s52 long cranking

[crazyvwobie]

Need some ideas 91 318is s52 with obd1 Randomly cranks long and takes 2 or 3 tries cold or hot.Some days starts 1st try.Fuel pump is original with 120000,new spark plugs,and hfm.Car shows no other symptoms runs great no hesitations and idle is steady.I found lots of threads on this but no one ever seems to post their results.I do have a fuel pressure gauge and that seems fine when running except when It wont start the pressure is low and jumpy until it fires,so im certain its a fueling issue. Im leaning toward crank sensor and maybe fuel pump?

leaning toward crank sensor fuel pump consistantly builds full pressure when I jump the relay

[EduardoGomez]

Install fuel check valve after the pump on the high side, part number 16 14 9 068 988,

I did that and it helped a lot

[bimmerteck]

Try installing a check valve from a 750il They run less than $10 and often solve long crank issues related to fuel if the check valve built into the pump has failed. ;)

16-14-9-068-988


edit- What he said^ :)

[87e30]

Interesting, what about on early model cars?

Is it wise to replace the pump under the assumption that the check valve failing means that the pump will fail soon?

How big a role does the starter play in long starts?

[crazyvwobie]

going to try this check valve before I go any further.thanks

[nickmcc92]

Did you install the check valve? Results?

[Gooch]

Rather than post a new thread, anyone have any updates on this? I am experiencing almost the exact same symptoms as the OP. (Except I'm OBD-II and have a TRM fuel pump with less than 5k miles on it).