highboy

my '88 951 is becoming hard to start in the mornings (cranks awhile before starting) and after sitting a few hours! In addition, she seams to be running not as smooth as she should at highway speeds. To give you a run down of the work done in the recent past:

new water pump,
timing belt,
balance belt,
thermostat,
plugs,
wires,
cap,
rotor,
coil,
fuel pressure reg,
fuel dampner,
fuel filter,
oil/filter change, etc...

OK - what do I need to look into? the always starts but not like it should - if you crank it over for a few - stop - then try it again, she'll fire right-up on the first to second crank! Fuel pump? clogged filter? bad regulator? vacuum leak?

Would the O2 sensor or AFM have anything to do with this? I have a new O2 sensor to install - failed emission test (old post) - and I have a complete vacuum replacment kit from Lindsey to install!

thanks for the help - gotta nip this in the butt, before she get's any worse!

Charlotte944

Could be either one or more injectors leaking by, or the fuel pump check valve is leaking.

The best way to test this is to depressurize the fuel rail, put a pressure gage on the fuel rail, start the engine, shut the engine down, and then watch the fuel pressure.

hosrom_951

Fuel Pump check valve or Fuel Pressure Regulator.

This could help:

http://www.clarks-garage.com/shop-manual/eng-15.htm

hosrom_951

Sorrym just noticed the FPR and FPD were replaced, looking at the check valve.

highboy

thanks - will do! - this board ROCKs!

mikec944

i've got that problem too. it's the check valve on mine. Just haven't changed it yet. i've been dealing with it for years and just figured it out a couple months ago...probably won't ever change it at this rate.

highboy

OK - got the starting problem fixed - cracked rubber fuel line (b/w filter and hard line) - and as an added bonus - I replaced the fuel pump check valve! I think I hate working on fuel systems as much as cooling systems - getting all wet with either fuel OR antifreeze - SUCKs!!