Not-so-cold starting problem

[WOODPIE]

Hello all,

I have had a problem (minor) with my '73 2.0 ever since I purchased it over a year ago, and after doing some valve adjusting and spark plug replacing recently, I thought I had it fixed. But, no.

When I completed the above said work, it was pretty warm here in Ga., with the nightime temps not falling below 65F, and when I would get in the car in the morning it would crank and fire right up, although usually on the second spin. Recently the weather has chilled to 45F overnight, and the degradation in starting ability is appalling. Seven to ten attempts are not uncommon. I have had the most success (it seems) by repeatedly turning the ignition switch on and off, letting the fuel pump to do its one or two second pump-up, and then immediately engaging the starter. When the engine starts, it coughs and spits only minorly, and settles into a good idle speed of about 1050 to 1100rpm. The first mile or two of running is a little sluggish, but then the engine runs very well. At the end of the day, with air temps at 75 to 85F the engine starts easily.

Why should this relatively small difference in temp have such a big effect on the engine?

This 2.0 is stock fuel injected, Mahle high comp. pistons, 440 web cam, decked for 9.7:1 comp ratio, lightened flywheel, Allison Crane ignition with Bosch coil.

I think I've read that the cold start injector valve should not come into play at the temps I'm talking about here. However, the starting becomes more and more difficult as the temps drop, and at below 32 is just about impossible to do before the battery gives up.

Does anyone have any ideas, suggestions, or similar experience?
I've got this three day weekend I can use to piddle with the car, except for a couple hours Sunday when I must watch the Indy.

Everyone have a pleasant and safe Memorial Day.

TIA

Ed

[Jim Smolka]

Could be a bunch of things.

1st, check the mechanicals.
2nd, points, plugs, compression etc.
3rd fuel pressure (make sure it is not bleeding off to quickly when the engine is stopped)
4th, the cold start valve should not be comming on at 45 degrees when starting
5th check the Aux Air Valve
6th Head temp sensor
7th add some Techtron fuel cleaner
8th Vacuum leaks

After all that, may be time to check the FI brain with the tester

[WOODPIE]

Thanks Jim!

I am bumping this thread up because I intend to follow Jim Smolka's checklist as well as I can, and will have questions along the way. Already have one.....

I bought a FLAPS fuel pressure tester, and while it is probably not the best quality, I hope it will suit my needs. I hooked it to the stub feeding the cold start valve, started the engine, purged the air out a couple times and got a reading of 28-32 psi. The range of this reading is so high because of the rapidly oscillating indicator needle. Maybe a better tester would be dampered better? Anyway, I am interpreting this reading to be acceptable.

I then turned off the engine and, even as I write this, am checking for pressure leak down. Question: What is an acceptable period of time to monitor the static fuel pressure to discover a leak or other problem? Right now, I am at about 30 minutes and the pressure is holding at 26 psi.

Thanks,

Ed

[RustyWa]

I am interested in how long pressure should hold also.

I just checked mine and running pressure was 34psi, ouch! I adjusted running pressure to 29psi. Needle was jumping all over the place but finally settled down. I don't have a way of purging the air out of my 7" hose, is that going to cause much of a problem?

Should the fuel pressure be checked with the engine off and the fuel pump jumpered so you don't get the fluctuations from the injectors firing or is it not that critical?

[RustyWa]

....bump on Woodpie's question above....

[Dave at Pelican Parts]

I think that if you're over 20 PSI at the end of a half-hour, you're fine.

Testing the fuel pressure can be done with the engine off or on. I'm not sure if my gauge is damped more than yours, but it tends to read pretty steady regardless of if the engine is running or not.

--DD

[WOODPIE]

Thanks Dave!

It was probably bone-headed of me to check fuel pressure with the engine running anyway. I should have jumpered off at the relay. But as I said, I am satisfied with what I could discern from the readings. And yeah, the holding the pressure thing....I can't imagine that the system would be able, or was even designed, to hold pressure for days on end. Thus the initial pump activation when you turn the key.

Things I have yet to do:

1. Check cyl compression
2. Check operation of Aux Air Valve
3. Check/ replace cyl head temp sensor
4. Add some Techtron fuel cleaner


I've got plugs, points (none), and valve clearance covered. I did find and plug a good sized vacuum leak in the intake air distributor. But it has been hotter than four hundred hells here in N. Ga. lately so I can't say if I've made any improvement. After a mile or two of warming up, it runs like a screaming banshee. For those of you not familiar with Irish folklore, that's a good thing!

Ed