts, no problem, repeated starts all day. Says
spark OK and voltage to main fuel pump OK. We go to pick it up - wont
start. He keeps it and the next day same situation, cant make it
fail.
We figure it is 90% probably main fuel pump so I ask him to change it.
Also FP relay. No problem since that time.

Then yesterday, wont start. Tow to the general repair shop, left
overnight. Today, he finds lots of spark, lots of fuel to the
injector. Pulls plugs - they are fouled, empties something (I forget)
lots of additional fuel. He also reattached tiny vaccuum hose that
goes from firewall to top of intake manifold (?) Starts OK for him.
We go to pick it up - wont start (!) Bring the mechanic out - he gets
in and cranks for 10 seconds - it starts. No problems since, but you
can understand our concern for reliability.

Some misc information: Changed rotor cap and plugs 3 months ago. Gas
was very low yesterday, added 1.5 gallons but still not able to
start. Filled the tank after leaving the shop today. Yesterday, I
could hear the relay click, but not the whirring of fuel pumps? Am I
just not listening at the right time / place? Once started, the thing
runs great, no dips in RPM or stalling.

Ideas? AMM? Tank fuel pump? Sensors?

I'll be bringing it back to the independent this week, but in the
meantime am looking for ideas. Sorry for the long post, I didnt have
time to write a short one.

Don O in ATL

 

I'm starting to sound like a broken record here but check the engine
wiring harness, '88 is right on the edge, it may have the updated
insulation that doesn't rot, or it may have the old stuff which is
cumbling to bits within the outer plastic sheath.

 

wonder if hes parking the car up hill or down hill allowing the fuel to
flow in spite of a faulty in tank pump.is you gear shift ok as the
contacts maybe out of alignment stopping the car from starting good
luck .OOOH AND CHECK THE FUEL RELAY THAT CAUGHT ME OUT ONCE THEY DIDNT
SOLDER THE CONTACTS VERY WELL ON THE RELAY.

 

All - I forgot to follow up on this and also to thank those that
responded. James Sweet suggested checking the wiring harness and I
did - all in very good shape. But I dug in and cleaned and ensured
all connections were solid. On the wheel well behind the battery
there was 18+ years of gunk etc. When clearing this out I noticed
that a couple of wires in the area of the ignition modules had worn
insulation so I taped them up - no issues at all in the past 6 weeks.

So thanks again, and happy motoring!

Don O. in ATL

 

Glad you got it going. Were the wires worn by something or is the
insulation crumbling off? If it's crumbling, you have further hidden
damage that will come back to bite you later.

 

The insulation was good, just looked like something had rubbed or
scraped through. But of course, since I cleaned and tightened dozens
of connections in and around the engine compartment, I may have fixed
multiple things - I hate when that happens :-O

D