MFI, 1972 warm-up issues (combined) - Page 4

wahoofan · 02-08-2006, 02:45 AM

Quote:

Originally posted by Bobboloo
No that isn't the gist. A stuck cold start solenoid will dump too much fuel into the motor after the initial start sequence. You need it for the start sequence, however, this means that warm running conditions as well cold will have too much fuel after the start and it will dilute your oil and the host of damage Grady outlined will occur. This could account for the gas odor.

OK, now I think I'm starting to get it - my cold start solenoid could be stuck open, basically "flooding" the engine until the thermostat cuts off enrichment, correct? If it is stuck open, would disconnecting the wire from the solenoid even have any effect?

Also, would this solenoid have anything to do with me getting about 10 mpg around town, or is that just about right for an MFI 2.4?

Peterfrans · 02-08-2006, 03:23 AM

The thermostat has no relation to the cold start solenoid. The cold start solenoid is either mechanicaly stuck, or there is something wrong with the electrics. You can confirm this by connecting a hose to the solenoid and applying +12V to the terminal on top of the solenoid (contact on). Careful! it will pump quite an amount of fuel, so take care and use some kind of cannister

Early_S_Man · 02-08-2006, 08:31 AM

wahoo,

I suggest a three or four tasks that need to be done before driving your car any further ...

1. Fix the manual throttle link!!!

2. Test the Thermo-Time Switch ... do a search for the details I have posted!

3. If TTS is OK, then test the Cold-Start Solenoid ... again, do a search, many threads to cover topic.

4. Get a set of spark plugs ... NGK, preferably, and change them after all issues above are resolved or fixed!

domtoni · 02-08-2006, 08:50 AM

I agree with all the advise.

- get the manual throttle fixed
- check the cold start solenoid
- clean the thermostat
- make sure the points are right and the motor is properly timed
- make sure the valves in properly adjusted
- make sure the engine emissions are corret

Your car should then run perfectly.

I got something like 23 MPG (U.S. gallon) last year on a run, and the car pulls incredibly well.

Dom

Andy Ring · 02-08-2006, 09:22 AM

Grady, I have benefitted from your help/advice in the past. I just stumbled across this thread and am blown away with the detail and care in your replies. Thank you!

As you may remember, I too own a 72 T with MFI and have received some help from you in the past. I'm still in the collecting data stage of CMA (pre-CMA?). I will be printing all of this out for my notebook. However, I'm sure that even with a notebook full of info, I may need help from the Pelicans--sure is nice to know you guys (and Grady) are around.

Early_S_Man · 02-08-2006, 09:34 AM

Oh Moderator ... you forgot a thread ... better make it 'Three to Combine' for the MFI munchies!

http://forums.pelicanparts.com/showthread.php?threadid=264965

wahoofan · 02-08-2006, 03:51 PM

Just an update - I tried disconnecting the wire from the cold start solenoid today and the car would not start at all, just cranked away. Hooked wire back up and started right up, but still behaves the same. Guess that confirms that it works, now I have to test it to see if it shuts off. I realize that reattaching my manual throttle cable will eliminate the need to hold the gas down once it catches, but there is still something not quite right in there.

By the way, I do intend to go about this the right way(CMA, etc.) in the Spring. I'm not ignoring all of this great advice, I just don't have the time/tools/inclination to fix it right now. My main reason for this new thread was just to make sure I wasn't destroying anything in the meantime.

Thanks again to all the MFI gurus here who are chiming in - I can't wait to get it tuned right this Spring!

jcarpio · 02-10-2006, 06:38 AM

This thread is indeed chock full of incredibly useful information. I have learned more about my 72T MFI than I ever would have thought.

I have a similar problem to wahoofan in that I idle at 500 when warm, have very poor gas mileage (~9-10MPG), and have that rich gas smell from the exhaust. I haven't changed the oil yet, so I don't know if there is gas in there. The car starts like a champ when cold, by the way.

I think my problem is that the hose from my heat exchanger to the MFI thermostat (black, paper like hose) was a bit crushed against the A/C condensor under the decklid and another piece in the engine. It's not in terrible shape but I can definitely see little open tears.

From what I gather from this thread, this may be leading to the engine running too rich because the MFI thermostat never gets heated up properly, resulting in poor gas mileage and the unburned gas smell. Does this sound correct to you good folks here? Are a few small tears enough to cause this situation, or does the hose need to be severed before this happens?

I'm attaching a dark, fuzzy photo, sorry, but I hope you can get the gist of the damage.

Jorge

David E. Clark · 03-01-2006, 01:50 PM

Please take a look at the Ultimate MFI resources thread and add your links and resources. It will make a great resource for all of us.

domtoni · 03-02-2006, 12:14 AM

Jcarpio,

You may have seen some my posts, but in the old days, I had an Ansa 911R system on my 2.0 1969 E. It was a headers only system. No heat rise to the thermostat.
The car belched black smoke, it gave me 10 mpg and ran like a sack of you know what. I even tried building a heat riser system around the header, but it produced too little heat for the thermostat to work properly.

When I got the car to the UK, I had a set of SSIs installed, and installed a new heat riser tube. The thermostat now works like it is supposed to do.

Replacing the tube should solve your problem. The other option is to put one of those manual rack actuators. Somewhat expensive, but you can control the cold start like you would if the car was carburated.

Best
Dom

wahoofan · 07-13-2006, 07:11 PM

Well, time to resurrect this thread again. I finally got around to testing my cold start solenoid per Grady's instructions, and it seems to be working right. Squirts gas for 3 seconds or so while cranking and then shuts off - no leakage when ignition left in "on" position for 30 minutes. Car still doesn't like to run cold and seems to be really rich. Otherwise, it is running great and doing well in daily driving and auto-x - no oil-dilution issues.
Can I assume now that this is unrelated to my cold-start system, or do I still need to consider the thermo-time switch?

domtoni · 07-14-2006, 12:21 PM

wahoofan,

Look into the thermostat on the back of the pump. A warm air tube runs to it. If the washers are dirty, they need to be cleaned. One of the posts in the Pelican library shows the washer cut-a-way. Don't disassemble the washers. Cleaning washers will, note will, improve your warm running. From my experience, the rich running at cold should stop pretty quickly.

Best
Dom

wahoofan · 07-16-2006, 05:40 PM

BIG UPDATE!! - After revisiting this and ither threads I decided to give my mfi thermostat another look and did some thorough cleaning and took measurements. I was missing a pair of discs () so I measured a pair and came up with a thickness of 2.75 mm at the widest point. I also found a thread somewhere that gave the measurements of the spacers as .25mm + 2.1 mm. By using a combination of spacers and washers I have increased the length of my disks/spacers to =25 pairs + 2.06mm, which seems to be within .3mm of factory. Hard to tell if it helped cold start(it was 95 here today) but car seemed to drive smoother almost immediately.

Anyone see a problem with this solution?

domtoni · 07-16-2006, 11:48 PM

wahoofan,

All I can say is the washers may be special. I cannot comment but perhaps others far more knowledgeable than myself can comment.

Glad you seem to be rooting out the problems.

Best
Dom

wahoofan · 09-26-2006, 07:59 PM

TIME FOR ANOTHER UPDATE! - After having my points close up for the 3rd time this year and having no luck getting my Crane ignition to work, I broke down and ordered the Pertronix. Twenty minutes later and, WOW, what a difference! Car started almost immediately(it had been sitting 2 weeks) and didn't stall. After about 15 seconds of rough running, idle settled in right at 1000 rpm and I drove off with no stumbling or hesitation. Engine seems very smooth and MUCH quieter(less ticking) than before. I didn't have time to drive it enough to get it up to temp. and really nail it, but it seems to pull stronger, too. What does it mean about my engine that the Pertronix made such a huge difference?

Early_S_Man · 09-26-2006, 09:57 PM

Your engine needed a new set of points after 34+ years???

domtoni · 09-27-2006, 12:14 AM

At least it sounds like the motor is finally running well. A month or so back, I installed a new coil to distributor lead (the old one was the original, and the mechanic who did the job replaced all the others - smart huh?), adjusted the timing an bang, the car from cold starts like this:
- turn on ignition
- let the bubbles work out of the fuel system (say in 15 seconds of turning the ignition on) - thanks Grady
- counting to 3, and bang, the car fires up !!!

Ciao for now

Dom

Grady Clay · 09-27-2006, 07:42 AM

Allright! More success stories.

There is nothing like good ‘ol CMA to ferret out the issues. Congratulations to you both on successful tuning (it really isn’t all MFI).

Best,
Grady

domtoni · 09-27-2006, 08:01 AM

Now all I need is a Pertronix unit !!!!

wahoofan · 09-27-2006, 10:47 AM

Quote:

Originally posted by Early_S_Man
Your engine needed a new set of points after 34+ years???

Actually, that is the crux of my new question. The points I have been fiddling with this year were new last August. Why would the Pertronix make the car run and start so much better than brand new, properly gapped points?