hard cold start

[robmog]

[ATTACH=CONFIG]215019[/ATTACH
finished my complete rebuild last year: 72 e mfi.
the car is really hard to get started after sitting, even 24h.
cd works fine, i tested it.
fuel pump works fine, it has a minor leak (is there such a thing?!) probably due to the o ring.
i plan to replace.
mfi rebuilt by pacific, injectors tested and cleaned.
i literally have to turn it over about 20 or more times.
timing is good, probably could be tweaked a bit.
i do try to energize the cold start solenoid, that doesn't seem to help starting.
should i disconnect the 4mm tubing and energize to check flow?
once running, a few backfires at start that stop once warm.
once warm maybe a little blackness (subtle) to the exhaust, too rich?
but i haven't hooked up all the paper hoses yet to the mfi.
once warm, starts right up.
once warm, it screams! (in a good way).
any ideas?

[RSTarga]

Are you engaging your hand throttle?
Is your cold start valve working?
Are you sure your dwell and timing are ok?
Is the retard hose on your distributor working properly?
You need the hose from exhaust to MFI for it to lean out as it warms up.

[robmog]

hand throttle on.
timing good dwell pending.
i figured about the hose.
cold start isn't doing anything, i sighted down the throttle body and energized it and saw no flow.
i disconnected the 4 mm hose no fuel inside.
next i'll pull the solenoid and see if it works, it did before..
thanks.

[sithot]

Didn't Henry at Supertec do a hand switch for cold start? The ST Rally car that I got to start a few times had one behind the seats in the middle of the tunnel (shifter coupling cover). You primed the engine and then fired it off. Worked really well.
Everything David says is spot on the money.

Good luck!

Tom

[MountainRoads]

These MFI engines can be a beast to get started without the cold-start enrichment working. Trust me, I know. There are tricks one can employ with flooring the gas pedal and then letting off while cranking etc., but it's hard to beat the stock setup unless you want to install one of the aftermarket kits, as Tom describes.

Some might object to the stock enrichment setup due to increased potential for an engine fire. It's a legit concern, but can be MOSTLY alleviated by switching to metal air horns, if that's an option on a '72.

- MR

accelerator

[classic]

No idea, but wow Rob great job on the engine!

[cmcfaul]

X3 on the cold start valve. Without it, it will take 15-20 seconds of cranking. Take the valve off the top of the fuel filter and make sure it moves. Then add a switch that runs off the starter to engage it. The switch will enable you to turn it off when the car is hot and does not need the cold start valve.

Should be an easy fix. It should fire right up once the cold start valve issue is resolved. Worse case, buy a new cold start valve.

Just had another thought. It's real easy to get the fuel lines to and from the fuel filter reversed, its counter intuitive. Check to make sure the are correct because that will cause all kinds of strage problems.

Chris

73 911 E

[RSTarga]

Normally cold starts are easy, if your getting fuel enrichment. Hot starts are usually trickier due to the crappy fuel we have these days. Dwell is normally done first before setting timing as moving the dwell alters timing. I normally set the points at the widest permissible gap as they close up with wear on the rubbing block. If your points are too closed starting can be a problem but it would occur in both cold and hot starts.
Chris is spot on it is easy to get your lines crossed.

[robmog]

i disassembled the cold start valve, the solenoid was stuck.
got a little lacquer thinner in there and it loosened up.
it is now working.
pretty sure the lines are correct, lt runs great once started.
in the process of trying to ascertain fuel flow, i removed the entire valve and turned on the ignition.
i was rewarded with a copious fountain of fuel out the top of the accumulator.
sure glad i disconnected the CD box.
i reinstalled the valve and with ignition on the solenoid is energized as per voltmeter(my error actually not).
a very slow drip of gas is coming out.
at this rate it would take a half hour to fill the lines.
how much flow should be coming through?
is there a way to adjust flow?
thanks for the replies, i'm on the right path for sure.
bob

[robmog]

the AHA moment.
i did a little research on the bird site.
i learned the cold start solenoid is powered by the starter circuit.
i had rigged a temp starter bypass so i could start from the engine compartment since i was having so much trouble.
so i had also excluded the cold start circuit.
originally the solenoid was frozen which started my troubles.
now with an unfrozen solenoid, and the starter connected, the ignition switch powers the solenoid and i saw good flow into the stacks.
too much fuel vapors everywhere to try to start tonight, i'm letting it air out overnight.
i bet tomorrow it'll start up.
thanks to all.