MFI hard to start

[zentoad]

I am having some trouble with a 2.7 MFI starting issue. The car has recently become hard to start:
starter spins... no fire
starter spins... fires for a second... dies
starter spins... fires for 2 seconds... dies
etc. until car will stay running with lively action on the throttle...
once warmed up and running, it runs fine

here is what I have done so far:

Tested fuel pressure

"unregulated" fuel pressure...first... spike to 60psi drop to 30psi (regulator in electric pump)
second... spike to 50psi drop to 40psi
third... no spike...40psi

fuel pump output... @1000cc's in 30 seconds

"regulated" fuel pressure... first... pressure spiked @ 12psi then dropped to 5psi (key on only)
second... pressure spiked @14psi then dropped to 6psi (key on only)
third time... no pressure spike, settled @5-6psi (key on only)
fourth time... pressure 5psi (key on only)
started car... pressure dropped to @2-3psi
when car finally started pressure was @ 4psi

I replaced the "overflow valve" at the filter housing (used)... pressure now is 11psi
within spec... 11.8 +/-3 psi

no real change in starting issues...

So I am planning on moving on to checking the ignition system, then to proceed with "check, measure' adjust"

Any suggestions, thanks in advance for any help.

Tony

[rsscotty]

Check the cold start valve for power when cranking cold. It is on top of the fuel filter console.

[tobluforu]

Originally Posted by rsscotty

Check the cold start valve for power when cranking cold. It is on top of the fuel filter console.

And make sure the middle fuse on the block has not blown out, or is getting power. Simple things first, but you have probably checked this.

[zentoad]

Thanks guys, I will look into this.... I was under the impression that the cold start only worked at a ridiculously cold temp., 17degreesF, or something like that, and therefore ignored the cold start system.

[Rot 911]

Originally Posted by zentoad

Thanks guys, I will look into this.... I was under the impression that the cold start only worked at a ridiculously cold temp., 17degreesF, or something like that, and therefore ignored the cold start system.

Incorrect. It starts to come into play even when temperatures are in the 60's! I also agree with the other posters, your symptoms definitely indicate a problem with the cold start system.

[tobluforu]

The wiring to the fuse block on my 72 was all messed up years ago and this caused horrible starting, especially when the car was warm and sat for a while after driving. Fixed the wiring at the block and it started like a champ, hot or cold.

[zentoad]

Just verified that cold start solenoid is flowing fuel while cranking.... but, I don't know that it was previously. It seems that the first time I tested for voltage at the fuse... I had voltage on #1 but not #2. I may have fuse or fuse block issues. I will see what happens in the morning once the car is "cold" again. Thanks for correcting my understanding of the siystem, at the very least. I will see if this was indeed the cause of my difficulties.

[zentoad]

Thanks for the assist. Sure sounded like a "cold start" problem, but, i was operating under mistaken info and looking in the wrong direction. Turned out to be oxidation at the fuse causing poor connection.

Interesting though, how replacing the "overflow valve" and it's resulting fuel pressure change from 4PSI to 11PSI made very little change in.... anything. I guess it really is the volume/quantity of fuel from the electric pump that is important... more than the pressure.