first start advice: 72E MFI

[robmog]

coming to the end of my rebuild.
including sending out my MFI to gus for refurb.
refurbished my gas tank too, and all new fuel lines.
so any advice as to the first start?
i plan on disconnecting the fuel pump and removing the spark plugs then cranking to
circulate oil and check pressure.
i know that running the fuel pump dry is not a good thing, how do i prime it?
also how can you tell when the MFI is delivering gas to the cylinders?
after all the time and $$$ i don't want to see fireworks!
thanks.

[boba]

Once you have turned the motor over by hand to ensure there is no mech interference and that the valves are moving properly. There is a story there.

You can crank a few times to get the oil moving and get some pressure.

When you are ready you should use the normal MFI starting sequence.

1 Lift the hand throttle
2 Turn the key and listen for the fuel pump let run 10-15 sec
3 Turn to start and let the engine crank for 10-15 sec
4 If it does not start re do steps 2 and 3.
5 You can tip into the foot feed just a bit at the end of the 15 sec of cranking but do not hold starter too long and do not pump the foot feed.
It should start just with the hand throttle.

Good luck with your new motor.

[Tyson Schmidt]

It will take a lot of cranking to prime the MFI pump. Have a battery charger ready.

In the past I've used an electric drill and a spare belt to prime the pump. Then reinstall the belt and time it properly, and it should fire right off.

If you turn the key on and let the supply pump fill the MFI pump, it won't be dry running at all.

[robmog]

thanks guys.
my main concern is running the fuel pump dry.
maybe a vacuum brake bleeder would be helpful?

[dtw]

Fuel pump has fuel more or less at the ready via gravity. Don't sweat it.

thanks guys.

my main concern is running the fuel pump dry.

maybe a vacuum brake bleeder would be helpful?

[power]

I usually run the fuel pump for a little while and look for fuel leaks first. I keep a fire extinguisher handy as well.

[Tyson Schmidt]

Originally Posted by robmog

thanks guys.
my main concern is running the fuel pump dry.
maybe a vacuum brake bleeder would be helpful?

When would it be dry? As soon as you turn the key on, the fuel supply pump fills the chamber in the MFI pump. They only thing dry would be the lines and injectors until they bleed out.

If you are worried about oil, you can fill some into the MFI pump through the drain back tube with an appropriately sized hose connected to the outlet nipple.

[robmog]

Thanks all, good advice,makes sense.

[Grady Clay]

All good points above.
As Tyson notes, YES – fill the MFI pump with oil and turn it over by hand. Let it drain out the return to retain proper oil level in the pump.
This is a critical part of the Factory procedure.

Get fresh fuel with as high octane as available. 100+ if you can (114 octane race gas works well).
The reason is that a fresh engine has oil in the cylinders (and the ring seal is new).
This oil reduces the octane rating of the mixture.
Detonation is not what you want with fresh everything (or any time).


It is simple to prime the pump, lines and nozzles just prior to installing the engine in the car.
Tyson’s method works well.
Use the car’s fuel system with a pair of extra long fuel lines between the fuel filter console and MFI pump.
Be EXCEEDINGLY careful with gasoline and vapors.


I’m assuming you still have the rear-mounted electric fuel pump.
When you first turn it on, have the car level or nose-up so the dry pump is gravity fed.
You can test circulate fuel without the engine by connecting together the two hoses from the filter console.
Check for any (I mean ANY) fuel seepage.


Make sure the distributor is timed correctly.
This is the most common reason for frustrating ‘first starts’.
The usual problems are non-firing ignition, 180º out of timing and mis-wired firing order.
Make sure the ignition system functions while cranking for oil pressure (fuel system deactivated).


Check throttle actuation from the cockpit.
Now is not the time for a ‘stuck-open’ throttle.


For your ‘first start’, use the cold start enrichment.
Temporarily wire manual actuation with a long wire to the cockpit or outside.
Do not use ‘ether’ starting fluid (it has octane rating of about 10).
Using a squirt bottle of gasoline is very, very dangerous.

Do your ‘first start’ outside, away from your garage.
Don’t ‘hurry’ the process – think things through.
Have a knowledgeable helper standing by upwind with a LARGE CO2 fire extinguisher.
Discuss what to do.
Start the engine without the air filter assembly in place (you can have a fire inside and not know it until the plastic melts).
Blasting with the CO2 will very effectively ‘turn off’ a running engine without damage.



Your caution is well placed.
The ‘first start’ usually happen perfectly.
It is the chance of the other outcome is the concern.
Careful preparation prevents problems.

Your first observations are: no fire, no fuel leak, good oil pressure, no big oil leaks and (finally) running on all six cylinders.

Enjoy the moment (and post a video).

Best,
Grady

[Rot 911]

All good advice. I remember when I first started up my 72E after the engine re-install. It took forever for the fuel lines to fill and get up to pressure before the car finally started.

[dtw]

Grady is stressing the fuel safety, and he is right on. I have had fittings and hoses spring leaks when setting up for the first time. One particularly exciting time, a leak sprayed fuel right onto the live CDI box. Good times! This is when you will want a helper and a fire extinguisher. Other thoughts in no particular order:

There's not really any need to pull your spark plugs to build oil pressure. The engine will build enough pressure to 'bump' the needle within 10 seconds - you will be cranking longer than that to push fuel out to the injectors.

If I am having trouble with a no-start on a fresh MFI install, and/or I am not sure I am getting fuel delivered, there is a trick to try out. Again, a spotter and fire extinguisher are needed. Crack the fitting slightly loose between an injection line and the injector on that line. Have your helper crank the engine while you watch the line - fuel should leak out between the fitting and the injector if all is well. I have actually seen injection hardlines that wouldn't flow fuel due to internal gumming/corrosion/general crud.

Other things to check - make sure that you do a really good, thorough job correlating the injection system. These engines really don't like to start when the correlation is off. Use the factory CMA booklet and the Lee Rice guides, and you will be fine. Also, use the factory documentation on timing the MFI pump pulley to the crank.

Use all your senses when working that first start. Like was mentioned, have the air cleaner assembly taken off and set aside - it makes it easier to see/inspect/work.
-Touch various fittings and fuel lines for wetness
-Look at cloth braided fuel lines to get darker - that means they are soaking in fuel
-Smell for strong/increasing fuel smells
-Are the MFI pump fuel/return lines secured, so that they are not rubbing in the pump pulley and belt?
-Listen for strange noises/leaks etc.

[dhamilto]

Thought I would add to this old thread instead of starting a new one on the same thing....

I'm just going through some of the startup procedures mentioned here and in other similar threads before starting my engine for the first time in maybe 5 years, since removing the fuel tank for front end panel replacement.... 1973 2.4T USA engine and MFI was set up and running good before this...

So, who things this old bugger will start on one battery charge?

So far, I have:

- cleaned out the new tank as per manuf instructions + cleaned the fuel outlet gauze.
- pulled the plugs (all black and wet, and one had a bad gap but maybe it was boinked on the way out)
- engine turned freely by hand
- bore-scoped the pistons through the spark holes (out of curiosity since I was using the camera anyway, and through paranoia because I once found some pieces of a plastic intake inside on another engine) - all look good. Found a copper plug washer and the rubber insert from inside of my 21mm spark plug socket down the plug holes- wondered where that rubber insert had gone and why one plug just kept turning and turning!!
- did the Biro test on the MFI pump - rack moved freely and returned great

Next steps are:
- disconnect the MFI inj. pump fuel feed and place the hose in a clean glass bottle
- put 5 litres of 99 RON gas in the new tank, operate the fuel pump and dump gas into the bottle (hopefully!)
- reconnect the inj. pump fuel feed and put the fuel back in the tank, operate the pump again to prime/fill the pump with gas.

HAVING TROUBLE with 2 things at the moment:
I want to pull the 3-pin CDI connector before cranking for the first couple of times to build oil pressure (hopefully!)...
- however, the connector will not budge - is there an alternative way to disable the spark, without removing the 3-pin connector? e.g. removing the ground terminal or the coil HT lead? BTW. many thanks to the Porsche engineer that decided to put one of the bolts for the CDI panel right behind the 3-pin connector!!
I want to fill the MFI pump with oil... it appears that the traditional way to do this is to fill it through the oil return that connects to the breather. However, the rubber hose section (see attached pic) doesn't want to budge either, but I am thinking of 'cutting' it off and replacing it with new hose.
- has anyone tried to get a new joining hose section on with the pump and breather in place? I am a bit worried that its going to be a royal PITA and cutting the old one up ight be a mistake.

Following on from that, I am taking some advice from Grady Clay et. al's suggestions in this post and this other one primarily:
Motor break in with MFI
- I noticed some differences, or alternative procedures, in Grady's suggestions for enabling/disabling CDI and fuel pump. I am going with fuel pump off and CDI off for initial cranking but then fuel pump on with injection pipes cracked to release air:

Does the following procedure look good to you guys that know this stuff?
- crank the engine and check for oil pressure build up with fuel pump off (but injection pump primed with fuel first) and CDI off (or alternative way to turn off the sparks).
- loosen the injector connections at the injectors, one at a time to the expel air (faster) and crank again with fuel pump on. I'll be soaking up the fuel with paper towels or funnelling it into a jar if possible...
- reconnect everything and try to start the engine.

I'll keep you posted - any suggestions or advice warmly welcomed

[dhamilto]

Quick update....

Ran the MFI fuel pump with the injection pump feed disconnected and into a wine bottle. Started to feed the bottle after 5 seconds or so and the flow was good. Reconnected the hose to the injection pump and ran it again for a few minutes and checked for leaks.

Fuel pump sounds good and runs cool to touch.

CDI sings like a bird !! Still looking for suggestions on how to disconnect it though so I can crank it without starting...

[frosty2]

You could likely just remove your coil wire and eliminate the spark to plugs. Just make sure to pry on the cap and not pull on the wire we don’t want to pull the wire apart.

[dhamilto]

Originally Posted by frosty2

You could likely just remove your coil wire and eliminate the spark to plugs. Just make sure to pry on the cap and not pull on the wire we don’t want to pull the wire apart.

Thanks for your suggestion. I was just reading the CDS section of the Haynes manual. It suggests that there needs to be a current path to avoid the coil arcing internally. Fortunately it does suggest how to do it - support the distributor end of the HT wire close to a ground to allow it to arc across Sounds like a plan...!

[Jeff Higgins]

This is going to sound really "cave man", but at the risk of inviting ridicule (I'm actually pretty good at that....), here goes:

When I put a new motor in, I take advantage of a few what I would call "complementing" situations.

As you have noted, there is going to be air in the lines from the MFI pump to the injectors. The engine won't start until there is fuel in the cylinders, and it isn't going to come from those injectors. Not yet anyway. Which is a good thing...

To get fuel in there, it needs to be primed via the priming ports fed from the fuel filter console via the bypass solenoid, either by letting the thermo-time switch do its job, or by pressing the switch you have wired to the bypass solenoid on the fuel filter console. But you don't want fuel yet, so don't prime it yet.

So, well, what if you don't prime it? It will crank for an awfully long time without starting because it is not getting fuel from anywhere - not the injectors, and not the priming ports. Long enough to, say, build oil pressure... So - just disconnect the lead to the bypass solenoid (assuming it still has the thermal-time switch) or just don't hit your priming button. Then crank away until oil pressure builds - it won't take long. And it sure as hell isn't going to start. Once it shows oil pressure, then prime it.

It will start and die on the priming charge a few times until it blows all of the air out of the injector lines. It will start to fire off of the fuel provided by the injectors (rather than the priming charge) in very short order. It will sound like an old airplane engine as it starts firing on more and more cylinders, then it will smooth up and run on all six.

In other words, take advantage of these "conditions". No need to disconnect the coil - there is nothing in there to light - spark away! No need to bleed the injector lines - they will do that very quickly on their own, running on the priming charge. Let all of this work to your advantage. YOU have control over when the fuel gets there - just don't introduce it until it has oil pressure and you actually want it to start.

[tobluforu]

If I do remember correctly, isn't' there a bleed screw on top of the mfi filter console? But since there is a return line to the tank, that pretty much bleeds the system for you. Granted, it's a long run. This is also the reason why you hear bubbles in the tank when you turn the key to the on position after its been sitting for a while.

[Jeff Higgins]

Originally Posted by tobluforu

If I do remember correctly, isn't' there a bleed screw on top of the mfi filter console? But since there is a return line to the tank, that pretty much bleeds the system for you. Granted, it's a long run. This is also the reason why you hear bubbles in the tank when you turn the key to the on position after its been sitting for a while.

Entirely different issue. The recirculating fuel supply from the gas tank to the MFI pump does not have to be bled - it's kind of an open system, really. No real way to trap air - everything just gets pumped on through back to the tank. We were discussing the high pressure lines from the MFI pump to the injectors, which are kind of a closed system that can trap some air. Some folks will tell you that, because of this, it needs to be bled, one high pressure line at a time. I've not found that to be the case, at least in my experience.

[dhamilto]

Thanks all, and especially to Jeff for such a pointed reply.

Before I saw the reply, I cranked the engine with the cold start solenoid disconnected and HT lead disconnected at the distributor end and supported 1/4" from the engine. I could hear it arcing as it cranked. The cold start solenoid definitely works (feeds gas) - dont ask me how I know and if it is anything to do with the hose that got in my way and was disconnected

The oil pressure only went up to about 40 PSI - does that sound OK?

If I understand correctly what Jeff wrote (I have not rigged up a bypass switch at the moment), I think I just need to reconnect the cold start solenoid (I think you are calling this the bypass valve - I assuming it is the same thing?), put the spark plugs back, and go for it ???? I think I could also just leave the cold start solenoid wire disconnected and just keep cranking until it starts and runs solely on the injectors???

I would go and do that now if I could find my feeler gauges and could re-gap the plug that got boinked and check the others.... expecting new gauges 2moro.

As a slight aside, this engine always smokes ridiculous amounts for a seemingly infinite amount of time whenever I start this engine in my garage and this seems to choke it and eventually kill the engine. Unfortunately, this time around it is reversed into my garage and I cannot take it out at the moment and turn it around to face the outside..... the neighbours will no doubt be really concerned when they see the smoke coming out of my garage Perhaps a couple of fans to blow the smoke out...

[Jeff Higgins]

40 psi is absolutely fine. If it's going that high just cranking over on the starter motor, you're golden.

Yes, the "bypass" and "cold start" solenoids are one and the same. It's the one sticking up on top of the fuel filter console.

The car probably will not start unless you hook it (the bypass / cold start solenoid) back up. Especially if there is air in the high pressure lines to the injectors. So, reconnect the lead to the solenoid and reconnect the coil lead and start cranking. Now that you have primed the oiling system already, it will build oil pressure before it actually fires up. And, again, expect it to die repeatedly as it burns off the priming charge delivered by the bypass / cold start solenoid - it will take awhile to clear the air from the high pressure lines and fill them with gas.