MFI Problems on 72`

WesH · 03-01-2013, 05:23 PM

Update... reinstalled MSD Blaster II coil.. Loosened dist bolt... Moved a bit..... Car runs..... Congrats to all..... Had another beer......
Car is running on 5 cylinders..... Narrowed it down to No 4 cylinder... I'll post pics. Pulled stacks the noticed the throat is full of fuel. (Thought I stripped the butterfly valves. Car sat for years.. Took a while to break loose the linkage)
Question: does this mean the injector is bad? Does not appear to fire. ( see pics)
Wanted to post progress before I dive any deeper. I do know V8's inside and out but this car and mechanics is new.

Asking help from the 'Experts'

BTW, if your anywhere around Paris Mountain in SC... Beers and Steaks on me. (Or a good single malt scotch)
Thanks in advance...
Wes

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Should I pull the Injector? Soak for a while? There is a good thread on servicing the injectors I can try or send off for service. Not sure if the injector is the problem or not
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Thanks James... Yes MFI... 68 911 with a 72 engine... Barn find with 69000 MI....
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check the butterflies to make sure they all open at the same time with the throttle. If that one is stuck closed (hard to have one stuck) and the rest open, fuel will flow into the cylinder but no air. long shot but it is something to rule out. the valves are opening and closing when turning the engine over? another thing to check. MFI guys should chime in soon, change the title of this thread to MFI problems
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Butterfly valves are consistent. Will change... My thanks...

Porboynz · Porboynz's Garage

The MFI injector is in the head casting below the throttle body so fuel on top of the butterfly maybe means the cold start injector is working over well on that cylinder, maybe not the rest? Is the cold start fuel line and injectors set up correctly and working?

Simple enough to swap that MFI injector with another to see if the problem moves. If it is the injector then I would try soaking the injector in an ultrasonic cleaner. Otherwise find a diesel mechanic with a injector test setup. You probably want to unzip tie those plug wires to avoid cross fire issues, the rubber blocks between the stacks are the proper mounting. Those butterflys look dirty, try some carb cleaner then baseline the entire assembly making sure each butterfly closes against the screw stop just before it binds with the throttle body. Careful with those throttle stops, the casting breaks real easy. Then add the linkages and work your way back to the accelerator pedal. I usually start out with the air bleed screws 1.5 turns out then use a flow meter to balance each stack with the engine running. MFI is great once you get it setup.

WesH · 03-02-2013, 02:02 AM

I'll clean and swap injectors around today to see if the injector is bad.
Thanks

WesH · 03-02-2013, 12:10 PM

Update. Cleaned all, checked spark all around again. same problem, noticed that the no 6 cyl is blowing back. (out). Valve stuck possibly? Also going to check plug wires to dist. Hey, could happen as I dont have history.;

WesH · 03-02-2013, 12:13 PM

Update #2. Had to move the distributor all the way counter clockwise to set timing. Still need a bit to go but its all the way? Jumped time? Getting fun now....

WesH · 03-02-2013, 12:34 PM

Another dumb question... I have a Haynes manual and searched the forums to no avail. Where can I find the order (or diagram) of spark plug wires that attach to the dist cap?

Peterfrans · 03-02-2013, 01:29 PM

Quote:

Originally Posted by WesH

Another dumb question... I have a Haynes manual and searched the forums to no avail. Where can I find the order (or diagram) of spark plug wires that attach to the dist cap?

A quick google on 911 workshop manual will provide links to several pdf versions of these manuals, providing much more info than a haynes.

WesH · 03-02-2013, 01:58 PM

Ran motor for 30 min... Hoping to free valve if thats what it is... At least she ran after 8 or so years....still have no suction on # 6 but idles around 6-700. Any ideas to correct? stumped at this point. Really don't want to pull the motor.

James Brown · James Brown's Garage

can you check the compression in the cylinders?

WesH · 03-02-2013, 02:07 PM

I have a long flex hose. I need to buy a shorter one to thread into the holes. I will Monday. Tried to no avail. Can I put something like Seafoam into the plug hole and let sit for a while to free the valve?

WesH · 03-02-2013, 02:08 PM

If its a stuck valve that is...... Wont try anything until I get more info.... Grin....

WesH · 03-02-2013, 02:09 PM

Tried a little seafoam down the throat... Just spits it back at me...

James Brown · James Brown's Garage

i would also...

Porboynz · Porboynz's Garage

If its a stuck valve then pull the valve covers and have a look, could be all sorts of mischief going on with stuck rocker, frozen valve. Check gaps and try again.

Firing order 1-6-2-4-3-5.

Check this link as well: Timing a 2.4 MFI T

The Grady Clay picture of the engine pulley will be a big help.

WesH · 03-03-2013, 07:52 AM

I'll pull covers and inspect this week and post results with pics.
My thanks to all. Any other suggestions welcome as I;m not convinced its a valve even though the no 6 stack blows back. Ran car for an hour last night in hopes to free it up or get the gremlins out.

WesH · 03-07-2013, 02:57 PM

Help from the Experts...... Pulled Starboard covers, set to TDC, rotated 120o for number 6. Both valves have no clearance (Which might not be bad considering...) Did not try to adjust, as I need to purchase a angled feeler gage. May cut and build one... Could not get a straight one in there. Will tomorrow.
Good news is: no visable damage.

Question: Could a bad injector cause blowback up the stack?
Hoping for the best luck here.....really do not want to pull the heads. Looks like I have to pull the engine to pull heads...

I will run through all the valves tomorrow night and report back.
My thanks to all.

tobluforu · tobluforu's Garage

Quote:

Originally Posted by WesH

Help from the Experts...... Pulled Starboard covers, set to TDC, rotated 120o for number 6. Both valves have no clearance (Which might not be bad considering...) Did not try to adjust, as I need to purchase a angled feeler gage. May cut and build one... Could not get a straight one in there. Will tomorrow.
Good news is: no visible damage.

Question: Could a bad injector cause blowback up the stack?
Hoping for the best luck here.....really do not want to pull the heads. Looks like I have to pull the engine to pull heads...

I will run through all the valves tomorrow night and report back.
My thanks to all.

No need to buy a feeler gage, take the one you have and if it's a set thats all the better. Now bend the end just enough, you can bend it how you like it. The rest of the feeler gages now become the handle. You grip it and use your index finger on the edge to slide it in if need be. I learned this from a WV mechanic years ago and I find it to be the best way to adjust. When done, don't bend it back, just put away for next time. I bought those special feeler gages from pelican and they suck.

WesH · 03-08-2013, 12:33 PM

Valve problem.. Adjust No 1 cyl.. Minor adjustment. Rotated to no 6. Exhaust (bottom) minor adjustment. Top intake......... Had to backout the screw almost all the way out to get adjustment.

What does this mean? The other screws are at least half way in for adjustment.;

HELP!

WesH · 03-08-2013, 12:40 PM

In other words, am I ok? Is this common? Or am I in for a head removal?

WesH · 03-08-2013, 01:01 PM

Just pulled spark plug in no 6. Looks now. I ran engine for an hour last weekend. Appears nothing was getting into the cyl. Scared to run again with new adjustment until I hear from teh 'Experts'