Please help me Diagnose my MFI problem

Eric P · 07-30-2006, 02:59 PM

Okay, here is the setup:

'71 2.2 E with MFI

ALL linkages and stacks were rebuilt a couple years ago by Eurometrix.

Pump seems fine.

This is a race car and I have headers. I've removed the cold start enrichment thingy and replaced with a knob designed to go there. The knob can be screwed out (rich) for cold starts and turned back in once warm (pretty quick).

I believe timing, wires, etc. is all correct.

The car starts fine cold (with the knob above) and runs tremendously low and high RPM. No complaints there.

The Issue: Once it is to operating temp, or even hot (on track) and I shut it off, after 5 minutes or so when I go to start it, it doesn't want to. It'll kick ONCE right away and then just crank and crank. Now, if I shoot one shot of starting fluid in there, it fires up and runs fine. A FEW times I've turned the knob out and had some success (which shouldn't be the case since the engine is essentially warm) but that often fails.

Any ideas?

Grady Clay · 07-30-2006, 03:29 PM

Eric,

That is probably leaking nozzles and probably way more than one. I would take the six nozzles (and any spares) to someone with the Bosch nozzle tester and evaluate for leakage, opening pressure (if they don’t leak too much) and spray pattern.

What is happening is you come in with the heads hot. The heat boils the fuel in the nozzle and adjacent pipe and leaks into the intake runner. When you go to start, the MFI pump has to refill the pipe and nozzle one little bit at a time. Cranks forever. If you have a ’69 governor cover, you can wire the cold start MFI pump solenoid and give it a full rich pulse to fill the nozzles.

You will also find a running improvement with good nozzles.

Best,
Grady

Jandrews · 07-30-2006, 04:00 PM

Grady,

When you refer to "nozzles" here, are you referring to the fuel injectors or are you talking about the cold start enrichment nozzles? I assume you are talking about the fuel injectors since you mention spray pattern and opening pressure.

Just curious...

Thanks,

JA

Grady Clay · 07-30-2006, 05:03 PM

John,

Yes, the high pressure fuel injection nozzles.

Best,
Grady

Eric P · 07-30-2006, 05:08 PM

Grady,

Excellent! Thanks!!

If it is the nozzles, am I stuck buying them for $98 a pop or can they be reworked?

Grady Clay · 07-30-2006, 06:18 PM

Eric,

Since race cars tend to sit a lot, I would try cleaning before spending. The current car cleaning chemicals, soaking and an ultrasonic cleaner should do it if it can be done.

New nozzles are a real treet for a MFI engine. Everything works better.

For track events I have two aluminum baffels/containers just outboard of the intakes and nozzles. After each session I bump 1/2 bag of ice cubes in each. It keeps the nozzles and pipes cold until the next session.

Best,
Grady